Sustainer Ideas

[psw]

Good Morning...just got up...so a little fizzy..err...fuzzy...

Very nice samples Pete.

Thanks, it has worked better, it has worked a lot worse! Now that this is set up, I should be able to add samples of stuff...

Did you use one setting per sample or have you've been adjusting settings while playing?

I think it is pretty much all the same sustainer settings, there are points at which I turn the thing off...can people hear that?...to illustrate the difference. The tonal signature of this medium bridge HB seems to remain, a little less "hair" perhaps. A little hard to get a "clean" recording and digital preamp adds some noise and distortion, as would the laptop soundcard I suspect, some of which is revealed by the noisegate effect on the amped samples (not so much the first two).

The AGC is pretty mild and there is a delay cap to stop excessive switching which is why you don't get AGC switching noise or failure...I tried a bunch of different resistors to get a release time that didn't "pump" the signal and this effect is pretty rare. Basically, it is a pure amplifier with a failsafe that switches off the drive signal when excessive, so it runs pretty free most of the time. This accounts for the ability to play with dynamics a lot more I suspect...maybe...hmmm

My harmonic mode does not work, so all the same setting, it wasn't reacting to the harmonics quite the way it had done with more power (and distortion) and by the time I had made the recordings happen, the battery may have been a bit tired too. A tired battery really adds to the "hair" factor. It doesn't create harmonics quite the way the old sustain-o-caster did with it's harmonic switch capabilities.

The strength of using agc is that it gives you a classy sound. But to me it seems that the fizz is more noticable when it occurs. With overdrive there is always some background nasty-ness but it sounds more creamy. I only need to find a way to make my sustainer not to react so aggressively right after the attack.

Well...I think most of you hear is no AGC really...I think it has more to do with a clean signal (not even preamped, just buffered) and running with low power. Unfortunately, it wasn't demonstrated but with high gains, you get more of this effect. Hence my idea that it is "hearing" the signal and yours is perhaps a more sculptured overdrive while mine is just an LM386 being pushed too far. Perhaps I should run the amp clean but hit it with an overdriven preamp signal...this would mean I could reduce the power to zero with the control and influence the kind of distortion produced at higher levels, effectively put an overdrive in front as you have done using clipping diodes like a tubescreamer circuit or something.

Could you perhaps make a sample of a problem area of mine?

A single G note 3rd fret on high e-string (on my guitar I get a weak, fragile 3rd)

Will do...give me a bit...a little later on. I have no real dead spots and the guitar reacts fairly evenly despite the effects of action. With the current set up, the high e is a little stronger and easy to peel into a harmonic on the higher frets up close to the driver (I think the clean chords or notes thing demonstrates this effect with those high harmonic things). I have adjusted the bridge HB a little ways back from the bass strings so these are weaker in response, but better in chords...this is something that needs to be adjusted to taste I think...might mess with it a little more.

I've thought about your switching troubles. How about this one (what's missing) ?

A bit early in the morning to analyze it properly, it is tricky without a description, but it doesn't look right to me. Is it bypassing the other pickups...and why does the neck pickup connect to the output of the circuit just before the driver? Also remember in positions 2 and 4 the middle is connected to the neck or bridge inside a 5 way selector.

I am still trying to puzzle a way of doing it with a dpdt switch...I have discovered some tricks to reduce things. For instance, you have a switch that turns on the 9v+ supply where as with some of mine, I use the 9v- supply and combine it with the -ve signal connection which goes to the common ground. This combines the battery on function with the bypass function, for instance.

Lately I have assumed a master tone, so the switch (s1b) is free to be used...I connect the neck and middle to S1a and the bridge to S1b and run two "hots" from the selector and cutting out the Neck and middle side when on and substituting the bridge pickup direct so regardless of position, the bridge is selected. Then you need to take care of the other ends of the coils...perhaps even attaching a load or simply connecting the two together. Unfortunately, there are still positions (#2) where the middle pickup connects to the neck and as we know, induced driver signals are created there...adding a the middle will alow them to flow into this pickup and so move them far closer to the bridge pickup to "hear"...if it doesn't scream on it's own. Even if controllable, the effect of being in position #2 will be different from #1 (neck pickup alone).

An exception to the load or shorting requirement seems to be with stacked single coils. I bought another one I was hopeful of, but it is solely for bridge position being considerably wider to allow for the increased string spread and angle in a Strat. The result is that the coil (as with the noiseless I had been testing) won't fit on the poles (a little wide). Still it needs to be isolated all the same, so not really useful.

Then there is the whole problem of switch noise. I have made schemes that "work" but in practice, particularly turning it off, there is a noticeable "thwunk". If you spot where I turn on and off the sustainer in the samples, the switching is often silent, of at worse a small click. So the problems of switch noise must relate to switching the other pickups back in, and proably connected with a latent build up of power that is released when they are suddenly re-grounded...hmmmm

I will try and resist temptation to change too much for a little bit. Switching causes havoc so I will leave it working as is a little longer.

I will instead do a bit of tinkering with the remote power idea...using a stereo lead and see if this idea adds noise...a reliable power supply would also allow for more clean headroom and if it is that it can be delivered through such a cable, it may solve some of the "distortion effects". In fact, I suppose I should just make an adapter first to connect a supply instead of the battery (wire it to a battery clip) and see how that goes first. It may seem a little extreme to run power into the guitar, but it may also be convenient in another way...an additional output from the little box on the end of the lead may be able to power effects also. I just can't come at the idea of an independent power cable as a necessity and I suspect the amps fizz and UI are using would not run on a battery for long if at all.

Pete has found the point where there is enough flux from a single coil while keeping the impedance as resistive as possible over the guitars range. It doesn't take into account corrections that can be made using a properly designed zobel network, active filters etc. It doesn't take into account the features of different core materials - It works well for some folks and not for others, some of the 'failures' will be because of not enough flux, and some because of to high an inductance.

And what is 'best' for a single coil driver isn't necessarily 'best' for a dual core driver in parallel configuration...

Quite right col. I hope to build some full sized HB neck versions of my present ultra thin piggyback design, and I am fairly confident of some good results, however the design considerations may well be different. I will first be looking at two 4 ohm coils with the same wire as a starting point.

As to it not working for some and not others, I really think that the most notable differences between drivers of this basic type is how much they vary from my "trial and error" derived design premises. I think you made one that worked, and curtisa did too...primal made one on half an HB with success. Of the failures, these seemed to depart in a few significant ways...G-mike (who started the tutorial) reported...

The system I have built works really well, but it does not do well to sustain the high E string and has a little trouble with the B as well. Hopefully this tutorial will motivate some people to build sustainers and give some input on how to improve on this design.

However...he used

My driver was built from a stainless steel bar that originall measured 6.2x6.2x61mm as the core.

Well it must have been magnetic stainless steel...all the same the dimensions 6.2mm wide was twice that of what I was using and a different material...

I used 30AWG wrapping wire from Radio Shack for the windings. As I recall this is 0.254mm, not 0.2mm as I prescribed and as has been discussed, although the extra 0.054 does not seem much, but trial and error it appears significant.

UI appears to be using a massive ceramic cored and deep driver...the effects are less turns and less overlapping turns, so quite significant variances to my suggestions.

All the same, it worked! So failures, a lot appear to have been down to build quality, potting and such and major improvements have been achieved when they built the second or third versions. It is hard for me not to assume that had people replicated my formula and design principles, that they would not have had similar results and the fact that curtisa for instance did just that (or banckia, etc) and it worked, in curtisa's case possibly better than my original, points to failures not being really the fault of the design but the execution of it...IMHO. Failures seem to be in line with old experiments that lead to the formula in the first place which only support the view. That is not to say that it is necessarily the "best" or only way, but repeating my failures and ignoring the specifications seems to be inviting "failure". A dual coil driver is a different kettle of fish however, and while I expect some of these ideas to be carried over to this design, it may be completely different specifications (as we have discussed, for instance thinner wires with dual 16 ohm coils).

Some failures seem also to be related to faulty circuits and we have currently two more examples of people seeking their own way with high powered amps and clipping preamps...not something I think I ever suggested would improve matters...and worth a try...but hardly fair to cite these as "failures" in the design either as they are quite different in significant ways.

One of the interesting things that I have been able to try out and will become more of a research project when other matters (switching and performance) are ironed out is that with my coil concept, the exact coil and amp setup can be moved from one pickup to another. Recently I used one with an iron core and a magnet on the back with very similar results as to it sitting on a pickup for instance.

As for the dual coil designs, similar premises seem to have been followed (thin coils, similar wire gauge) with some success. More work seems to be required here, but fizz is a dual coil driver as is yours col...avalon mad a beautiful one (two 16 ohm coils if I recall)...I made one as a rail...very thin cores close together and 2x16's. My next one will be wider spread (HB sized) and less coils with a thinner design...in line with my personal theories and for practical application principles...but it is a little unknown how this will go till it is done.

Yes, good suggestion - Stainiacs system is also prone to fizz, but there are different causes, and core saturation could be causing extra problems for our weedy little cores. I found this at allaboutcircuits.com

"Normally, core saturation in a transformer results in distortion of the sinewave shape, and the ferroresonant transformer is no exception. To combat this side effect, ferroresonant transformers have an auxiliary secondary winding paralleled with one or more capacitors, forming a resonant circuit tuned to the power supply frequency. This “tank circuit” serves as a filter to reject harmonics created by the core saturation"

Ahhh...a nice find...secondary coil effects, possibly benificial applications...hmmm, sounds familiar...hehehe. Of course my secondary coils are in no way tuned or designed for the purpose, but still...obviously there is some potential there and accounts for it having an effect...

Unfortunately, we can't easily create a tank circuit because we have a wide frequency band to deal with. And even if we could with some sort of dynamic capacitor circuitry, it would kill the desirable harmonics in our drive signal.

Which may be why it seems that shorting the secondary coil detracts from performance, or being open is so much more efficient. I tried a few different resistive loads and some capacitors across the secondary coils and got a few different "effects", but it is all trial and error and would vary greatly with each pickup secondary coil situation.

While it may seem that the cores we use are "weedy"...certainly my hardened steel saw blade derived 1mm cores of my rail driver were a little suspect...I really don't think that a row of six alnico 5mmx12mm+ cores could be considered that weedy. The noiseless pickups which seemed to work really well (dueling secondary coils aside) have very deep core poles, extra lower coils and significant side magnets, all effecting inductance I assume. Yet with all the variations, the performance is still remarkably consistent...they all "work".

So maybe a chunkier core would help prevent some of the fizz. Of course, then we have to seriously re-consider the effects of eddy currents and probably go for a laminated core. And also look at the effects of a bigger core on the inductance and therefor reactance vs resistance of the driver.

Yes...moving away from my model and more towards the sustainiac ideas. Obviously this is possible, but against what I am trying to do, which is to simplify it to resistance and avoid all the compensation procedures and circuitry...if only because it is outside of my skill set.

I have my own "rationals" for my design ideas...moving the whole coil by making it thinner as close to the strings as possible, for instance, effects of maximizing overlapping wires, the driver coil and the core being "faster" (able to change states with minimum phase delay), etc...whatever the reasons though, it has been somewhat successful, but hardly the "last word" on the matter.

___________

Now for some breaking news...

In the driver/pickup configuration used in the clips and presently in the test guitar, I changed from the alnico pickup to a steel pole core with smallish looking ceramic magnet under cheapy. One of the reasons was to attempt a different set up, but it performed much the same, perhaps a little less power with less magnetic pull...but much the same. The other reason was that, once my maths was corrected, it left the door open to try the parallel pickup and driver coils as driver idea. I didn't know if it would damage a pickup to do this, so I switched to something a little more sacrificial. And it does seem to work!!!

There is no massive improvement, a bit like the performance of the pickup with a load attached, not as bad as "shorting the thing. As you can hear, it does work. The coils are in parallel so with the heavier driver coil wire and less turns, I assume that the driver coil is still doing the bulk of the work and carrying most of the current. Performance is very similar as I say, which is interesting as it goes against the ideas of mine of thin coils, low turns, etc..except if it is assumed that the pickup coil is carrying far less current and so is having less of an effect on drive. In this configuration though, it may well be having a beneficial effect on eddy current effects and EMI...little hard to tell. It needs to be wired right, reversing the coil direction to one another, or turning the driver over is a little disasterous...quite which direction I am not sure as I can't tell with the pickup windings. I can't really tell if in the working setup if the secondary is working against the driver coil (canceling EMI and eddy effects) or, as I suspect working with it but having little influence, positive or negative on overall performance.

I get no heat at all (the poles remain cold) and no vibration or other effects that could be detrimental, so I assume that the pickup won't self destruct!!!

So...if not a boon for performance, it does entertain some different switching approaches and calls into question if the pickup coil is actively being powered, if it is actually storing energy that will dissipate with a "thwunk" on switch off.

For instance...one side of the driver and the pickup itself can be left connected to earth the whole time (the signal driver and pickups all connect to a common ground) and, the driver can stay connected to the pickup/driver unit and only needs to be lifted on one end to bring the pickup back in to normal operation. Connecting -ve power to the driver for instance, may effectively turn the circuit on as soon as the driver is connected...we will see. Quite how the middle pickup will be handled is another issue I guess.

So...interesting results and thanks to fizz (I think) who suggested running the pickup coil in parallel with the driver coil and to Setain for pointing out the error in my maths. The combined coil came in at about 7.2ohms, but the replacement coil is unknown but I suspect perhaps 7.5 ohms, so little difference in resistance created and within the workable tollerances fo coils I have made with similar results.

What it won't do as well, and it shows, is the harmonic thing so well. With an open coil you get harmonics pinging off all over the place with pick attack and strength, similar effects as fizz may be getting and even the lowest power of the LM386 is a little much with an open coil. This setup is very similar to the negating dual coil secondary with a stacked pickup I guess, which will happily run open or a loaded single coil...better than shorted though...

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Anyway...when I get time to set it up again, I will do a few more clips including that G...any other requests? I will try and get a sample of what I call "fizz" as opposed to the "hair" distortion that is most evident. To me, "fizz" effects are tinny, filtered "electronic" like distortions that emerge as the note blooms, and on my system is very low in the mix and perhaps disguised by the "hair". This "hair" I think could be tailored and is different when my system is run at higher gains (a little more buzzy) but could be made more attractively "creamy" with fizz's approach to preamping perhaps. This would also disguise the "fizz" too...so it is hard to separate the two unless you can run it "clean" without the "cream"

However, low level fizz and hair are virtually completely hidden by high gain and distorted amplification, as is demonstrated between the lackluster directly recorded sounds and those "amped", even moderate overdrive is effective in this regard.

At times I get an almost vocal response, though less so with this setup which is less harmonically reactive, where long sustained notes evolve through dynamics and harmonics...and so are less "sterile" than a prolonged fundamental sine like sound as col gets and the sustainiac very much succeeds at. This is the area I'd really like to explore more, but basic clean performance and switching and practical application issues are still at the forefront at the moment for me at this time.

later with clips... pete

Oh...and for those who have not checked it out, the sound clips can be heard on the link in my ever expanding signature (second link) below...p

[Fresh Fizz]

Is it bypassing the other pickups...and why does the neck pickup connect to the output of the circuit just before the driver? Also remember in positions 2 and 4 the middle is connected to the neck or bridge inside a 5 way selector.

How shall I put it? In my switching system the pickup selector has priority over the sustainer switch. When the Neck, Mid or combinations are selected there will be no feedback. Only when bridge pup is selected there will be feedback depending on the sustiainer on/off and power standby/off switches. These 2 switches could be combined into a single switch, but personally I think it makes more sense to have 2 switches. The quiescent current is low, around 4 mA. When using only 1 switch you have to deal with spikes, pops every time the sustainer is switched on and filter cap(s) are charged.

Unfortunately, there are still positions (#2) where the middle pickup connects to the neck and as we know, induced driver signals are created there...adding a the middle will alow them to flow into this pickup and so move them far closer to the bridge pickup to "hear"...if it doesn't scream on it's own. Even if controllable, the effect of being in position #2 will be different from #1 (neck pickup alone).

Then it could be something like this:

Fresh Fizz, I've been doing some simulation of the Fetzer Ruby, and the phase and amplitude responses are terrible. Are you using the basic F/R, or is it modified ?

Using this circuit could easily be the cause of your problems with the lower notes.

If you can post a diagram of the circuit and settings you are using (assuming they are non-standard), FET biasing voltage, pot settings etc., I'll check them out and see what the response curves are like.

Thanx Col, but I'm doing my own calculations in Excel. I haven't updated my schematic yet but the old one is not here.

The Fetzer Ruby at best (LM386 input attenuator an most attenuation) goes from 92º shift @ 80Hz down towards 0º @ ~2KHz.

With the attenuator at minimum attenuation, 80Hz gives 115º of shift !

The magnitude is equally hairy, theres a hefty drop from from 300Hz down to 80Hz of between 5 and 10db depending on settings.

That's because the input impedance of the lm386 is only 50kOhm. You need a bigger capacitor. In my schematic there is a voltage divider on that spot which takes care of that problem.

I have been looking at the lm836 national semiconductor datasheet. I saw that there is an easy way to get a 6 dB low boost with only 2 components. That's pretty cool!

(see amplifier with bass boost)

Cheers

Fresh Fizz

[psw]

Thanks for trying to tackle these switching problems fizz...no, I don't think these will work. For instance, in the last example, the ground of the middle pickup is still grounded to earth...previously this has not worked too well....if there are currents induced in the middle pickup coil, noise/fizz will appear in the ground. (However, is this also related to the shared ground of the driver itself???). Still, I don't understand the purpose of the resistors R1 and R2 and in particular why R2 is connected to the amplifiers output.

How shall I put it? In my switching system the pickup selector has priority over the sustainer switch. When the Neck, Mid or combinations are selected there will be no feedback. Only when bridge pup is selected there will be feedback depending on the sustiainer on/off and power standby/off switches. These 2 switches could be combined into a single switch, but personally I think it makes more sense to have 2 switches. The quiescent current is low, around 4 mA. When using only 1 switch you have to deal with spikes, pops mad.gif every time the sustainer is switched on and filter cap(s) are charged.

Well...I am not sure that this is the actual problem (that is more of a stompbox explanation) and so that this is an actual solution. It is also far more complicated and requires more switches than the most complicated 4pdt's I have come up with!!!

For instance...in the clips you heard, the guitar has only the bridge pickup wired in for sound...so a single pickup guitar. At various points I turn the sustainer off to show the similarity of sound on or off and the lack of appreciable switch noise. The start of "sitar" has no sustainer and on the last chord I turn it off so that the notes decay. Occasionally there might be a small click (tiny... for example 0:15 seconds on first track).

If it was the capacitors discharging, I would have thought that there still would be switch noise...do you guys get switch noise? More likely it is the pickup coils themselves discharging stored current, especially the neck pickup which shares the core with the driver.

No...it would appear the switch noise is related to the addition of multiple pickups.

I really don't think two switches, one of which appears to be a 3pdt and the selector used together is a practical application...hardly a seamless integration of the device into a real world guitar. Ideally one dpdt...but if you are content with the selector being used to activate it, perhaps a better way would be with a superswitch using one of the positions as a sustainer...but being able to bypass directly to the sustainer and then back again is a pretty cool feature. Basically, if you use sustainer for solo work, you can go directly back to whatever selection you have chosen...and the battery gets a rest.

Also..you appear to have fallen into the fatal flaw of position four. On a fiveway selector S1a will connect the middle and bridge pickup, and you have the middle connected to ground (shorted)...so to the bridge pickup will be shorted and so the guitar will be dead!!! Not good at all.

Nice try though...it is not easy. But even with solutions similar to ones I have posted before, the switch noise exists, usually on switch off. It could be that the parallel pickup coil/driver has some influence...hard to tell, but this arrangement needs to be taken into account. I have been working with paper and pencil so not so easy to post them...but I got a really interesting dpdt with the new arrangement that offers more possibilities. However...I am now working on the remote power thing.

It just occurred to me this morning that the remote power/shared ground with stereo lead will mean that -ve switching will not be possible (grrr) which will require a separate switch function for power on.

There are some interesting ideas though there...for instance, besides the selector, the other switches S2 a,b,c and S3 ar3e all single pole (two poles, normally open)...this means that if the scheme did work, you could use a 4066 to activate them on the connection of power to the circuit and the chip and be open with the power off. Most things I try require double pole switches so that wires exchange with a common (three terminals) and so would require something different. One reason that a 4066 might be interest is that it may be possible to delay the switchings relative to one another...so the driver is reconnected before the neck coil is reconnected perhaps.

My understanding was that Fresh fizz was using a tda7231 amp like this...7321 schematic.

It is an interesting chip...a little hard for me to get it would seem. Not sure about the battery consumption and other factors that may effect it in this application over the LM386...hmmm

I notice that there is a 100uF cap to the negative input (pin 3) to ground. This is possible with the LM386, I simply tie it to ground. This is something I was going to play with when the switching and such is addressed to tweak performance. How does this effect the operation of the chip...would this effect phase?

Phase stuff is relevant and has potential issues here, but phase changes with frequency so I don't quite see how we can address phase without some form of variable compensation system being the outcome...exactly as the patents describe. Similarly, we are now introducing phase differences between the locations of the pickup and driver...another variable and again influenced by frequency.

There is reason to assume that it is not as much of an issue as we might fear. Is it proposed that the phase differences are the cause of fizz...'cause I am not so convinced from practical observations of the effect. The fact seems to be that it can work and that clean performance is possible. I still work on the faith that a driver can be built that will operate satisfactorily within the range of guitar frequencies.

It is still a bit of a mystery as to why my device will not do the reverse phased harmonic thing though (except on the low e) and perhaps there is a clue in this. Is this a phase problem or does my circuit filter out these very high frequencies and so wont drive them so well...hmmm...confusing.

Does anyone have any thoughts on the remote power proposal. I have a 4 lead cable, all with shields, but these shields are not isolated from one another. I was thinking a smoothing cap may help between the + and -ve input. I was thinking running the signal ground and power ground separately, however, eventually they will connect together (at the guitar end) and also with the common shield...should some kind of resistor and or cap be applied to limit "grunge" effects that sustainiac war prohibit this scheme working with their device? Is there a way in which this could be set up so it could run from a battery when using a normal guitar lead...will some kind of special switching socket be required...I have something that might fit the bill, but I am not completely sure as to the switching mechanism.

Remote power may open up other possibilities such as permanently on power and switching, but it is a shame if the guitar required such a contraption to work as normal.

pete

[Fresh Fizz]

It is an interesting chip...a little hard for me to get it would seem. Not sure about the battery consumption and other factors that may effect it in this application over the LM386...hmmm

Tda7231 or tda7231A 's quiescent current is 4mA at 9 volt.

Also..you appear to have fallen into the fatal flaw of position four. On a fiveway selector S1a will connect the middle and bridge pickup, and you have the middle connected to ground (shorted)...so to the bridge pickup will be shorted and so the guitar will be dead!!! Not good at all.

That was the best thing I could come up with. Makes a great kill switch though. Don't you want a stutter effect à la Gibson Les Paul?

Another idea of mine: a small resistor in stead of the wire to connect the S2a and S1b neck pup connection. When sustainer is switched on it'll give bridge pup with neck pup in series. In combination with the harmonics switch it'll give bridge with neck pup in series out of phase!

Phase stuff is relevant and has potential issues here, but phase changes with frequency so I don't quite see how we can address phase without some form of variable compensation system being the outcome...exactly as the patents describe. Similarly, we are now introducing phase differences between the locations of the pickup and driver...another variable and again influenced by frequency.

There is reason to assume that it is not as much of an issue as we might fear. Is it proposed that the phase differences are the cause of fizz...'cause I am not so convinced from practical observations of the effect. The fact seems to be that it can work and that clean performance is possible. I still work on the faith that a driver can be built that will operate satisfactorily within the range of guitar frequencies.

I think that there are two approaches. One is the hi fi type of approach. Make phase and frequency response as flat/neutral as possible. The other is the musical approach of letting the ears decide (what utopian isotope is doing with the use of an eq). I think that the hi fi approach is a good starting point, especially if you're in the process of setting up agc and/or overdrives. At the beginning there just are too many parameters to take into consideration. Now I'm arrived at the point that I'm going to experiment a bit with different eq to see if there is an improvement in sound and feel of the sustain effect.

Why don't you use a simple connector for the outboard power supply. I use a plastic female 6,3 mm connector. Then you have the option of using the power supply or a battery in a small box attached to your guitar strap.

Fresh Fizz

[psw]

Thanks fizz...that switching stuff is trickier than it seems...

I did have a scheme that used a dpdt switch and the -ve supply to the driver, the driver itself was switched in connecting the power at the same time as connecting the driver in parallel with the neck pickup, but taking the neck out of the selector. At the same time, I lifted the neck and middle sides of the selector and connected the bridge pickup directly to the controls...this effectively bypassed everything and connected the bridge, connected power and paralleled the neck pickup...

It takes a while to analyses and then it needs to be tested...which means completely rewiring the now working guitar again...grrrr This would seem to work, I don't know if it addresses the switch noise, the only thing that may help there is that the neck is in parallel and connected to ground permanently and so may not be building up energy in the same way as a shorted or loaded coil.

The middle pickup may potentially be a problem, this scheme would see the middle pickup connected to ground also but be lifted (de-selected) in all positions at the hot...so maybe...otherwise it may need to be shorted or loaded also...again, experimentation will only go to show.

Meanwhile...I made up a magic power box. I realized though that the guitar and circuit are wired for -ve power switching and so, with my stereo, shared ground/-ve earth, the circuit would automatically be on the whole time...grrrr

This means an extra switch...so now a 3pdt and maybe another 4pdt if I need to short the middle also.

The box worked out ok so far, it even has an LED to show that the power pack is connected. Basically, the -ve and ground are connected, the tip takes the hot signal and the middle of the stereo plug the +ve supply. That rules out -ve switching.

I also have a problem with the idea of having an internal battery for use without this magic lead and box and if the thing wont short the power supply anyway if a normal lead were to be used. Ideally, you would have something that would work with a normal lead with internal battery, and without removing it, draw power when a stereo lead is used...and absolutely ideally would be a recharging scheme where the internal battery was recharged when being used with external power...but that may be a bit to ask.

Otherwise, without it drawing any current, the guitar will work as normal with the "power lead" it seems with just a bit of hum when the guitar's volume is reduced a bit...not sure why. I have connected the shielding in the cable to the guitar plug end and left the other end free, but as the -ve and ground wire are connected at the guitar end, all is connected anyway...I am a little wary of ground loops and such.

Why don't you use a simple connector for the outboard power supply. I use a plastic female 6,3 mm connector. Then you have the option of using the power supply or a battery in a small box attached to your guitar strap.

I really don't like the necessity of having a separate power pack external to the guitar and attached via a second lead. The only point of this is to gain better and consistent performance and save batteries, there is a marked difference between a tired battery and a new one...external power supply holds promise of cleaner headroom and more power and no batteries at all. But this will not be for everyone....and adds to cost.

Any ideas on how to have the battery disconnect when external power is supplied, obviously plenty of consumer products can do this kind of thing, or even recharge...but I don't know how!!!

I think that there are two approaches. One is the hi fi type of approach. Make phase and frequency response as flat/neutral as possible. The other is the musical approach of letting the ears decide (what utopian isotope is doing with the use of an eq). I think that the hi fi approach is a good starting point, especially if you're in the process of setting up agc and/or overdrives. At the beginning there just are too many parameters to take into consideration. Now I'm arrived at the point that I'm going to experiment a bit with different eq to see if there is an improvement in sound and feel of the sustain effect.

It would be great if we could hear these things a little. It is a little easy to be skeptical when you have made so many mistakes oneself. For instance, is UI's eq helping things because he uses it to eq out troublesome frequencies but at the same time lessening the effect. The loop idea seems to influence squeal as verified by col, but is it working as well as mine which requires no such strategies, far less power, runs on batteries and has a very simple single coil driver...plus the complexities of multiple pickups and secondary coils.

I do think that eq's and diode clipping have a lot of potential for widening the scope of the device...particularly in the area of making it less sterile and for eliciting interesting harmonic effects...but I still think that it should be able to run clean (as col aspires to) and be controlled and predictable too. I am aiming for low level clean drive with the ability to turn up and get touch sensitive and blooming harmonics and further into an "attractive" overdrive sound with less "control". I am a long way towards this though the clips may not indicate it. I think that eq and clipping may play a role as well as other kinds of preamp means (remember I only use a buffer so am a little limited as to what I can do with it as it also doubles as the AGC and is balanced in this way).

However...it is hard for the "ears to decide" if it can only do what it does with accompanying fizz and distortion. I also think that limiting a guitar to only one pickup is too much to ask for a working non-experimental instrument.

So, for me...switching and integration strategies are still priority, then some performance perhaps addressed by better power strategies and then...additional performance. Until the device can be properly integrated, there really seems to be little point in developing it further if it is not ever going to be practical in a real multi pickup guitar without clicks, pops, thwunks or dead selections and secondary coil effects altering with selector positions. If I wanted a kill switch, I would add a kill switch...on the recent build from December I designed both a toggle "kill" and "maim" switches with spring return action and an oversized push button kill that will look really cool. A kill switch would be a good addition to a sustainer however you don't really want to do it by shorting the pickup as you are likely to kill the signal to the circuit and so kill sustain. The idea of holding a chord say indefinitely and tapping out a rhythm is way cool. You can get a similar automated effect with a tremolo...sounds like the Who's synth on baba o'reily or won't get fooled again...especially if the harmonics can bloom as the signal is chopped up.

It is getting a little closer with every little advance, but it is so frustrating, some of these schemes I have come up with seem to have so much potential. Unless the parallel pickup/driver has had a significant impact on the switch noise however, nothing much will have come of it as the switch noise is likely to remain. Still there is reason for hop[e, with the parallel switch the neck and middle pickups stay permanently connected to ground and in the present working guitar, this is the case. I still have the switching installed to turn the thing on and off and it will bypass...but to nothing as neither the middle or neck pickup are connected to the selector.

Ok...enough for me. I used to do all the things you guys are doing with power supplies BTW...but it can give misleading results and if that is not the intention of the end product (to run from external power) then there is a limit to how much you rely on it. While the current appears to be 4mA...that must only be in idle mode...not when it is driving at a watt and a half surely. I found another one of interest...a 2.5 watt JRC 2073D in BTL mode (stereo 8 pin dil) that is used like this in the guitar fetish artec speaker amp thing which arrived today fro future testing. This may also be of interest as being stereo it may have other applications for canceling or bi-amping multi coil drivers...something I think col and I have had an interested in exploring...

pete

[curtisa]

Any ideas on how to have the battery disconnect when external power is supplied, obviously plenty of consumer products can do this kind of thing, or even recharge...but I don't know how!!!

The socket you plug into needs to have a switched contact on it somewhere, so when the plug is inserted the two contacts are forced apart. That's how it's done on guitar amps with a channel footswitch jack that overrides the front panel channel switch. Any electronics store should stock them. Finding one with more than three poles is going to be trickier though.

Regarding multi-pole plug/single cable options, Jaycar (and other electronics suppliers if you live elsewhere) stock 5-pin XLR plugs and sockets which are heavy-duty and locking, which may be another option worth considering.

In other news, I'm seriously considering re-visting the whole installation of the sustainer again, primarily sparked by Pete's resurrection of an earlier quote in this massive thread - the one with the dissection of the sustainiac coil - and also because of the way I currently use my DIY sustainer guitar. With the DIY guitar I find that I almost never use the neck pickup by itself anymore (awful sounding pickup at best anyway), leading me to believe that perhaps I would've been better off building a dedicated driver rather than a combo driver/pickup with all its quirky switching and termination requirements.

I'm still quite intrigued by the prospect of installing a dedicated driver in place of the single coil of my HSH Ibanez S470, a pickup that I personally wouldn't miss if substituted with a more useful item such as a sustainer. I think there's still a lot of things to experiment with in regards to driver construction that we've talked about, but never actually done anything with other than theorise - the dual-wound laminated core of the Stealth system in that photo dissection is just begging for some closer attention, and Sustainiac's patent has quite a lot of useful information regarding shielding and cross-coupling effects of the driver and surrounding pickups.

As of today I start 4 weeks of annual leave from work, and I'm sincerely hoping to have a crack at fiddling with some of the ideas floating around in this thread during my holidays. I have some old transformers kicking around somewhere that I'm hoping to pull the laminations out of and build up some trial laminated driver cores with. Should be interesting...

[psw]

That's great curtis...

I am glad that your original DIY version is still being put to good use. The version I currently have is a lot better, even though the switchable harmonic mode doesn't function, it is more than made up with in even performance and other effects...when it is on a full battery (the clips had a diminished battery and range it would seem as it is working really well tonight with a new one).

If you use it a lot, then remote power is well worth considering...a completely different connector is a possibility, but you know, guitarists are pretty conservative and I don't want to modify things too much. There is hope yet for the switching.

The socket you plug into needs to have a switched contact on it somewhere, so when the plug is inserted the two contacts are forced apart. That's how it's done on guitar amps with a channel footswitch jack that overrides the front panel channel switch. Any electronics store should stock them. Finding one with more than three poles is going to be trickier though.

I have a multi pole socket to put in the guitar...this is stereo and has, two switches in it. What happens though is that with the plug connected, the two switches are open...this might work in the footswitch application...but with this I thnk it may be around the wrong way and of no real use. Perhaps the only way is with an electronic sensor that switches when it gets a +ve voltage from the jack plug, disconnecting the battery...but even that is tricky. If there is a battery in there, surely the insertion of the jack plug will short the positive and negative wipers on the common ground shaft of the plug....we have a problem where it might have to be an either/or solution or some sort of manual switch to use external power...hmmmm

---------------

As for driver designs...many have talked but I don't think any of use have ever really attempted the sustainiac bi-lateral style driver. My next one will be a HB version of the ultra thin coil.

The parallel pickup/driver is pretty cool and I did try connecting the middle pickup to the driver too...I don't know what that would be in parallel with the other two...and the pickups are mixed...but it would appear that attaching one end of the middle to ground doesn't seem to bother it...so that makes switching a little easier. There may well be a few tricks yet to be explored.

A new battery not only provides more power to get harmonics out of the thing...but also increases "fizz" and distortion rejection...further reinforcing a clean signal as preferable if this is something one wishes to avoid.

The stereo lead/box power thing has promise and I think that it can work...but it really needs to be tested out. So far, I have not yet worked out how to switch it all with a dpdt switch, which is my aim, but I am close. Perhaps there is yet a way...it can be done with negative switching which is fine but it won't work with this remote power arrangement...I will try and post drawings soon of these ideas.

I'm still quite intrigued by the prospect of installing a dedicated driver in place of the single coil of my HSH Ibanez S470, a pickup that I personally wouldn't miss if substituted with a more useful item such as a sustainer.

You could be in for a frustrating time with that...I tried a mid driver remember, in a rail format. It did kind of work, but it was very close to the HB in the bridge. I found it to be really intrusive as the driver needed to be extremely close to the strings and really got in the way of picking...plus you can't run it as flat out as this thing can now go with more space between driver and source pickup. A more likely success is to get a neck HB and modify it as I plan to do to get a Avalon style HB driver and perhaps a reasonable neck pickup as well.

There is nothing wrong with a single pickup+driver combo either...certainly easier and mine works well. I often describe to people that what I spend so much time tinkering with is a kind of "super-charger" for the guitar. Basically, you have all the pickup options and normal guitar potential...but then it has this incredible turbo function. It is important for me that the thing can run clean BTW as I want to be able to explore chordal harmonies with it, this is the only device that has the promise of sustaining two and three note harmonies without the mush of distortion. As such...I don't have a problem that it doesn't have a variety of sounds in sustainer mode...as long as there is plenty of expression and dynamic potential in this "turbo" mode!

But before I mess with that, I have to get a switching solution of one sort or another. There has to be a way...sustainiac use extensive electronic switching to achieve it, though without a battery apparently the bridge pickup will still function.

Oh...by the way...I did do a little test connecting only one coil of the bridge HB to see how it would function...seemed to work ok so perhaps a scheme that split the HB is possible, but again, you would have to be very careful how this is done so as not to short the signal to the circuit or select a coil of reverse polarity.

Once the switching solution is sorted, I will switch out the bridge pickup for various single coil versions. I may also test a few different neck pickup variations with the same driver. Plus then I may build an HB prototype as a driver. I may even get around to trying a few preamp variations and such. If one was prepared to go completely active and use external power....then there is a lot of potential for small onboard tone shaping circuits and the like which would radically alter performance and sound if the sustainer on the bridge pickup alone was not enough. If one was interested enough, perhaps someone could build some kind of circuit to compensate for the lack of neck pickup and other sounds with a single pickup guitar...solving the limits of a single pickup guitar and allowing different tones to be used in sustainer mode at the same time...if the single pickup instrument is seen to be the best format for the device.

Anyway...anyone who wishes to tackle the switching thing is welcome by me. On the mid pickup thing, one should recall dizzy's mid driver strat...this was a bi-lateral design but had secret circuitry to compensate for phase, etc. Some detail and a sound clip is in the sustainer sounds thread (see link below) as I recall. I did once see a pic, but they no longer exist...I assume the sound is still working, but if not, I may have it on file somewhere.

Also, somewhere...I have an original flexi-disc from a guitar player mag demonstrating both the sustainiac and bass sustainiac systems that was insanely impressive. Strangely, they don't seem to have anything like this for promotion anymore and in general the sustainiac and fernandes promo clips...even the Youtube stuff is pretty lame IMHO...unless others have seen something of note.

better run, time for sleep...welcome back curtis, perhaps by the time you get to play with this I will have found some better switching solutions...or maybe you will have better luck, the last one went very well as I recall...

pete

[col]

@Pete:

I think Fresh Fizz is right on the money suggesting a system in which the sustainer power switch is separate from the pickup combos and 'sustainer active' switch.

Not only does this simplify the selector switching. As he explained, it also should help prevent some of the switching noise that can occur when you combine the power switch with the selector.

The idea is that you switch the sustainer on when you pick up the guitar - even maybe have it automatically switched on when you plug the lead in like curtisa suggested.

The power usage is very low unless you are actually using the sustainer (thats the 4mA figure thats being talked about - 'quiescent' current is what is being drawn when the circuit is on, but idle). I guess that it will be somewhat higher than this when you factor in the quiescent current from other devices in the circuit, but still low - similar to a stomp box.

If the sustainer power switch is only to be used before and after playing, it can be hidden away - doesn't have to be 'ergonomic'.

So how much would it help taking the power switch out of the picture and having that extra switch pole available for the selector ?

@curtisa

I was looking back at that thread about the stainiac and mentioning it prompted Pete to post a pic (not the one I was referring to unfortunately heres the one I was referring to). You can still find that thread here although, the pics don't display for me, the links can be pasted into the address bar.

The more I've learned about this project, the closer I'm getting to thinking the stainiacs driver design is a damn good solution, it has a lot going for it. Certainly my next driver (that is fully potted and installed) is likely to be something very close to their design. I've tried to find a supplier where I can get the 'I' part of an 'E' transformer core but to no avail. I guess that leaves either ripping/cutting apart a tranny, or laminating some metal sheeting myself. It has been stated here at some point that cutting laminated transformer core is a really tough job... any other suggestions ?

cheers

Col

[psw]

@Pete:

I think Fresh Fizz is right on the money suggesting a system in which the sustainer power switch is separate from the pickup combos and 'sustainer active' switch.

Well it is a solution but not ideal. I am not at all sure that power on is causing the problems. For instance, that the moment it makes little if any switching noise at all...yet the bypass switching is still being done from before (though admitadly pickups are not connected to the selector). This would indicate that it is not a "power on" problem like a stompbox, but a pickup discharge problem in which case, permanent power on would not solve it.

Is this not so? If I run it from remote power, I don't really care if it sits in idle, but all the bypassing still needs to be done I suspect, the selector can not do it alone...and I still think all the switch back to normal mode operation will exist, as above...or am I wrong. For instance, switch on has never seemed to be an issue and while that might indicate capacitor discharge, in fact the problem only exists with the re-introduction of idle pickups...not a single pickup guitar.

So how much would it help taking the power switch out of the picture and having that extra switch pole available for the selector ?

I have a dpdt scheme which bypass the pickup selector, attaches the driver in parallel with the neck pickup and connects it to the driver and bypasses/deselects the middle pickup (all pickups remaining connected to ground). However, I could even connect -ve to the driver so when it switched in, power is applied (I think) but not with the remote power...that requires another switch...so a 3pdt perhaps. I will tinker some more with it, perhaps there is a way! Negative switching greatly reduces the number of wires...the driver, signal, -ve power, even the LED are all connected to the ground rail and with the parallel pickup, this can remain connected.

However, with the stereo lead power thing, the negative is always connected too. Further, if using a mono plug, the battery will be shorted through this common ground and so not work and destroy the battery. Any thoughts on this dual supply conundrum.

I threw together a basic circuit using LM386 and an op-amp that has an almost flat amplitude response and a much better phase response (32º @ 80Hz 10º @ 300Hz 2.5º @ 1KHz)... I'm not sure If this will be 'better' because of other issues, but its certainly a lot more linear. I've not tested other than simulating it so I'll not post it unless anyone really wants to try an untested circuit out. Should be a 'better' F/R (assuming it works). Plus if you use a dual opamp chip, theres a spare op-amp that can be used to stabilize the power, or provide harmonic modes, or to buffer the guitar through signal.

@Col...I'd be interested in this...you can email or PM it if you really don't want to post it.

Also...the idea that the sustainer may cause noise in the power cable came from the sustainiac instructions...

Optional Regulated power supply;

This wall-plug-in option eliminates frequent battery changes. It costs $25. It comes with an 11-ft cord, having a 1/4 inch mono plug. The (+) terminal is the "tip" terminal of the plug. Longer cords are available by special request. You must install a second guitar jack to the side of the guitar. Mono jack is $3, jackplate $3. If we do the installation, we charge $25 unless special problems are present requiring much labor.

IMPORTANT NOTE: This is a REGULATED power supply. It produces 9 volts regardless of the current needed by the sustainer. DO NOT USE A COMMON "WALL-WART" SUPPLY. These are not regulated. With an unregulated supply, the actual voltage can be 12 volts or even higher in the STANDBY condition of the sustainer. The neck pickup will not function in this case. Also, the higher voltage might damage certain components on the Sustainiac circuit board. Use only a regulated 9-volt supply.

When running the 9-volt supply, do not attempt to connect the battery using a stereo jack, plug, and cord, by connecting the (-) terminal to the ground terminal of a stereo guitar jack. The problem comes in when you use the shield wire for the (-) terminal of the battery. Pulsating dc current will travel down the shield. The small resistance of the shield plus the resistance of the connection between the jack ground and the plug ground will develop a small pulsating voltage due to the current flowing in these resistances. You will hear this pulsating voltage as a large, ugly, grungy distortion. You can do such a thing with a very low current device such as a preamp effect. But the larger currents of the sustainer will cause this problem.

If you need to use a single cord to deliver power and and also handle your guitar signal, you must use a 4-pin XLR and a small "snake" cable with separate shielded wires for the guitar signal and also the battery (+) and (-) terminals. This way, you can have separate guitar signal shield, and battery (-) wires.

from here...http://www.sustainiac.com/power.htm

I have a 4 conductor cable but the shields all seem to touch, so effectively one I assume. While the quitessential current may be low, this thing does draw a lot of current and while a battery will last a fair while, it needs to constantly "rest" and even a little diminishing of power increases distortions and performance.

I am only in the early stages though of trying this out...I will have to rewire again to install it so I am a little reluctant. Just plugging it in with power connected seems ok, but you do get a little hum with the guitars volume reduced...of course it is not drawing anything!!!

Sustainiac's solution is two guitar leads, one for power....hmmm...again, not ideal...but I have been forewarned!

I was looking back at that thread about the stainiac and mentioning it prompted Pete to post a pic (not the one I was referring to unfortunately heres the one I was referring to). You can still find that thread here although, the pics don't display for me, the links can be pasted into the address bar.

I believe I have the pics, or most of them saved to my photobucket account if there is a problem or someone would like me to post them somewhere for reference. A few were posted here at one point by me I think so the pics are safe. I did loose the thread link though with the data (coil resistances and such) so good work finding it again.

laminating some metal sheeting myself.

I think this could work out well...even thin gal is pretty magnetic...you could hold them all together with some thin double sided tape which would insulate it too. Eventually, the whole thing would be best epoxied. Maybe cut up the metal from a computer chassis, these also seem to be easier to cut and pretty magnetic in qualities...no mu metal, but free!

Another option is to use actual ceramic magnets...if you are going for the whole sustainiac model (thicker wires, more turns, deep wide thick core...kind of the opposite to my thingies) then these might be an option too. Ceramic does not conduct and I imagine that eddy currents would react differently and be advantageous. I have seen plenty of magnets around that would be suitable for such a bi-lateral design.

I will be interested to see how this all works out, but the problems I have are not driver design related I suspect (sustainiac use elaborate electronic switching) and I suspect that phase and other issues that my thin designs seemed to have overcome will be encountered too. You may even require more power to run it.

For me the problem is not driving the strings, but integration into a normal guitar and consistent power in a paractical way. I'd be prepared at a pinch to have a little slider with the on-board battery so that you could switch to this mode with a normal lead if this is the only way...but I assume that my proposal is possible in some way, so still canvasing ideas...any way of using this switch socket to achieve this...some kind of FET perhaps that switches when it receives power from the lead and so configures it for that mode...any ideas on noise prevention strategies if they occur as sustainiac suggest without going to their extremes. Sustainiac and fernandes do use a bit of power and two batteries are recommended...even then they may go flat. Once you go that far, remote power with it's improved performance and consistency, plus so much cheaper than buying all these 9volts and finding space in the guitar becomes very attractive. Perhaps I do need a separate wires and a different lead or another socket to get 4 connections...but dual leads is too much IMHO.

pete

[curtisa]

You may even require more power to run it.

On the contrary - I expect to require a lot less power to run it, or at least a lot more effecient use of the power we have now. I suspect that the loss in power from the transforming effect of the driver/pickup combo (depending on how the pickup winding is terminated), the solid un-laminated core of the driver (big eddy current losses), and the use of a linear power amp stages are big factors in the life of the battery and the effectiveness of the sustainer.

Side note: I notice in the sustainiac patent that they use a feedback AGC topology, except they talk about current regulation of the driver itself, rather than voltage regulation of the input signal.

I was looking back at that thread about the stainiac and mentioning it prompted Pete to post a pic (not the one I was referring to unfortunately heres the one I was referring to). You can still find that thread here although, the pics don't display for me, the links can be pasted into the address bar.

Yes, there seem to be about 9 photos there in total, which is handy. The really interesting info is mainly in the thread itself - the number of turns on each coil, size of the magnets, size of the bobbin window, guage of wire etc. And comparing with the sustainiac patent you can even work out the correct way to connect the two coils.

Handy note if anyone is interested in purusing this themselves: a couple of the photo's clearly show a copper foil shield around the bobbin assemblies that is obviously earthed as some form of electrostaic shielding. I can get bags of the copper foil from work - it's commonly used as a screening layer in industrial control cables, and when a cable is stripped to get to the inner conductors, several metres of the stuff is cut off and thrown away.

The more I've learned about this project, the closer I'm getting to thinking the stainiacs driver design is a damn good solution, it has a lot going for it. Certainly my next driver (that is fully potted and installed) is likely to be something very close to their design. I've tried to find a supplier where I can get the 'I' part of an 'E' transformer core but to no avail. I guess that leaves either ripping/cutting apart a tranny, or laminating some metal sheeting myself. It has been stated here at some point that cutting laminated transformer core is a really tough job... any other suggestions ?

I don't reckon you could get transformer laminations in anything other than commercial quantities (particularly something odd like just the "I" sections), but cheap mains transformers are probably good enough to tear into. You'd only need a dozen "I" sections at the most to build up the core, should be possible to build up several cores from the one transformer. Insulation between the lams needs to be maintained though - waxed paper or varnish would probably work nicely.

Not sure how hard the material is to cut ("grain oriented silicon steel"?). I'll let you know when I get stuck into one myself

Doing your own laminations is a possibility. The trick would be finding something thin enough the use (more lams per core width = less eddy current losses+higher inductance), and easy enough to cut cleanly without making daggy edges that short onto each other.

[psw]

On the contrary - I expect to require a lot less power to run it, or at least a lot more effecient use of the power we have now. I suspect that the loss in power from the transforming effect of the driver/pickup combo (depending on how the pickup winding is terminated), the solid un-laminated core of the driver (big eddy current losses), and the use of a linear power amp stages are big factors in the life of the battery and the effectiveness of the sustainer.

You may be surprised. I suspect mine lasts as long as the sustainiac! Actually the jury is still out on the transformer effect...it doesn't necessarily have to have a detrimental effect and recently I did a test of a similar coil as a stand alone driver with no incredible performance differences...but then nothing yet has had the effect of the open secondary coil which seemed way over-powered. If you have a mind to, You may wish to try a few of these variations with your present sustainer. As I understand it, you have it shorted so it would not be difficult to add a load in there I imagine...even this has an effect...2meg worked well for me. Another thing to try is the parallel pickup and driver too...seems to be a little better than the driver on a shorted coil.

I don't know that there is anything particularly more "efficient" about the design, but it's EMI rejection qualities are sound so you could run more power to it. With thick wires and all those turns, I do suspect that it will require a bit more power and some circuit tweaking involved. Remember that I have done some stand alone drivers with powdered cores, ferrites and some basic laminations with out any dramatic improvement in performance because of these factors...or so it would seem.

I am tempted to make a mini version myself though. I have a couple of 30mm creamic mags with the correct orientation, 5x5mm which would make nice cores for such a device. I have a telecaster project and made a coil for a chrome covered SCN pickup but the cover interfered with performance. I plan to put a separate small driver next to this and while I could simply use my powder core coil...perhaps I should also experiment with this design. For sure I will be watching with interest.

I was looking in DSE today...didn't see anything really suitable for an adapter. I was thinking though that I could do something with a suitable multi-pin plug and then make a small adapter to allow a standard cable to be used. Such a separation in power would allow an onboard battery to be used I imagine and help prevent noise problems. If you wanted, you could perhaps devices some kind of electronic switching scheme and turn the thing on with a footswitch I guess!

I may even try these illuminated latching push-push button switches...these are cheap and small and are 4pdt plus the LED and could perhaps be mounted directly to the PCB. It would mean that a 5mm hole is required to be drilled into the guitar but that is probably not a lot worse than a toggle and it may have advantages in use over a toggle switch for activating it on the fly. A dpdt solution though means push-pull pots are possible. Does anyone know much about these push-push activated pots...guitar jones push push pots...pulling a pot is tricky...especially with strat knobs!

Been playing the thing again tonight for a few hours...it is quite addictive when its working properly! I don't think though that i'd want to have to have standby and activation switches and stuff just to get to that place...it is something you want to apply, not and end unto itself. By far the best sounds are fairly clean...quite different from any other kind of effect. The blooming harmonic effect is particularly good to, and this was something the sustainiac didn't seem to do as well (but it may have been this guitar and install) even though you could switch in harmonics very effectively...in the short time I played it too, there seemed to be less of a dynamic range...not really compressed, but kind of sterile and lifeless even though it was doing exactly what it purports to do...sustain!

good luck with the new drivers...should be interesting.

pete

[col]

A quick note about clipping/harmonics due to magnetic saturation.

One of the ways that unwanted magnetic field seems to be getting from driver to core is via the strings.

I did some tests as suggested by Utopian Isotope using sheets of different metals. I found that no magnetics like aluminium had a far less significant effect than magnetic ones like steel. This suggests to me that there is likely to be more coupling through the strings due to magnetic flux and less due to current.

Now as has been recently suggested, saturation of the core of the driver will lead to harmonics/distortion.

The strings are very thin so they will be easily saturated by the field from the driver, hence any signal caused by magnetic coupling via the strings will have plenty of this type of distortion.

Makes me think that having a permanent magnet that is exactly strong enough will be an important factor in minimizing fizz.

If the magnet is not strong enough, then we need a bigger drive signal == more fizz.

If it is too strong, the strings will be more heavily saturated == more fizz.

Get the balance perfect == minimize fizz due to this effect.

cheers

Col

[col]

I've been playing with femm again

I was trying to find out roughly how big the gap should be between the two cores in a bi-lateral driver to give a nice even field.

The ideal gap seems to be pretty wide, so fairly short magnets will work well.

Description, starting from the bottom:

The long bar thats nearly full length is just a slab of steel. it joins the magnetic circuit on the underside. This does two things - it prevents the field from radiating downwards, and it causes more of the flux to be concentrated where the strings will be. Of course, it is also a useful structural component.

Above that, the two thinnish plates are the magnets. In this model they are basic alnico magnets, one is North up, the other is South up.

Above those are the two core sections These are laminated in 1mm thick laminations, although that doens't make much difference in this kind of model.

One either side of each of the core sections is a coil bundle. The coils are each 256 turns of 0.3 wire with 50 to -50 mA being put through them - they have opposite current polarities to counter the opposite magnets.

The model is 7mm deep, changing that doesn't do much to the result other than changing the magnitude of the flux. Each core is 16mm long, the gap is also 16mm making the bottom bar 48mm.

the distance from left edge of left coil to right edge of right coil is 56mm - so you can see that the field will cover the strings, although it may be better if slightly wider.

It is interesting (but not surprising) to see how much more 'throw' (as Pete likes to call it) this has when compared to a bi-longitudinal driver.

Last thing to note - Just in case its not obvious, this is a front on model unlike most of the other femm models that are side on... so if the strings were in this animation, they would be six tiny circles in a row along the top.

cheers

Col

[col]

Here's a tweaked version with strings and slight changes to dimensions to try and even out the field where the strings are:

Col

[curtisa]

Good animations Col. Just as a side note, the steel laminations from the transformer I'm cutting up are easy to do using a hacksaw. Nothing special there. I'm actually finding the middle leg of the "E" section is a more useful size - it's just a little bit wider than three strings, which will make it a good size for the dual-winding bilateral driver, I just have to cut the length down so that it's not too tall. The problem I'm seeing now is finding something that will make a nice neat bobbin out of. I was thinking of going down to the hobby shop and seeing if they had any plastic rectangular extrusions I could use. Any other suggestions?

[psw]

Yes...nice animations...I don't suppose it is possible to model the side view convincingly...this is more critical for EMI but being a 2D model I suspect not going to be sensible. I never got the hang of the whole coil thing either...is that how the animation is done...it is illustrating the coil working?

The problem I'm seeing now is finding something that will make a nice neat bobbin out of. I was thinking of going down to the hobby shop and seeing if they had any plastic rectangular extrusions I could use. Any other suggestions?

I have used plastic from containers (ice cream lids are often flat) but they are difficult to glue. Plastic folders is another one I have used with some success. You could also consider gluing laminations of paper or thin card...you can print out a shape on it to cut it and if you use superglue for instance, it will be pretty stiff. The original sustain-o-caster was done with very thin black folder and the core was cut and folded and so stuck with PVC tape to the core and with all that potting glue and wire wrapped around it, held together still to this day. It was very flexible of course, but thin...so to wind it I double sided taped some stiffening pieces to it which were removed once the potting glue had set while winding it. I think it is illustrated in my pictorial in the link below. Some people have used CD cases but I have never had much luck...too brittle. However, if you can get some DVD cases, this might be better, softer plastic so would cut with a knife and could be sanded too!

ANother possibility is to work out a way of molding a 5 minite epoxy top and bottom (depending on the magnets, these may serve this purpose. Sustainiac use metal plates on top of the laminated cores, I suppose it may be possible to do similar and have these oversize to keep the wire on.

What are you thinking of potting it with?

I am on the lookout for some plastic to make a pickguard from...any ideas for this...preferably plain white. The tele I am making needs a customised oversized pickguard to fit a vintage fender "full-range" HB which is a completely different size from a standard HB. I have a normal tele guard, but I have not yet found a way of making an extension that is convincing.

pete

[Fresh Fizz]

The problem I'm seeing now is finding something that will make a nice neat bobbin out of. I was thinking of going down to the hobby shop and seeing if they had any plastic rectangular extrusions I could use. Any other suggestions?

For my driver I used some left-over 3 layer strat pickguard material. I can understand that people find it too thick, but it's easy to saw and when sanded it can be superglued easily.

[col]

Yes...nice animations...I don't suppose it is possible to model the side view convincingly...this is more critical for EMI but being a 2D model I suspect not going to be sensible.

You're right in thinking that a side view of a bi-lateral driver is not going to be doable in femm, however, I don't agree that it is necessarily more critical for EMI. What is critical is how contained the field is, and the front tells us much more about that for this kind of driver.

It would be great to be able to create a full 3D model of course, but even with the correct tools and the time and energy to learn how to use them, each model would take a lot more work to create - I can do one of these femm animations in a few minutes (once I've remembered how that is).

I never got the hang of the whole coil thing either...is that how the animation is done...it is illustrating the coil working?

The animation is done via a script I wrote that controls Femm (femm has the scripting language 'Lua' built in). What it does is vary the current using a sine wave. What you're seeing is a series of snapshots of how the pull of the coils effect the permanent magnetic field+. What you don't see is the effect of hysteresis, phase etc. however, they're not particularly important to this kind of model/animation. What it is for is to see the shape of the field, and what effect the electro magnet has with a certain coil spec and current.

Another thing to bear in mind is that the colours are not mapped the same as those in some of the other femm models I've done, so direct visual comparisons can't tell you anything about relative flux density etc (the colours are however the same for both of these animations).

If anyone wants a copy of the femm file with a script to play with and use as an example, I can zip it up and e-mail it

cheers

Col

[col]

..the steel laminations from the transformer I'm cutting up are easy to do using a hacksaw. Nothing special there. I'm actually finding the middle leg of the "E" section is a more useful size - it's just a little bit wider than three strings, which will make it a good size for the dual-winding bilateral driver, I just have to cut the length down so that it's not too tall.

I think 3 strings (about 20mm) is probably too long, although only building and testing will tell for sure.

The problem I'm seeing now is finding something that will make a nice neat bobbin out of. I was thinking of going down to the hobby shop and seeing if they had any plastic rectangular extrusions I could use. Any other suggestions?

That got me thinking - what about some sort of U section plastic strip of some kind - you could use it to make something with reasonable structural rigidity, it would be slightly thicker due to some overlap, but I think that will only be important if your trying to build a piggy-back driver.

A refinement if this kind of idea might do the trick ?

cheers

Col

[utopian isotope]

How do you guys laminate the core? I have disassembled small transformer, and tried to make core(s) of "I" pieces.

I found it quite hard to align the pieces properly. Maybe it is the superglue that I'm using. It cures way too fast.

Using epoxy could be one solution, but when you apply that to pieces, and clamp them together, they tend to slide away.

Lazy as I am, I took 0,8 mm steel sheet(maybe Fe37), and cut two 4mm x 210mm pieces out of it with plate shears.

Then rolled them so that they form about 4mm x 5mm x 30mm pieces of mild steel each.

I'm sure that eddy current(s) will occur with this, as there is no isolation between sheet rolls.

Anyway, I got two cores ready to winding as soon as I make bobbin(s) out of plastic.

Should the twin coils have 4 or 8 ohms each?

What I have in mind is to use a pot to adjust balance between wounded and plain strings.

Edited March 2, 2008 by utopian isotope

[psw]

Should the twin coils have 4 or 8 ohms each?

It depends on what your amp is wanting. You may need two 16s as I used on the rail if I recall...

What I have in mind is to use a pot to adjust balance between wounded and plain strings.

I have always wanted to run a stereo amp to run the two sides, but then I also used to want (and built) 6 drivers! With stereo you may be able to use two 8's for instance...again depending on the amp. I am not sure how you could do the balance pot thing in mono though.

QUOTE

I never got the hang of the whole coil thing either...is that how the animation is done...it is illustrating the coil working?

The animation is done via a script I wrote that controls Femm (femm has the scripting language 'Lua' built in). What it does is vary the current using a sine wave. What you're seeing is a series of snapshots of how the pull of the coils effect the permanent magnetic field+.

You could send it to me, but I am not sure If I would know how to use it properly. I have stayed away from femm for a while, it would be interesting to see what different effects the secondary coil might have with different configurations however. Nothing in static permanent magnet fields is revealed.

Good luck with all that driver building, hopefully they wont all be so different as to not be able to properly compare. Also, watch that build quality UI, the arts and crafts aspect is what puts a lot of people off but it can make a big difference...it doesn't have to be "pretty" but gaps in the core and coil, poor potting, magnets not fully touching the core...all these things can make a big difference.

One thing to consider...if not making a laminated core...is using bolts as poles. My 6 pole/pickup drivers seem not to suffer too greatly from not being of a rail design with bent strings. What seems to influence it more is deflection from the bridge pickup poles, at least on mine. Particularly with the high e. A whole step bend puts it over the b driver pole, but drive is reduced as it gets less signal from the pickup as the string (bent above the 12 the fret) is now between the e and b poles of the pickup. You could glue together a row of small nuts and wind around these and then have adjustable driver poles screwed into them perhaps...just a thought.

Making powdered cores is easy too...you need to make some kind of mold, create a powdered iron and epoxy mix and pour into this. You can even "align" the filings by attaching a magnet to the bottom of the mold and the iron will be attracted to it. To me it is a little easier and probably a better "laminated" effect in many ways.

In reality, I have not derived a real benefit from my explorations in laminated and powdered cores...but my work is not so scientific as to be conclusive and relates mainly to thin coil designs and relatively narrow (3-5mm) rail like drivers. A driver that truly mimics the sustainiac is different, the core is deep and wide and the coil pretty narrow (less overlap) around it. Perhaps real differences can be seen with such a core and it may need to be laminated for it to work properly.

I wonder what Fernandes is using, some of them look exactly like conventional HB's these days (gone are fancy side drivers and such) and I wonder if they don't simply wind a driver onto conventional HB parts. As far as I can tell, the fernandes is equally comparable in performance.

As a side note...I bought a secondhand BR600 mini digital multitracker over the weekend so when it gets here, and I learn to use it, I may well be able to make better produced and more realistic demos of the device. It continues to work really well and with the battery in in now, has lasted quite a few hours with intermittent play.

On the remote thing, I may need eventually to get tricky with the whole stereo lead/ dual power supply thing. I take it you need to disconnect a battery when using a remote power supply, connecting a remote power source to the battery and the circuit would have detrimental effects??? I was thinking that perhaps a fet could be rigged on the jack and when it senses positive power from the centre ring coming up a lead, it disconnects the battery some how, when no power is present, as with a conventional lead (or none) it relies on the internal battery. Any thoughts??

I looked at a few different alternative socket and plug things, nothing yet has quite taken my fancy...what does a variax use? Ideally it would fit in a strat jack plate and must not easily be pulled out. Something that relies on a special power lead concerns me as if something were to happen with it, then you could be left high and dry without a spare.

Anyway...must run...good luck all...

pete

[col]

Anyway, I got two cores ready to winding as soon as I make bobbin(s) out of plastic.

Should the twin coils have 4 or 8 ohms each?

How long is a piece of string?

The DC resistance of the coils is not the key factor - whats is important is the impedance over the systems frequency range.

If you were making a higher inductance single core driver with more turns of thicker wire and a bigger core, and you were targeting an LM386 based amp, you might be looking at a DC resistance of something like 4 ohms. Even though the LM386 is most efficient when driving an 8ohm load, the higher inductance means that the impedance rises more noticably with frequency, so you would be looking at a compromise... maybe tweaking the system so that you get an 8ohm impedance at around 320Hz (open 1st string).

If you're building a dual core driver, then it depends if you are going to wire the coils in series or parallel.

If series, then each coil should have half the impedance it would for a single core driver.

If parallel, then each should have twice the impedance...

If you were looking at simple DC resistances, then it would be 4 & 4 for series or 16 & 16 for parallel.

If you're going for a slightly higher inductance, you will probably be best looking at a lower total DC resistance (probably best not to go much below 4ohm unless you're going to install a heatsink.... even then, I'm not sure what the consequences might be).

For my next driver I will be going for dual core in parallel config with a total DC resistance of 4ohm. I will work out what the maximum inductance would be so that the driver still functions at what I consider to be a high enough frequency. This will involve building a dummy coil on my intended core and measuring the inductance, then calculating from that how many turns of wire I need to get that inductance... then finally working out what gauge of wire is required for that number of turns to give the desired DC resistance of 16 Ohm per coil.

Then when it's built I will measure the actual specs to see how far off they are to guide the next effort. And then of course, test the thing out - I should find out pretty quickly the answers to the questions I still have as to how running coils in parallel effects the field that is generated.

I also want to have some bobbins that allow the core to be removed, so I can compare parallel and series versions with the same overall inductance, impedance and resistance...

Just need to get an inductance meter, some suitable magnets and a few other bits and pieces - probably will happen in a couple of months.

What I have in mind is to use a pot to adjust balance between wounded and plain strings.

Not sure how that would work?

Would it not mess up the balance of the field dramatically, change the phase response and cause some hefty inefficiency in the load to the amp ?

better to have two coils with different specs - basically a 'woofer' for the low strings and a 'tweeter' for the high strings. Has been suggested a few times, but its still a valid idea, and still hasn't been tried... hmmm... its certainly a possibility for a bi-lateral driver - another reason t ohave a standardized bobbin and removable core for comparison testing.

cheers

Col

Edited March 2, 2008 by col

[curtisa]

I think 3 strings (about 20mm) is probably too long, although only building and testing will tell for sure.

Dunno, that photo dissection shows the width of the laminations of the sustainiac driver core being about three-strings wide.

What are you thinking of potting it with?

Was considering using the good old exterior-grade PVA I used last time. My thinking was I'd wind a layer of wire on, brush a coat of PVA on, wind another layer, brush another coat etc...

Maybe varnish as an alternative (layer of wire, brush a coat on, layer of wire etc)?

How did you find working with that "glosscote" stuff I mentioned last year? Any good?

I am on the lookout for some plastic to make a pickguard from...any ideas for this...preferably plain white.

I think you can get big uncut squares of pickguard material from the spare parts department of guitar stores. Try online?

[psw]

How did you find working with that "glosscote" stuff I mentioned last year? Any good?

Yeah...I thought it was going to work..."Glasscoat" by the way...but it didn't work right for my construction technique. It will dry hard like glass so with a bobbin and all, it might work fine...takes about 3 days to really harden apparently! I went through a few different epoxies and something a little slow is better, but that was a little too slow and didn't have the structural strength...I have a litre of it, maybe I should mold a scratchplate from it...hehehe

Dunno, that photo dissection shows the width of the laminations of the sustainiac driver core being about three-strings wide.

Yes...you have to have the space between the two coils between the d and g strings.

Maybe varnish as an alternative (layer of wire, brush a coat on, layer of wire etc)?

I tried this once and it didn't work...the varnish (oil based) didn't set properly due to the lack of "air" inside the coil...or so it seemed...seemed to stay sticky...

I think you can get big uncut squares of pickguard material from the spare parts department of guitar stores. Try online?

I have found white/black/white laminates but it can be a bit dear and not quite what I wanted...plain white would be best. If necessary, this is what I will have to do, or come up with some other idea to build a ring around the HB and fit it with the standard tele guard. Still this is supposed to be a side project.

The only thing that I have done but play the thing was try a scratch connection of the middle pickup...I will really have to do a complete rewire though to be sure if there isn't switch noise with the bypass...the key will be to have that ground connected, but the switching in there has a total lift which causes a bit of a click on off. However, connecting the ground seems to fix that...so it is hopeful. Still need to do the neck pickup of course.

Anyway...better run...although there is a lot of merit in the bilateral design theoretically, and I know I am a little precious about my own thin coil ideas, and I am sure it will work...for my I am happy with the concept and performance of my design. I think that If I were to make such a device, I'd combine it with the successful attributes of my own designs, but I really would miss the neck pickup and all that a "normal" guitar can do. Sustainiac's active pickup/driver actually sounded pretty good but then I'd have to develop preamps and have the pickup comprimised between driver and pickup performance...easier for me to continue with the piggyback passive thing...

good luck... pete

[utopian isotope]

How long is a piece of string?

String? Do you mean steel sheet that I used for cores?

The DC resistance of the coils is not the key factor - whats is important is the impedance over the systems frequency range.

If you're building a dual core driver, then it depends if you are going to wire the coils in series or parallel.

If series, then each coil should have half the impedance it would for a single core driver.

If parallel, then each should have twice the impedance...

If you were looking at simple DC resistances, then it would be 4 & 4 for series or 16 & 16 for parallel.

If you're going for a slightly higher inductance, you will probably be best looking at a lower total DC resistance (probably best not to go much below 4ohm unless you're going to install a heatsink.... even then, I'm not sure what the consequences might be).

Yes, I'm building dual core driver, so that both coils have separated inputs. That way I can test them in series and parallel, in phase,and out of phase. Maybe I wind 16 ohms coil around those cores also. That means six wires... and lot of testing possibilities. I have no clue about theory, and how that works with sustainer, but for me there is only one way to find out...

For my next driver I will be going for dual core in parallel config with a total DC resistance of 4ohm. I will work out what the maximum inductance would be so that the driver still functions at what I consider to be a high enough frequency. This will involve building a dummy coil on my intended core and measuring the inductance, then calculating from that how many turns of wire I need to get that inductance... then finally working out what gauge of wire is required for that number of turns to give the desired DC resistance of 16 Ohm per coil.

Then when it's built I will measure the actual specs to see how far off they are to guide the next effort. And then of course, test the thing out - I should find out pretty quickly the answers to the questions I still have as to how running coils in parallel effects the field that is generated.

I also want to have some bobbins that allow the core to be removed, so I can compare parallel and series versions with the same overall inductance, impedance and resistance...

Some kind of plug-in system would be great. So that core(s) and coil(s) and also whole driver could be removed or replaced without hassle.

Just need to get an inductance meter, some suitable magnets and a few other bits and pieces - probably will happen in a couple of months.

What I have in mind is to use a pot to adjust balance between wounded and plain strings.

Not sure how that would work?

Would it not mess up the balance of the field dramatically, change the phase response and cause some hefty inefficiency in the load to the amp ?

better to have two coils with different specs - basically a 'woofer' for the low strings and a 'tweeter' for the high strings. Has been suggested a few times, but its still a valid idea, and still hasn't been tried... hmmm... its certainly a possibility for a bi-lateral driver - another reason t ohave a standardized bobbin and removable core for comparison testing.

That's what I'm after, since wound strings seem to be somewhat slower in response when compared to plain strings. That slowness might be one cause of fizz.

-----------------------

BTW, I took stick of wood (about 35 cm), and wound 10 rounds of coil wire to it. Then measured resistance, and did some simple calculations. Certain amount of rounds gives about 8 ohms, twice that gives about 16 ohms etc, so that I can cut 4, 8 or 16 ohm amount of wire for future drivers.

Don't know if that method is already in use, but no more guessing when winding.