Sustainer Ideas

[ghendrickson04]

Would it be possible/plausible to remove this 'fizz' you all talk about with a simple noise gate (like removing my strat's 60-cycle hum)? It could be a simple addition to a preexisting circuit and I don't think it would add a terrible amount of draw on the battery.

[psw]

Welcome jamforthelamb...I wonder how many other people there are out there that have tried this or have successfully built their own sustainer?

The loop thing is interesting...squeal suppression...hmmm

I had an idea of sending a tiny signal through a pickup coil...perhaps say a middle pickup on a strat, perhaps fed by an op amp to avoid impedance problems....this creating a kind of magnetic shield or "loop" of many turns of wire (already in the guitar anyway)...just a thought.

Any thoughts on that 4pdt switching thing...

how about that pop suppression cap idea?

It is a shame that I seem to be on my own with the multi-pickup installation problems, as this is a unique challenge.

A note on the diagram from the previous post on the harmonic switch...it was impossible to tell from the sustainiac if this was connected to the driver as everything seemed to connect back to the board...I suspect it does it's reverse phase thing on the front of the amp and so not a diagram that is an obvious applicable fix...may try some experiments today perhaps.

Col...the all pass filter schematics I have found have all used expensive hard to get instrument op amps (interesting in themselves)...any ideas on alternatives?

I am not sure if I asked already, my long posts often obscure points... ...

Any other ideas or suggestions about how to narrow down the causes of fizz ?

Is it possible that distortion or even the fizz is entering the signal chain via the shared ground of the signal and the driver as much as from EMI? A dual coil driver that reduces the EMI effect, would also reduce any back voltage into the ground from the driver by having two coils of opposite polarities for instance. Perhaps the ground of the driver output and the signal output require some separation in some way. It is one of the reasons I was looking at BTL amps of various kinds, but I am not sure that this is the answer either and I didn't have much success in that area.

Perhaps there is a clue to the added fuzzyness that appears when turning the volume of the guitar down...some of the hot input is being tied to the ground lowering the input impedance or something....

I have 2 grounds (?) one for the pickup ,treble booster, guitar cable and another one for the sustainer device. Both are interconnected through a 100 ohm resistor.

Perhaps you have already done something like this...can you explain this two grounds a bit more?

Despite my newer circuit running of a lot less gain in general than my previous versions and with little to no preamp gain, battery drain is still a problem...perhaps a week of intermediate use...but while it continues to work, lower power capacity does diminish the effect a little. Given that it is hard to find room in a lot of guitars for a battery anyway, perhaps it is time I looked into the remote power options a little more. Previous ideas saw power being provided via a stereo cable with the -9v sharing the ground. This would then plug into a splitter box with a power supply and split off to a conventional mono lead to the amp. This is probably a more practical real world solution to powering the thing than a separate 12volt supply and wires into the guitar.

The other variation would be a dual system...but I am not sure how you would do this so that the battery is switched out if remote power is supplied. A third variation would be the use of a rechargeable battery...again I am not sure how to do this...that if used with power attached would recharge, and when no outside power available, run off it's own power.

I used to use a pair of rechargeable 9v batteries to economize on the batteries. However, they have a lower capacity and go flat faster than a good alkaline or something. I found I would use one up as fast as the other charged when I was doing a bit of work with this...

My volume pot serves as sustainer drive controll as wel.

I am not sure about this...so to turn down the gain of the sustainer you loose guitar volume as well? The device needs to be balanced...it could be that you have sufficient power capacities to run the driver under sqeal too hard...but to dial it back, you are also loosing your guitar signal too.

Also...some of this "ringing" may even be a factor of very low action where the strings may be slightly touching the frets, especially if the strings are being driven hard.

Another thing that is important to play with is the driver and pickup heights. Both are very important. Perhaps you could back off the driver a little...generally raising the bridge pickup as high as possible is hugely advantageous to the drive signal and reducing EMI. From my experience, the dual coil blade type drivers need to be very close to the strings (the reason I abandoned my mid-driver ideas in the main) having far less "throw" or something. On the single coil drivers I find the driver will still be effective even if backed a fair way from the strings...which is good as too close and this type of pickup/driver could upset intonation and such if set too high.

Note however, that I persist with my single coil design out of simplicity (half or less of the work) and application (fitting to a single coil format pickup), not in a belief that it is a "better" driver. There is a lot to be said for the principle, just as with HB pickups to reduce noise, and it is interesting that every commercial unit to date appears to have featured some version of this configuration.

Also...there is nothing "wrong" with making single pickup sustainer guitars with dedicated drivers. A single pickup guitar is a completely valid platform for this device which adequately compensates by it's additional effects over multi-pickups that only function when it is off anyway! I am surprised by the amount of difficulties people seem to have with this. I had very little problems with any symptoms with the neck pickup out of the system (other than these unusual coil interaction effects previously noted and nullified by shorting of the coils anyway).

1. When I say that there is no squeal I notice that there is sensitivity point, a specific frequency band, where the system would like to sqeal if it only had enough energy/volts/whatever to feedback.

When I listen through a compressor in front of a distortion/overdrive into headphones I imagine I can hear that frequency band in the background. When I switch off the sustainer it's gone.

When I hit a low note on the low e string it seems to waken up this monster. Like it's thinking: "finally enough energy". But there's not. So it's like a short colorization of the sound (emphasizing that particular frequency band) and then going into string feedback.

This is a very unpleasant sound effect (not musical sounding)

I am not sure where you are at. So you get perfect sustain all over in fundamental mode, however you get a tinny/ringing kind of overtone behind it as it struggles to take hold of the note that disappears when the sustainer drive takes effect...is that the kind of thing? This is something that I have found to be a problem with the harmonic setting...there is a transition. It is one of the reasons I am interested in exploring alternative means that are a bit more natural sounding...

Do you have a harmonic switch or tried reversing the wires...how is that performing. Also, if you have a lot of preamp clipping (which you have purposefully employed) you are raising up all the harmonic content within a note...it sounds like the device is wavering a little as to which frequency to feedback on, finally settling on the fundamental perhaps. The employing of a treble booster before the clipping is likely to make this worse, boosting the higher harmonic partials of note then clipping them to equal volume with the fundamental.

There are "risks" when you follow a hunch as you have by effectively using a fuzzbox (diode clipper and treble booster) as a preamp. It would be good if you could test it without the clipping and the treble boost and see if a lot of your problems don't disappear. There was a lengthy and repeated debate here over the merits of clipped vs. clean drive signal that generally came down on the side of a clean signal being more effective and less problematic. It would definitely benefit you to try out both approaches I suspect.

oh...and perhaps your preamp is overly empathizing pick attack noise and confusing the signal with a high frequency "ping" at the begining of the note that the driver is trying to reproduce. Again, treble booster and clipper causing this emphasis!

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Ahh...an new post while I am composing this...

Would it be possible/plausible to remove this 'fizz' you all talk about with a simple noise gate (like removing my strat's 60-cycle hum)? It could be a simple addition to a preexisting circuit and I don't think it would add a terrible amount of draw on the battery.

No...the fizz is apparent in the signal while the thing is operating, not when there is no sound. A noise gate turns off the signal when no sound is present making the silences quiet, but all the noise is there when the signal is present, only usually masked by the sound or effect.

Interesting though, the principle may well be applicable for other areas. Perhaps a noise gate like sensor that shuts off the power when no sound is played, preserving battery life?

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Back to fresh fizz...

You are using a much more powerful amplifier and an unusal application. Here is a schematic for this chip amp

tda7231 schematic

It lists the power as 1.6w into 4 ohms. We are running LM386's typically into 8 ohms...between 0.5 and 1 watt, but restrained by the capacity of batteries, with outboard power, you are giving it virtually unlimited current capacity! This project is a lot about balance and more power does not equate to better or improved performance. Also, there is little to no experience with this amplifier and the effects of running low ohm loads on the amp or such driver designs. It could be an advantageous choice of amp (any reason for choosing this?) however battery operation is probably not an option at these wattages, if you were seeking improved headroom to get a nice clean signal. Your preamp though undermines any advantage of this though. Remember, if you run a LM386 at full blast, you will automatically get some clipping, and with a battery, the power is clipped at the level to which the battery can supply it.

Again, we are all heading on our own paths and direct comparisons are difficult...oh well...the general problems are universal but the fixes may not!

pete

[col]

The loop thing is interesting...squeal suppression...hmmm

I had an idea of sending a tiny signal through a pickup coil...perhaps say a middle pickup on a strat, perhaps fed by an op amp to avoid impedance problems....this creating a kind of magnetic shield or "loop" of many turns of wire (already in the guitar anyway)...just a thought.

I also wondered about using something slightly more substantial than a single loop. However the most important thing is that one side of the loop is VERY close to the pickup - basically touching - this means it can carry a very low signal and still have a cancellation effect, so any other coil used for the same purpose would have to be very close to the pickup (maybe under it ?)

I'm not sure to what extent the phase response of the loop has an effect - maybe working on that might get something that can help with fizz - dunno at this stage.

Col...the all pass filter schematics I have found have all used expensive hard to get instrument op amps (interesting in themselves)...any ideas on alternatives?

I just built a simple all-pass using a standard op-amp. no need for high speed stuff as this is an audio frequency circuit (comparatively, very low frequency).

Here are some links to docs and pages with a nice selection of op-amp circuits, including all-pass filters with notes on how to tweak the response.

A Single-Supply Op-Amp Circuit Collection (Texas Instruments)

Audio Design With Opamps (ESP)

From your description of how the sustainiac functions, I would say that the mixed mode is probably not based on an all-pass filter. It sounds more like a higher(than 1st) order bandpass filter (think wah-wah) with a sweapable peak an octave or so wide. This would be more likely to allow you to pick specific harmonics as you described.

Google op amp bandpass filter schematic

Any other ideas or suggestions about how to narrow down the causes of fizz ?

Is it possible that distortion or even the fizz is entering the signal chain via the shared ground of the signal and the driver as much as from EMI?

Thats something we should be able to work out on a test rig like the one I described:

If we setup a driver on the rig thats getting a signal from a guitar sitting a meter or two away(as far as possible anyway), and the pickup on the rig is feeding a battery powered headphone amp - there is no ground connection at all between the pickup and driver on the test rig. If the fizz is still pretty much the same, then the earth connection is unlikely to be the main source of the problem. If however, the fizz disappears, then we know that the shared earth it is something to take very seriously. (we have to make sure everything else is as it would be on the guitar, so we need strings, correct distance between driver and pickup, circuit in same relative position etc.

Perhaps there is a clue to the added fuzzyness that appears when turning the volume of the guitar down...some of the hot input is being tied to the ground lowering the input impedance or something....

I've never noticed that - probably coz I don't turn the volume down very often

Another thing that is important to play with is the driver and pickup heights. Both are very important. Perhaps you could back off the driver a little...generally raising the bridge pickup as high as possible is hugely advantageous to the drive signal and reducing EMI. From my experience, the dual coil blade type drivers need to be very close to the strings (the reason I abandoned my mid-driver ideas in the main) having far less "throw" or something.

Yes, adjusting the heights of the pickup and driver can help.

I think it is very important with a rails type driver to ensure that there is a good space between the two rails - the gap caused by using a standard humbucker magnet seems to work pretty well, but according to femm, if you reduce the gap too much, the peak of the field goes too low for a sensible string gap.

The employing of a treble booster before the clipping is likely to make this worse, boosting the higher harmonic partials of note then clipping them to equal volume with the fundamental.

Have to agree with that - treble boosters are amazing things (I love my home-brew Rangemaster) - but I've never considered putting something like that in the sustainer circuitry - It's just to wild with a really peaky response and lots of noise.

Interesting though, the principle may well be applicable for other areas. Perhaps a noise gate like sensor that shuts off the power when no sound is played, preserving battery life?

Ah, you mean an AGC

A great thing would be a good compander chip - use the compressor as a limiter to bring the low levels up to good drive. Use the expander to wipe the very low levels to prevent very low level signals, fizz and noise from causing sensitivity problems. Unfortunately all the groovy compander chips that used to be used in tape recorders have been phased out.

cheers

Col

[psw]

Interesting though, the principle may well be applicable for other areas. Perhaps a noise gate like sensor that shuts off the power when no sound is played, preserving battery life?

Ah, you mean an AGC

I don't think so, even if an AGC cancels out the signal into the amp, the amp is still running is it not? I see what you mean, but an AGC tends not to be a sleep function...now I am having problems explaining....

Anyway...thought I'd report on that switch idea. Clever as it seems, this will not work quite as expected. In the bridge selected position, when the sustainer is on, no load is connected to the neck pickup as it is bypassed by the selector...rats!

With a little arranging and false starts (mis-wires) I am getting a noiseless on but still the off click. The capactor (I used a 220uF) does seem to have an effect, but not enough....hmmmm

So...still major troubles in installation land....grrrrr

From your description of how the sustainiac functions, I would say that the mixed mode is probably not based on an all-pass filter. It sounds more like a higher(than 1st) order bandpass filter (think wah-wah) with a sweapable peak an octave or so wide. This would be more likely to allow you to pick specific harmonics as you described.

I suspect that you may be right...I am a little surprised that f-fizz isn't getting screaming harmonics with his treble boosted setup...

As for your idea of a testing bench...would it not be better simply to use an actual instrument adapted for this purpose...

This is what I am presently using...

This strat has the pickups double-sided taped to some squares of ply with foam below for height adjustment and easy removal (even with the strings on. The small plate holds the controls and can be screwed on with a couple of screws or left hanging. some parts can be brought out from the control cavity for adjustment and ease...here you can see my small circuit hanging out and below that the load pot attached to the neck pickup coil when sustainer is on.

I was using a dpdt 3 way as a selector but was getting clicking noises. The on function was with a push pull on on the volume. I have since changed to a 5 way selector using only the bottom 3 selections to select between the three pickups...no more switch noise... I also gone back to the toggle 4pdt for on off function.

On a practical note...with strat knobs, the push pull knobs are virtually impossible to pull up...cant get a grip on them. A tele type knob is fine but not these slippery buggers. Also, as col has indicated before, having a toggle does make it easy to see where you are at as far as selections go...the switches are either down or up... Something to keep in mind I guess...maybe for a less critical or complicated function like the harmonic switch it would be of use...

A test bed guitar like this makes it easy to test drivers either mounted in place or held over the strings...you could even tape a breadboard to it if you wished. I have mounted the battery in the trem cavity...taking out the centre spring and tightening it right up. I used to have it next to a pickup on top under the strings which was fine also.

I had intended to add screw in wire connectors, in fact I tried some, but they always seemed to play up...I have found it better just to solder things...they tend to stay connected that way.

So...still all the old installation woes and noises and distortions, even with a two pickup guitar...perhaps it needs a new approach...perhaps the sustainer should only be selectable on the bridge pickup position and turn off when other pickups are chosen...so in position 5 it is bridge pickup with sustainer on or off...problem is what happens in position 4 where the middle is combined...you don't want it on!!!

Back to the drawing board. I would really like to be able to have a means of installation down without the clicks and pops and noise so that I can simply insert filters and circuits in there without having to worry about how it will eventually fit into the real instrument. By far this is my biggest concern at this stage, the sustainer works enough to be a great addition (sure it has the potential to be better and/or more versitile) but without being able to install it properly, any improvements are a little pointless. Ultimately, I am looking to get it working in strat type 3 pickup guitars at least, so even this test guitar is a little "artificial"...not many guitars have this format (though it does sound good)...

pete

[curtisa]

Ah, you mean an AGC

A great thing would be a good compander chip - use the compressor as a limiter to bring the low levels up to good drive. Use the expander to wipe the very low levels to prevent very low level signals, fizz and noise from causing sensitivity problems. Unfortunately all the groovy compander chips that used to be used in tape recorders have been phased out.

You shouldn't need one. The difference between compressors, limiters, expanders and noise gates is all in the sidechain circuitry. By combining the functions of each sidechain circuit you can do the whole lot using one VCA element. That's how they do it in large format mixing consoles where each channel has it's own compressor/limiter/gate and VCA fader element - it's easier, cheaper and cleaner to use one VCA in each channel with multiple sidechains than have one VCA for each function.

[Fresh Fizz]

I'm amazed how rich this thread is. There are so many ideas going on at the same time! You could call ourselves the sustainer think tank.

I had an idea of sending a tiny signal through a pickup coil...perhaps say a middle pickup on a strat, perhaps fed by an op amp to avoid impedance problems....this creating a kind of magnetic shield or "loop" of many turns of wire (already in the guitar anyway)...just a thought.

Which means you're creating a second trafo-like coupling, just like your flat driver/ neck pup. This could mean more unwanted side effects.

Perhaps you have already done something like this...can you explain this two grounds a bit more?

My problem is that I'm still catching up with you guys. Maybe I shouldn't have mentioned it already. My sustainer device is still suffering from diseases that you have already solved. Like optimalizing signal levels, eq, amount of overdrive/compression to fight the fizz and squeal. But I have the idea that this might be a way to address the shared earth problem. In your guitar the sustainer device is earthed means the guitarcable. But what if there is a slight resistance (because of connectors). Let's say that resistance is 0,2 ohm. It means that there will be some of the sustainer device's output voltage on that resistance.

V_on resistor = V_sustainer * 0,2 / 8,2

You could say that 0,2 / 8,2 is feeded back to the guitar pickup (same earth). The sustainer device has an overall amplification that might well exceed 8,2 / 0,2 times. So there is allways a concern for oscillation/instability. Because of phase shifting of the combination of driver coil and zobel network there allways will be frequencies where the phase shifting (driver output to pup input) is not exactly 180 degrees.

With the 100 ohm resistor I use the feedback is 0,2 / 108,2

The idea is that the cable of my sustainer device's power supply will serve as connection to earth. So from the power supply goes a connection to the earth of my guitar preamp. At this point it's not working this way because my adapter is not earthed. But even so it should improve the problem with the shared earth. Technically the sustainer device's ground is floating from earth but the efffect should be minimal.

I remember, Pete, where you said that you got squeal when the strings touched the core of your flat driver. I think it has to do with this shared earth phenomenon. Core 's connected to earth together with eddy currents.

I remember spazzyone with the outboard amp who said not to experience any big troubles with fizz.

I am not sure about this...so to turn down the gain of the sustainer you loose guitar volume as well? The device needs to be balanced...it could be that you have sufficient power capacities to run the driver under sqeal too hard...but to dial it back, you are also loosing your guitar signal too.

I'm a compressor junk, I don't loose a lot of volume. To me it's a very natural thing that by adjusting the volume you get more sustain. Just the same like when people use their volume pot to get more overdrive of their amp.

You are using a much more powerful amplifier and an unusal application. Here is a schematic for this chip amp

tda7231 schematic

It lists the power as 1.6w into 4 ohms. We are running LM386's typically into 8 ohms...between 0.5 and 1 watt, but restrained by the capacity of batteries, with outboard power, you are giving it virtually unlimited current capacity! This project is a lot about balance and more power does not equate to better or improved performance. Also, there is little to no experience with this amplifier and the effects of running low ohm loads on the amp or such driver designs. It could be an advantageous choice of amp (any reason for choosing this?) however battery operation is probably not an option at these wattages, if you were seeking improved headroom to get a nice clean signal. Your preamp though undermines any advantage of this though. Remember, if you run a LM386 at full blast, you will automatically get some clipping, and with a battery, the power is clipped at the level to which the battery can supply it.

Reason? Maybe the same why people stick safety pins in their nose. Trying to be different.

In 8 ohms I should be able to get 1,8W. But I settle for about 1,2 W. I have outboard power so consumption is not a big deal. In understand that the combination of having lots of compression/overdrive and lots of output power could be too much but I was a bit concerned that my driver with the slim blades wouldn't be that strong. Better to start with too much than with too little! It prooved to be very strong. When my high e string wasn't yet at right pitch the feedback made it almost to woodpecker itself into the fretboard.

Another advantage of the ic is that one side of the dil package is connected to ground. So I can use a ic socket with a peace of tin soldered onto it. It makes a perfect heat sink. I sticked my sine wave generator to it and let it run full blast for a few minutes. Kept it pretty cool.

The specs talk about soft overdrive characteristics. Tubey?

Pete thanks for the advice given. I'm sure that I can use some of the ideas you mentioned.

More food for thought

Enough said

greetings,

Fizz

[utopian isotope]

Maybe Fresh Fizz and I have same kind of situation. Overpowered sustainer amp and wall adapter. Anyway, that allows you to take sustainer/driver to its limit,

where all kind of things are exaggerated, thus more noticeable(at least for me).

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Once again, I found totally strange phenomenon, that saturates sustainer and/or driver, and adds even more fizz and grunge.

To test this, simply hover some non-magnetic piece of metal above driver, and you should hear the difference.

Metals that I have tested: copper sheet 0.1mm, brass sheet 0.3mm, aluminum: sheet 5mm and solid bar 50 x 50 mm, and lead sheet 6mm. Thicker material gives more dramatic effect.

I was surprised that even pure lead sheet affects so much for the driver. Since lead doesn't resonate easily, it must have something to do with capacitive forces. And maybe electrostatic too?

Seems that relationship between driver --> strings--> pickup(s) isn't purely magnetic.

Since all those elements can cause excessive behaviour(raw fuzz) in sustainer/driver, maybe they can also offer counterforce that can be used to eliminate them?

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Anyone here that has used sustainer with flatwound strings? Since they give more mellow tone,

I assume they don't produce as much fizz as regular wound strings do.

Any thoughts?

Edited February 17, 2008 by utopian isotope

[psw]

I'm amazed how rich this thread is. There are so many ideas going on at the same time! You could call ourselves the sustainer think tank.

It is certainly convoluted. After seeing the sustainer I have to wonder whether someone hasn't been through all this before in private though!

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Many years ago...15-20 years I suspect I tried a naive experiment where I took a coil of wire and hooked it up to about 15 watts of hi-fi amp in an attempt to get a sustainer going. It kind of worked but the thing actually pulled the strings out of tune in operation and the driver acted as a heater element and could only operate for a very short time before the strings got a little too hot to touch!!!!

That was my first attempt at this kind of thing and opened my eyes to some of the difficulties.

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Now days I tend towards the idea of trying to make the driver as efficient as possible and run on as low power as I can.

I think this has a lot of merit. It is the way I choose to address these "symptoms" of EMI and such however most of it is "intuitive" from experimentation, no knowledge as col is aiming for.

This technology has so many aspects to it that are fascinating...the basic idea is pretty simple, but it is not until you try it that you get to appreciate the difficulties.

I remember, Pete, where you said that you got squeal when the strings touched the core of your flat driver. I think it has to do with this shared earth phenomenon. Core 's connected to earth together with eddy currents.

Yes...this is a notable symptom...of course not really a problem if you don't push the driver on to the grounded guitar strings. But there you are again...if it creates this kind of effect in the core (remember I have even observed sparks from core to strings)...surely one could expect some distortion to creep into the system somewhere. I guess my feeling is that more power will only make such things worse, allowing these currents to travel far enough along the string to be picked up by the bridge pickup and into the signal, if not sent back through the driver's shared earth wire to the signal also.

The idea of magnetic shielding is where I am coming from in the idea of running a signal through the middle pickup...or indeed the principle behind the "loop" idea...create a reverse signal to cancel out these harmful signals.

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Jumping around a little...It has been observed that fernandes have a small transformer on their circuit board...the purpose of which is still unknown. Perhaps it adjusts the driver impedance, but perhaps it counteracts or isolates the driver in some way.

The sustainiac had no obvious transformer nor is there any mention in patents and such.

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One problem that I have had is encapsulating all of the various problems in a manner that is easily explained to people. I recently had contact with someone that kind of treated it like a "stompbox" problem...click switch, well there are various known techniques that can be tried...but they are not effective to date. The assumption is that I have done something wrong, or to give up. I have become wary of people who of people who are over confident in their advice, and these people are knowledgeable in electronics and stuff. There are so many aspects that we have failed to completely grasp what is even happening, that it seems very often to be insurmountable.

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As col pointed out, the fact that sustaniac et al have overcome these problems effectively means that solutions are available.

Additionally, my device works and offers another take on the effect in higher drive settings which can be very expressive in it's own right. It is in this direction I'd like my performance criteria to go.

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Overlaying all of this is the problem of practical implementation however. I am getting performance that I can be proud of, however I am consistently failing to effectively implement it into existing guitars. Even the test guitar without the neck pickup connected and with a load attached worked well but exibited some switch noise as I recall.

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Jumping about again...you mentioned eddy currents and such and I have observed that a lot of noise and fizz and even some harmonic resonances can be suppressed by attaching a load or shorting the pickup coil. Obviously the signals from eddy currents are generating forces in the pickup coil and so it may be an opportunity to use such a secondary coil to displace these into some kind of less harmful place...or even beneficial application (returning the energy int the system somehow, or driving a cancellation signal).

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I am not sure that separate power is going to solve the problems miraculously. I did use well regulated power adaptors in the early days, if only to save on battery expense. Besides giving some unrealistic real world results (it did not equate to the battery that was intended to drive it), it also effectively connected the grounds anyway through the common ground rail of the circuit so as far as I can see, the driver and signal ground are intrinsically linked in our common circuits regardless of how it is powered. You may even encounter mains earth loops with the amp if your adaptors were grounded (which apparently, and typically, they are not).

On big potential I see with the idea of remote power is that the power can remain on possibly addressing the switch pop phenomenon. But even then it may be complicated. If the driver was switched out but the power remain on, would this loss of load damage the circuit...and still all the bypassing complications exist.

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I am feeling overwhelmed with the whole switching problem. Another night scratching my head over it...another plan to try, but however clever the switching arrangement, I fear that other factors will still create problems with this. I am still "stuck" on this as without a solution here, further developments in fancy harmonic control and such mean very little.

What we need is some new ideas to counter or absorb the forces generated within the system. The dual coil approach is a very valid one in this, the equal and opposite effects of the two coils withing the driver most likely does counteract a lot of the problems I am encountering. But then, I am working on a particular application that restrains the design a little. Even so, with my mid driver I found the raw drive power to be less and so required being set very close to the strings...

For those who may have missed that...it looked like this...

This was a dual coil driver in a rail format with additional side shielding. The intention was to make something so EMI reductive that it could work with either pickup or combination and thus circumvent a lot of the problems of pickup bypassing and complicated switching and the like. It worked but not entirely effective in this aim and substantially more difficult to make. It had to be set so close to the strings also, that it really got in the way of picking and so....abandoned for the ultra-thin driver coil I am working on now.

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Anyone here that has used sustainer with flatwound strings? Since they give more mellow tone,

I assume they don't produce as much fizz as regular wound strings do.

That would be a pretty rare person...however...turning the guitar's tone control down does effectively reduce the harmonic effect and fizzy distortions...but at the expense of a bright tone. The strings don't effect fizz, but the frequency response of the signal may well.

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well enough of a scattergun post there...

pete

[psw]

You know...I think some if not all of the switches I have tried are not reliably make before break and so may be the cause of some of my problems despite my best efforts.

Some another strange phenomena...I was getting silent switchin just before as long as the switchin was activated while the note was sustaining, not when the guitar is silent. Also, worse if selector in a position other than bridge only, but only slightly...there does seem to be some inconsistency too.

Todays switching version is what I call an 'exchanger'...it replaces the neck pickup with the bridge pickup. I also went back to switching the positive power and keeping the -ve connected. Pretty silent switching on...but still a pop switching off.

Running out of ideas. I think there could be aneed for some kind of switching delay, even with electronic style switching...anyone know how to do this...or any links to fet switching? I have consistantly heard tell that the 4053 are noisy if not carefully conditioned with lots of extra components...in which case discrete components may be a viable alternative afterall, if I really must go that direction. With out some answers though, electronic switching may not address the pop issue at all.

What are other peoples experiences with power on or off noise...???

pete

[Fresh Fizz]

Once again, I found totally strange phenomenon, that saturates sustainer and/or driver, and adds even more fizz and grunge.

To test this, simply hover some non-magnetic piece of metal above driver, and you should hear the difference.

Metals that I have tested: copper sheet 0.1mm, brass sheet 0.3mm, aluminum: sheet 5mm and solid bar 50 x 50 mm, and lead sheet 6mm. Thicker material gives more dramatic effect.

I was surprised that even pure lead sheet affects so much for the driver. Since lead doesn't resonate easily, it must have something to do with capacitive forces. And maybe electrostatic too?

Seems that relationship between driver --> strings--> pickup(s) isn't purely magnetic.

Since all those elements can cause excessive behaviour(raw fuzz) in sustainer/driver, maybe they can also offer counterforce that can be used to eliminate them?

It looks like these tests can give us a new perspective of how to fight the fizz. Maybe a breakthrough? The dummy coil was indeed an eye-opener to me. Thanks utopian iso!

So the capacitive forces are against us too.

inductive emi is more likely to happen (high currents). capacitive emi is more likely to occur with high voltages. This could be the case with Pete's flat driver on top of the neck pup, where the neck pup produces high voltages.

The bad thing with guitars is that everything is so high impedance there could be a problem with capacitive emi.

Have you done or could you do these tests under the following conditions:

1. sheet not earthed

2. sheet earthed at guitar cable

3. sheet earthed somewhere more down the line like earth connection of wall plug, preamp to avoid currents through the guitar cable

I'm looking forward to hear the results from you

Cheers

Fresh Fizz

[utopian isotope]

It looks like these tests can give us a new perspective of how to fight the fizz. Maybe a breakthrough? The dummy coil was indeed an eye-opener to me. Thanks utopian iso!

So the capacitive forces are against us too.

inductive emi is more likely to happen (high currents). capacitive emi is more likely to occur with high voltages. This could be the case with Pete's flat driver on top of the neck pup, where the neck pup produces high voltages.

The bad thing with guitars is that everything is so high impedance there could be a problem with capacitive emi.

Have you done or could you do these tests under the following conditions:

1. sheet not earthed

2. sheet earthed at guitar cable

3. sheet earthed somewhere more down the line like earth connection of wall plug, preamp to avoid currents through the guitar cable

I'm looking forward to hear the results from you

Cheers

Fresh Fizz

Yes I tested 1-3, and nothing seems to tame that effect. Tried to earth the sheet to all possible points what I can think of:

guitar's ground(bridge and strings), sustainer's input and output, even wall adapter's + and -.

Also tried sustainer with battery, and got same results. I guess that this effect doesn't care what kind of power supply is in use.

Tried to figure out, what kind of effect that is. Capacitive electromagnetostatic maybe? Suggestions?

Since I can't describe it in proper terms, it is hard to get more information about it.

Anyway, all ideas are welcome to clarify that phenomenon.

Edited February 18, 2008 by utopian isotope

[col]

Yes I tested 1-3, and nothing seems to tame that effect. Tried to earth the sheet to all possible points what I can think of:

guitar's ground(bridge and strings), sustainer's input and output, even wall adapter's + and -.

Also tried sustainer with battery, and got same results. I guess that this effect doesn't care what kind of power supply is in use.

Is your drivers core earthed?

If not, try earthing the core and the plate above - does this make any difference ?

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

How does on go about measuring eddy currents ?

cheers

Col

[jamforthelamb]

Hey All,

I got it working! I tried the "loop technique" and it seemed to help a little, but ultimately what got rid of the squeal was mounting (hot gluing) the driver at an angle facing away from the pickup. I still have the usually grunge/fizz, but it's nice to have it doing something anyway. The guitar is pretty ugly right now, but I plan on cleaning everything up hopefully in the next few weeks.

Thanks for everyone's (especially PSW and Col's) contribution to this massive thread, I could have never built one of these without it.

God bless,

-Kevin

[utopian isotope]

Is your drivers core earthed?

If not, try earthing the core and the plate above - does this make any difference ?

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

How does on go about measuring eddy currents ?

cheers

Col

Thanks for the tip. Eddy current seems to have something to do with this effect, as far as I searched on the net.

Got stuck for long time when reading about it.

Haven't tested that core earthing yet, since whole driver is tight epoxied packet.

[Fresh Fizz]

I'm in the mood for being long-winded again. I hope I'm telling something new to you. I kept a present for you at the end of the story!

I've told you a few days ago that my sustainer device had a tendency to squeal during the note attack. What I haven't told you is that in harmonic mode the bugger was out of control screaming like an emotional pig. This might well be due to the heavy overdrive in combination with the strong output level.

Both my guitar pickup as well as my driver are humbucking devices. So why is there a difference in the amount of squeal between the fundamental and harmonic mode?

The only answer I can come up with is the following:

I think the easiest way to explain this is make a comparison with guitar pickups. You all know the strat with its 3 single coil pickups which pick up hum easily. There is a way to buck the hum in the combined positions by using a middle single coil pup with a coil that either is been wound or connected the other way around (I don't know which one is clockwise/ counterclockwise) .

The middle pup is electrically out of phase with the other pups. But that doesn't mean that the sound is out of phase. That depends on the orientation of the magnets of the pups. Only if the middle pup has a reversed orientation of the magnets the pup combined positions are in phase soundwise. This is like the fundamental mode of the sustainer device. Can we make the strat's combined positions out of phase soundwise by swapping the connections of the middle pickup or by some way inserting a signal inverting amp? Yes we can but we loose the humbucking effect.

The only way to create out of phase sound and keep the humbucking effect is to reverse the magnet of the middle pup. The same goes for the sustainer device. If by switching from fundamental to harmonic mode the squealing worsens or improves it means that both configurations are not equal when it comes to bucking the hum.

And this works the other way around. If we can reason that there are 2 different configurations there is no point trying to make the bad one as good as the good one.

So are there 2 different configurations? I think there are. When we imagine the sustainer driver to the left and the guitar pickup to the right we could have these combinations.

S and N: orientation magnet

+ and -: relative phase of coils

What matters is the relationship of the driver coil and pickup coil that are closest to one another.

1.

driver_pup

SN___SN

| |___ | |

+-___ +-

Electricaly out of phase

Good for fundamental mode

2.

NS___SN

| |___ | |

+-___ -+

Electricaly in phase

Bad

3.

SN___SN

| |___ | |

+-___ -+

Electricaly in phase

Bad

4.

NS___SN

| |___ | |

+-___ +-

Electricaly out of phase

Good for harmonic mode

The best quiet configurations are 1 and 4, to go from 1 to 4 you need to reverse magnet!

This could be the reason why the commercial sustainers use a split coil for the driver. But there is an even bigger gain by using a split coil. Because of symmetry of magnetic field created by the split coils there is a lot less inductive crosstalk induced in the guitar pup.

Utopian Isotope introduced the dummy coil. I haven't tested that one but most likely it works that well because it works in an out of phase condition.

I wanted to take this dummy coil thing a step further and therefore I present to you the Siamese Twin Coil . See schematic. (The circuitry still needs to be improved.)

I have no problems with squeal anymore! Maybe worth trying.

Bye

Fresh Fizz

[psw]

I am not sure what the SCT actually is from that diagram! It look kind of like a bi-lateral driver.

I am not sure that we are all talking about the same phenomenon and so am going to attempt to put some sound clips of the kind of sounds I am getting from my system.

In doing this and monitoring through headphones with a clean sound from a digital pedal, you really can tell some on the small background noises and such. I can't be sure, but I suspect I am getting a lot less of the symptoms that others describe.

I have noticed however that battery power really does effect the distortion and effectiveness of the device and fizz is made more apparent when the battery is low or struggling. I think this has a lot to do with headroom...meaning that a clean signal is likely to cause less problems IMHO.

I think it will be worthwhile trying to power it with a remote source and it is probably about time someone tried the stereo lead power idea. I can't see anyone really wanting to operate the thing with remote power with the guitar plugged directly into a wall wart and the amp...such a hassle.

It may be that there are advantages to a higher powered amplifier if remote power was required...but only to provide some clean headroom to address distortion.

If it is that electronic switching is the only way to get reliable clickless operation...then this is probably advantageous, but it is a shame to have a guitar that requires this kind of thing to work at all (ie...you can't just plug it in a play without a special lead, outboard box, powersupply, etc).

I'd still like to hear how others are finding the power on and off functions are working even with single pickup guitars and powersupplied amps...

pete

[Fresh Fizz]

I am not sure what the SCT actually is from that diagram! It look kind of like a bi-lateral driver.

STC is a dummy coil but humbucker style and made out of copper foil. I've put it in between driver and guitar pickup. The idea behind is that it creates some sort of flux shield. I favour an all humbucking configuration: humbucker driver, humbucker pickup, humbucker STC dummy coil.

I got rid of the squeal. I'm still hearing some distortion, but I'm not sure it is the same fizz thing you are talking about. It's more that the string resonates with what it receives from the driver. And because I'm using heavy overdrive it's fundamental with a third (down the neck). It's not an unpleasant distortion it has a nice zooming quality. (Zooming as in: What would you rather be or wasp?) When I palm mute the strings and pick I have an undistorted sound (so no distortion on the pick attack).

I have to focus now on another problem area which is the low part of the high e-string. If you ask me what the problem with this string is I would say that it has to do with what the guitar pickup makes of the string movement. It looks like there is too little fundamental and 2nd and 3rd harmonics. It looks like the sustainer tries to build feedback on even higher harmonics but for some reason won't make it. And falls back onto those lower harmonics. Sustaining but weak sound. Maybe that's the Helmholtz motion, Col!

I have allready tried to change the overdrive character, more even harmonics instead of odd harmonics, but it doesn't make a lot of difference.

I think it will be worthwhile trying to power it with a remote source and it is probably about time someone tried the stereo lead power idea. I can't see anyone really wanting to operate the thing with remote power with the guitar plugged directly into a wall wart and the amp...such a hassle.

Well it depends on how much use of the sustainer device you're going to make. I can remember that Les Paul even wanted to have a microphone connected to his guitar.

I'd still like to hear how others are finding the power on and off functions are working even with single pickup guitars and powersupplied amps...

I only have pop noise when I switch on. I'm pretty sure I can fix this.

Fresh Fizz

[psw]

Hmmmm...

I will have to try and get some sound clips posted as I suspect that a lot of these fixes are to compensate for things that really shouldn't be happening with the standard formula and unlike the efforts of people like col, curtisa and avalon et. al., and myself...these strategies appear to be aimed at addressing problems that shouldn't really be as big an issue as they appear to be in these instances.

Perhaps if you heard how mine is performing you would have something to aim for as far as possible performance...remember with mine we are talking a low powered circuit with no preamp gain and a single coil driver. I think it is right to consider dual coil drivers, however if mine works this well with the minimum of noise, you have to ask why you get any squeal at all, fizz on low level sustain should be minimal if any while bearable and mask-able with overdrive on higher settings.

BTW...Les Paul did put a mike on a gooseneck on his recording LP as well as controls for multi-tracked tape players and stuff...it is all a part of his shtick...probably best not to emulate!!!

I think once you have a properly working sustainer in a guitar, you will make regular use of it and battery power will become an issue perhaps. Each to their own. But there is also an issue of consistency of performance too. There are a lot of sounds that are only available with this device (especially if you can run it pretty clean) and as a result, if it becomes a part of your "style" it will be indispensable.

Mainly I am back to a turn off "pop" but as I say, there may be an issue if the switches I have tried aren't true break before make switches. It is still a little inconsistent which makes me wonder.

Fizzy...have you tried disabling the overdrive part of the preamp stage to see how it would perform with a clean sound. Clipping preamps have been tried before however, it would seem that a better, cleaner less difficult signal for better efficiency is obtained with clean drive signals. I understand why you went in this direction, I tried it too...but I suspect you would get better results by going the other way.

Very early on I set up a single string with a driver and tuned the string to a note generator on a computer. I then tried feeding the driver various signals, sine, square, triangle...etc...all worked to a degree...but the true sound of the string (from a pickup) seemed to win out and the sine a bit quieter perhaps...still that was years ago and I don't recall it all that well...I just recall going down that road and having to come back a ways...

pete

[utopian isotope]

Brainstorming again.. Has anyone tested/used split power supply(be it battery or wall adapter) with sustainer?

Since it would give sustainer and driver its own ground, instead of using negative as earth. And maybe stabilizes sustainer(and driver) too?

I'd like to test that, but how do you feed split supply voltage to sustainer? Is there simple way to test this?

@col: is your drivers core earthed?

If not, try earthing the core and the plate above - does this make any difference ?

Yes I tested it, and unfortunately no difference.

[psw]

I have been on about this kind of thing for a while 'UI' and fizz suggested a voltage divider...I'm not sure that that would necessarily work either though...may help though and have yet work out quite what to do and to try it....

I am not sure that separate power is going to solve the problems miraculously. I did use well regulated power adaptors in the early days, if only to save on battery expense. Besides giving some unrealistic real world results (it did not equate to the battery that was intended to drive it), it also effectively connected the grounds anyway through the common ground rail of the circuit so as far as I can see, the driver and signal ground are intrinsically linked in our common circuits regardless of how it is powered. You may even encounter mains earth loops with the amp if your adaptors were grounded (which apparently, and typically, they are not).

If you look at any of our circuits, check even fizz's one above there is a direct link in the ground rail from the driver coil to the signal and so the guitar amplifier. While EMI effects are obvious, some may mistaken for distortions transmitted directly into the ground rail.

On an earlier question about grounding the driver coil...I don't and this is not advisable. Eddy currents are being built up in there and you don't want those transmitted to ground either. The effect (squeal) is immediately apparent if the strings which are grounded touch the metal poles regardless of the fact that there is no wired connection. The power of these forces are obviously being transmitted into my secondary coil, and this arrangement offers some tantalizing oportunities for experimentation (in the right hands, not necessarily mine!)

Over the last few days I have been running the device with the secondary coil shorted...it gives a very clean response and strong fundumentals...this morning went back to a 100k load resistor...previously I had used a 2meg pot all of which work fairly well. These loads are pretty variable but even a 100k load enables a dramatically more powerful response.

I have yet to make the "breadboard" adjustable version of my circuit (been a heatwave down here again) but perhaps this will give some more scope for tweaking. For instance, the LM386 has a both positive and negative input (pins 2 and 3) yet we tend to ground the negative as a reference...perhaps there is some scope there to address the grounding issue...or to run a cancellation signal or filter back into this and cancel out interference. The forces are pretty powerful, but I wonder if I could take the signal from the secondary coil and cancel out distortion/fizz effects in this way also. Perhaps an even more powerful effect could be achieved if the electromagnetically induced voltage from the secondary coil were to somehow drive the signal also...if controllable, it would seem that power (amp and battery) could be much smaller...though distortions are likely to be a big problem...and oscillation (squeal) very hard to control...

so yes...any ideas on virtual or more likely floating grounds (is that a term???) or ways to isolate the driver further from the signal?

pete

[Fresh Fizz]

so yes...any ideas on virtual or more likely floating grounds (is that a term???) or ways to isolate the driver further from the signal?

Hi Pete, I'm going to make a drawing of how I think the mass, ground, earthing whatever works best. As soon as it's ready I'll post it.

Over the last few days I have been running the device with the secondary coil shorted...it gives a very clean response and strong fundumentals...this morning went back to a 100k load resistor...previously I had used a 2meg pot all of which work fairly well. These loads are pretty variable but even a 100k load enables a dramatically more powerful response.

I have yet to make the "breadboard" adjustable version of my circuit (been a heatwave down here again) but perhaps this will give some more scope for tweaking. For instance, the LM386 has a both positive and negative input (pins 2 and 3) yet we tend to ground the negative as a reference...perhaps there is some scope there to address the grounding issue...or to run a cancellation signal or filter back into this and cancel out interference. The forces are pretty powerful, but I wonder if I could take the signal from the secondary coil and cancel out distortion/fizz effects in this way also. Perhaps an even more powerful effect could be achieved if the electromagnetically induced voltage from the secondary coil were to somehow drive the signal also...if controllable, it would seem that power (amp and battery) could be much smaller...though distortions are likely to be a big problem...and oscillation (squeal) very hard to control...

Wouldn't it be best to connect the secondary coil (= neck pickup ?) to the driver coil? (Driver coil and neck pickup in parallel). This can be done because the neck pickup has a much higher impedance. Meaning the load the lm386 sees stays allmost the same. Induction voltages are gone. ( Technically you don't have a transformer anymore, but 2 coils in parallel.)

Fresh Fizz

[psw]

Wouldn't it be best to connect the secondary coil (= neck pickup ?) to the driver coil? (Driver coil and neck pickup in parallel). This can be done because the neck pickup has a much higher impedance. Meaning the load the lm386 sees stays allmost the same. Induction voltages are gone. ( Technically you don't have a transformer anymore, but 2 coils in parallel.)

Interesting idea...hmmmm

So an 8 ohm coil and a 9000 ohm coil in parallel...I never thought of doing that...however...

It is not just about resistance...a coil with so many turns of such fine (and fragile) turns of wire is seeking some problems I suspect. Remember, the design is such as to be reasonably "fast" in response...more turns big high coil, may not be so efficient.

Actually, I don't think that my secondary coil is a "problem"... it seems to help things and is another element to play with.

Think of the secondary coil as a new kind of driver arrangement.

Anyway...still poping and it's eating batteries...so a little disappointing in that regard, but it is great when it is working properly (full battery and adjusted). Pop is still "turn off" only. I suspect that this is less a problem with dual coil drivers.

pete

[Fresh Fizz]

I hope this makes sense to somebody.

[col]

There seems to be a lot of work right now into alternative grounding schemes.

Has anyone worked out if this is even an issue (at least for there system)?

If all this work is based on hunches and guesswork, then not only might it be pointless, it might even cause more problems by making potential solutions to real problems more difficult to achieve.

It shouldn't be too difficult to find this out through experimentation.

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

@Pete regarding grounding of the driver core.

You said that this was a bad idea because you get squeal when you touch the strings to the ungrounded core on your setup.

Three things:

#1 It is very possible that grounding via the strings is going to cause oscillation due to earth loops (DC offsets?) and suchlike. Creating a proper earth connection in a 'star ground' formation (or some similar acceptable form) should not cause this problem.

#2 There is a big difference between having a constant earth connection from power up, and not having one, then making the connection after charge current etc. have had time to build up.

#3 This is born out by looking at the Sustainiac stealth driver which unsurprisingly has the magnet and core earthed

Another question for you - this time about the secondary coil business.

You've suggested that this coil is improving the response or drive in some way.

Is this when compared with the driver on the pickups core but with no extra coil, or just when compared with the other ways of wiring the secondary pickup coil ?

If its the former, then that is very interesting, if its the latter, then it doesn't really mean much at all.

Do you have a pickup to test with that has an easily removable coil ?

That would enable you to find out for sure what impact that pickup coil is having (assuming you haven't already done this of course )

cheers

Col

[utopian isotope]

Thanks for suggestions. Fresh Fizz, as I looked your schematic, is there any buffer between guitar and sustainer?

My current setup doesn't include any dedicated buffer, only an eq.

As those have common ground, turning sustainer's volume down turns also guitars's volume down. Strange that I haven't noticed it before..

Next I have to make some decent splitter/buffer, something like Craig Anderton's "spluffer". It uses an outdated ic's, so I have to re-draw the schematic.

It also uses split power supply, so we'll see what it has to offer.

Edited February 20, 2008 by utopian isotope