col Posted March 18, 2008 Report Share Posted March 18, 2008 Is anyone familiar with the Artec tone expander? http://www.artecsound.com/exp.html What sounded fine a while back is lacking oompf after putting the home made sustainer down for a few months...the circuit needs more gain than what I currently have, and I wonder if one of the above expanders might accomplish that? Do you mean that the basic guitar sound is not as good since installing the sustainer? Or just that you are not happy with your sound? If its the former, then there is probably some 'tone sucking' going on. You might need to try adding a second buffer, or using a different circuit to drive the sustainer - maybe something basic that is better than the fetzer/ruby will be available one day. I don't think the tone expander is the way to go - it will help in the same way any good high impedance input buffer will, but its hard to say how it will perform if its sharing a battery with the sustainer, and the only other option would be to have two batteries in there... not exactly ideal. If tone sucking is the issue, then a simple LM386 circuit with a 'through' buffer for the guitars output signal would be the best thing - and it DOES work, one of my early circuits had this feature, and my guitars sound without the sustainer on was better than it had been - clearer with a more open tone. No need for EQ of any kind, just a buffer! cheers Col Link to comment Share on other sites More sharing options...
col Posted March 18, 2008 Report Share Posted March 18, 2008 I have a dual blade driver in single coil format - and the sustain is weaker (on all 6 strings). would it be possible to take that apart and increase the gap between the two coils? My belief is that with a 'rails' configuration, you need a decent space between the coils. The field getting to the strings is dependant on 'fringing' effects, the fringing becomes larger (and more diluted) as the gap gets wider. I'm sure there is some optimum gap size, but for us, all things considered I think its probably about 13mm or whatever the width of a standard humbucker magnet is - this seems to give a field that projects far enough, and also makes finding a suitable magnet much easier. My guitar has a fairly high action, and my rails driver works well over the whole neck with it's standard humbucker sized gap. cheers Col Link to comment Share on other sites More sharing options...
psw Posted March 18, 2008 Author Report Share Posted March 18, 2008 Is anyone familiar with the Artec tone expander? http://www.artecsound.com/exp.html What sounded fine a while back is lacking oompf after putting the home made sustainer down for a few months...the circuit needs more gain than what I currently have, and I wonder if one of the above expanders might accomplish that? I posted this on the previous page...is that where you got the idea? I am considering building a dedicated driver to slot in the neck position, perhaps even exploring something like an expander circuit for the tone control for added sustainer response...something like this guitar fetish SRV expander although these appear to be a remarketing of artec products...artec expander. Such a unit might compensate for the loss of the neck pickup (which on a tele isn't so hot and not suitable for the piggyback idea) and improve tone control and perhaps even bring out all kinds of harmonic effects, plus it is a preamp which wouldn't hurt either... I was/am interested in this as a tone control, not as a preamp, although it my produce some interesting harmonic effects too. Col is right, if your guitar sound has changed, perhaps it is not being buffered right, if you didn't like the sound in the first place, then perhaps a buffer or preamp is the way to go. I am not even sure where to get the full artec range or if the SRV thing is the same. An active buffering or preamp on all the time does take some loading from the guitar lead and the pots away (upping the value of the tone and volume pots, perhaps 1Meg will provide more ommmph and brightness too) The sustainer was never intended to "improve" a guitars tone, just sustain it!! @FF Have you ever tried bridging the sustainer current on/off switch with a diode in opposite direction of the current flow? This should help against induction voltages. You are going to have to be more specific...what are you suggesting, can you draw something. Some of these signals may be AC and some strategies may affect the device in operation. I have a 4004 in the powersupply part of the circuit BTW...I also use an LED, could this cause a pop? Unfortunately the test guitar and device is incapacitated again due to partial rewiring...time to rewire, but am looking for suggestions. I'm still working on a new sustainer driver. My complaint with the current one I have is what I believe Pete calls a lack of throw. What was the old one? Jan you post pics, I don't recall if we have seen it...is it single coil? The same applies to pickups, HB's can and should be adjusted much closer to the strings, they have dual polarities with the two coils, a single coil with the single coil will have just one polarity pulling on the string, too close and you get wolf tones. Generally, single coils have a higher magnetic field which I call "throw", an analogy to a leaver I guess. A lot of the dual coil's magnetic energy is generated between the two opposing coils and less of it (indicated by the closeness of the field lines in FEMM) intersecting the strings. The closer the rails or poles the more this is true. I think that col might be right in the idea that my Hex design if not any design like this will have less "throw"...I am not sure, for the same reasons. A wider gap may produce a bigger bulge above the pickup and provide more action upon the strings. The bi-lateral is perhaps better in that it has two coils but they are spaced a fair bit and work across the strings in a narrower window...nice concept. Besides the other considerations and a desire to keep the thing simple, I have persevered with the single coil desigh for this reason. We have two strategies here. The dual coil drivers seek to limit the EMI by generating two opposing signals and by containing it via mutual attraction. I am seeking more throw and less power and am using design aspects like an extremely low profile to limit EMI. Both have their charms, both will work. However, my mid driver did have to be adjusted very close to the strings with a rail gap of less than 10mm. High up the fretboard it's sustaining beautifully. My sustainer seems to be capable to do what I haven't heard in the clips of you, a Jimi Hendrix or Adrian Belew-like reversed volume swell. I need to play more staccato because the strings are swinging so fiercely while sustaining. But low down the fretboard is a different story. It seems that the strings are a bit out of the magnetic field - I have a dual blade driver in single coil format - and the sustain is weaker (on all 6 strings). Yes well...your action is pushing the strings closer to the driver up high, col did some clever compensating AGC to try and address this BTW, the feed forward compressor ideas. I also find this less of a problem with a single coil driver with a lot of throw. Col uses an HB sized driver so the gap is a lot wider, I don't have a guitar that would suit such a device just now though I intend to do something like this and have wound one of the coils for it that will fit in the test strat. For a single coil size, the bi-lateral sustainiac style design provides the SC size with a wider gap, so something to consider for sure...let's see how curtisa makes out with his. Less throw seems to make the effects of the action much more evident. BTW Mine will do these reverse swells, it is one of the really cool non-sustaining effects, if you cut the notes short, it will sound like you are playing backwards as the notes swell and stop. I probably didn't demo anything to well yet, they were all done pretty quickly. It is something that everyone can enjoy with this and is in no way linked to the number of coils or driver type, it either works or it doesn't. My new driver won't improve the throw. At least that's what I think. I hope that it will reduce the amount of fizz I'm experiencing. A lot of fizz or rather EMI reducing strategies actually are intent on reducing the throw...containing the magnetic field. However, on some you may have to give it more power to compensate, defeating the purpose and so an ideal needs to be reached...as with all things on this it is a balancing act. If you are having fizz problems, perhaps you are getting more or you could reduce it by losing the clipping in the preamp and greatly reducing power if you are still driving it with 2.5 watts and remote power. This means it is not enough to prevent the sustainer amp + driver to distort, the output level needs to be as low as possible to avoid the fizz phenomenon. So was the experiment that you moved this magnet 1-2,000 times a second by hand? Moving a magnet over a pickup will generate a signal, what you are hearing is the sound of the magnet moving I suspect, and probably a pretty loud signal at that because it is a magnet, not just a metal string. But this is the theory, that EMI (electromagnetic interferance) is generating distortions. You may be right, but if EMI is necessary (without it putting out EMI it wont be putting out string moving energy at all...say if it were completely controlled) and if it is that it is unavoidable that some of the driver signal were to be "picked up" by the pickup, then that signal you'd want to be clean. If you listen to your circuit through a speaker on a high gain then listen to the fizz distortion, I think I can hear similarities in character and that the fizz changes with this. An LM386 is going to distort a lot if pushed hard for instance, I have been running them now with very low gain and no gain in the preamp with only a hint of fizz in the lower strings perhaps...more power, more fizz/distortion...but could it be that at lower power the circuits signal was considerably cleaner, that perhaps you could hear the character of the circuit behind the note, but being clean, it doesn't come across as fizz? My attraction to the idea of larger amps is that perhaps you could achieve less distortion, more clean headroom...not a desire to run it to the max! It's a theory anyway. ------------- I made a driver yesterday for my tele, but it got destroyed...grrrr...it looked so cool. I made a thin tortoise shell top bobbin plate (a theme on some of this guitar) with six 3mm screws. Under this 1mm plastic I put 3mm deep nuts. This produced a coil compact enough to fit between the chrome tele neck pickup and the neck....made the two together look like a matching pair or HB, one chrome the other tortoise...lovely! However, to hold it tight I used longer bolts right through the winding bobbin that I tried to remove...the result was with all the epoxy, some of the nuts inside the coil turned stripping the inside of the coil and shorting the entire thing out...don't you just hate that, it looked perfect! I dug around last night and found two suitable 20x4x4mm ceramic magnets with edge polarities. These would be ideal as cores for a very small drivers IMO in a bilateral design. However, I have to wonder about the effect such magnets would have being so close to the neck pickup...also, this is a SCN pickup which has rare earth magnets in the mid side, a far stronger attraction to the side than to the poles!!! It would have to change the sound a bit, which is perhaps ok...but also, it would have to change the sound between the lower and higher strings...wouldn't it?...not so great. If such a driver really did work, I suppose it could be used in the middle and avoid such problems...hmmm...let's see how curtisa goes there too. Any opinions of this? I might use them to make two coils of the same polarity in series...so effectively a single coil kind of thing with internal magnets... This is not a guitar that I want to do too much experimenting with, it is too good for that and it is taking a lot of time because I get nervous every time I drill a hole in it!!! It has some interesting features and I was finally able to find a solution for the fitting of the HB which really was holding it up. This HB is a lot wider than a gibson so nothing fits and is attached with 4 bolts and springs and a large cavity that will need to be hidden but keep in character with the whole project, if not enhance the look. I am intendeing to use the sapce below the bridge HB for circuitry and stuff that obviously wont fit in the tele cavity. The tele control cavity however is attaced with two screws and is exactly wide enough to hold a battery below the pots...so that side of it is sorted if I can keep the area clear in there. I'd really like a sustainer in there, almost to the extent of making it as a tele pickup and having no neck pickup at all, solving all the problems, but I'd prefer to have the versatility of multiple pickups (I like combined selections). Hence bring up the expander idea...is there a way to get a neck pickup sound, with a bridge only pickup guitar? Anyway...my experimenting has messed up the house and after a week of earing heat here, I hope to be able to clean up and get some work done at home...keep up the good thinking and the good experimenting and good luck top all... pete Link to comment Share on other sites More sharing options...
Captainstrat Posted March 19, 2008 Report Share Posted March 19, 2008 Do you mean that the basic guitar sound is not as good since installing the sustainer? Or just that you are not happy with your sound? Neither, I fixed the fizzies 6 weeks ago, that's not the issue. I don't think the circuit I originally built has enough gain. To save space I ended up using fixed resistors rather than pots - well I did use a trimpot for the volume, in retrospect I should have done this for both the gain and volume functions, it might have saved me this headache... What I don't get is that I was getting good controlled feedback when playing through my J-Station some 6 weeks ago...I tried the same thing through my newly acquired Fender Champion...the notes won't feedback, they just decay much too fast. And it's not a matter of weak batteries either as I've figured out a way to use my Variax's power supply to power up the diy sustainer (Yes I own a Variax, no I didn't mount the sustainer in the Variax, I mounted it in my Stratocaster and I replaced the standard jack with a stereo jack to supply power to the circuit- just take my word for it, it works! ). I was perusing Ebay and came across the expander circuit, and I liked the space-saving design, mounted at the back of a push-pull pot, in a circuit much more compact than my all-thumbs soldering capabilities could accomplish... If a power amp section could be attached to the Expander circuit I could avoid the current tangled mess of wires under the Strat's pickguard and feed a hot enough signal to the driver. Because I'm pretty sure that's the problem right now: not enough juice going through the driver... Link to comment Share on other sites More sharing options...
psw Posted March 19, 2008 Author Report Share Posted March 19, 2008 I was perusing Ebay and came across the expander circuit, and I liked the space-saving design, mounted at the back of a push-pull pot, in a circuit much more compact than my all-thumbs soldering capabilities could accomplish... Ok...can you tell me where on ebay you saw it because other than guitar fetish who has some of this stuff relabeled as SRV, etc, I don't know where to get it, they have quite a big range. Also, I got a mini-amp from GF with a JRC2073 2.5 watt BTL chip in it...very neat but have not got to doing anything with it. I am interested in higher power for clean headroom. This amp will require a buffer or preamp for this application though. Also, there are no fancy AGC's or anything...just a raw poweramp. It is small, but slightly larger than my present circuit design I don't think the circuit I originally built has enough gain. To save space I ended up using fixed resistors rather than pots - well I did use a trimpot for the volume, in retrospect I should have done this for both the gain and volume functions, it might have saved me this headache... If it is LM386 based, the gain between pins 1 and 8 is controlled by less resistance. Therefore for max gain simply put a jumper between these two (no resistance)...but better yet is to attach them with a 10uF capacitor to avoid oscillation. A 1k trim pot is what I use for gain control, my sustainer will work with 1k on there and no preamp gain. What I don't get is that I was getting good controlled feedback when playing through my J-Station some 6 weeks ago...I tried the same thing through my newly acquired Fender Champion...the notes won't feedback, they just decay much too fast. So...if you plug it into the J-station, will it work as before? Perhaps we need to know a little more about this circuit. The j-station like most stomps have preamps that, like an onboard preamp may help with loading issues. It sounds very much like that without something like this straight into an amp, your guitar signal is so loaded down that the tone and the circuit are suffering...definitely sounds like a loading problem. So...if this is the case, then perhaps making the guitar active with some kind of circuit like this would help. Also, you may get some interesting harmonic effects. Perhaps some pics, sound and definitely details will help with an assessment. And it's not a matter of weak batteries either as I've figured out a way to use my Variax's power supply to power up the diy sustainer (Yes I own a Variax, no I didn't mount the sustainer in the Variax, I mounted it in my Stratocaster and I replaced the standard jack with a stereo jack to supply power to the circuit- just take my word for it, it works! wink.gif ). I'd love to know more about this. I was/am in the process of trying to power it with a stereo lead, I thought the variax required a multi-pin plug, not a standard stereo to work, or are you just using the power supply with a lead you made up. Either way...more details please! I had forgotten about the variax, I thought you had put it on a variax, or someone had, and then nothing more was heard. I really like the idea of using it with the variax and a lot of people have asked, but I don't know where you would take the signal from it's circuit to power the sustainer's. The piezo system though would be ideal as EMI would not be a problem for it, nor I suspect would switching! Because I'm pretty sure that's the problem right now: not enough juice going through the driver... Beware though, more power means generally more problems. The idea of making more efficient drivers is to reduce EMI and so allow the use of more power, but mainly an attempt to make it work on as little power as possible so that, that in of itself reduces EMI. So...a dual rail driver may benefit from more power and you may get away with it because of it's EMI suppressing capacities, but the end result may be the same as a simple single coil with more throw and less power. I am contemplating making a bi-lateral myself now though, in an attempt to install it into the middle position, something no single coil is ever likely to be able to do on it's own. And, the rail thing kind of worked but man did the closeness of the device to the strings in this position get in the way for me. I was also thinking about my short lived experiment in side coil drivers. I think I have only made one, this was very compact with a very small gap between blades, maybe 4mm and 3 blades, so perhaps 10-12mm wide. It failed to work at all well on it's side, but untill it broke , it worked remarkably well as a stack separated by steel blades, go figure. The middle blade was the opposite to the two outside blades in polarity and the centre twice as strong magnetically...errrr, I think. I am not sure that the side driver is such a good idea, although it was in production and obviously worked for fernandes for a while there. But, if it were to work, again perhaps col's idea about distance between blades being important is something I should have factored into the design. Now of course, if you have fixed the fizz problems and have it in a strat, you know I have to ask how you were able to fix these problems. I have not that much trouble with fizz myself except at high gains, but do you have a silent switching solution? pete Link to comment Share on other sites More sharing options...
Fresh Fizz Posted March 19, 2008 Report Share Posted March 19, 2008 @captainstrat I am considering building a dedicated driver to slot in the neck position, perhaps even exploring something like an expander circuit for the tone control for added sustainer response...something like this guitar fetish SRV expander although these appear to be a remarketing of artec products...artec expander. Such a unit might compensate for the loss of the neck pickup (which on a tele isn't so hot and not suitable for the piggyback idea) and improve tone control and perhaps even bring out all kinds of harmonic effects, plus it is a preamp which wouldn't hurt either... I was/am interested in this as a tone control, not as a preamp, although it my produce some interesting harmonic effects too. Col is right, if your guitar sound has changed, perhaps it is not being buffered right, if you didn't like the sound in the first place, then perhaps a buffer or preamp is the way to go. I am not even sure where to get the full artec range or if the SRV thing is the same. An active buffering or preamp on all the time does take some loading from the guitar lead and the pots away (upping the value of the tone and volume pots, perhaps 1Meg will provide more ommmph and brightness too) The sustainer was never intended to "improve" a guitars tone, just sustain it!! This change of tone is explained in the sustainer patents. The sustainer in operation pushes away the magnetic field of the pickup towards the bridge. Because of this the tone thins out. I haven't experienced it myself but I've read about it. @psw Have you ever tried bridging the sustainer current on/off switch with a diode in opposite direction of the current flow? This should help against induction voltages. You are going to have to be more specific...what are you suggesting, can you draw something. Some of these signals may be AC and some strategies may affect the device in operation. I have a 4004 in the powersupply part of the circuit BTW...I also use an LED, could this cause a pop? Unfortunately the test guitar and device is incapacitated again due to partial rewiring...time to rewire, but am looking for suggestions. I'm only referring to the switch that switches on the power of the sustainer amp, the fetzer-ruby. The one that connects/disconnects the battery. You could try to bridge that switch with a diode in opposite direction of the current flow. This is also being done in circuits with relays. So was the experiment that you moved this magnet 1-2,000 times a second by hand? Moving a magnet over a pickup will generate a signal, what you are hearing is the sound of the magnet moving I suspect, and probably a pretty loud signal at that because it is a magnet, not just a metal string. But this is the theory, that EMI (electromagnetic interferance) is generating distortions. You may be right, but if EMI is necessary (without it putting out EMI it wont be putting out string moving energy at all...say if it were completely controlled) and if it is that it is unavoidable that some of the driver signal were to be "picked up" by the pickup, then that signal you'd want to be clean. Well, if I could move a magnet that fast Yngwie Malmsteen should better quit playing the guitar. No, I mean 1 or 2 times per second. And because of that movement I hear overtones of the string when played. What I was saying is that when it's fizzing you don't hear tones from the driver that bleed through. It's more that the driver causes the magnetic field of the pickup to fluctuate. And because of this fluctuation there is fizz. I don't think there is anything revolutionary about my remark and in some way we have to live with the fizz but I think that the magnet experiment shows that there is no qualitative relationship between the sounds the driver produces and the overtones that are heard as fizz. It's more the quantity of the flux produced by the driver that determines the fizz. @col and @psw My humbucker driver in single coil format looks almost like a Seymour Duncan Cool Rails. It has 2 thin blades and ,yes, maybe the gap between the blades is too narrow for a sustainer driver (only 7mm). I could modify the driver but I like its looks. First build the new driver, then test it and then I'll decide what I do next. Cheers FF Link to comment Share on other sites More sharing options...
psw Posted March 19, 2008 Author Report Share Posted March 19, 2008 This change of tone is explained in the sustainer patents. The sustainer in operation pushes away the magnetic field of the pickup towards the bridge. Because of this the tone thins out. I haven't experienced it myself but I've read about it. Hmmm....I don't ever recall reading this...but that doesn't mean it isn't there. I can see how putting a magnet or driver next to an existing pickup, as I am considering with my tele, would radically change the magnetic field...with traditional skinny tele neck pickups, possibly not a bad thing!!! I don't see how a neck driver could effect the bridge pickup though, too far away. I don't experiencing any thinning of the sound except in harmonic mode, but I think this is to be expected as it is playing pure harmonics which are thinner, that is the way the string vibrates. If anything, I get a thicker sound at higher gains with the added distortion....hmmm I'm only referring to the switch that switches on the power of the sustainer amp, the fetzer-ruby. The one that connects/disconnects the battery. You could try to bridge that switch with a diode in opposite direction of the current flow. This is also being done in circuits with relays. Still not quite sure what this is, however for a long time I have added a power protection diode to my circuits. This is a power diode (4001 I think) reversed between the positive and negative so that if the battery were reversed, no harm would come to the circuit...but perhaps you are suggesting something different. Actually, the pop comes I think from a sudden release of power from stored in the pickup coils when the are reconnected. The only suggestions that seems to be hopeful at the moment is a delayed switching so that this power is released before the pickups are reconnected back into the circuit. This seems to be what sustainiac is doing with the electronic switching but this is not an area that I have a lot (or any experience in) and I am not sure it will be simple to design if you don't really know what causes it and how to resolve it. For instance, if this theory is correct and I was to create a delay, what is to stop the power draining simply a little delayed so you just get a delayed pop?! A lot of trouble if you don't know that this is a solution...I don't think I am up for that at the moment, I have a very low frustration threshold at the moment so probably best I don't push that issue, or any other...but still, open to suggestions or further explanations... It's more that the driver causes the magnetic field of the pickup to fluctuate. And because of this fluctuation there is fizz. Hmmm....kind of, I hear what you are saying, basically this is how the sustainer signal is being transfered magnetically to the pickup and into the guitar signal...in effect the pickup is hearing the sustainer circuit. Now, either you move the driver further away so it can't hear it, make a more efficient EMI reducing design that does not affect the bridge pickup's magnetic field, reduce the power, or accept that there will be some interaction and make sure as far as possible that the signal affecting the bridge pickup is as clean as possible...hence my reservations about the clipping preamp. I don't think there is anything revolutionary about my remark and in some way we have to live with the fizz but I think that the magnet experiment shows that there is no qualitative relationship between the sounds the driver produces and the overtones that are heard as fizz. It's more the quantity of the flux produced by the driver that determines the fizz. So on this, we disagree I guess. Basically, as a theory (I may well be wrong), fluctuations in the driver are an analogue of the signal going into it. So, it is a magnetic version of the bridge pickup coloured by the circuit and the drivers ability to reproduce it. So, if these fluctuations are moving about and being picked up by the pickup...perhaps traveling along the steel strings for instance, it is hearing itself. Too much and you get squeal or oscillation, the fizz is often a precursor to this, so nearing oscillation threshold. If you can get the effect well below the oscillation threshold it will be relatively fizz free as in my driver. But the little circuits tend to be driven pretty hard and in listening to it with a speaker you can hear it is distorting. Adding clipping preamp will raise the harmonic content and give it some clipping compression which may help produce the sustain effect remarkably, but it wont eve run clean if the bridge pickup hears it. If you get what I mean. Anyone want to support or explain this better...or prove it wrong? @col and @psw My humbucker driver in single coil format looks almost like a Seymour Duncan Cool Rails. It has 2 thin blades and ,yes, maybe the gap between the blades is too narrow for a sustainer driver (only 7mm). I could modify the driver but I like its looks. First build the new driver, then test it and then I'll decide what I do next. There is no reason why it can't work...they have been made commercially...here's one by kramer baretta driver... notice also the metal piece on the pickup side of the driver as well. And I don't think you were around during the whole debate and building of rail drivers, but I built this "mid-driver"... Also, are people aware of the fernandes old side driver...here's a pic from the patents... I guess I just broke all the picture/post rules here... I am pretty certain that I will try and make my own version of a bilateral driver as I have some perfect magnets for it and I have a couple of telecasters, one in particular that I would like to use it on. I imagine that if a mid driver is possible then I could build everything outside of the guitar as with the old "sustain box", perhaps even dig this out, as if it works then all you would have to do is turn it on right, no bypassing. If small enough (as I hope to do) then it would perhaps surface mount so I could slip it under the strings and tape it down at least for testing. What I have is a pair of edge magnetised 20x4x4mm ceramic magnets. I was thinking of using these for the core and wrapping around a series pair of compact 4 ohm coils in 0.2mm wire. I expect these ceramic cores to be "fast" and being non conducting have low impedance effects and eddy currents in them. The cores being magnets means the total depth of the driver should be little more than 4-5mm. I could do 2x16 ohm coils in parallel but I have a "feeling" that it would be such a departure from the "formula" that I would need to consider different wire gauges and such. As with the previous mid-driver attempt, I am attracted to the idea not so as I can get sustain with different pickups (that's a bonus) but because switching it on would be so much easier...just like a single pickup guitar. I am reluctant to "copy" the sustainiac design, but there is a lot of sense to it and really it is something that someone should have tried a long time ago, it is kind of odd that for all the drivers I have made (there have been a lot), I have not made this design (unless you count the hex drivers as an elaborate extension of them). I guess it would be prudent to see how curtisa gets on with his, but I am concerned about the idea of putting it between two HBs and expecting it to work...that is very close to both pickups so EMI is going to be very hard to avoid. Bear in mind that although they have a patent for the mid-driver on a strat, they never made a commercial version. However, I hope people have listened to Dizzy's mid driver clip, he did get it to work and work well, at least on a single coil strat so it must be possible...and he used a linear LM386 to do it, which also bodes well in my book. As FF was saying, the magnetisim of the driver pulsing affects the bridge pickup, imagine how much greater the effect if you try and run the thing this close to the pickup...fingers crossed curtisa, do you have a plan b? good luck... pete Link to comment Share on other sites More sharing options...
col Posted March 19, 2008 Report Share Posted March 19, 2008 Do you mean that the basic guitar sound is not as good since installing the sustainer? Or just that you are not happy with your sound? Neither, I fixed the fizzies 6 weeks ago, that's not the issue. I wasn't referring to fizz, but to tone sucking which is a different problem. I don't think the circuit I originally built has enough gain. To save space I ended up using fixed resistors rather than pots - well I did use a trimpot for the volume, in retrospect I should have done this for both the gain and volume functions, it might have saved me this headache... What I don't get is that I was getting good controlled feedback when playing through my J-Station some 6 weeks ago...I tried the same thing through my newly acquired Fender Champion...the notes won't feedback, they just decay much too fast. If you were getting controlled feedback at low volume with your J-station 6 weeks ago, then there is nothing wrong with the gain settings on your circuit (if you were playing at a loud volume, then its impossible to tell - becuase there will have been at least some acoustic feedback). Assuming that the feedback 6 weeks ago was caused by the sustainer, then there are a number of possible reaosns why its not working now, and gain setting is not one of them! * power supply - if this has been changed, it is a possible cause, try going back to your original power supply - fresh (and tested) battery. * change in the guitar - have you switched the strings to a different guage or type? different types of string have different properties, it is likely that some are better for sustainers than others. * change in the guitar #2 - has the setup been modified, action changed (this can happen with different strings if you have a trem) * change in the guitar #3 - has the pickup height been adjusted ? * change in the circuit - I fear that this is a likely problem for all of us using the LM386 based circuits. Many folks including Pete and me have had initially great results, and then over time been less happy with the performance of their systems. I have been wondering recently if this is because we are pushing the amp chip too hard and it is basically dying on us slowly, or becoming damaged and therefor working less well. I did some checking up recently using figures from the datasheet and a simulation, and I reckon that this is highly likely! e.g. my system went from really good harmonics to poor harmonics, and I couldn't understand why, but if there was damage to the LM386, that might kill its high frequency response.... It is possible that your system worked ok with the battery becuase it limited the available current, but when you switched to the external power supply, it was able to supply more current and that crippled the amp IC? Lots of possibilities, but using basic logic, if the thing sustained well 6 weeks ago, and you haven't changed the gain setting since then, then the gain setting is not the problem. If the output of the amp has been effected by damage to the chip, then boosting the gain by adding a bigger preamp, or increasing the gain with a pot isn't going to help, it will probably sound good for a few minutes, then just make it worse. If a power amp section could be attached to the Expander circuit I could avoid the current tangled mess of wires under the Strat's pickguard and feed a hot enough signal to the driver. Assuming that the phase response of the preamp and the poweramp sections you buy are linear, then it might work. If you can get data on the phase and on how much current the amp can take, and they are good, then go for it. cheers Col Link to comment Share on other sites More sharing options...
col Posted March 19, 2008 Report Share Posted March 19, 2008 I don't think there is anything revolutionary about my remark and in some way we have to live with the fizz but I think that the magnet experiment shows that there is no qualitative relationship between the sounds the driver produces and the overtones that are heard as fizz. It's more the quantity of the flux produced by the driver that determines the fizz. What your magnet experiment shows is that waving a magnet around above the pickup can cause some fizz. It doesn't explain why, and it doesn't show that it is the only possible source of fizz either. Have you considered that your magnet may have been causing saturation in the pickup due to increased flux density, and that this alone could be causing the fizz you heard - if this is the case, then its unlikely to be a problem for us until we start trying to position the sustainer very close to the pickup. Or maybe your magnet was increasing the inductance of the pickup enough to cause clipping in your amps input section? There are other possible explanations, but the main thing is: don't jump to conclusions. It's an interesting experiment with interesting results, but it's just one of many things to factor in.... besides, it's already been proved that it is possible to get a sustainer working well with no audible fizz. cheers Col Link to comment Share on other sites More sharing options...
col Posted March 19, 2008 Report Share Posted March 19, 2008 There is no reason why it can't work...they have been made commercially...here's one by kramer baretta driver... ... notice also the metal piece on the pickup side of the driver as well. One of the possible reasons for the metal edge strip is to help pull the field our more in order to help it project further - might be worth a try on a narrow rails driver ? Link to comment Share on other sites More sharing options...
Fresh Fizz Posted March 19, 2008 Report Share Posted March 19, 2008 What your magnet experiment shows is that waving a magnet around above the pickup can cause some fizz. It doesn't explain why, and it doesn't show that it is the only possible source of fizz either. Have you considered that your magnet may have been causing saturation in the pickup due to increased flux density, and that this alone could be causing the fizz you heard - if this is the case, then its unlikely to be a problem for us until we start trying to position the sustainer very close to the pickup. Or maybe your magnet was increasing the inductance of the pickup enough to cause clipping in your amps input section? If saturation was the case wouldn't I also experience fizz when keeping the magnet still above the pickup? It wasn't even my intention to generate fizz. I was thinking of mounting a magnet above my sustainer driver to create a more homogenous flux field to get more "throw". So I was checking how the bridge pickup performed with the magnet above it. I didn't notice much difference except when waving the magnet. It's an interesting experiment with interesting results, but it's just one of many things to factor in.... besides, it's already been proved that it is possible to get a sustainer working well with no audible fizz. True, I can get fizzless sustain high up the fretboard but then it's impossible to get good sustain in low fret postions. Maybe my current driver is a lousy piece of crap in a kramer barettas disguise. Doesn't matter. There is a new baby coming. I think that the metal piece in the kramer serves as magnetic shield. FF Link to comment Share on other sites More sharing options...
Captainstrat Posted March 19, 2008 Report Share Posted March 19, 2008 Ok...can you tell me where on ebay you saw it because other than guitar fetish who has some of this stuff relabeled as SRV, etc, I don't know where to get it, they have quite a big range. Also, I got a mini-amp from GF with a JRC2073 2.5 watt BTL chip in it...very neat but have not got to doing anything with it. I am interested in higher power for clean headroom. This amp will require a buffer or preamp for this application though. Also, there are no fancy AGC's or anything...just a raw poweramp. It is small, but slightly larger than my present circuit design Right here, the seller's called GuitarHeads : http://stores.ebay.ca/GuitarHeads The circuit in itself has lots of possibilities. As far as my DIY Sustainer goes...I'm this close to throwing in the towel. I tried it again through the J-Station last night and guess what? The controlled feedback is more evident when using a dirty, heavily compressed patch. Through a clean patch: same results as through the Fender Champion; which is no "in your face" controlled feedback. Sooo...I might as well admit that my stubbornness isn't enough to see this through. My electronics knowledge is spotty at best and my soldering technique is severely lacking. I'm seriously considering to restore my Stratocaster to its former glory: 3 Dimarzio Virtual Vintage pickups and the standard switches and knobs. I might add the expander circuit out of curiosity, but as far as my version of the DIY sustainer goes...it doesn't cut it, plain and simple. Still, it was fun to give it a shot! Link to comment Share on other sites More sharing options...
psw Posted March 19, 2008 Author Report Share Posted March 19, 2008 Ok...can you tell me where on ebay you saw it because other than guitar fetish Right here, the seller's called GuitarHeads : http://stores.ebay.ca/GuitarHeads The circuit in itself has lots of possibilities. As far as my DIY Sustainer goes...I'm this close to throwing in the towel. I tried it again through the J-Station last night and guess what? The controlled feedback is more evident when using a dirty, heavily compressed patch. Through a clean patch: same results as through the Fender Champion; which is no "in your face" controlled feedback. Sooo...I might as well admit that my stubbornness isn't enough to see this through. My electronics knowledge is spotty at best and my soldering technique is severely lacking. I'm seriously considering to restore my Stratocaster to its former glory: 3 Dimarzio Virtual Vintage pickups and the standard switches and knobs. I might add the expander circuit out of curiosity, but as far as my version of the DIY sustainer goes...it doesn't cut it, plain and simple. Still, it was fun to give it a shot! Great...I am very tempted to try this thing...postage is high, but the buyer beware $27 for the unit $21 in shipping...hmmm, might have to find another way, perhaps guitar fetish is cheaper, maybe I can find someone down here or in asia... A shame if you bow out, but this is exactly the reasons that I have been trying frantically to produce a "commercial" version of this, or at least my ideas which other's could build on or go their own way with. A driver coil and circuit with instructions to make it work...but it is no good if it is so specialized that it only works with unusual pickups or if there is switching noise. It still could be a loading issue or the driver build. I don't really know, I doubt that you can kill an LM386, I've soldered them in backwards, heated them up severely all kinds of destructive things that would have killed most things over the years, and have had DIY sustainers running for years with the things, it is one of the appeals of the things. The controlled feedback is more evident when using a dirty, heavily compressed patch. Through a clean patch: same results as through the Fender Champion; which is no "in your face" controlled feedback. This kind of suggests that you were getting some controlled feedback and the j-station compression and distortion was bring this very low level sustain up...again perhaps loading or driver inefficiency. More power won't help if it is loading, though a preamp would. It also highlights the need to test the things clean. It is easy enough to get fairly long sustain with super processed distorted sounds and simple try squarewaving old school fuzz boxes can produce it at very low levels acoustically through an amp. And that sound and styles associated with it do lend themselves to such sustain techniques. Clean sustain is something very rarely heard and so very little music is about to inspire, mainly because this device is so rare that few people can create it. Also, it is interesting to note that lots of people own ebows, yet they are rarely prominent or featured on records of any commercial note. The only famous song is U2's "still haven't found what I am looking for". Musically to me it inspires a more vocal like lines for lead playing or perhaps instruments like pedal steel guitars that have super long sustain and very clean. Santana is of course the king of controlled feedback and it is essential to his style. That whole compressed bee in a jar like metal tone, especially some of the presets on these digital units are a bit much really and destroy the guitar's tone and subtlety and dynamics. It makes anything but power chords and riffs sound like mush and all the detail of the notes are lost, IMHO. Don't get me wrong, I like distortion but it is kind of limiting overall and everything can start to sound pretty similar...plus it hides a lot of player's technique for better or worse, try doing those 80's tapping riffs really clean, not easy is it! I might add the expander circuit out of curiosity, but as far as my version of the DIY sustainer goes...it doesn't cut it, plain and simple. I am not sure what "your" version of the DIY sustainer was but a lot of mine went this way and many times, including right now as it happens, I have felt like throwing in the towel. It is not an easy thing to do to start with, making alterations to the design can have a big impact and even if you follow the guidelines, inconsistencies in build can have a serious effect on performance. Everyone working on their own, despite this thread, and describing what well might be quite different symptoms like "fizz" doesn't help. Even people with good circuit skills and soldering have had problems with the arts and craft aspects (coil winding, bobbin building, etc) and I have met lots of people who are very knowledgeable fail to grasp the problems associated with a device that conceptually seems quite simple...a reverse pickup, etc. Stubbornness, I guess my main attribute and not wanting the thing to beat you, are probably important and in the end will eventually find the solution. My new version for instance works remarkable well for what I want from it except for the switching, but I have now being doing this for years banging my head against this wall, I have made a dent in it, but this switching thing (not really a performance issue) is the big killer for me. This is an issue where I don't think pure stubbornness is going to pull me through, you have to make a lot of failures and my constitution isn't up to the frustration the way it used to be. I used to be ok about this, even enjoying the lessons learned, but right now this is really getting to me. So, I have put it aside and considered a few other things for now, but I know it will get to me and I will return once something or someone inspires something new. Anyway...leave it for a bit, keep everything and perhaps something will come to mind or you will see or hear something hear that will inspire, perhaps even I will solve the problem with my project and make available coils and circuits to give people a jump start for a successful build or a platform to develop things further. Best of luck, and hang around... pete Link to comment Share on other sites More sharing options...
utopian isotope Posted March 19, 2008 Report Share Posted March 19, 2008 (edited) @psw: One problem that should be obvious in making any kind of plastic molded part is that you need to have a part to take a mold from. So, you have to be able to make the perfect model, make a mold and make a successful cast from a mold...all very tricky and specialized skills. If you can do the first, for a one off, the rest is redundant. (Almost) perfect template can be made, if you have accurate reference(s). For example, I used four similar ball bearings when filing test piece. Ball bearings have an exact diameter and they are hardened, so they don't wear easily. Maybe that picture explains better what I mean: Ball bearings effectively keep you from filing too much. Takes some work, but resulting piece is most accurate, that you can make without cnc. Edited March 19, 2008 by utopian isotope Link to comment Share on other sites More sharing options...
psw Posted March 19, 2008 Author Report Share Posted March 19, 2008 There is no reason why it can't work...they have been made commercially...here's one by kramer baretta driver... ... notice also the metal piece on the pickup side of the driver as well. One of the possible reasons for the metal edge strip is to help pull the field our more in order to help it project further - might be worth a try on a narrow rails driver ? Maybe...one of the novel things I put into my mid driver were rails not only in the core but on the outer edges...so effectively 4 blades. The design was so radically different from what I had been working on (these had parallel 16ohm coils with 0.2mm wire, a lot of eddy current inducing metal in their that was largely aesthetic I guess ). I never really experimented too much with it, building only the one. I did find it took days to build whereas I can do single coil types very quickly. I also built it specifically for the middle position, a tall order for any design. If you recall, Avalon had a lot of success with a dual coil design in HB format. For any future new designs for me, I guess I would be looking at carrying over what I know has worked, so a bit conservative even if they are different from the sustainiac model. For instance series coils with 0.2mm wire and thin coils in a compact bi-lateral format appeals...but really, perhaps a dual coil design is quite different and needs a new approach and new specs (as with what curtisa is attempting). There is still a lot to be explored, so many variations and applications but it is frustrating futzing around making the thing run at all and not getting into improving the performance, response and effects possible from it. Perhaps I would be better advised to quit with the multi-pickup angle and build what I have into a guitar with a single pickup and driver and look at these things, after all I don't have a switch noise problem in this format and apparently you guys don't either. If I do, I guess my candidate would be a telecaster, ultimate clean and sustain and the neck pickup isn't that great anyway, no pesky mid pickups...hmmm....now I feel a bit of the old bug coming on, and I have a tele here, my house is full of half finished guitars at the moment though....grrr pete Link to comment Share on other sites More sharing options...
utopian isotope Posted March 19, 2008 Report Share Posted March 19, 2008 (edited) My addition to diy porn section... I made a mold out of candle wax, and poured epoxy glue to it. Slowly it goes.. as it takes 16 hours to cure. Candle wax might not be the ideal material to make a mold, as some epoxies could melt it. ---------------- For those, who wonder what I'm talking about, answer is simple; to find an easy way to make bobbin(s) of desired size for desired driver. Edited March 19, 2008 by utopian isotope Link to comment Share on other sites More sharing options...
psw Posted March 20, 2008 Author Report Share Posted March 20, 2008 Nice ideas there, of course the traditional material is modeling clay...you can get epoxy putty for instance that will dry strong and sand for making prototypes or even one off bobbins and such if you want to go to all this trouble, but it is probably not worth that much effort. Similarly finding ball bearings exactly the right size, and 4 of them at that is going to be tricky and expensive. Better to use a ball bearing router bit or something. Keep thinking though, but unless you want to make a lot of them, you may as well glue things up in pieces. These things don't have to look as "pretty" as all that and a bobbin doesn't make for a good coil...it's all in the winding and effective potting. If it works, you can pretty it up later by casting it in resin or something. --------- I did a little FEMM of the bilateral magnets that I am considering using for my version...I don't think I am going to get out of trying this, and in a mid position at that... A surprising amount of throw there and I had not anticipated the ends being so hot. I don't know why the lines appear to cross in the middle, this would be an impossibility (probably two V's). Magnetic lines don't cross and with this design the lines from one magnet need to travel quite high to be attracted to those on the other side. However, this program is not 3D so it is hard to visualize what is happening in the other dimensions. For instance, looking end on or from above, what is the field doning to the sides, is the field thrown wide here to, or kept in close...if wide, this would be very bad, but then this would defeat the purpose of the arrangement and the throw is most likely above and below. A 2D model like this is tricky, the lines of magnetism are attracted to the nearest opposite pole without crossing, obviously quite a bit will be attracted to the underside of the magnet as in the ends in this model. Does the depth of the core/magnet help to keep the preference to the opposite magnet and less to it's own underside? These things are particularly important for the idea of running a driver in the mid position. A deeper coil may help to keep the magnetic preference across the strings as this may be shorter to travel than around the sides to the opposite...any thoughts FEMM gurus? Of course the aim of the thin driver is in part a practical one, to have it surface mount. Other aspects relate to the whole thin coil theory which in part suggests that a more condensed magnetic package is going to have a more condensed EMI field and perhaps provide a punch also in a more condensed area and so making it more efficient. The small core and low profile coils also seem to have a more "resistive" than "impedance" characteristics...meaning less phase changes and a "faster" response. In this proposal where the magnets are non conductive ceramic and there is no metal parts other than the coil, I expect there to be far lower eddy current effects to interfere and slow it down, having some of the characteristics of curtisa and sustainiac's laminated cores, without me having to make them, perhaps a bit more like ferrite as is favoured in inductors for these very qualities. Any thoughts on this proposal? Series coil, low profile, 3D realization, other aspects? ------------ Update: I thought instead of talking I'd just do it, just come back from winding a series bilateral coil...should turn out very pretty, but the proof will be in the working of it. Each coil is 5mm deep with an interal coil of 22x5x5mm with fairly square ends. Unfortunately my counter isn't working, maybe a flat battery so I wont know the turns but I did it by measuring resistance and the construction was done in a double bobbin so could tell by eye roughly by they were even. The coils will be very slim because of the added depth so I am not sure if it truly fits with my general design ideas where I have had the coils on the top halves of the magnets. All may not be lost if this is a draw back, potentially I coul add another pair of magnets underneath and build it into a pickup housing to replace the neck pickup. The intention is to surface mount it though, similar to the old hex designs, to the scratchplate on a tele. The coils were machine wound and epoxy set while winding, the whole thing will hopefully come apart and be pre-wired in series with one continuous coil wire so will be very neat indeed, I may even set it into a fancy clear epoxy block so all the magnets and windings will be visible! I took a few pics so you will get the idea of how it was done, let's hoe it works! pete Link to comment Share on other sites More sharing options...
curtisa Posted March 20, 2008 Report Share Posted March 20, 2008 Update from me: Haven't been able to do much more on the sustainer over the last week-and-a-half as I've been busting my gut building natural stone walls in the garden. However I've finally found a pair of Ferrite/Ceramic magnets that fit perfectly under a single coil pickup. Having finally got my hands on the magnets I got all re-inspired and started working on the driver again - I've built up a baseplate that holds the magnets in position and supports the two coils, and will eventually provide the connection points for the cable exiting the driver assembly, in much the same way a normal single coil pickup construction does. I've built it out of laminated plastic (cutting the holes for the two rectangular magnets removes a lot of plastic, so it needs extra strength), and I'm just waiting for the glue to dry. I still need to get a black single coil pickup cover to hide the coils, but that shouldn't be too hard to source. It's looking like I'll have to rewind the coils using thinner wire as I can't fit the bobbins under a single coil cover (too wide), but with the apparent preferred arrangement of parallel-connected coils, I'd probably have to rewind my slightly-too-low-impedance coils anyway. Been having a closer look at the sustainiac amp and thinking that it might be a pretty good design to fiddle with - the driver actually sits within the negative feedback path of the amp which none of the current solutions do (LM386, linear BTL, class D etc). In our "traditional" approaches the amp doesn't really "know" what the driver is doing because the load is connected outside the negative feedback loop. The sustainiac patent puts the driver within the negative feedback path, which may help further iron out any non-linearities in the amp/load combination. More later... Link to comment Share on other sites More sharing options...
psw Posted March 20, 2008 Author Report Share Posted March 20, 2008 That's great curtisa because I have been inspired by you and am hot on your heels with my own design. I am surprised you would want to cover these coils up and remember sustainiac are pretty careful to say that you can't use a cover for them. A cover is possibly going to put even more distance between the driver and the strings and the bobbin and the cover more again between the strings and coil. While a bi-lateral design may have more throw up and not out, see FEMM above, every bit of space between the driver and the strings is space that will be filled when an optimum distance is found, and if it is going to work in the middle, and in your case very close to two humbucker pickups, I'd be careful. Perhaps consider testing it before covering it to see, I know I have been burnt before. Still, mine is going to look very pretty also (in a different more "naked" way ), a lot more compact and petite for sure. Glad you found the magnets...did you get a secret supply somewhere? What is your feeling on the 3D shape of the bi-lateral field...doh...I just realized, I could manually test it for myself with iron filings...I will try and do that perhaps tomorrow, the sideways "throw" of this design is I suspect crucial, especially for a mid-driver. Anyway, good luck and happy easter, good friday down here, curtisa and my time... pete Link to comment Share on other sites More sharing options...
col Posted March 20, 2008 Report Share Posted March 20, 2008 A surprising amount of throw there and I had not anticipated the ends being so hot. If you mean that the bright green area is larger then in some other femm plots, that is meaningless unless you use the same upper and lower bounds as used in those plots - and also use the same materials... As far as the ends being 'hot', the colours in the plot are showing flux density not field strength. The flux density at the ends is higher because there is a shorter easier path from one pole to the other. For instance, looking end on or from above, what is the field doning to the sides, is the field thrown wide here to, or kept in close...if wide, this would be very bad, but then this would defeat the purpose of the arrangement and the throw is most likely above and below. Its not really so important what shape the permanent field is as long as it gets to the strings - whats important is where the influence of the electromagnet reaches, and where it is stronger and weaker. You would get a pretty good idea of what is happening at the sides of the field by just modeling one of the bi-lateral sections from the side. Make sure you are comparing like with like when 'judging' the success of a design using a femm plot and don't make assumptions about the usefulness of a design based on the permanent magnets alone. In your design, it seems that you intend to use the magnets as the core of the coils? what is the inductance factor of the magnets you have? what if they have a poor inductance factor causing poor performance? If it doesn't work, how will you know if it's the concept or the specs of the arbitrary magnets used ? cheers Col Link to comment Share on other sites More sharing options...
Dirge for november Posted March 20, 2008 Report Share Posted March 20, 2008 I'm interested in trying my hand on a sustainer. I've carefully followed PSW's advice not to read all the pages of this thread . These questions must have been answered plenty in the past, so I'm sorry if it's a bother. I have some questions on PSW's pictorial of the driver. 1. Could you make a list of what's needed? (I know everything is in the pictures, but I can't see exactly what you're using) 2. What's the right kind of magnet and where can I get this? 3. I can't see on your pictures what exactly you are putting together in what order, could you elaborate on that? 4. What kind of wire did you use? 5. As I'm not an electric miracle (I want to do this to learn a bit more about it) I don't get where and when you solder the connecting wires. Stupid questions I know, sorry 'bout that, but I hope you can answer them anyway. Cheers Link to comment Share on other sites More sharing options...
psw Posted March 20, 2008 Author Report Share Posted March 20, 2008 (edited) Welcome Dirge for November... I'm interested in trying my hand on a sustainer. I've carefully followed PSW's advice not to read all the pages of this thread . These questions must have been answered plenty in the past, so I'm sorry if it's a bother. I have some questions on PSW's pictorial of the driver. 1. Could you make a list of what's needed? (I know everything is in the pictures, but I can't see exactly what you're using) 2. What's the right kind of magnet and where can I get this? 3. I can't see on your pictures what exactly you are putting together in what order, could you elaborate on that? 4. What kind of wire did you use? 5. As I'm not an electric miracle (I want to do this to learn a bit more about it) I don't get where and when you solder the connecting wires. Stupid questions I know, sorry 'bout that, but I hope you can answer them anyway. Cheers I will add more later, but for a different take on the same thing, have a lok at this other pictorial which may be clearer... DIY software Sustainer Tutorial Also, my pictorial shows the making of a driver on top of a pickup, you have to get creative and plan a lot to find a way to build on top depending on the pickup and every pickup is different. The pickup in the linked version is used to make a driver only, mine I could insert a blade, but others the poles would be fine. It may even be better to make a driver completely separate from your pickup before you start ripping into it as it can take a little practice to get it right. Also, you may need help with the circuit aspects and the wiring can be a little complicated. See the other links in my signature at the bottom of this post like the tutorial that shows this a bit more. It is not simply a coil of wire and a lot can go wrong so if you are not familiar with soldering and wiring then you are likely to need some help with it... --------------- @col... If you mean that the bright green area is larger then in some other femm plots, that is meaningless unless you use the same upper and lower bounds as used in those plots - and also use the same materials... No...not the amount of green, but the shape of the green. Some dual coil designs clearly show a shape of field that largely curls back on itself. I am not comparing this to others directly, but simply noting that compared to say the hex idea or close rails, the mutual attraction due to the space between the magnets creates a large field (ie more throw") in the direction of the strings. The lines from the middle of the magnet for instance go straight up, but of course curl back off the page to the opposite magnet, this kind of "throw" or shape is reminiscent of a single coil design for instance. The above hex model has far higher strength magnets but a very different and more contained field shape, for comparison. As far as the ends being 'hot', the colours in the plot are showing flux density not field strength. The flux density at the ends is higher because there is a shorter easier path from one pole to the other. Is not such flux density, the closeness of lines an indicator of field strength. If I set the magnets up like this and hold a nail lightly above at string height and move along it, I can feel extra pull at the hotter areas...or am I imagining this? I built a magnetic field strength meter once with a hall effect on a probe and a needle meter, unfortunately it was so sensitive that it really was of use only to tell me the polarity... Its not really so important what shape the permanent field is as long as it gets to the strings - whats important is where the influence of the electromagnet reaches, and where it is stronger and weaker. I know (I think) what you are saying, and I don't know how to model this, however, all the field is interconnected and so effected by the electromagnetic forces acting on it. If you look at any of your pulsating models you can see this effect... You can see here how potentially the field to the side also pulsates, if these lines were close to the pickups magnetic field or dissected that of the pickup, then that signal would be produced in the pickup, isn't that the definition of the EMI effect? Electromagnetic radiation Interfering with that of other elctromagnetic sensitive devices such as the coils in a pickup. By running the driver in the neck position and using the bridge pickup, we seek to address this by physical distance. By the bilateral design, it is also addressed in magnetic attraction largely across the strings rather than along them, is that not so? You would get a pretty good idea of what is happening at the sides of the field by just modeling one of the bi-lateral sections from the side. I don't think you would...the FEMM models cant be looked at from above and if looking end on, it assumes that there is only one magnet and can't take into account the presence of the equally large opposite magnet just behind it. If one were to imagine that this side view that I modeled was similar to the upper view (which I don't) then this would be a disasterous design for EMI reduction. In reality, I suspect what magnetic lines are attracted to the opposite pole of the same magnet to be close and condensed and the side field to be narrow with little throw...an ideal for EMI reduction, EMI largely being thrown down and up towards the strings where you want it, and close to the driver at the sides. These things are crucial the nearer you intend to get the device to another pickup, especially the one or ones you intend to take the signal from. Any coil is going to act on the entire field and so, the size, shape and "throw" and direction of the magnetic lines to the side is very important I would have thought and this is very hard to reconstruct in 3D in your head from the FEMM models that can be made. Make sure you are comparing like with like when 'judging' the success of a design using a femm plot and don't make assumptions about the usefulness of a design based on the permanent magnets alone. Generally, I no longer use FEMM very often, for me it is a visualizing tool, the proof is in the testing. However, it does make visible the shape of a field and you can imagine the pulsing effect the coils would have on it, strengthening or relaxing the entire field and extrapolate from that the effect it may have on other nearby fields and so what the pickup may hear of the coils pulses. The result being distortions (fizz) or oscillations (squeal) that we are seeking to minimalize by such designs, is this not so? In your design, it seems that you intend to use the magnets as the core of the coils? what is the inductance factor of the magnets you have? what if they have a poor inductance factor causing poor performance? If it doesn't work, how will you know if it's the concept or the specs of the arbitrary magnets used ? True, it is hard to impossible to tell from a single experiment. I have used ferrites and magnets before as cores so there is some experience in there. I am not making this at all to disprove the design, quite the opposite. If mine fails, well that does not disprove the design, however I could compare it to a single coil for instance. I will also be able to make a little comparison between it and the sustainiac and curtisa's one in construction. There are so many other factors involved, the magnetic field is only one. The design may be really good magnetically, but the coils fail to be efficient to drive it and the strings. I have used 0.2mm wire and two 4 ohm coils in series as an analogue to the successful single coil designs...no reason particularly to think that this would be the best approach. I have used internal magnets and spread the coil deeper, far deeper than my most recent designs (5x!!!) and not situated only in the very tip of the core...perhaps this would be a downfall. EDIT: On inductance factor, if my designs are successful due to lower inductance factors and this I assume is the reasoning for things like the laminated cores, then a non-conductive ferrite/ceramic based core which happens also to be a permanent magnet would seem like an ideal choice. I have a lot of magnets to choose from, these were not chosen entirely at random although their ideal size was a big factor. They seem to have adequate strength especially in an application where they are physically quite close to the strings as opposed to being under a core. A low "inductance factor" would seem to be a good thing (though I am not sure quite what you mean by this)...how do you define a poor design for a core? In my mind, less inductance means less phase differences and "speed", making a "fast" driver that derives efficiency by being better synchronized with the actual actions of the strings, not fighting the phase. Similar to the effect of the glass breaking singer using efficiency of resonance to have such a dramatic effect. To me this is the ideal and while there are many factors to consider (the distance from the driver and the pickup along the string creating phase differences, circuit phase discrepancies) the closer the better and evenness across the frequency ranges (an impedance factor) the better. Hence, the thin driver designs and many other rationals of my designs have been in this quest for "speed" over raw power. I have very good reason to believe that it would do something though, haven't I? The coils will pulse the field and so I can expect that the strings caught in it's sway will react to it. I think that the design creates a field shape that extends largely up and down, not so much to the sides and therefore transmit less EMI and the actions of the attraction of the two coils across the strings not towards either pickup should be a lot less, I would expect. All of these factors are crucial to a mid-driver application, after all, a single coil will work in the neck position so the gains I am attempting to make is purely in the area of EMI reduction, that is the fizz and squeal and other influences that may act upon the pickups. That is not to say that there maybe other advantages to dual coil drivers. For instance, I can see that in generating equal and opposite currents in the coils that they may potentially address some of the switching noise issues. I know it may seem that I have a single coil bias and have had some success with these designs, my tendency is to drive and idea to death, and yet the simplicity of the single coil driver has not been killed. I have not yet seen any great leaps in performance from multicoil designs while I have in changes in my own SC designs (making them even thinner). Having spent a year making only hex designs though, I can't really be considered to have a bias against the idea of multi coil drivers. I do have a tendency to try and innovate and not to follow an established design, often to my detriment and so is perhaps a personal character flaw. I do feel a little sheepish and reluctant in attempting a design that so much follows the principles of the sustainiac and, perhaps I have altered the design to appease my sensibilities, in some part. Curtisa is creating something a lot more like the sustainiac. I also am trying to address a lot of different design and utilitarian principles here that may handicap the design a little. I am looking to make something very low in profile, 5mm deep total in a quest to surface mount it. Perhaps a deeper pickup size and shaped device would be better, but it wouldn't work in the application (mid position on a telecaster, or even between the neck pickup and neck as a plan where I have no routing. However, like the thin devices I have made, perhaps it will prove to be of benefit by keeping the magnetic field and coil power condensed directly under the strings. There is no point really in talking it up though, the intention is to try this and see what happens in the hope that it will work. I am sure something will happen, and then I will need to think about why it didn't happen enough or other ways it could be adapted to lessen EMI further if that is the problem (maybe side fins or something). Like curtisa, I am putting a lot of care in the construction as this will give it the best chance, plus in truth aesthetics do matter a bit and so my eye is always skewed a little towards that angle if I am going to put this much work into building and conceptualizing the thing. Unfortunately, sexy may not cut it for performance , there is something very sexy however about these epoxied bobbinless coil designs. If I ever get to complete this project (the whole sustainer thing) enough to try something else, I'd like to take these ideas over to pickup construction. For instance, it would be very cool if I were to make a bi-lateral pickup design with internal magnets and held together and potted entirely in epoxy, perhaps with a driver coil on top. If this design is superior but only works in the neck pickup position, perhaps such a dual piggyback idea could be used to make a cool telecaster neck pickup in of itself, and humbucking too! The dispensing of the bobbins gives a remarkable amount of extra space for coils of wire so things like slightly over winding may be possible without the need to reduce wire size for instance. It may be enough to allow the two bi-lateral coils to sit end to end unlike the staggered arrangement that fender required for his Z-coils that I suspected failed in large part due to the reluctance of people to change the actual shape of their pickups over standard sized devices (they were not interchangeable with SC pickups for instance), not because the design idea was wrong. Anyway...we will have to wait and see...the epoxy is likely to have fully set now so I will be taking out these coils and seeing how they turned out, I may even get a chance to do a little testing of the things, we'll see, it is easter morning, so I am back off to bed! later... pete Edited March 20, 2008 by psw Link to comment Share on other sites More sharing options...
col Posted March 20, 2008 Report Share Posted March 20, 2008 No...not the amount of green, but the shape of the green. Some dual coil designs clearly show a shape of field that largely curls back on itself. rI am not comparing this to others directly, but simply noting that compared to say the hex idea or close rails, the mutual attraction due to the space between the magnets creates a large field (ie more throw") in the direction of the strings. The lines from the middle of the magnet for instance go straight up, but of course curl back off the page to the opposite magnet, this kind of "throw" or shape is reminiscent of a single coil design for instance. ... The above hex model has far higher strength magnets but a very different and more contained field shape, for comparison. As I said, the green stuff can be deceiving: with a few tweaks to the upper and lower bound settings in femm, the field shape in that hex model would start looking a lot more like the dual core version you posted (which incidentally looks a lot like many of the different models I've made of bi-lateral drivers, and also similar to some of the bi-longitudinals seen from the end). As far as the ends being 'hot', the colours in the plot are showing flux density not field strength. The flux density at the ends is higher because there is a shorter easier path from one pole to the other. Is not such flux density, the closeness of lines an indicator of field strength. The closeness of the lines depends on how many lines you choose to use which is again purely arbitrary, you can change it in the femm settings. What the colours and lines do show is the shape of the field and the relative(unless you set specific values for the bounds of the colours and the lines) strength of different parts of that particular magnetic field - so you notice the stronger and weaker parts when you play with a nail. ...however, all the field is interconnected and so effected by the electromagnetic forces acting on it. If you look at any of your pulsating models you can see this effect... Its not true that all parts of the permanent field will be equally effected by the electro magnet - that depends on the position of the electromagnet relative to the permanent magnet - this is one reason why it may be a very good idea to use a soft magnetic core with the magnet at one end and the coil at the other. You would get a pretty good idea of what is happening at the sides of the field by just modeling one of the bi-lateral sections from the side. I don't think you would...the FEMM models cant be looked at from above and if looking end on, it assumes that there is only one magnet and can't take into account the presence of the equally large opposite magnet just behind it. If one were to imagine that this side view that I modeled was similar to the upper view (which I don't) then this would be a disasterous design for EMI reduction. In reality, I suspect what magnetic lines are attracted to the opposite pole of the same magnet to be close and condensed and the side field to be narrow with little throw...an ideal for EMI reduction, EMI largely being thrown down and up towards the strings where you want it, and close to the driver at the sides. If the magnetic lines are attracted to the opposite pole of the same magnet, are close and condensed with a narrow side field, then the same will be true for a single magnet of the same proportions. There will be some difference, most notable in the centre of the driver, but nearer then ends, the sideways throw will be similar to a single cored driver - maybe slightly less, but not significantly less. Remember that the flux tries to follow the easiest path back to the opposite pole? so near the centre of a bi-lateral, it will tend to be attracted to the other magnet, as the distance is less, but at the extremeties, the distance through the air from the top to the bottom of the same magnet is much less than the distance to the other magnet - in this area, the behaviur will be more similar to a single core driver (at least with respect to side 'throw'). If you want to reduce the side throw of a bi-lateral, one way might be to make it taller - this makes the flux more likely to go from one core to the other rather than to its own opposite pole. The flux that still goes from top to bottom of the same core will be projected further, but there will be less of it. My animation of a dual core has a much bigger gap than your plot, and yet still has a field that is even across the top because the cores are taller, encouraging the flux to jump to the other core instead of back to the opposite pole of the same core. Another approach is to give the lower section of the magnetic circuit a nice conduit so that the field in that area is much more compact. The idea is that this causes more of the flux to travel horizontally from one core to the other. And less to go from top to bottom of the same core, which would result in more side throw. Notice how you have a dip in the field near the centre with just a small gap: whereas in this plot, there is no dip even though the gap is significantly larger. Also notice the bar along the bottom. Adding this helps to improve the magnetic circuit between the two cores - and hopefully causes more flux to move from end to end, and less out to the side. These things are crucial the nearer you intend to get the device to another pickup, especially the one or ones you intend to take the signal from. Any coil is going to act on the entire field and so, the size, shape and "throw" and direction of the magnetic lines to the side is very important I would have thought and this is very hard to reconstruct in 3D in your head from the FEMM models that can be made. Make sure you are comparing like with like when 'judging' the success of a design using a femm plot and don't make assumptions about the usefulness of a design based on the permanent magnets alone. Generally, I no longer use FEMM very often, for me it is a visualizing tool, the proof is in the testing. That makes sense - except, you can only 'prove' things in testing if you can compare like with like. e.g. comparing a bi-lateral driver with a single core driver is only going to prove anything if you know the exact specifications of the magnets, the core materials etc. otherwise all you can prove is that some arbitrary driver A is better or worse than some other arbitrary driver B - you cannot generalize your results. Even if you build many of both designs, and one type is always noticably better than the other, you still cannot be sure why. EDIT: On inductance factor, if my designs are successful due to lower inductance factors and this I assume is the reasoning for things like the laminated cores, then a non-conductive ferrite/ceramic based core which happens also to be a permanent magnet would seem like an ideal choice. Inductance factor is as important as e.g. the gauge and number of turns of wire you use for your coil - generally, we want it as high as possible because that gives a stronger field for the same coil and current, however as we know, the higher the inductance, the more we have to worry about the impact of frequency response and the more we have to consider circuit designs that deal with this effect. If your cores inductance factor is too low, there will be no sustain or at least poor sustain! laminated cores are to reduce eddy currents - fortunately, (I think?) they don't have a significant impact on inductance factor. Ferrite cores are not good for us because they saturate too easily - not sure about their inductance factor compared to iron/steel because I stopped considering them as a viable option ages ago. I think that the design creates a field shape that extends largely up and down, not so much to the sides and therefore transmit less EMI and the actions of the attraction of the two coils across the strings not towards either pickup should be a lot less, I would expect. Why would you expect this? What makes you think that the field will not bulge out at the sides? cheers Col Link to comment Share on other sites More sharing options...
psw Posted March 21, 2008 Author Report Share Posted March 21, 2008 Pete's bi-lateral pickup progress... Ok...so the epoxy set and it all came apart really well, this may prove to be a very neat method of making such coils or variations on it and I have taken a few pics. It would require the use of epoxy and possibly a drill with a slow variable speed or something else, mainly so that you can work with the epoxy without making a big mess or risk. The results are though perfectly potted solid coils and cores with no gap between the core and the coil and no wasted space of bobbins...plus of course, no need to make the bobbins at all. For this, because the core is a part of the design, I did not need to make special fancy super accurate bobbin plates, but simply cut them out of a margarine lid very roughly and oversized, used doublesided tape and superglue and a lot of care in the winding. Anyway...all will be clear with pics Now, taking them apart they fit perfectly under the strings and into the size and shape of a tele neck pickup which I intend to use as a mold for the thing if it works in the middle pickup position. I don't know if I will use it, but to make sure they didn't get moved about too much, I stuck them to a metal ruler. Then, recalling much earlier experiments of using staples as a cage to direct the magnetic field, I stuck the coils to to lengths of staples with about 10mm between them and the coils/magnets. With these attached, they no longer stuck to the metal ruler under it! Using a screwdriver above and to the sides, there is still a strong field above but virtually none to the sides either. The attraction above was stronger too. Of course, it may be a disadvantage to "throw" or the effective space between these new outer blades which are magnetized to the reverse of the core...or possibly even undo some of the bi-lateral designs attractive features, attraction across the strings. Still a nice neat fit and can be tested temporarily. Even with these fins, the whole device will still fit int the space provide by a tele pickup cover mold. Anyway...looking good, not sure if I will get around to testing it or how elaborate I will make it at this stage, I should learn from previous builds that concentrating too much on aesthetics or getting carried away with adding more features only confuses things and makes it harder to tell which of these features are actually help and some that might be detracting, even if it was to work with that handicap. I will probably mount the coils onto paper and just sticky tape the thing in position and worry about the cosmetics later, test it as is then think about adding the fins, etc. pete Link to comment Share on other sites More sharing options...
curtisa Posted March 21, 2008 Report Share Posted March 21, 2008 I am surprised you would want to cover these coils up and remember sustainiac are pretty careful to say that you can't use a cover for them. A cover is possibly going to put even more distance between the driver and the strings and the bobbin and the cover more again between the strings and coil I wouldn't have thought an extra 1mm of plastic was going to make much difference? Anyway, the idea is that I will contstruct a pair of steel "endplates" that sit on top of the laminations of each coil, flush (or even slightly proud) with the surface of the pickup cover. I'd imagine the proximity of the steel to the strings would have more of an effect than the poximity of the windings. Glad you found the magnets...did you get a secret supply somewhere? I couldn't find anything locally at all! I could find bags of craft shops with magnets, but they were all the wrong size, shape, north-south orientation...In the end I bit the bullet and went with Aussie Magnets. A bit more expensive than I was hoping, but I was getting desperate, and in the end I didn't give a hoot where the magnets came from, just as long as I could get the right type. @Col: What happens to the pattern/intensity of the field if the steel bar at the bottom of the sustainer is removed? I'm just putting the finishing touches on the magnet bracket/baseplate for my sustainer and I've installed a channel underneath the magnets where I can insert a similar steel bar to see what difference it makes. Link to comment Share on other sites More sharing options...
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