Donovan

Hello all- The lead in those clips shows very nice sustain, Pete. Nice work. I think I understand what Col was getting at... just that your results may not be indicative of what us noobs can expect to get if you are not using the "standard circuit" shown here, even if you do not endorse said circuit. We need SOME circuit to use as a reference for expected results. Regardless, the past few pages of posts have prompted me to continue sitting, waiting, wishing... so something came to me, a test to try. Once it occured to me to try it, I felt like a dumba$$ for not having tried it before... testing the sustainer circuit sans the preamp and listen strictly through the wood. Is my thinking right that I should not care about loading the pickups if I am not connecting the guitar output to anything? Or would the loading still affect the loop in a negative manner? If not, then some testing last night convinced me that my driver needs work as the phase issues are still present, even sans pre-amp. Amp circuit is standard LM386 (but -N4) with only some extra power filtering in the form of bypass caps, which to my knowledge should not be the cause of any phase issues as it is not part of the signal chain. This driver is a standard strat neck pickup, originally a Fender Tex-Mex custom staggered. The bobbin was blocked off with fiberglass strips at the top, leaving a 3 mm gap and wound with 0.2 mm polysol wire to 7.9 Ohms, potted with urethane and vacuum degassed. I was VERY careful in its construction. The pole magnests have been lowered flush with the top of the bobbin. The problem I believe at this point is relative to 2 items: 1) The stock pole magnets for 2 reasons... A) although I have no evidence, I think I may need to remove these in favor of smaller, disc-shaped ones, such as the craft magnests I have heard mentioned here previously. I am thinking the extra length sticking out of the bottom of the driver is at least a potential issue for excess EMI and/or phase issues. I also am not entirely clear on optimizing magnet position in the Z axis. Should the magnets sit entirely below the coil, partly below, or span the entire depth? I am not sure if these are ceramic or AlNiCo magnets. Being as I do not care about ruining them, should I try cutting or filing/shaping them? This pickups polepieces do not align directly beneath the strings, as if the pickup were designed for the bridge position or another guitar altogether. However, I know this did originate as a neck pickup as the stock bridge was a full-size HB. Also, the original middle pickup seems to be the same geometry. Is this common or did I get the wrong pickups stock?!?!?! I have a bunch of scrap ferrite strips used in transformer lamination. The pieces are small enough that I couls layer them to create a blade or fill in the holes between the pole pieces on the bobbin. Does anyone think I should attempt one or the other? That was supposed to be a "B", not a stupis smily sunglasses guy... doh.

OK, some I'm understanding the whole kink thing. I need to process it for a bit. I am ordering a cheapo Squier strat as a guinea pig guitar tomorrow as well. I have been wondering if my full size JB might be a negative in any way. Might there be phase issues also arising from signal induced and mixed by the separate coils in a fullsize bridge HB? Might cabinet emulation in the circuit be worthwhile? Has anyone tried sending any effects from a DSP unit to the driver?

Pete- I am not thin skinned, so keep it up. I am not trying to be argumentative either, just challenging what may not make sense to me. This is part of the way I learn. I do tend to conced once the understanding arrives. Col- Currently, I am experimenting with cascading 1st and 2nd order all-pass filters, passive and active, after a closely controlled band-pass stage. I am cutting out in my 1st stage anything from below 80 Hz and anything above 2.4 kHz. This is in hopes of reducing the overtones that likely are contributing nothing "good" to the sustain. Results are good so far and I am theorizing this is the key to getting an overall phase correction. I have listened to your clips a few times and they are very nice, my favorite being the atmospheric noodle. Do you still have some fizz ? Listening closely, I can hear some, unless it is my crappy PC speakers. I have a strong fizz now to where distorted playing is my only option, but I have plans on fixing this with novel techniques which redirect EMI to a safer path,rather than attempt to "shield", but it is not my main concern at this point anyway as I am mostly a distortion aficionado. I do understand it affects this channel as well, but I can live with it at this point. I didn't comprehend your statament about broken bends, VST? What is that? Are you sure this is not just the fact that phase shift varies with frequency? What are you basing this assumption on? I can see how something like that might be easily/intuitively supposed, so can you provide a source for the theoretical to educate me? My intuition (though it is just that) would suppose that the macro distance is not the issue as there is a whole number of wavelengths within that distance and as they are whole waves, their effect on shift is inexistent. I would think it is the last, leftover, fractional, tiny, almost quantum portion of the wavelength remainder that causes the shift. Just conjecture at this point, but I want to know more. This is exactly why I am feeling increasingly strong that a high-accuracy reproduction of sound is a necessity of at least equal importance as the driver with regard to the whole system... hence I am growing increasingly anti-LM386, though my latest circuit has finally after hours of tinkering, stabilized it enought to avoid oscillation at full gain. If the latter portion of that is the case, how can anyone (with the currently proclaimed DIY configuration) be getting fundamental or harmonic mode reliably all the way up the neck on all strings? Or are they actually not? How can there be anyone NOT encountering phase problems? Agreed, and I am not sure how I feel about this. I LOVE harmonics. A lot of my lead techniqure revolves around false harmonics. My mixed mode (as I do not yet have a 100% fundamental mode) kills artificial harmonics and brings them to either the fundamental or the harmonic that is dominant at that particular fret/string location. I too share this sentiment, but I do have confidence that much of the work to be done in figuring out the optimal driver has been completed by Pete and I feel confident in believing this and/or at least I feel that the evolution of the circuit is WAY behind that of the driver. I also know my driver is capable of reproducing all required frequenices. My challenge so far has been getting them to all be accesible at the same time. I know little of your driver, but would like to know more, sans trying to find it in this encyclopedia. What I do not feel confident in at all is the whole fetzer ruby idea. It is just not worthy of inclusion in this project IMO and I am continually surprised at complacency with this circuit and that it is not viewed as a huge hindrance to progress. I have looked at your circuit, but do not want to implement anything I don't have a complete understanding of. Being a circuit design noob, I am learning quickly, and the curve is quite steep, which I enjoy, but... I do not have the expertise at this point to look at your schematic and say to myself... "oh yeah, that cap is doing this and this op amp is biased like this to provide xxx" if that makes sense. I would be thankful if at some point you might re-post your latest schematic and give kind of a verbal breakdown of its parts and HOW it functions or rather how its components interact with one another... then again I realize this is a lot to ask of someone. I am also realizing through research that dual power supplies is probably going to be the way to go to eliminate a great deal of these phas issues by removing the need for a great deal of passive components.

I can already reproduce this mechanism, so it is just a matter of packaging it for ease of access. You have mentioned inability to measure/quantify anything, so how do you know this? It actually is fairly simple, regardless of the fact that offset varies with frequency. Implementation is no more complex than using a jfet, opamp, or an LM386. Point me to the points in this thread where others or yourself have tried and failed if this has happened, else I think the assumption can be made that the details of the theory were overlooked or others simply were not interested enough in the idea to pursue it. Again, this is not going to be that difficult to overcome. Humor me for just a moment... if what I am saying is true, wouldn't this be the way to tailor the system to each guitar? [\quote] So again, please point me to the place in this thread where others have tried these things and failed and figured out why. I can without experimentation with this as of yet concede what you say makes sense here and thank you for providing a clearer idea of the speaker functionality. The phase shift occurs within the circuit. This is fairly simple to verify. It doe not occur at the pickup at more than negligible amount. I have measured it several times. The interactions that cause it, yes even the frequency-dependent offset, which are really just filtering interactions, can be neutralized. You have clearly made this point repeatedly. What you have done so far is excellent, and many have enjoyed its fruits. However, not all of us (myself point case) can get the same results as you for whatever the myriad of reasons are. That leaves us wit... the circuit is grossly... well gross in most ways. It does not take much googling on the web to see what a POS chip the LM386 is, honestly it is older than me and so prone to oscillation it's not even funny and there are more folks out there with bad things to say than good. The J201 preamp may be ideal, but I can not prove this as I have little success getting a better result than I can get with a TL082 op amp preamp and this is a mediocre at best op amp. I know the reasons you say LM386 ... it's good "enough" for our purposes, but we don't all have YOUR coils, so the circuit is the ticket and I am surprised you are as complacent with this. There is already the path for simple DIY. Let there be more as well, no need to limit. I did not ignore. Thank you for that. I do feel I understand that better at this point and you are corredt on where I missed this. I was under the assumption the speaker cone was magnetically at rest. So, please confirm so I can be very clear... a speaker cone is not magnetically neutral when at rest? Why did the equal forces stuff you did fail? It seems to me it would be easier to vibrate the strings under tension if they were truly at rest, not being pulled more to one side.

It was a brainstorm for power savings... that was my angle. This is exactly what I meant when I wrote... Kind of like the speaker with an offset in the pull direction, so /push/-/neutral/-/pull/ becomes /pull least/-/pull more/-/pull most/. Basically, pull and different levels of release, but never an actual push to where the string is under zero magnetic influence, whatever that might be. A shame is can't be more like the speaker and have true neutrality. I've heard this many times before and maybe I am misunderstanding, but I often get the notion that you underestimate the driver's capabilities to switch polarity quickly. Of course a halfway decent coil can handle switching states at audible frequencies. If it could not, we would not have speakers capable of high pitches. Even a $2.00 set of headphones can switch within the audible range, so I think it's reasonable to count switching frequency out as a weakness unless the craftsmanship is poor.These cheapo headphones don't seem to have a problem, so what's the difference between them and the driver then? The driver switching speed is not the problem, supplying the signal quickly enough is, but then again not even that is! Supplying a properly phase-corrected signal is. If the signal is properly adjusted, it shouldn't matter if you're 5 or 10 wavelengths behind. I think the biggest problem with this project at least in my case is phase relationship. This can be corrected and I would go as far as to say "corrected" may not even be entirely desirable... given recent experiments, with a little tweaking, I will in one month's time have this "correction" in place and user-adjustable not as a set and forget, but as an on-the-fly, user adjustable phase/fundamental/harmonic control. I have discovered how to tweak my circuit at this point to switch out components which raise the fundamental, the octave harmonic, the 5th harmonic, the and the 3rd harmonic. For the rock player, these Xth non-octave harmonics are much more powerful than the octave harmonic, which suits a more subdued emotion. This past few weeks I have been disappointed, thinking I was getting nowhere, getting killer harmonic sustain (of the Zakk Wylde kind) on some frets and not others, but now I am seeing why and this as an opportunity for improvement and yes I dare say innovation. Think 5-6 distinct modes via selector instead of 2 or even infinite incremental adjustment via knob. I'll be posting clips within the next few weeks.

Hello all- Sorry to hear about the devastation out there, Pete. My sympathies are with you and your people. Let's see what kind of replies this generates. This is regarding the signal sent to the driver. My apologies if this was covered somewhere else in this encylopedia of a thread. Assuming a clean (meaning sinusoidal waveform with no clipping) is being sent to the driver, what is the physics of what is happening to the guitar string? I got to thinking that if the driver were exactly like a speaker (which it is obviously not), then they might exhibit similar behavior... with no signal the cone is at rest, centered between to extremes. Then, with a pure AC signal, there is a pull on the cone during one half (which side is trivial), let's say the positive half of the cycle. Then during the opposite, negative side of thecycle, there is a push, so the cone can move in both positive and negative directions. This bidirectional movement is possible because the cone is centered when at rest. However, our drivers are not centered. I would venture to say they are nowhere near centered for a couple of reasons which I of course am completely, intuitively assuming... 1) The strings are under constant pull force of permanent magnets. 2) The strings, although loosely analagous to the speaker cone... as they are not magnetic, can not ever be pushed, only either pulled or released by the momentary field. 3) The polarity of the permanent magnets employed is never reversed only strengthened and weakened by the driver's induced field. What I mean is that the driver only has the ability to exert different pull values, never a push value. First theory of the day... if number 1 and 2 is correct, then the string need never be pushed. I have a vague feeling though, that one might envision the at rest condition as a pull of say strength 3 (on some made-up scale), then on the half wave peak, pull is up to 5 (strength of +2). Now the wave crosses origin and we're back to strength 3. Once we hit max negative cycle, we can go 2 less than the positive 3 value, bringing it to only a +1, which is essentially less than the at rest state, so both sides of the wave ARE useful. Next theory... if 3 is correct, then there is no sense in trying to push, only pull, and as such half the waveform is useless. Next lame theory... if both 1 and 2 are correct, but lame theory 1 is incorrect, then The only other idea I have... and this one I am not entirely convinced of at this point as it feels far fetched, is that the string is being pulled on both sides of the wave, in effect being pulled at double the audible frequency. To clarify, imagine that the negative sides of the wave were being turned upward, so there were only positive values. What would be the behavior? How would we know if this "driver" was or was not behaving this way? The reason I think it might be is because I was reading about AC electromgnets today and if I understood the material properly, an AC electromagnet with no magnetic core is possible given constanct frequency, meaning at say 60 Hz, the N and S poles change at 60 cycles per second, yet there is a perceived constant pull. There must be more or less a constant pull, as an equal pull then push scenario would lead to net zero pull, no? I would like to hear what you all think is happening on this level. I am making good progress with my units, with more bugs to work out, but at this point, I would really like to grasp this a little better to decide where I am going next. Keep rockin.

Would anyone care to comment on the point I raised previously? One thing I have not seen discussed is the fact that once harmonics bloom, the pickup is then sending this harmonic signal to the circuit, then with circuit amplifying the harmonic, not the fundamental, the driver must be pushing that same harmonic. I wonder what the effect will be if my filter cuts out the higher harmonic frequenices. In other words, if I cut any frequency above a normally fretted 24th fret on high E, any harmonic above that frequency will be ignored, not amplified. I am speculating that assuming there were no phase issues, it might cause an oscillation between fundamental and harmonic, or keep the note just on the edge of becoming a harmonic. What do you guys think?

If you look at the 2nd drawing I posted, I moved C2 (and I think it is called C5 in the second one) right next to the IC chip. Like I said before, there were things about the original F/R layout I didn't like.... The from scratch circuit I am working on will be the 2nd (new version) drawing that I posted. Yes, that ought to keep any noise picked up in between to a minimum.

For fundamental frequencies, I reckon this is the band of frequencies (for a 24 fret neck)... String 6 E = 83Hz open string thru 332hz (highest fret) - however to allow for alternate tunings, say 70Hz thru 400hz String 5 A = 110Hz open string thru 440hz (highest fret) - however to allow for alternate tunings, say 85Hz thru 500hz String 4 D = 146.8Hz open string thru 552Hz (highest fret) - however to allow for alternate tunings, say 110Hz thru 600hz String 3 G = 196.0Hz open string thru 784Hz (highest fret) - however to allow for alternate tunings, say 150Hz thru 820hz String 2 B = 246.9 Hz open string thru 987.6Hz (highest fret) - however to allow for alternate tunings, say 210Hz thru 1050hz String 1 E = 329.6Hz open string thru 1,318Hz (highest fret) - - however to allow for alternate tunings, say 290Hz thru 1480hz but for a sustainer, you'd obviously want the octave harmonic, so when factoring for filters, you'd need to double those figures above. Yes, thank you for the correction! I don't have the foggiest how I ended up with the 8kHz! I am designing an opamp bandpass filter today for the range of 70-2960... will follow with preliminary schematic.

Which capacitor are you refering to? Is it in the part of the circuit that is like the one 1 posted, or is it in your new preamp? I've just gotten the rest of the parts today that I need to build a from-scratch version of my circuit layout (found a few pages back). I know the older F/R-like layout works, but there are things I don't like about it so I'll compare the two, and see if my new layout fixes the problems. I'm also re-wiring the guitar again from the ground up, so hopefully this latest attempt will produce a (consistently) working sustainer. If it does, I'll definitely post some demo sound clips and videos too. I'm going to work on the new unit over the weekend, so we'll see how far I get... Hi MRJ. Good luck with your rewire. Can't wait to hear your sound clips. I am referring to your C2, supply decoupling, bridging Vs and Gnd. From what I have read, that should be placed as close to the IC body as possible as you can pick up noise anywhere in between the cap and the IC and that will help to smooth it out. I experimented with my op amp preamp tonight and found that noise decreases as I raise the value of this cap, but the biggest one I had was 470 uF. A 1000 uF might even be better. One effect of a larger value is when you kill the circuit, it runs for a few extra seconds as the cap discharges. I got my preamp working a lot better tonight. Pete, you are absolutely right about using an AC adapter for testing. It is 100 X noisier than a battery. The one I have is a floating ground. Perhaps one with an earth ground would work. When my band plays, we always use a power conditioner, so I will be curious to see its effects as well. Some interesting effects during testing with a battery... touching nothing but the battery case during play through a speaker increases volume of signal and noise (or gain, not sure), touching nothing but electrolytic capacitor body tops during play quiets noise. These circuits themselves are very prone to picking up noise. One fequency I am picking up is exactly the same frequency as an open B string! Strange. I also found my C7 was an error on my part. I removed it and flipped a couple connections and now 1 less component. Now, it takes the 4.5 VDC and AC swing, compares it to 4.5 straight volts, and amplifies the difference (the AC swing). This is more efficient, BUT, I am beginning to think with these op amps it would be alot better to use 1% tolerance resistors on my voltage dividers (R1 & R2, R7 & R8), as mismatches will lead to amplification of the DC (junk). I also confirmed tonight that the TDA7267 will not accept a volume control pot at all. It must have a capacitor as the last component before the input. I have no idea how it "knows" this. I am going to order some of Strib's IC's (TBA820M) as I think this is a better choice and Strib's sustain sounded nice, even using the antiquated LM741. I am getting nice harmonic sustain, but still no fundamental mode. More testing on the scope is necessary to confirm what I am 99% sure is a phase issue. Next, I am going to create a bandpass filter with a band of 80Hz to 8kHz as this seems to be about the guitar's range and see how this helps my noise issues as I find it more important than missing the fundamental mode. One thing I have not seen discussed is the fact that once harmonics bloom, the pickup is then sending this harmonic signal to the circuit, then with circuit amplifying the harmonic, not the fundamental, the driver must be pushing that same harmonic. I wonder what the effect will be if my filter cuts out the higher harmonic frequenices. In other words, if I cut any frequency above a normally fretted 24th fret on high E, any harmonic above that frequency will be ignored, not amplified. I am speculating that assuming there were no phase issues, it might cause an oscillation between fundamental and harmonic, or keep the note just on the edge of becoming a harmonic. What do you guys think? I do want to get that working, but to be honest, I am in this for the harmonic mode. I can't wait to play Santo and Johnny's "Sleepwalk" live with that! It is going to be so sweet. I also think my driver may be trying to rattle wires inside my guitar! ...or, my driver is slightly microphonic. I can hear a very slight, very high frequency tone emanating from somewhere beneath the pickguard area, but can not confirm the exact source. I also suspect it may be my bridge pickup, Duncan JB full-size. I may rewind it (driver) yet again and try a different potting material. Who knows, Pete, I may even try PVA, but that would be conforming to confirmed methods and we know we can't have that! For anyone interested, here is an awesome link on op amp basics... the whole site in general is an indispensable resource for anyone as new to all this as I am... ALL ABOUT OP AMPS The end of the article makes some recommendations on op amp sourcing by application. There are even op amps that can put out 100's of mA. That might be nice to cut this circuit down to 1 IC. There goes half the components and probably the phase shifts with them! I found some others too that are very fast and clean according to datasheet, much better than TL082 or even 072. Check out OP275. Very low noise, kick-arse slew rate of 22 V/uS which can keep up with changes 44 X the speed of the LM741 and 26 X the speed of the TL082. I think once noise is sorted, this is going to be a better preamp than the fetzer valve. Op amps seem much easier to set gain. You can do it with resistor and pot choices instead of having to bias anything so tediously as the JFET. I think you guys are going for no gain on the JFET, correct? To do this with the opamp, you just leave out the resistors and pot on the negative feedback loop, easy! That is one reason I am staying away from the JFETs. And that reminds me, maybe I need to try no gain. I have been putting in minimums of 2 X.

I have also had this noise problem with my sustainer circuits. Do you only get it when you turn the thing up to a certain point? Mine always would start in buzzing rather quickly, and as you went up in power, the buzz frequency would change a bit and sort of 'sweep' across a range of notes, and then settle on 1 nasty hum, regardless of adding any more power. I would describe the final hum as sounding like a 60 cycle hum, or the car engine/amp analogy. It IS NOT the 386 itself, since I have had plenty of perfectly working 386 circuits... but, it seems to be a recurring problem at least with F/R based circuits. I actually spent a lot of time recently on my previous 2 circuit attempts (I should add, these circuits were NOT the new schematics I have posted -- they were differently and less modded F/R's) trying to rid them of this buzz... hmmm... some troubleshooting: Keep in mind my test guitar has only a bridge humbucker, and a single 500K volume control, so I doubt this buzz is caused by other pickups or guitar switching/electronics. (Note: As Pete and others have discovered and have said numerous times, other pickups in your guitar can and will cause problems if not dealt with correctly... but in this case, I am ignoring that set of problems for troubleshooting purposes, since I have eliminated them from my setup.) The buzz I experienced was totally uneffected by outside forces such as EM radiation, computers, tvs, lights, etc. No matter where the guitar was, it buzzed the same. So if it is a grounding/power supply issue with the F/R type circuit, it must be internal with the interfaced guitar and sustainer circuits, and not an external shielding issue. The buzz like I had, and you seemed to describe, is definitely NOT a result of driver/pickup feedback and interference. That is more of a squeel and is effected by driver position, etc -- this buzz is not (trust me, I tried moving it all over the place...) Soo.... that kinda leaves 2 things. Slightly bad driver (and I say slightly bad because even a driver that internally vibrates and has flaws CAN work to an extent, although never well), bad circuit. The circuit could be anything from design, to bad layout arrangement, to bad solder joints, etc. Maybe check where your input voltage is running carefully... good luck man! Yes, I only get it when I turn it up to a certain point and it seems what you have described is identical to what I have experienced. I did some reading today suggesting that there is more to choosing a decoupling capacitor than just its value and that sometimes you might introduce more problems if the cap is not carefullt chosen. I am wondering if this might be the case. I am going to play around some more this weekend, but I am moving to breadboard as I am tired of trying to troubleshoot densely populated perfboards. I don't think it is my driver construction unless it is something specific about that dimensions causing some internal or intermingling oscillation? The dimensions are spot on what Pete has specified, the resistance is good (7.9 ohms) and the thing is quite solid as I potted with urethane varnish while winding and then vacuum potted it to degas under 32 inches of HG. I have pushed the magnets into the bobbin, making their ends level with the top of the bobbin surface. Should they be lower?

Hey Hank, if you are going down the hex driver road, check out coilcraft.com. They make some power inductors that have bobbins that might be sized nicely for you. Pete, here's my update after a day in. I broke down and removed my neck pickup so I could test without holding the driver over the strings. I was also getting suspicious that taking the signal from my guitar jack might be varying the results due to the cord length, volume control, pickup selector, and tone control. So, like I said, I broke down, removed the neck pickup and replaced it with my driver, lifted both leads from my middle pickup, and split the signal off my bridge pickup. I ran both sets of leads through the small hole for the ground wire that goes to the tremolo claw and out the back plate. My daughter was sick this morning, so I had to stay home with her, which meant I had a lot of time to tinker. After burning through two batteries, I hacked up an old AC adapter (9 VDC, 210 mA) and soldered on a 9 V battery connector. I think I'll not be buying batteries for a bit... probably should have done that a lot sooner. My preamp entirely failed this morning and frustrated, I built another, a 1 stage inverting based on the LM741 (I have several to tinker with and I know... 741 is even a worse choice than the TL082), but it works. I built in variable gain (2X to 5X). I tried the new preamp with an amplified speaker set and it sounds fine. Then, I tried it with the LM386 amp circuit and I got really bad hum. This does not sound like squeal from being too close to a magnet. Distance does not seem to matter at all. This sounds like 60-cycle hum, but very pronounced. This happened before and this is why I first decided to move away from the LM386. I do not have easy access to the J201 JFETs and I have read here many times that the fetzer was never designed to be really good and clean. The other reason I do not like the fetzer ruby is too many pots! How is anyone supposed to figure out how to set the thing when there are three possible places to go up or down and the effects are mostly inaudible? Anyway, I did try the move to a .022 uF decoupling cap as you mentioned last week, but this did not work either. You meantioned that you weren't sure your circuit even had a decoupling cap in there. Does the 386 not need one? Wouldn't that mean you are putting gain on the AC plus a 4.5 VDC offset? I should mention I do get sustain with the LM386 circuit, but it is weak with my best attempts at adjusting the circuit and while I am patient, I am not that patient. So I got frustrated and went back to the TDA7267 amp. I get strong sustain on all six strings with the 2nd string ( being the strongest, but I have that same annoying hum as I did with the LM386! It is not as pronounced, but it is still unacceptable... sounds like noisy power, like if you have ever hooked up an amplifier in an automobile and heard the engine idle coming through when the music was quiet. I noticed the noise is exactly the same pitch as an open 2nd string B note. Coincidence? I should also mention the sustain is not on all frets, but rather in nodes, strong on some frets and inexistent on others, yeah strange!!! The sustain is for the most part harmonic in nature. Switching the intput leads gived me no sustain, but leaving them... an open low E goes into a killer harmonic bloom that sounds incredible with heavy distortion, then I only get sustain on certain frets moving up the neck, as if I am hitting certain nodes as I move along, that it likes. The same goes for all the other strings. I suspect another phase shift problem. I thought I had that kicked, but will have to look again on the scope tomorrow. Enough negativity though. Now that I have a taste of playing with it, I am hooked and won't give up until my Fender really sings. The blooms are really kind of magical-sounding and to feel the string vibrating or attempting to as you dampen them is also a very new, awesome sensation. This has to be the coolest specialized application of electromagnetics.

Thanks for the encouragement. No reason I could not run the preamp into the LM386. In fact I did, but in a much different configuration. I believe will come back to it at some point.

Pete- I do understand the fetzer/ruby circuit is proven as well as other things from which I may have deviated already. As you mentioned, everyone wants to put their own spin on things myself included. I am looking toward newer design for what improvements I might be able to achieve, as well as the overall learning experience of it. I do appreciate all the time others have spent on this project and I hope my attempts at improvement are not taken as some sort of slam on anyone's efforts. Indeed, I never could have got this far without this 4+ year, 280-page thread and everyone here's perseverance (especially yours). I may come back to the LM386 as I have a good stock of them on hand, but the fact that it is being run so close to its max potential bothers me to some extent, hence my wanting to go up to a bigger chip. Regarding the TL082 vs 072 choice... I agree the 072 is a much better choice, being lower noise and higher slew rate, but I have easy access to the 082 right now and will be switching it out with an 072 when I am more in the finishing stages. Regarding the TDA7267, it does not have variable gain like the LM386 as far as I know. As such, its behavior needs to be controlled in the preamp stage or with a volume control between stages. I will be opting for using preamp gain only, which I have added into my circuit today... a simple 2X to 5X variable gain. So I think the TDA7267's consumption is based on what, how much, and the manner in which you feed it. The quiescent current of the TDA7267 is very low. Combined with my dual op amp preamp, it runs now at about 35 mA where it is most efficient (guitar mid-range 500Hz to 750 Hz), up to .120 mA where it needs A LOT of work (frequency shaping). It is almost as though I am starving it and it is trying to compensate? I have ideas which I know are possible (just have to work them out properly) through which I plan on making this thing very efficient. I want to combine a simple AGC, even more simple than anything Col worked on and then couple this idea with some serious frequency shaping, which I just began educating myself on today. This will be space-consuming, but if I finish this I will move to an SMT circuit. SMT is what I teach and do in a production environment everyday since 1999, so it will not be all that difficult to make that move. Update... I did some testing on the scope yesterday and plotted frequency response, gain, and current. I don't have a chart, just some raw data. What is showed me was that my circuit attenuates the lower frequencies in the preamp stage, causing the amp to work hard below 500Hz, hence my low E-string problems. The gain increases with frequency. I believe this is due to my C7 choice or its mere existence. I believe I can remove it with no ill effects. I attempted raising it today to 1 uF and this exacerbated the problem, basically killing all signal below 10kHz! Amazing! I switched the TL082 out several times and even rebuilt my circuit from scratch thinking that I blew something or had an incorrect connection somewhere... until I realized the amp was working perfectly at high frequencies, above 10kHz. I do not understand filtering enough to comment on why this effect was so dramatic or in this direction, but if anyone else does, have at it. I am going to experiment with lower values (lower than 0.1 uF) next and with it removed. I know it may seem as though I am shooting for the stars and I am, but I am fairly confident in my abilities to get there with the help of those here and at my employer. Once I get this working efficiently, I am going to attack Moog's damping! How's that for star-shooting?

Hi Hank. The circuit is nowhere near ready. There are some issues regarding frequency response to figure out. I found today that C7 in that schematic is one of the keys and I am working on that now. The signal is 180 out. The amp does not correct that. But for the reasons Pete mentioned, this does not concern me.

Hi PSW and all. Here's an update of my progress toward a working sustainer with a focus on the amplifier circuit. I am on driver number 3 at this point after a few fumbles. It takes up the top 3 mm of a Fender Tex Mex single coil pickup, with staggered magnets manually moved level with the top of the bobbin surface. It measures 7.9 Ohms of 0.20 mm Polysol wire (32 AWG), was hand-wound under moderate machine-provided tension and potted in urethane varnish simultaneous to winding, then placed in 32 in of vacuum for 30 min to degas. I believe this driver is good due to test results of getting sustain on each string at least once during tests with various amp circuits, which is where my current focus is. I have wanted to create an amp circuit that is simple, very clean, and having sufficient headroom to guarantee the minimum necessary output to drive the sustainer coil. My current circuit is based on the TL082 op am as a preamp. This is followed by the TDA7267 2W power amplifier. Note, the plan is Not to utilize the full output potential of the 7267 chip. I will be utilizing about 1W and with supply is still one 9V battery. TL082 op amp preamp: The idea here was to create as simple a preamp as possible, using as few components as possible. As you will see, problems I encountered brought the component count up substantially. I first attempted to create a simple non-inverting voltage follower, using no external components beyond the 0.1uF DC-blocking capacitors on the input and output. I wanted to use the non-inverting input as I have read it is a higher impedance input than the inverting input. However, this failed with the TL082 as the chip goes to positive supply voltage on the output if it does not see a minimum voltage around 1v. I read this is a common problem with many op amp designs. To correct this behavior, I added to 50k resistors to bias the input to half of supply voltage following the input capacitor. The results were a very nice and clean 1 to 1 upon testing, but power consumptiom goes up due to the resistor network. Next, I attempted to add a 5X gain, but the TL082 did not seem to accept the standard divided negative feedback to ground technique as described in non-inverting mode on this page at allaboutcircuits.com. I still do not understand why this dod not work as expected, but as a work-around, I used the remaining half of the TL082 as a gain stage. This uses the inverting input, biases the non-inverting input to half of supply voltage again with 2 50k resistors, and produced a very clean, inverted output up to 2V AC. I knew at this point, the gain would need some tweaking, but have not installed a potentiometer for this purpose as of yet. I would rather see real world results with known values beforehand. TDA7267 power amp: I chose this chip as it is a relatively new design in contrast with the familiar LM386 and includes a 2W rating, de-pop circuitry, a standby mode, and good supply voltage options. This was relatively easy to implement, having only a supply + and -, input, output, standby, and 4 grounds to connect, utilizing only a cap for the standby line (47uF) and one on the output (470uF). My first attempt included a 10k potentiometer for colum, but the chip did not accept this between the 0.1uF input capacitor and the chip input. For now, the potentiometer is removed, leaving the preamp gain as the only circuit control, but I plan on reinstalling the potentiometer before the 0.1uF capacitor to see if this corrects the problem. Results: This circuit takes signal from the bridge pickup (Seymour Duncan JB full-size HB) from my Fender strat and will successfully drive 4 strings, the A, D, G, and B, but struggles on the low and high E. I believe preamp gain may be too high. I reduced it to 3X replacing a 20k resistor in the negative feedback loop of the TL082 second stage with a 33k resistor. This somewhat improved results. I also suspect the problem is due to my choice of capacitors and welcome suggestions on these values. The system seems to be biased toward mid-boost and the strongest sustain, which is very strong, is on the G string. I think I need to equalize this a bit, but do not yet understand how capacitor values affect frquency response. Also note my strings are sized .011" to .050". All other observations seemed normal, ie. I did observe the expected EMI squeals when the mid position pickup was selected or when I moved the driver too close to the bridge pickup. As I am a novice at circuit design/implementation, comments welcome and graciously solicited. Thanks.

Hello Pete and Hank. Hank- I am very new to the worl of electronic design. I am in electronic manufacturing, but inner workings of semiconductors and their integration into circuits is something I am getting a crash course in as we speak. I hope we might be able to assist each other through this adventure. I am an instant op amp fan and it sounds like you have some experience with them, so I would be interested to hear more of your regulated idea. Are you suggesting a zener setup for the Vcc? Pete- Yes, you did answer some things there, Pete, thanks! A colleague also suggested one of the caps was causing the phase delay. I will remove it and see what happens. I am also going to create an entirely new preamp circuit, as bare bones as possible, and see what happens. I have a feeling that you are right about me overdriving the LM386 and a simple op amp voltage follower (no gain) might be the key to something good for a very basic preamp. I am also contemplating dual power supplies to get a bigger window. Any experience with this? I am wondering how a contrived ground at the -9v of one battery and the +9v at the 2nd battery might affect the guitar ground and any signal processed from the guitar to a regular piece of sound equipment with ground NOT at that same potential. I have 5 pieces of LM386N-4 which will take up to a 22v supply voltage. Back to op amps though, from what I read recently, most op amps have very high impedance inputs and as such should not load the guitar's output by nature. If my learning is correct, then the simple voltage follower pictured in my last post is all that is necessary for a preamp (sans gain if desired. With the TL082, which is dual op amps in one 8 pin DIP package, one could conceivably run a follower on one and gain on the other. The TL072 you mentioned might even be better as it is a lower noise version, but for now, I have very easy access to the 082's. Also, from what I have read the TL082 is a better choice than Strib's LM741 op amp, which is a very antiquated and slow design. I have a few of those as well and will attempt to confirm this at some point with a socket as you mentioned. I believe the zest of Strib's circuit is the TBA820M. I have samples en route of the TDA7267 2W amp chip from STMicro which I am eager to try out as well. This has a "depop" and a standby feature included and is a much more modern design. than the 386. I thought the "depop" might interest you. I know you are of the experienced mindset that driver construction is most of the puzzle, but I can't help think that a really clean circuit is also key. I tried my new driver and I have sustain on 5 strings now when held by hand above the neck pickup. I can also get sustain on these strings with bridge and middle running, as well as middle alone, with no EMI noise! I am getting excited now for sure. To add another twist just to further confuse from the norm, the sustain is harmonic sustain, not fundamental. I find this strange, since everything I have read in this thread has led me to believe fundamental sustain was easiest to get. When I reverse my leads, I get nothing except the oscillation (string not EMI) that sounds like the driver is trying, but no dice. OK, one last question (for now)... input to the circuit has a hot and a ground. While I understand the AC signal coming in should not really matter much which lead off the pickup is considered ground, isn't there a difference in some way with respect to the DC, since the guitar's ground is a much more massive body of metal and after all, the bridge pickup is connected to this ground when switched on. The reason I ask is my circuit, when hooked up to drive a speaker, will only work in one polarity when taking signal directly from the guitar jack. The mass of the guitar's ground is the only line of reasoning I could come up with to explain this phenomena on my own. I know it is real life that is turned upside down for you and was commenting that it can easily manifest here after answering the same questions over and over for us newcomers. I have been there, meaning low and with seemingly little hope, and lost everything due to my own mistakes. Counseling turned out to be the best thing I could have ever done to help get me back on track with my family and myself. Knowing nothing about your problems except what I have caught glimpses of in your posts, I can safely say you seem to me to be a good person. Keep your head up and you will find your way through it.

Yes, exactly. I am not planning to use all 2 Watts, just looking to maximize the cleanliness at 1W output through more headroom. I understand. I am guessing to further make things difficult, there is no direct correlation between what will make an audible 8 ohm speaker show oscillation and what will make an 8 ohm driver oscillate. Ughhh. Once again the difficulties of having no natural human sense to pick up on. With the sustain your system is getting now, if you do have a similar phase shift in your circuit, I would imagine the performance would increase somewhat if the shift were eliminated. I am thinking about an op amp voltage follower followed by a push-pull transistor circuit to simplify this even more. I did not wind by machine. I wound by hand and the traverse was all but completely random. I auto-tensioned the wire as to not have it slack. I must be mistakn, but thought I had read somewhere in here where you (at least I thought it was you) said something to the effect of... it takes a few tries to get the tension right, so I assumed there was some tensioner being employed. I will have another go with the same circuit, but with the preamp at unity gain. Sure, the amp is the modded LM386 exacxtly as is on page 280 of this thread, as posted by MRJ. However, the preamp is not there. I have clipped off the fetzer portion and left only everything from the volume control and over to the right. The preamp (left) portion of the circuit has been replaced with this. The only difference is I have added a potentiometer and a resistor in place of the 100k and 1k resistor negative feedback loop to bring the gain down to an adjustable 2 to 70' sometyhing' ish. To make this a "unity gain" voltage follower, I will try something entirely different, a simple something like this to feed the LM386. Then, if the output is too low, I can add gain resistors back into the feedback loop. I've been there and wish you the best. You have taken and continue to take on a lot with this project... answering the same questions over and over... must get very annoying. Maybe something to mitigate this is creation of a very organized thread locked to all but you and maybe an "assistant" or something, where current best practices, circuits, driver design, etc. can be in a "read-only" format and updated as progress occurs. One last thing... you didn't answer about the temporary test box setup, more specifically I am wondering if it is futile because there is some key something I am overlooking. Does the setup I described sound OK? To recap it is: I am also building a signal bypass/passthrough box for simplicity and ease of hookup for testing purposes with capability of switching phase at different points throught the cicuits to see just what the effects will be. I am building this box very modularly to facilitate ease of swapping out different preamp and amp circuits as hand slicing and even gator clips are a royal PIA. What if any are the consequences (other than EMI) of taking signal from the output jack of the guitar with pickup selector at bridge only, rather than the pickup leads themselves? I'd rather not mod my guitar (even adding leads) if I do not have to! My test box would take signal from guitar output, split to bypass jack (for out to Fender amp) and to sustainer circuit, then feed driver which is hand held until I get more positive results.

Hi Pete and MRJ. I have spent the last week or so building drivers and an amp circuit, testing, and plundering on. I do have a few questions which I am hoping you might clear up, but first let me bring you up to date... I have one driver built from old strat pickup> I removed old windings, blocked up the lower portion of the bobbin with epoxied on fiberglass strips. This left approximately 3mm at the top of the bobbin for the driver. I hand wound using only a mechanical tensioner. I had the tension set quite high which I now think was a mistake. Since, I have another driver with windings under moderate tension in the potting curing stage as we speak (or I write). The resistance of the original was spot on 8 ohms and very solid as I used urethane varnish to pot throughout the winding process and followed with 32 in of vacuum to degas. The amp circuit is functional. I have opted not to use the fetzer valve, but rather built a preamp based on the TL082 op amp, with variable gain from 2X to roughly 75X. The amp circuit is the "modded" LM386 Ruby found on page 280 of this thread. I attempted to optimize the amp for max clean output in the lab at my employer. We sent 1kHz sine wave at roughly 100mV through the input and proceeded to "tune" the pots from preamp gain, then to volume, then to amp gain. All looked good on the scope. The circuit was processing 1 kHz clean up to about 1.2W. However, there was about a 1/4 wave phase shift in the circuit, which is something I did not expect. Then, in real life application, the amp is very touchy, picking up a motorboat sounding low-mid frequency hum if gain is set too high. For this reason I am investigating other preamp/amp chip combinations, all looking for totals under 2W. I am also building a signal bypass/passthrough box for simplicity and ease of hookup for testing purposes with capability of switching phase at different points throught the cicuits to see just what the effects will be. I am building this box very modularly to facilitate ease of swapping out different preamp and amp circuits as hand slicing and even gator clips are a royal PIA. So actual sustain... I get it on the low E, the A, and the D, with a hint on the G if I really try, but nothing on B or E strings. This is all with the driver handheld at the 12th fret. The sustain is not exactly the fundamental or a nice harmonic. If I strum an open 6th string E, the driver fights with the string and gradually takes over with a harmonic that simulates the 7th fret on that string. The oscillation during the "takeover phase" is not all that pleasing. If you have ever tuned using the beginner 5th-fret-to-next-open method, the oscillation reminds me of this... as you get close to in tune, it disappears, but nothing at all like the nice sound bytes I have listen to which were posted via this thread. I am guessing this may be the embodiment of the 1/4 wave phase shift I mentioned earlier? Next step is to build a better circuit to try with the new driver, which will be ready tomorrow. Question 1: Is my 1/4 wave phase shift normal? I think it is more of a time constant xxx ms delay than a true phase shift and I am wondering... if I can not get rid of it, can I add a simple phase delay or phase shifter circuit with a knob control to "tune" such a delay out of the equation. Question 2: What if any are the consequences (other than EMI) of taking signal from the output jack of the guitar with pickup selector at bridge only, rather than the pickup leads themselves? I'd rather not mod my guitar (even adding leads) if I do not have to! My test box would take signal from guitar output, split to bypass jack (for out to Fender amp) and to sustainer circuit, then feed driver which is hand held until I get more positive results. Thoughts or suggestions? One comment I have from the beginner's perspective... not knowing if your driver or amp circuit is good is troublesome as there is no way to eliminate a variable!

Yes, the links do not work, sorry. I could e-mail them. It is just a screenshot of an Excel sheet where the links do work, but I was not able to upload it into my post. Is there a way to attach it? The pots are for the 2nd scheme, but I am contemplating the 1st scheme as well and as you suggested, I am not going to rush anything,but it also makes sense that once working properly, I would prefer to only have the fundamental/harmonic mode switch located outboard. Further, I am not going to shoot for an internally mounted preamp/amp circuit as of yet. I want to get a functional outboard unit going, then slim the whole thing down using SMT components. I know what you mean about their size. As I mentioned in my first post, I have extensive experience building through hole and SMT assemblies. I am a subject matter expert in the electronics manufacturing process (certified trainer for all IPC manufacturing standards). If you are unfamiliar with the IPC, check out www.ipc.org. IPC spans all things electronics and is worldwide-recognized, but again, I am a mfg man, NOT design. For five years, I programmed and debugged high speed SMT lines for prototype runs of assemblies from all sectors of the market. I made it through the huge slew of layoffs after 09-11 and came up to New Hampshire from Massachusetts in 2005 after meeting my beautiful wife, only to end up at another electronics mfr, only this time it's solely electronic assemblies for interior/exterior aircraft power and lighting systems. I might be of service to you with your SMT-related endeavors. I do have some contacts that I might be able to coerce into laying out multilayered PCB that would allow a circuit with this low component count to be built amazkingly small. Their actual fab might be somewhat costly as as small production run, but I think interest here is enough to get others to chip in... I know I would. I also have a few resident nerds at my employer that I can probe on circuit-related matters. The LM386... by "clones", I meant copies my companies not familiar to me... example NJR (New Japan Radio Company). Did you ever come up with an op amp based pre-amp? I saw a few posts from about 6 months ago, but lost the trail. I stumbled across a chip I thought might be useful. Please take a look at the TL082 datasheet and tell me what you think. The statement within that caught my eye was... Anyway I have one and was wondering if it might be something to try. I would need some guidance on the design side. Thanks again PSW and MRJ for your time and support. This thread is a huge body of information and its existence is very much appreciated.

I had trouble with finding the LM386 and an appropriate PCB from Mouser. The LM386's they have available are clones, something I did not want to risk without hearing of prior success. The PCB was chosen as I could see what I was getting on the website... Mouser's selection was broad, but not very visual in this area. Please do make suggestions. Thanks!

Agree about mini HB's with regard to the SD Hot Rails and Duckbucker. I have not played any other mfr's mini, but my middle position Hot Rails (not really that "hot") serves as a buffer for the JB and VR. Now the Vintage Rails... that's another story. You ought to get your hands on one! The beauty is with the warm pickup, it is just right... not very LP at all; still a strat , but easier/better on the ears. The SD Vintage Rails for the neck position is by far my favorite and I would recommend it to anyone. I've gotten numerous positive comments and questions from other players about that pickup. Whether you are a strat-i-ness fan or not, it is well worth the investment. It is very sweet and rounded sounding clean and then surprisingly, it can hit some strong harmonics with a distortion channel... something I found sadly lacking in the the stock Fender pickups, which I honestly could not even stand to play clean. Now that I think about it, the VR does take out the strat-i-ness (after all that is the definition) to some extent, BUT, this does not have to be a bad thing. I have always found the stock "shimmering" highs a little much. I guess maybe I'm a bit strange because I have always loved the looks, nostalgia, and ergonomics of the strat, but have always felt like they are all just a bit wrong out of the gate in some areas... sound needs changing immediately... and locking tuners and LSR nut are the 1st necessity since they have a synergistic effect on playability, even over pickups for me. If I ever have another go on my old SSS strat (or a new one), I would not hesitate to put VR's all the way around. Then again, all these decisions occured way before I was aware this community even exists, so now I am wondering if some low $ wiring, switching, or cap/resistor changeouts might have achieved the same results. As such, take my opinion as you may or as my badge calls it... Noob. P.S. Your noiseless driver is sweetly stealth. Any sound bytes to go with that? Indeed, I will miss my neck pickup when I DO get a sustainer permanently installed... that's one of those sad, but strangely alluring tradeoffs

I put together a BOM (adding the DPDT switch, some wire and a board) with vendor info for what I "think" are OK components. Would you guys please review it and comment on anything specific I might have wrong before I begin ordering things? I am particularly concerned with my potentiometer choices. Even some "yeah that component will work, but this is a better idea because it's one-third the size" type comments would be perfect! It may also help out others like me in the near future... this did take a few hours to sort through and although the costs may not be accurate as time goes on, the P/N's and such should help out at least and no need for each individual to have to start from scratch. BTW, tonight I also found that upon registering, you can request "samples" of LM386M-1 (SMT version), N-1 and N-4 from National Semiconductor. Going to bed now as it's about 4:00 am here. Cheers!

Are wattage ratings for the resistors important? Voltage ratings for the capacitors? Is there a more specific BOM somewhere? If it is considered bad form to post a BOM with vendor & P/N specifics... might I get one PM'd to me? Thanks for your time.

I understand that part. Is the "0.2mm" inclusive of the coating? Have you calipered the wire and if so would you mind clarifying? Is it equivalent to 32 AWG? Well, it is all in French, so I could do nothing more than view the photos! Would you please point me to an explanation of, or explain the "loading"? I am not familiar with this concept. I am very anxious for some serious sustain and morphing harmonics. Thanks again for your time.