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Sustainer Questions


al s.

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Oh...it's not a criticism not to have a neck pickup. Very few of the sustainer people seem to have a problem with this set up...for me, the sustainer is an addition to the instrument and loosing the neck pickup or having to use a particular or active pickup breaks my criteria for success.

Similar with hex pickups and such...really once you start modifying the guitar and signal to this degree, i'd be considering a different interface and technology.

That driver looks again, extremely neat FF. My drivers have never really been used as a pickup...they will "pickup" but they would need a lot of preamping to bring it up to spec and not sure that I'd get a good sound (compared to a good passive pickup...though sustainiacs can sound fine) out of them.

My suggestion over theorizing to deeply or postulating about what might be required or work is to build some stuff, even crude experiments that will prove your hypothesis. I think that there is enough evidence about to show that you may be a little misguided on some aspects, and not entirely clear about some of the problems you will be encountering in such an endeavor.

I don't recall seeing that Hex driver thing FF...again very neat. The 'problems' you describe existed for me as well...but then I got really tricky with these 2D concepts and such...and really, all you introduce is more quirks...and the whole thing interacts with each other anyway.

You will find plenty in normal sustainers in reaching the goals you seem to be looking towards, I'd suggest making something like me or col of FF or some of the others that have succeeded as a starting point. Of course people have looked towards hex things, but few have continued to pursue it and those that have did not find the rewards you might expect.

The goals are still not clear either...is there something you expect from such an expensive complicated system that a conventional sustainer wouldn't produce?

Otherwise, it seems you have not yet hit the search button and seen that for the last year the main thread had disappeared and almost every thread has been closed down in recent time. As a result also, you have missed out on all the kinds of variations and discussions on the subject that have already taken place and even experimented with. Before delving in too deep, perhaps it would be worth while digging into this vast amount of material for some answers, and finding some of your own through experimenting and reporting back. All this is really largely speculation with moving goal posts, the tail end of the thread, some deleted, went heavily into such proposals with the end result something a virtual copy of what had come before. All the same discussions about digital processing to compensate and 'natural vibration' theories and such were hashed till the thread imploded, and most subsequent ones as well.

It has come up time and again over the years as well, but nothing so far has come of it for all the work and talk that has transpired. Largely I feel, because these discussions never are fulfilled by actual work being conducted and almost everything based on supposition and assumptions. Such plans are enormous, they have to be taken in smaller steps...but the thing that has often been lacking is taking those small steps to the point of demonstrating conclusively anything much.

But in the end, these things will sound as you choose to make them sound. There are limitations to what you can make a metal string do in the real world...and once you introduce digital stuff (not midi, but modeling and processing even) there is so much more you can do. If you read some of the early stuff and the hex era, you can see that I too felt that there was some potential that was perhaps more than physically possible...building things, setting real goals, working to them, that's what kept me on track.

Oh...and plenty on D class amps...a lot of amps are not really designed or suited to this application. That there are caps or basic blocks of amps can be an advantage in tweaking these things anyway. The signal from a guitar string in feedback loop should not be underestimated compared to music for which these things re designed. A constantly sustained string outs out a heap of constant signal at a high level, noise and distortion do matter to a degree...any processing, especially digital conversions is going to introduce phase lag...the more complex, the more things that need to be compensated for. The reality is that many modern chips are not designed for such signals and will simply go into hibernation to protect themselves.

Sure, there are alternatives, many have been discussed and explored...but don't be fooled by specs or assumptions about how these things will work in practice. I still use the old LM386 (I have my own criteria to work from) but tried many others and potentially "better" circuits that have failed on other grounds. Some have advocated chips, despite having discovered the same problems that I encountered with them...overheating and shut down, but instead have chosen to ignore these major faults.

The reality is that you do not want a lot of power...more power generally leads to more problems. This is particularly true with hex systems. More power will out out more EMI and interactions between drivers...less power of course helps.

So, the direction and goals of say Col are extremely admirable and of benefit to the ambitions of someone like yourself McS. A 40% increase in efficiency would be an amazing boon to anyone interested in this technology. For some it will simply be battery consumption...for others it will be the technical advantage of clean headroom...for people with loft ambitions, it will be crucial to something like a hex design, or better polyphonic drive, or whatever the succinct ambitions turn out to be.

For the work, goals and ambitions of myself, I'd have to be able to find a means to exploit such advances should they happen, in line with and compared to what I can already do with the more basic forms and simple approaches. I suspect it would be a tall order for me.

That said though...I still have an interest and possibly even some things in mind post this move that starts today. The idea of a tapping instrument that has it's strings activated by a sustainer really appeals...to do this really well...a more polyphonic multi amped driver likely is the way to go...but then, I wouldn't be trying to force it all into a un-modded telecaster control cavity like the last one!

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Why not some web cam pics of the new driver?

Next project will be to make the driver usable as guitar pickup (in order to silence all critics. :D ).

No, I meant, double coils for each string, something like that:

   |  *|*  |  *|*  |  *|*

  *|*  |  *|*  |  *|*  |

To save space you obviously have to place them in the alternate order.

Your configuration looks like 6 coils connected in parallel? At least the connector looks like just a 2-pin one. It eliminates the whole idea of driving all 6 strings simultaneously. Or, am I wrong?

I'm kinda confused again. What are the metal sticks on top of the coils? Does does your driver consist of two rows of coils, in a humbucker-like configuration, 12 coils all in all?

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In the post above I indicated that this was exactly the kind of way my hex drivers worked...although not with so many coils but with balanced magnetic fields.

A mono sustainer will attempt to drive all the strings simultaneously. The lower ones or the resonant ones will often win out over time. The thing is that if all the coils or magnets are linked by their interaction with one another, there are limitations to what you expect from these things. Combine them with the quirks as both FF and I describe and you are not getting more, but restrictions to performance. These thins will become clear with experimentation...

So...yes, the effect is much as you describe in some of my work, I am not aware of others that have tried this path...moog, maybe...but still a big maybe I suspect.

I think you will find the "metal sticks" are the bobbin tops of each coil.

Also, getting an optimum drive force and action in such a small space for each string may well be a problem. I had to find a way to make such things without winding coils at all to get these things so small...

CP9xHEX.jpg

There is an incredible amount of information now available again on all of these things really...

CP6X2.jpgCONCOIL1.jpg

This kind of stuff must be pretty early in the main thread as I found these pics on my earliest page in my photobucket account. You can see them dated around 2004...

In fact, this is the first pic loaded into the account...

SideDriver1.jpg

which is much like the kind of thing you are describing. I did build these kinds of things btw, and that is where the work really is, where the rubber hits the road. Speculating won't get the answers you seek about the possibility or practicality of such ideas. I can only explain what I have tried and some of the failings in them, but if committed to the concept, the only way forward really is to try them for yourself!

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Why not some web cam pics of the new driver?

Next project will be to make the driver usable as guitar pickup (in order to silence all critics. :D ).

No, I meant, double coils for each string, something like that:

   |  *|*  |  *|*  |  *|*

  *|*  |  *|*  |  *|*  |

To save space you obviously have to place them in the alternate order.

Your configuration looks like 6 coils connected in parallel? At least the connector looks like just a 2-pin one. It eliminates the whole idea of driving all 6 strings simultaneously. Or, am I wrong?

I'm kinda confused again. What are the metal sticks on top of the coils? Does does your driver consist of two rows of coils, in a humbucker-like configuration, 12 coils all in all?

The second post ("Why not some web cam pics...") was not related to the hex driver but presented a dual blade HB I just finished building.

I understand what you're after but from my picture you get an idea of the proportions. In order to succeed you have to use small pole pieces and wind some very neat coils. There is a guy with a CNC machine that I believe could do this type of precision work but he is living the life of a Chinese dissident at the moment.

My hex driver has 6 coils in series. Of course you can use 6 coils (or 12) in parallel instead.

FF

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I wound a 5mm height coil, 38 AWG, about 26 ohms DC resistance. In fact, I made a mistake, it's supposed to be 36 AWG, but it's just experimentations, not a big deal to re-wind it.

I used a drill as the lathe to make cores from humbucker pins, soda-bottle plastic for the washers. I can describe this "homecooking" technology in detail, with photos. It's not very practical and takes time, but you can make almost any coil you want for your experiments and optimizations.

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Oh...it's not a criticism not to have a neck pickup. Very few of the sustainer people seem to have a problem with this set up...for me, the sustainer is an addition to the instrument and loosing the neck pickup or having to use a particular or active pickup breaks my criteria for success.

For me it's the other way around. I didn't need a neck pickup. But now something is mounted that looks like a neck pickup I want to use it in that quality.

That driver looks again, extremely neat FF. My drivers have never really been used as a pickup...they will "pickup" but they would need a lot of preamping to bring it up to spec and not sure that I'd get a good sound (compared to a good passive pickup...though sustainiacs can sound fine) out of them.

Once you have found a way of creating a driver that functions and looks good it's only a matter of repeating the same trick. But it's very personal. You have to find out what works best for yourself.

Yes they need some amplification (some 40 dB !) But the impedance at 10 kHz is around 120 ohms (very low) and I don't have to be worried to lose that classic vintage paf sound (it wasn't there in the first place). My expectations are not that high, how microphonic are coils soaked in wood glue?

Cheers

FF

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I wound a 5mm height coil, 38 AWG, about 26 ohms DC resistance. In fact, I made a mistake, it's supposed to be 36 AWG, but it's just experimentations, not a big deal to re-wind it.

I used a drill as the lathe to make cores from humbucker pins, soda-bottle plastic for the washers. I can describe this "homecooking" technology in detail, with photos. It's not very practical and takes time, but you can make almost any coil you want for your experiments and optimizations.

That's a good start! Is your end goal a 8 ohms driver? (12 coils of 24 ohms, 2 x 24 / 6)

Well, a picture of the coil you've built would be nice.

So what is the next thing you have in store for us, a one-string-only sustainer? That is the big challenge with this new design, to get sustain at all!

FF

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Yes they need some amplification (some 40 dB !) But the impedance at 10 kHz is around 120 ohms (very low) and I don't have to be worried to lose that classic vintage paf sound (it wasn't there in the first place). My expectations are not that high, how microphonic are coils soaked in wood glue?

microphonics would be NIL!

The sustainiac driver sounds really quite good as a single coil...nothing super special but certainly doesn't sound "cheap" for what it is...I was surprised.

Who knows, with that kind of format you might have something really cool sounding and useful. For me and my purposes, I have avoided the need for active electronics...but that is my choice of course...

Once you have found a way of creating a driver that functions and looks good it's only a matter of repeating the same trick. But it's very personal. You have to find out what works best for yourself.

Very well said, it is very personal...many of my things may not be that repeatable by others, but something that works functionally the same and maybe looks better is entirely possible.

That's a good start! Is your end goal a 8 ohms driver? (12 coils of 24 ohms, 2 x 24 / 6)

Well, a picture of the coil you've built would be nice.

So what is the next thing you have in store for us, a one-string-only sustainer? That is the big challenge with this new design, to get sustain at all!

A few people have made single string drivers. My first was on page two and worked amazingly well...with a tiny neo-mag on a 10cm coil bobbin-ed in paper and a ferrite bead as a core...about 4mm deep. However, getting six of them right next to each other, side by side...there is going to be interaction and all kinds of quirky effects as anyone who has tried it discovers...be prepared for the unexpected (and to have theories dashed)

It is interesting to see FF's hex driver, I ahd not known about that...in part because clearly it is well made and the kind of thing many envision...the one that is in the guitar is in fact a more conventional format. It is not then that people don't think of or try such things, it is because perhaps that a more standard format can work surprisingly well with less effort and disadvantageous quirks...and there are some major hurdles iwth such schemes that have yet to be, or perhaps are near impossible to solved.

Nice work FF and good statements...

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Hey PSW, could one use one of these for the amp and build a driver? :D I have built this already and if it could be used that would be cool.
Noisy_Cricket_Schematic_Smaller.gif

Hmmm...not bad, it has a buffer and an LM386 with a zobel on the tail end. I'd still be trying a 100uF output cap instead of the 220uF (C8) and the switching would likely need to be redesigned for multi pickup guitars. You might delete the 'tone control" and add a 10Uf cap between pins 1 and 8 in series with the "gain pot" to protect against internal isolation. Not sure that the tone would do a lot, might want to leave that out along with the cap (C5) as it is much like a guitars tone anyway.

Otherwise, not a bad find...no gain in the preamp so best with a decently strong bridge pickup as the source signal.

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dont know if it would be relevant or not, but my guitar teacher has a noisy cricket that the creator himself (a good friend of my guitar teacher) had built for him, and It is a very good sounding little amp and is incredibly good with battery life. great little amp to plug into a cab.

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Well..it's as good a proposal as any. Remember that the Fetzer/Ruby was just someone taking two run off groove 'designs' and mashing them together (G-Mike) without any peer review...and so it became the standard.

The noisy cricket is the same thing, jack ormans buffer into a generic data sheet LM386 amp. In my earlier experiments before all that, I was messing with the CHAmp and PreCHamp kits which did much the same thing (although the CHamp...Cheap and Handy Amplifier...used the full high gain specs from the data sheet that this lacks for more stability).

The main purpose of the buffer stage is to prevent loading as the LM386 is not designed to take the signals of a straight guitar, and certainly not to have the signals split between the sustainers amp and the guitar amp without degrading both. In earlier work of mine I was using a guitar with a very low powered SC in the bridge of a strat so felt I needed a little more "boost" of a pre-amp over a straight buffer...for a long time I was giving a huge amount of gain into the chip...but really, all I was doing was adding distortion into the mix and have backed right off of that kind of thing for years now. The Fetzer has a little gain, but I am not sure that this is really necessary for most people...if you have an HB in the bridge it probably is plenty of power to work with a buffer like this...a good driver should be sufficient to work fine.

There has been a lot of negativity about the LM386, especially in recent times, and derogatory remarks about my supporting the thing. Really, it is a 'standard' for this kind of application and has been for a long time. It is a simple device, but that means it is easy to tweak to our purposes and get creative with the design process of circuits should people wish to. It's still used in the E-bow for instance...it does the job. So, simple, cheap, indestructible, adaptable, works...good enough for me.

What I don't like about the fetzer/ruby is the need to bias the transistor with a trim pot, and i suspect this is where some people come unstuck. I don't like the space it takes to do this and the potential for things to go wrong, and the point of the fetzer design anyway (to mimic a valve stage) for this application...so I have never used it...plus the transistor is not common in this country and many others. But the basic idea is sound and this too can work, it really isn't that much different from this.

The other thing though is a few mods...the sustainer when working properly puts out a fairly extreme signal. A constant, usually increasing signal...not like the signal that many modern amp chips are designed to deal with. Music tends to stop and start and is has all kinds of his and lows in frequencies and volume...the kind of signal these sustainers things put out can often overheat an amp, you can feel the heat in an LM386, in many chips, the thing simply turns off to protect itself!!! Still, I have never blown an LM386 in all the time I've used them, even soldering them in backwards and applying power supplies to them, or taking them in and out of scrapped circuits

So...if you look at the data sheet for high gain applications, the gain set pins between 1 & 8 could benefit from a capacitor (10uF say) with the gain set trim pot (before or after it) for stability...a couple of cents worth, so I'd put it in.

The output cap of 220uF is to give a certain amount of bass response. Of course how much you'd like is dependent on the kind of speaker you have. The kind of "tone control" in the noisy cricket is much like that of a guitar...it simply cuts highs. However, the problem many have is poor high string response, or over active bass strings going nuts. A little tweaking of these things can make a big difference in response. So...I tend to use a 100Uf instead of the 220uF on most guitars and this tends to balance things out. I do get a harmonic response on the lower end of the guitar, but I rather like this "mix" of sounds and can control this with a little less drive...or one could I suppose switch in different caps or other circuit tweaks for different effects.

As I recall, Al was asking about drivers with adjustable poles and such, others have sought complete hex coils...and there is some merit in these strategies, but not as much as some of these simple circuit tweaks that one would make with an amp design if you could hear it and seems generally to be avoided as the first point of call in addressing these kinds of issues. There are simply not the gains that people imagine by moving magnetic poles up and down for response when they are so close together and interacting.

You mention battery consumption...and many seem to be resorting to remote powering of these things. If you use these things continuously for long periods at a time, they are not great with batteries...they are amplifiers often running hard for what they are. Col is looking at ways to make the driver more efficient, and so the system more efficient and that will help a little. But really, they can last a long time with normal use. The beauty of most of these DIY systems, and certainly all of mine, is that the guitar works fine without a battery at all...not so the commercial systems that require the pre-amps and such. My DIY sustainers only use power when the device is on, again, saving a lot of power potentially over the commercial units...so I don't change my battery for months at a time generally.

I use an LED indicator which drains a bit of power, but then, it dims when the battery is overworking to show it's potential power...I find it useful, but certainly not necessary.

So, the Noisy cricket is a bit of a mash up of the old LM386 and the JO buffer thing....not entirely original or "designed". I was surprised that people didn't by now create more adventurous and less plagiarist solutions for this particular project over all this time. An example there would be Col's remarkable circuit. My early things were essentially tweaking the gains setting resistors and filters in the old pre-champ and other designs and starting out with a complete LM386 data sheet circuit for maximum stability and tweaking the output cap for response. I did try all kinds of alternative chips, and they are out there...but many failed from overheating, not living up to the hopes and claims in this application and generally being hard to get and expensive (not the best for a DIY criteria). I have used opamp preamps with success as FF has done in the most basic form...I found that a discrete circuit with something basic is good enough, cheaper and smaller. I have used higher quality components and SMD's to reduce size say in the tele's circuit...i felt that this was an important thing in line with my 'low mod' criteria. These newer circuits do have a bit of a nod to the AGC thing, but nothing as complex or elegant as Col produced. Generally a filtered and decoupled feedback switch to turn off the signal if it gets too hot letting the string sustain by itself. But, I also have a different "drive" control that never goes to zero and a trim pot to adjust the maximum gain the guitar can take before squealing. The reality though is that this thing switches so fast that it is defeated at high gains and runs as a straight amp, not unlike this proposal, the F/R or any other amp circuit you might choose.

So...a noisy cricket, a F/R, FF's op-amp with a different chip...it is all much of a muchness with the basic premise of the normal DIY designs developed in this forum. That is that a sophisticated phase compensated circuit as you will find in the commercial sustainers about, is not really necessary with an appropriate driver design. That's why so much emphasis is put into the driver in this project and that there are things that work well with this premise, and there are some things that might work ok with a circuit that compensates for another's quirks...the kind of things that McSeem and others have proposed.

My feeling is, and I have done a lot of work with hex driver and such, is that there is a cycle of diminished returns you can get into. If you want the strings to be sustained, or generate harmonics...well a simple design can do this in a very small package, easily adaptable and with small simple circuits like this surprisingly well. The idea that you can make individual string drivers is all well and good, if you make one, yes you can use different wires and such and run a lot of power into them, I certainly was captivated with this. But then, if you put them side by side they will necessarily interact and take more power and certainly more complex circuitry, perhaps six amps and then of course, a hex signal....the question I ask myself then, is what are the returns for such a complex system. Proposals to house such a thing outside the guitar creates significant problems...a multicore lead for a start, but also...anything attached to the driver, such as the leads....is effectively an extension of the driver coil and will be giving off EMI and lowering efficiency and causing problems. More power to compensate will only increase the EMI and the problems. So, for me at least, things that get this complex or require this much mods really don't seem to hold the promise that many theorize for them...once you start making the things, you soon discover all kinds of drawbacks, even if you can get them to work. And I had all kinds of schemes to overcome them...just adding more complexity...like switching the drive sequentially between each driver so that only one of the six would be operating at any given time....it becomes a little bit of a madness after a while, when the simple works so well.

This even applies to the OP's question...adjustable poles...or just make a driver that will work for all strings and adjust the amp to suit the response you are after...far more effective! Separate poles effectively become as one...when bending a string with a pickup you don't really hear a "drop out" between them and my drivers seem to be fine (though no longer hex which is a different thing) with a normal pickup configuration...I just found for custom and compact stand alone drivers, the blade is easier to build, more compact and reliable...and cheaper!

Anyway...just a few thoughts at 5am in the morning...

edit for spaces deleteded...grrr....

Edited by psw
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Thanks for the ideas PSW. I built this little amp awhile back after seeing it on here and it sounds incredible for what it is, i run it through a 12inch celestion vintage 30 and get some really nice blues crunch out of it. I just saw that it used the same chip as your sustainer circuit and was wondering if i could use it as is to drive a, driver. :D I will most likely just build a sustainer circuit if i attempt it. Its on the list of things to do, just got to finish all the others first :D

Edited by chops1983
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It is a good option...the thing with a lot of these LM386 amps, and there is a lot of them about, they can move a fair amount of air if you hook them up to a proper speaker...use a 3" computer speaker and it ain't going to sound too good. This also shows the limitations..."blues crunch" is not necessarily the signal that you want to drive the strings, but potentially it might be cleaner than the F/R.

I think the only way to get really clean headroom is to use remote power...the LM386 can run fairly clean with adequate power or tamed down...on the other hand...Col's proposal to increase efficiency in the driver design might make getting a cleaner signal and less problems easier as well for the same or less power.

Unlike with speakers, you don't hear a driver, so it is difficult to tell what the signal coming out truly is other than by the effects it has. My feeling has always been that a little amp like the LM386 is perfectly adequate enough power to have the desired effect, as long as there is enough efficiency in the driver design. If there isn't, adding more power may often just be adding more to the problems that are in the system, not the circuit.

Hence, most of my attention remains on the driver side of the equation and resist the idea that the "magic" is in the circuitry with this project.

But, why not use a variation on this idea, similar mash ups tend to be what most have proposed and this is certainly better than some I have seen lately...tillman for instance with a different amp chip...it really is much of a muchness. I'd probably prefer this kind of thing to a F/R myself...no bias trimmer for a start, easier tranny to locate over here at least, still potentially very compact. But, there are far more knowledgeable people than me on circuit design, I'm just disappointed that none have come forward with an equally good standard amp proposal to this one or the F/R after all these years for a small battery powered amp.

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Re... adjustable pole pieces. The reason I asked this question was because some people had recently posted about drivers which used pole pieces:. ..specifically Elmo, and Hank.

It seemed to me that the common problem of uneven string response could be alleviated by varying the pole-heights. I guess that my armchair logic failed again! I see that if I had thought it thru I would have realized: if that were the case then varying the pole-height of the pickup pole would have the same effect. But alas, I know that doesn't work.. .. for the reasons Pete pointed out.

I know many have built successful AGC into their circuits and achieved an even string response. (Latest clips by Fresh Fizz were great!) But I didn't remember reading of someone who actually tried varied pole heights.

Anyone tried a multi-band Equalizer between the driver signal and its amp?

Thanks ALL for the awesome discussion!

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Hey Al

Well, the question needs to be asked, and tested. There might be a bit of an effect, but unlikely enough...perhaps with hex designs a little more...but then there are other problems. Thanks for a great reply though...obviously I used the same thoughts when I did things like this.

I confess that since moving a year ago, I have done no further construction on these things, though having moved again, it may well be possibly that I will explore a few areas and still have some projects to complete. However, far more than was ever posted by me, believe it or not, was tried. I have literally made hundreds of variations on all kinds of devices over the years...some I didn't report on because in retrospect they were a bit stupid, trying showed me why...so it goes. It can be frustrating when I see some dogmatically suggest things that I have experienced to be a bit of a dead alley without trying it and so revealing the things I have missed...or demonstrating where I went wrong, which of course would be even better!

...

AGC can really help...it's a tricky thing, it could be come a little too sanitized in overall response for my tastes, it really depends on the effect you are after, certainly the commercial systems are a bit more evolved and go in this direction...there is a lot more that can be done. Col really got a handle on this a showed a circuit with several modes and a lot of AGC, and it got something of the effect he was after, but it lacked some of the dynamic range that I seek in my devices. These things are a little a matter of taste. It will be interesting to see how a bi-lateral driver with separately atuned coils for the string sets might further address these things.

...

Anyone tried a multi-band Equalizer between the driver signal and its amp?

Early on i had a fair hope in processing the signal that drives the strings in the hope of vibrating the strings in novel ways. Some were interesting, some had little effect and some seemed to have little effect at all. Far more effective to process the actual guitar than the trouble it was worth. A flanger can have an interesting effect by sweeping through harmonics and making bird chirping like effects...not sure how musically useful these things are.

However, a radical tone control will have fairly dramatic effects...such as an equalizer.

As I mentioned above and before, I tweak my circuits with adjusting the output cap so they have less of a bass response than you might want with a speaker...this tones down the lower strings a bit and ensures a powerful high string response...so in effect, evening the response of all the strings. So, there are some myths about string response though they are not as even as if this were combined with some good AGC. If you play with distortion or a compressor on the guitar...this itself produces a pretty good evening out of things, so there are solutions even with a highly dynamic system like mine, as long as all strings are being driven well.

A side effect though is that notes below C on the g string, 5th fret blom to harmonics, generally a 5th above in the fundumental mode. I quite like this effect, I can moderate it a bit by turning down the intensity...but it is a by product of the circuit tweaking. I could have added a switch I suppose to switch in different output caps.

An alternative might be some kind of active tone control as you suggest. The effect of using such an equalizer would be to accentuate different harmonics in a strings vibrations and therefore create different harmonic effects. However, if adjusted to produce a nice even bass fundamental, you might lose high string response. But then, does this even matter if this is the kind of effects you are after. A wha like device has some really interesting effects...to the drive circuit, or simply on the guitar itself with a sustainer. The "Sustainiac" equiped guitar I have played, had such a control on it and was very effective...it was an older model and I am not sure they offer this anymore.

But as far as string response evening, radical tone shaping may not be the way to go...for an effect, yes. Remember that behind the lowest fundamental frequency that a string vibrates are all these harmonics and driving different frequencies generally brings these out. What you might fix in the higher strings, you may lose in the lower. This is exactly the kind of compromise I am happy to live with in most of my designs...I actually like the effect, and the harmonic function creates yet another harmonic sound to those in the 'normal' mode.

...

For me the "sustainer" is not so much about the ability to sustain a string for as long as you want. What interests me is that it is a way to excite a string....just like picking it. It is a way to play with the envelope of sounds and to manipulate a sound while being sounded and to produce harmonic effects that are organic. It is also an extremely powerful kind of sound and a really different 'feel' to the instrument. However, it does require learning to play the thing, especially a system with a lot of dynamic range like the kind I favour. I was using it a lot last night in fact...it really can be a cool device when you are in the mood...but the guitar itself is pretty cool, so you wouldn't want to build anything that might take away from that in the pursuit of sustain.

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So...yes, a bit of an equalizer can be an interesting effect, but how much you are going to want to put into a guitar and power and all the rest of the problems associated with playing such a thing...well, that's up to the builder.

My goals were always to try and make the things effective and as simple an small as I could, to leave the host guitar in tact as far as possible...then work out how to use it in an effective musical sense...still working on that last one...adding a graphic equalizer into the guitar seems to go against that for me. But, it will only work well, with a decent sustaining system...it won't fix problems inherent in the designs or construction and there are limits to what such things can do.

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Anyone tried a multi-band Equalizer between the driver signal and its amp?

I use some treble boost (8 dB at 1.5 kHz). But not to get different harmonics. It's more to balance the 'sustainability' of the strings. Give the fundamentals on the high E in higher fretting positions a helping hand.

FF

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Re... adjustable pole pieces. The reason I asked this question was because some people had recently posted about drivers which used pole pieces:. ..specifically Elmo, and Hank.

It seemed to me that the common problem of uneven string response could be alleviated by varying the pole-heights. I guess that my armchair logic failed again! I see that if I had thought it thru I would have realized: if that were the case then varying the pole-height of the pickup pole would have the same effect. But alas, I know that doesn't work.. .. for the reasons Pete pointed out.

I know many have built successful AGC into their circuits and achieved an even string response. (Latest clips by Fresh Fizz were great!) But I didn't remember reading of someone who actually tried varied pole heights.

Anyone tried a multi-band Equalizer between the driver signal and its amp?

Thanks ALL for the awesome discussion!

I guess the main thing to remember is that the effect will probably be slight, e.g. often the G string is a bit too lively. You would probably need to take the pole piece under the G string down a lot to get it's response even with the B and E strings.

Thinking about it from another angle, the field from the sustainer driver will still be pretty good even if you remove the core completely (maybe 60% of its strength with the core). The significant thing may be the permanent field. It might be that there is a fine line between plenty of domain alignment and not enough, so to tweak the response in a finely grained way by adjusting poles may be tricky. This would be due to the fact that the field drops off with the square of the distance....

It's hard so say for sure, but intuition suggests that adjusting the balance of the permanent field might yield more obvious results than trying to tweak the field generated by the coil. Worth experimenting with though.

Col

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