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Sustainer Ideas

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Progress Report:

I've been playing with circuits again.

I've found a simple and effective way to use the LM386 as a current mode amplifier - it can be set up to push a constant current through the driver that doesn't change with frequency (up to the point where it starts to clip). It also has a very good phase response (I think - the phase is fairly level at around 0º after the driver!).

This really works well, however because it pushes harder the higher the frequencies get, upper harmonics and any harmonics associated with clipping or noise are causing lots of fizz (what a surprise).

It should also cope much better with differences between different drivers - it keeps the current constant over a range of driver inductance values and can handle various output impedances (as low as 2ohm).

So to counteract this, the next step is to test a low pass filter on the input - a simple RC network doesn't cut it, so I'm going to try a second order low pass. This means an extra op-amp 2 caps and 2 resistors :D. The filter has been designed and simulated, and works so far - just need to breadboard it up and test it for real.

So far the circuit uses 2 op-amp sections (1 for input buffer and one for filter) the LM386 and a bunch of capacitors and resistors.

Testing this has reminded me just how fundamentally important it is to have ACG in a sustainer system. Without it, here is just a huge discrepancy in response between the notes that are easily driven and those that struggle.

Still, I will post a version sans AGC for those who don't want the complexity.

cheers

Colin

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Someone like Donovan may be interested in this idea. These are converted push pull pots. They combine the dpdt push pull function and a 4pdt switch (equivalent to an S1 switch or the kind of switch power required to turn on the sustainer as it stands) and a pot. I even transplanted the guts of a 1k pot into the push pull to get the value required for my circuits drive control.

Yes, I do like the versatility that uber-switching makes possible. I would like to learn more about them, any online site suggestions? I would like to read a simple site that goes into basic guitar wiring, especially switching and tone/volume controls. Uou seem to be the switch-king around here. The S-1 switch on my strat is intimidating to say the least and I would like to rewire everything neater than stock, but am at a complete loss... and yes, I've looked at the drawings on the fender.com site, but they are mfg drawings, not really a good schematic/dwg mix... sorry to get OT.

Col-

Have you played with dual power supplies at all to get rid of all the half power supply biasing and most of the capacitors that a single supply makes necessary?

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Are you familiar with the Guitar Nuts 2? forum...they are really friendly and helpful and dedicated almost solely to guitar wiring things...more knowledgable than me. There are a few sections there that covers some of it. The main site has some good stuff I believe and a fair bit on shielding and such.

People wanting to go completely nuts though...should check out the "secret" site...DGB Studio with 1,000's of schematics for all kinds of combinations of pickups and switch types. Also, factory wirings (not sure about the S1).

If the S1 is working to your liking, I wouldn't be fooling with the wiring. It is a 4pdt switch...so the kind of switching power that I use to turn the sustainer on and off and bypass other pickups effectively. However, fender do not sell them individually and the people like the Stratosphere are getting big dollars for them reclaimed from parted out fenders. As a result, I have never had the opportunity to wire with one.

The "Uber-Switches" are something I invented myself...I constructed some plates that operate a pair of very small dpdt switches onto a pot that already has a dpdt push pull switch. There is a bit of a cheat, my strat is a mahogany rear routed affair...in order for these things to work, they need to be attached from the rear...

antiKISSwiring1.jpg

There is a thread here somewhere about this still to be completed project...the above wiring probably shows why! The intention was to make a control, similar to that of a car radio I guess...for the sustainer. So the on/off/bypass function is the bottom part, the harmonics by pulling up (as used on my tele) and the drive control pot.

It worked so well that I made two more (because I could and spent so long on getting the parts right, I might as well have duplicated them...and added a super switch selector as well. An incredible amount of switching power, more than I could think of using really. One will be used to do a universal series parallel kind of thing, a push pull will perhaps be used to split the HB, another for phase perhaps...and another for adding a piezo element into the electric sound. But even with this, there is still switching power in there...and it all needs to fit in a tiny cavity!

You can also see (kind of) the battery solution that I came up with...a discrete cavity behind the tremolo block. There is some aluminium bar there that screws the uber switches in from behind. There is a yellow taped thing nex to the middle switch, this is my sustainer circuit. Between the two ribbon wires looms, you can just see a blue and white trim pot...this is the piezo preamp.

I don't have a photo of the front of the guitar handy, but it looks much the same as it did before moding and hte pot holes didn't need to be enlarged for the U-S's.

switchpotknob1.jpg

The little black Allen head bolt makes it easy to turn and feel where the switch is...these bolts have replaced screws all over the guitar so it kind of fits, though you don't really see them. I may have gone a bit far though and wired myself into a corner! It did inform the tele project though...so not all was lost!

I realize that there is the potential to do a lot more with the DIY sustainer project, and I applaud col and others for there efforts. Mine is sufficient for now for what I do and expect from it (although it would be nice if the battery would last a bit longer, got to replace mine again).

For a long time however, my concern has been with some of these other issues, and I still feel a lot has yet to be done with aspects of installation, switching and lo-mod and multipickup guitars. On my strat, the driver is completely "stealth"...

th_n-pickupdriverfitted.jpgemuring.jpg

this being the ultra thin coil concept (with added LED's that light up the neck pickup/driver through the cream cover) while the tele which came after was not suitable to this kind of thing and uses the 3mm stand alone driver in a compact format.

...

Drifting around the topic...my apologies.

Yes, AGC is possibly important...part of the tele's problem is that it sustains and increases drive till the strings are banging into the frets. But then, some people like this kind of extreme response from the thing.

It's good to see people working on circuitry and some even on driver stuff...I'm sorry I am not able to join you other than a spectator at present. What excites me more these days is the practical application and a successful installation...but I am sure that will come and I'll just have to wait!

pete

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Col-

Have you played with dual power supplies at all to get rid of all the half power supply biasing and most of the capacitors that a single supply makes necessary?

I've considered them, but I want to use a battery for this project.

The extra op-amp and two resistors that are needed to setup a virtual ground, and the very few extra components elsewhere are a bargain to pay for being able to use a single 9v battery IMO.

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Col-

Have you played with dual power supplies at all to get rid of all the half power supply biasing and most of the capacitors that a single supply makes necessary?

I've considered them, but I want to use a battery for this project.

The extra op-amp and two resistors that are needed to setup a virtual ground, and the very few extra components elsewhere are a bargain to pay for being able to use a single 9v battery IMO.

The LM324 in the upper left of your schematic (this one) is the virtual ground, correct? It looks like you referenced the input signal to this after the 220nF cap, right? It is OK to reference as many other op amp inputs as you want to this as well? I thought they would interfere with one another somehow and so what I've been doing is referencing each op amp to half supply using the two resistors and two caps where you've used the one to send transients to ground. The results are LOTS of components, which is why I inquired about using two batteries. Space issues aside, if you were to use two 9V batteries instead of the op amp virtual ground, then theoretically, doesn't it become possible to remove not only the signal biasing, but the input and output capacitors as well, alleviating most of the circuit-induced phase issues? I'm a little hung up about understanding the difference between a virtual ground setup at 4.5V vs what I've read can be called a "true" AC when you tap the center of two seris-connect 4.5V supplies, whether they be batteries or whatever. I have trouble seeing the midpoint of two series-connected 9V batteries as being somehow different than tapping one 9V battery using a resistor network. The sources I believe are trying to say that the center point of 2 batteries is actually 0V, where intuitively I would see it as 9V. Can you comment/enlighten on any of this? :D

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I'm a little hung up about understanding the difference between a virtual ground setup at 4.5V vs what I've read can be called a "true" AC when you tap the center of two seris-connect 4.5V supplies, whether they be batteries or whatever. I have trouble seeing the midpoint of two series-connected 9V batteries as being somehow different than tapping one 9V battery using a resistor network. The sources I believe are trying to say that the center point of 2 batteries is actually 0V, where intuitively I would see it as 9V. Can you comment/enlighten on any of this? :D

Two 9V batteries in series...

-ve term 9V +ve term ....<-Common (Ground) point ->.... -ve term 9V +ve term.

Mid point is 0V.....or did I misread your question?

The problem with using two batteries to supply your opamps using the above method, is that they may have slightly differing potentials, therefore without extra regulation circuitry, they'd possibly not bias the opamps symetrically. Using a resistor divider network off a single supply battery, will ensure the mid point voltage is always mid point.

Edited by Hank McSpank

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The LM324 in the upper left of your schematic (this one) is the virtual ground, correct? It looks like you referenced the input signal to this after the 220nF cap, right? It is OK to reference as many other op amp inputs as you want to this as well? I thought they would interfere with one another somehow and so what I've been doing is referencing each op amp to half supply using the two resistors and two caps where you've used the one to send transients to ground. The results are LOTS of components, which is why I inquired about using two batteries.

yep, the LM324 section in the top left is for virtual ground - the op amp buffers the half supply voltage created by the divider (2 x 100k resistors). The op amp can prevent multiple references from loading the divider and pulling it away from half supply voltage - as long as the load doesn't exceed the ammount of current it can supply (I think?)

In that circuit I have LOTS of things using the virtual ground - no extra dividers are needed, and it all works as it should, although the filter cap should be MUCH bigger to prevent low frequencies from the signal getting into the ground - should be the same as the output cap I think.

There are lots of great docs on the web that explain various techniques for providing virtual ground, but this works, is simple and uses readily available components.

Anywhere you had a half supply divider, scrap it and connect to the virtual ground

Space issues aside, if you were to use two 9V batteries instead of the op amp virtual ground, then theoretically, doesn't it become possible to remove not only the signal biasing, but the input and output capacitors as well, alleviating most of the circuit-induced phase issues? I'm a little hung up about understanding the difference between a virtual ground setup at 4.5V vs what I've read can be called a "true" AC when you tap the center of two seris-connect 4.5V supplies, whether they be batteries or whatever. I have trouble seeing the midpoint of two series-connected 9V batteries as being somehow different than tapping one 9V battery using a resistor network. The sources I believe are trying to say that the center point of 2 batteries is actually 0V, where intuitively I would see it as 9V. Can you comment/enlighten on any of this? :D

Theoretically sure, but what when you pull two batteries out of their wrappers and one reads 9.8V, while the other is 9.4V ?

Suddenly your reference isn't half supply any more. As the batteries are used, this could get worse limiting headroom.

I've seen circuits attaching the external ground to the virtual ground, effectively making that 0v and the + and - on the battery become -4.5 and +4.5 rather than 0 and 9v, but I havn't looked into this any further as it doesn't simplify things a whole lot anyway, and may cause issues with components/circuits designed specifically for a single supply - e.g. LM386?. Coupling caps are pretty useful just for keeping DC offsets and drift out from stage to stage. I have enough trouble understanding whats going on without worrying about stuff like that :D

The centre point of two batteries is the centre point of two batteries.

if the -ve of the 'lower' of two 9v batteries is connected to earth, then it is at 0v, it's +ve terminal (and the -ve of the upper battery are at 9v and the +ve terminal of the upper battery is at 18v.

If the centre point is connected to earth, then it is at 0v and the lower and upper terminals are at -9v and +9v respectively.

cheers

Col

Edited by col

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Col's approach is a good strategy and well explained.

I'd be interested in a dual battery set up, I think even from a LM386 you would get a lot better clean headroom and it would last longer. However, I have had no guitar (unless I built a special "sustainer guitar") that could easily accomodate two batteries. Some of the early commercial models did seem to require a dual battery supply.

One of the strategies Sustainiac seems to have adopted has been D-class amps that have a lot better efficiency.

...

alleviating most of the circuit-induced phase issues

Comments like this make me wonder if the potential "phase issues" in this project have completely come to terms with. I know I sound like a bore and have my own biases...but a coil does have it's own lags and capacitence as well as inductance (that varies with frequency) and the measurable resistance.

It is these issues, especially at higher frequencies (compounded by the low mass, tension and magnetic qualities of the higher strings) can come to play. There may be phase issues also as the space along the string between the pickup and the driver is quite large and varies with fretting.

While it may be true that you want to cut back phase issues in the circuit design, it is not known what phase issues are built into a particular driver. You will see that early on in the thread I looked at many if not all the patents I could come across, and with few exceptions (ebow for instance, but that is a different case as it is mobile along a string and only one string at a time and...self contained) had to address phase problems.

With the encouragement of LK, I sought to find a driver design that would work regardless. He had a feeling that a suitable driver that was not too far off would drag a string into phase...but I am not entirely sure about that. Others have postulated that the thing driver concept works because it has a very low inductance variance and operates much at a value of the resistance...I'm not sure of the reason, it was developed by trial and a lot of errors!

However, if you were to assume (wrongly) that the driver was a neutral component in all this, circuit phase would be a major concern. But I think it would be wrong to make that assumption. I feel that the emphasis on phase in the patents may be a factor of the type of drivers, the specs and many more turns within them...frequency dependent phase correction seems to be the order of the day here. But than, LK had some doubts about that and he owned a sustainiac or fernandes!

Anyway...one wonders whether phase in the circuit might not be beneficial if it makes the driver work. I quite like the "sound" and response of my LM386 circuits with a 100uF output cap. I did try some other circuit types and an interesting push pull dual lm386 thing that did not require output caps and it was far from satisfactory. Obviously I have no way of testing these ideas, maybe that was a bad design for this...but it is conceivable that any "phase issues" built into my circuits have been of a corrective nature to the kind of drivers I use...I honestly don't know. But it is an aspect to consider...the drivers internal phase issues and the potential issues raised by the pickup sampling the string at one location and driving at another.

LK was a pretty perceptive guy, and more and more I get the feeling that he was right in that what I ended up with was simply pulling the string into the phase of the system...or was "close enough" to work.

...

As for circuit design, I think the less components the better...but remember not to panic every time you see a capacitor. Not all are in the signal path..many are power conditioners and some may be filters above the audio range for stability purposes. To keep the LM386 happy, I tend to use a 100uF cap from + to - and a 10uF from pin 7 to ground and another 10uF between pins 1 and 8...I don't think these create phase issues and certainly the amp is happier for them at high gains. These mods though are simply the kind of thing prescribed by the data sheet...for less demanding applications like a practice amp, perhaps they are not required.

So...my perspective was that there was only so much I was capable of doing, phase correction circuitry was perhaps beyond me...so I worked on the driver side of things as that was something I seem to be a lot better at...and hoped for the best! Until someone works out a way of testing these drivers and nuts out any issues in this application (if that could even be done except by a case by case diagnosis) I suppose that's all we can do.

...

To give Hank some encouragement...it may not seem obvious...but the "thin driver" idea came directly from my work with the hex things. I had been making these things increasingly smaller and I had a feeling that some of the beneficial qualities may not have been from my tricky designs...but that they were simply a smaller profile and perhaps limiting the amount of EMI and other issues. I also felt that a thin driver held promise for my other "criteria" and it was of some surprise to me that after trying a few wire gauges it worked as well as it did.

There were quite a few problems with the hex things, perhaps you will have better luck...but I can confirm that they worked...they were just so much harder to do and in the end, the more conventional coils worked better. There's a year of R&D down the drain...oh well, you live and learn...or at least for now we live...

Sustain on!

pete

PS...I have been writing a lot of tunes and getting into an almost surf sound...very clean. The sustainer works for this pretty well, it would be cool if someone were to make it even cleaner...but on lower drive settings it's not sounding too bad at all. The tele has turned out to be a really versatile guitar!

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Hey,

I've found a 1W amp circuit sold by Maplin, and I'm thinking it might be a cheap and easy circuit to play around with. Here's a link to the amp: http://www.maplin.co.uk/Media/PDFs/N48FL.pdf

It'll need modifying, most certainly, but it'll be interesting to see if it works at all. I'll get one at the weekend and start playing around with it. I'm not looking for an easy way out of building my own circuit, but for the price, I'm willing to take a look and see if its workable. I'll keep you guys posted.

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Hey there...

Well...it's essentially the "CHAmp" circuit that I started out with and the LM386 part of the F/R circuit with my suggested mods (other than my preference for a 100uF output cap instead of the 220uF)...

However, there is no preamp...this will cause loading and by itself will not be enough. You need some kind of buffer such as the F/R transistor stage, or some kind of op-amp or perhaps active pickups (you could use a stomp box as a preamp perhaps)...

You might find that they sell a mono preamp kit as well...something like the related PreCHAmp could be adapted...or anything that accepts high input sources such as guitar pickups, then into this kit...

There are lot's of this LM386 kits about and sometimes they can be cheaper to buy than separate components...however there are very few that include a preamp stage. I did find one at hobbytron (canada) but was unable to get one outside the USA so not really a solution for most of us.

Anyway...good luck!

pete

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Yes...there you are, a typical IC preamp. There are some obsolete parts...like the 10K trim pot after the preamp stage, and the same before the LM386 stage.

But with a gain of 100 in the preamp stage, this is going t be overly "hot"...this could be adjusted with the gain set resistor...but the more you "tweak" these things, the closer to getting to your own dedicated design.

You are also making something significantly bigger and harder to fit into the guitar. Certainly all the earlier experiments I did in this thread was with modifying such circuits...but nothing really special...experimenting with preamp gain, playing with the LM386 gain (pins 1 and 8 resistor) deleting duplicated component functions and the output cap values...nothing super special.

Working this way allowed me to concentrate on the driver aspects while I learned a bit more about how these things work till I could develop my own ideas from them.

The danger of excessive preamp gain is that you could be generating a lot of distortion and over powering things...hearing the completed circuit through a speaker is an easy way to hear the kind of signal you are sending the driver...at the very least, you get a practice amp out of it!

pete

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Well one way to find out if it'll work, an hour or two in front of the soldering iron and an oscilloscope... Might as well, I have the time.

I was doing some thinking about the EMI interference problems. Its my understanding that the horrible squeal is heard because the driver's magnetic field is influencing the pickup, so you get a sort of feedback thats magnetic, it bypasses the strings. Well I had an idea - You have the middle pickup going to the sustainer circuitry, it doesnt go to the guitar's output at all. Then, the bridge pickup goes directly to the guitar output, doesnt go through any sustainer circuitry. Surely the EMI feedback would be contained in the sustainer circuit, which isnt heard? And the bridge pickup doesnt drive the sustainer, so there wouldnt be any feedback there?

Just an idea, i'm sure its flawed and i'm sure somebody else has suggested it over the last 295 pages, but yeah I thought I'd bring it up :D

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You have the middle pickup going to the sustainer circuitry, it doesnt go to the guitar's output at all. Then, the bridge pickup goes directly to the guitar output, doesnt go through any sustainer circuitry. Surely the EMI feedback would be contained in the sustainer circuit, which isnt heard? And the bridge pickup doesnt drive the sustainer, so there wouldnt be any feedback there?

I did do some stuff like this...but their are flaws and in some of the logic perhaps. I had thought of it being like a big ebow...but the ebow does actually exploit the driving of the pickup in use...the signal is coupled from the ebow driver into the pickup as it get's close to it...but that's a separate subject perhaps.

The squeal is oscillation. It is exactly like putting a PA mic too close to the speaker...oscillation feedback. You can stop this by turning it down, and or moving away, and sometimes some EQing. The sensitivity can also be affected by the mic's pattern and if the soundwaves are blocked (by say a speakers head getting between the sound source and the mic).

Considering this analogy we can use many of the same techniques:

~ Move the driver and the pickup further apart (the middle neck idea brings them closer!)

~ Running the device with less power (but still enough to be "hear" or in our case drive the strings adequately)

~ Filter problem frequencies, especially in the high end, but then you risk poor high string response and a balanced sustain.

~ Design drivers that direct the energy towards the strings, but less towards the pickup (as in the intention of the thin coil theory, magnetic shielding, in part dual coil and hex systems)

~ Put something to limit magnetic coupling between drivers and pickups...in the ebow there is a metal ring around both coils for instance.

However, squeal can be completely eliminated as say on my guitar and others, or the commercial sustainers clearly. The manner in which this is done is a combination and more of the above basic principles to limit it.

What needs to be realized is that if the system goes into oscillation, the fact that you can't hear it makes no difference...unless it is putting out something akin to the physical vibrations of the strings (which squeal obviously isn't) there will be no sustain!

Looking back at the above list, I notice there are few circuit related issues there. A stable circuit is important as you generally need high gains and the circuit itself could self oscillate...however, the principles of driver placement, efficiency and power limiting still seem to be paramount...at least in my thinking...but perhaps I am biased or blinded.

There have been people who have tried to address issues of a poorly made or performing driver design by subjecting it to more power. Generally, this will make matters worse. It is the equivalent of trying to stop PA squeal by turning the PA up...not likely to make things better!

Col's and others use of AGC in circuits can offer a lot...it provides enough power and only enough and so giving a more controlled response, better battery life, etc. It still needs to be limited to a certain maximum threshold to avoid squealing though, but certainly a refinement.

Anyway...not sure if that clears things up any...but you will still have issues if you try and use the signal from a middle pickup to drive the neck driver because you have halved the distance between the driver and the source. There lies the challenge of the mid driver that we have so far failed to resolve I guess!

pete

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~ Put something to limit magnetic coupling between drivers and pickups...in the ebow there is a metal ring around both coils for instance.

Interesting.

I've been toying with the idea of winding a coil around the whole driver perimeter (hard to describe without a diagram - ie where a normal pickup mount would be wrt its pickup!). Then, when the sustainer is active....apply a small voltage to this coil - you've then got a non-alternating electro-magnetic field (this coil won't generate an EMI itself ....except when first energised - I need to think about that one!), this electro-magnetic field ought to stop some EMI spilling outside of the driver's immediate vicinity & into the other pickups.

Needs some experimentation!

Surely the EMI feedback would be contained in the sustainer circuit, which isnt heard?

I'm working on the basis that I don't think any sustainer solution should force the guitarist to sacrifice a pickup (as with the commercial offerings)...& surely the simplest way around this is to locate the driver as far away from say the bridge pickup as possible & only allow the sustainer to work when the bridge pickup is selected (ie disable the sustainer in any other pickup position). This can be achieved by use of a micro switch on the pickup select lever ie underneath the scratchplate mounted on the pickup selector switch (which has been previously suggested by a Spanish chap on here - Juan) ...or a simpler offering with a bespoke switch mounted to the face of the guitar which would be made/broken by the 5 position pickup selector

Edited by Hank McSpank

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This got me brainstorming......anyone remember an Ibanez from the 80's which had a series of push switches instead of the normal 5 way switch option? The beauty of this approach is that you can also obtain the Br+M+N positions in any combination or all on at once.

However what also crossed my mind, perhaps more importantly is the possibility of a push/push switch replacing the normal Bridge position part of the circuit - allowing an integrated version of Juán's micro-switch idea. Does this make sense to anyone?

As I remember the switches in question, the ones fitted to the Ibanez were of the same type as were fitted to many MFX processors of the day, such as the Alesis and Rocktron stuff, and they were just right for p/up selection, both in size and pressure needed to engage the switch - very positive feel. In fact, thinking about it, Fender also fitted this switch to the guitars fitted with the TBX Tone control (as fitted to the Eric Clapton models and Jeff Beck US Strats of the '80s)

So basically the idea would be to have the first position switch for the bridge with a second circuit, which when engaged would have the same effect as the micro-switch Juán (zfrittz6) ingeniously suggested.

Furthermore, mini push switches should fit into the existing 5 way slot space just as the flip type switches will, with only slightly enlarged holes. This is a mod many have done on Strats, but for our purposes a push or push/push switch would be better suited. This approach would no doubt also please Steinberger players who want the option of a Sustainer, but who have very little room for anything extra on the small body. (There are more of these than you might expect, because Steinberger type guitars and their various replicas are very popular instruments, and these already have three flip switches for p/up selection for the three p/up versions.)

This still does little for Gibson players, but perhaps for them the idea might be to substitute the Vol/Tone controls for a similar push/push pot idea.....

David L

I'm working on the basis that I don't think any sustainer solution should force the guitarist to sacrifice a pickup (as with the commercial offerings)...& surely the simplest way around this is to locate the driver as far away from say the bridge pickup as possible & only allow the sustainer to work when the bridge pickup is selected (ie disable the sustainer in any other pickup position). This can be achieved by use of a micro switch on the pickup select lever ie underneath the scratchplate mounted on the pickup selector switch (which has been previously suggested by a Spanish chap on here - Juan) ...or a simpler offering with a bespoke switch mounted to the face of the guitar which would be made/broken by the 5 position pickup selector

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You may well find that you need a 4pdt with any multiple pickup installation...the mini switch on a selector has problems as he did replace the neck pickup from memory so didn't need to do the bypassing which is the difficult part. However, a 4p5t super switch is capable of this so you could have sustainer and full bypass simply as one of the selections. Remember the bypass is not just deselecting the pickups, it is completely removing them.

I have found some suitable push button 4pdt switches...sometimes for computer rest or power buttons and the like...I even got something that illuminate. Not the most practical thing on most guitars...but oddly enough a lot cheaper than the toggles of similar power...not sure how they would hold out. Strange I guess...but all push button fenders and the like have failed (although there is a new MIM that features on I believe). The new high end S-1 switch pot would also work...but they wont sell it to you!

I toyed about with some "active shielding" as I called it. I don't think that would necessarily work as you envision it. It is in some respects how the dual coil drivers are supposed to work emitting equal and opposite EMI like a reverse humbucker. I have to say, it didn't work quite...well, it didn't work!

I'm working on the basis that I don't think any sustainer solution should force the guitarist to sacrifice a pickup (as with the commercial offerings)...& surely the simplest way around this is to locate the driver as far away from say the bridge pickup as possible & only allow the sustainer to work when the bridge pickup is selected (ie disable the sustainer in any other pickup position).

I am glad to see people are coming around to the criteria I originally set...and you may see that for a while the Hex drivers were considered almost small enough to be housed in a modified pickup ring itself :D . The commercial units do allow the driver to be used as a pickup...and the sustainiac is not a bad pickup in that mode really. But, my compact stand alone driver was in line with this, my strat pickup conversion coil even more so. Converting an HB guitar is tricky...a Les Paul or 24 fret Jem has no room on it for stand alone drivers and no HB conversion system has really been developed.

Anyway...good to see people are thinking and making progress!

pete

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Tricky that...diy ebows aren't incredibly practical...but there are a few things about.

Here are some threads...

GN2 thread here I am known as 4real...you can see a bit of my experimentation with the thing.

Paul Marossy (member here also) has a great site and owns a disected ebow...see here http://www.diyguitarist.com/...at the bottom of the page are links to the patent and other info...as well as this...Ebow Guts

There was one made here...http://www.diystompboxes.com/smfforum/inde...p?topic=34264.0...do a search on ebow and you will find heaps of threads.

There are heaps of "problems" recreating this and in the end if could be easier and cheaper to simply buy one. One big problem is the enclosure, the device rides the strings adjacent to the one that's being driven. There are other concerns as well...it is likely that an LM386 circuit is used without the need of a preamp, but this is because the pickup coil and driver are desinged to be impedance matched.

The ebow is often assumed, I have never played one (except for my own experiments) but I have heard and read about them. They actually tend to be used with the neck pickup and the driver will be "heard" through the pickup as it gets closer to it causing distortion and added drive (sometimes negative drive where the magnet of the pickup is opposing creating a tremolo like effect when it moves over the pup).

It's different to the sustainer while obviously sharing the principle. I was experimenting with adapted relay coils to make a pickup and winding another for the driver. I didn't do a lot on it and it was kind of crude...

relay1.jpg

This is a relay part deconstructed...didn't end up working the thing too much...still a few problems with it but as I have sustainer guitars, it seemed a bit silly to spend too much effort on it. I had hoped that I might find some easy way of dioing it from prewound coils like this to offer as an alternative project...maybe you can come up with something.

Put DIY Ebow into google and you will see a number of references...some have been successful, most just wnat to know if it's possible. People who have been successful have found their version crude compared to the elegance of the original design...

pete

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Hi all,

Would someone kindly remind me who has successfully applied this technology to acoustic instruments, and what were the findings? I have been informed that the criteria is somewhat different, in that the driver technology applied to electric instruments would not necessarily be suitable for acoustic instrument sustainers - I'm not clear whether that is an accurate statement or not, but I understand that such a project would be potentially more simple, because there is no longer the problem with EMI from magnetic p/ups if one is only dealing with piezos as commonly fitted to acoustic guitars - so there is no need for the complicated isolation between the driver and p/ups.

I would greatly appreciate as much detail as possible on this please, as I intend attempting to build such a project in the near future.

Incidentally, I just found an interesting phantom power cable/preamp mod, perhaps this might be a move towards the goal of getting the power supply off the actual guitar? The guy seems to have some interesting designs and ideas too.

http://www.till.com/articles/PreampCable/index.html

Thanks in advance,

David

Edited by Truth_David

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Would someone kindly remind me who has successfully applied this technology to acoustic instruments, and what were the findings?

I think CurtisA tried it as an experiment. I played around a bit with the idea.

There are a number of problems...one is acoustic strings have windings that are non-magnetic...it relies on the steel cores to work. Another problem is the high harmonic output and characteristics of piezo pickup systems.

An up side is that the piezo system will already be preamped...the piezos are not magnetic, but there can still be some interference.

I predict some other problems with an acoustic guitar. With the electric we are dealing largely with the vibration of the strings, on an acoustic the top too is vibrating. As the strings are being driven, these too will be driving the top (and potentially vibrating the driver and pickup/s) and I suspect that the result could be a kind of "howl" like feedback at any decent volume.

So...not a lot of work done on this really, I suspect like bass sustainers the appeal is limited...but it certainly isn't an "easy way"...

...

On the tillman. This is a well tried decent pickup design...it could work in place of the fetzer but still requires a poweramp circuit to drive the driver.

We have discussed remote power...there are even products about like the x-bat. However, the sustainer is a different beast to a low current preamp. Running high power alongside the signal and sharing the earth all along the cable may well cause problems. Certainly have the circuitry remote and running the driver leads up the lead poses significant problems. But even power in the lead may cause significant noise and pop issues. I started working on something, but the project wasn't completed. It was actually quite costly to make a stereo lead of any really length and not the most practical solution compared to accommodating a battery. I'd still like to see someone fully explore this aspect...there's a bit about on this thread for reference.

pete

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Oh, just in case anybody's wondering, my .315mm driver works alright on my bass guitars. E and A strings are very lively. I have yet to make or test a .2mm driver, I've had this roll of wire on my desk for a few weeks now without getting around to winding it, when I get around to it I'll post up my results with the bass.

I agree the nylon strings and vibrating top could limit the usefulness of an acoustic sustainer, but perhaps on a solid body guitar the piezo pickups could be of use? We wouldnt have the problem of the top vibrating the driver, and the interference problems would be lesser, I imagine... Piezo pickup on the bridge, neck driver, contained in one easy-to-mount sustainer system?

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Oh, just in case anybody's wondering, my .315mm driver works alright on my bass guitars. E and A strings are very lively.

That's an interesting result..I wondered if a different wire guage might even work better with a bass...the 0.2mm works too...but not done a lot of serious work on it.

I agree the nylon strings and vibrating top could limit the usefulness of an acoustic sustainer

Nylon strings will never work...nothing magnetic in them. Bronze wound acoustic steels have some issues which is what I was saying.

Piezo pickup on the bridge, neck driver, contained in one easy-to-mount sustainer system?

Maybe...but still experimentation required and a specialized limited instrument i'd assume

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Oh, just in case anybody's wondering, my .315mm driver works alright on my bass guitars. E and A strings are very lively.

That's good, always good to hear about a success, although its hardly surprising!

The low frequencies are no trouble for a sustainer, its the higher frequencies that introduce design limitations. In fact, it should be possible to create a more powerful and more efficient system for bass guitar as you can use a more powerful electromagnet withought having to worry as much about the effect this has on the higher frequencies.

FWIW, my latest research suggests that the optimum wire gauges for a normal 6 string guitar driver are in the 0.25 to 0.31 range. Unfortunately, this assumes a current mode amplifier set up for the purpose, so don't expect the heavier guages to work with a basic datasheet voltage mode LM386 poweramp.

I will be testing this all out soon, and if it does turn out to be correct, I'll post a lot more details. I'm worried I might pop my LM386 in which case, I'll have to design a custom power stage using discrete transistors - this would take a lot longer... so don't hold your breath :D

Although I would say that anyone who is about to build a driver or circuit should hold off for a week or two!

Also, hold off buying wire until I've done a few more tests - buying wire is by far the most money I've spent on this, and I wouldn't want others to go through the same process and end up with loads of reels of winding wire that they don't have a use for !

My current thoughts are that the ideal guage is 0.25 or 0.275... I've just bought some 0.275 to test this with and will do that asap.

BTW, I just had the pleasure of stripping 330 turns of epoxy potted 0.23 wire from a pickup bobbin - not a pleasant task, but interesting that it's even possible :D

cheers

Colin

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Hi. I just want to pass on something that is working well for me,...

in the area of the stand- alone driver. as in Pete's Telecaster.

I have been winding the magnet itself. The neodymium ones .

No steel,. no bobbins. just the magnet and the winding.

It makes a very small package. . There are a couple tricks to know,

but the procedure is actually very easy... If there is interest, I will elaborate.

I haven't tried these drivers with a 386 amp, so I would be curious to

to see how they compare in sound to Pete's thin style driver.

But it seems to me that the principle is the same.. They do great in my setup.

And they may have some advantages...:ease of construction, size , etc.

Al

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