Help With My Sustainer

[Prostheta]

Fizz - try not to poke the animals through the bars please?

PSW is currently on a temporary mod preview only. The same will be carried out with anyone directly or indirectly stirring flames. Abusive behaviour will be addressed directly. Go read the board usage guidelines and play nice. If you've got nothing nice to say, be a better human being and don't post it. Equally, apologising for transgressing board policy by stating that "I WAS WRONGED!" is not satisfactory and indicative of a lack of self-moderation. If you can't manage this, we're more than happy to do it for you except that we use a hammer and nails - not the delete button. Board policy is what it is, and applies to everyone equally whether they are a fountain of information, a troll or a midget.

Take a step back and remember what the board is and isn't. It may be public, but it's not a day nursery or soapbox. Please play nice and drink more water.

[Fresh Fizz]

Fizz - try not to poke the animals through the bars please?

Not in the way you mean it, I guess. Or do these animals of yours start to curse in finnish when poked?

You're making the mistake to think in terms of good mods, bad forum members. That the good mods use the forum rules to keep the forum members on the right track.

Not so long ago there was a "prove to me you're not a sociopath" incident where the hunter became the hunted. A very nasty event that only stopped after Drak and I intervened. Can you tell me why there wasn't a moderator prepared to take action?

You say that abusive behaviour will be addressed directly. Can you tell me that there was a verdict or some conclusion reached after this event took place?

Read it back in the topics, more abusive behaviour by one and the same person was never addressed. Afraid of him?

Don't know about Drak but I never got a thanks by the mod team for acting in a critical situation.

Greetings

FF

[Prostheta]

Moderators do this purely on a voluntary basis, FF. We rely mostly on the forum users to report issues via the Report button as it would be both intrusive and impractical to "police" every thread. Our job isn't to force users into complying by some Big Brother overseeing of every keystroke, it is to keep the board on a reasonable track and address complaints as they are reported.

FWIW, my post wasn't directed at you (only the poking the animals bit) so I apologise if you construed it as being so. Must remember to proof my posts :-\

[therizky]

"I appreciate the help psw, and anyone else who helps."

cool. my main concern of you aren't about your involvement with the conflict or building sustainer ,but how would you deal with -that- guy...later. he's kind of sensitive. seriously.

no offense.

"See...now that's gratitude...if you don't want assistance, quit asking me...if you have something to offer, publish it in all it's detail (resizing your pictures would help)...and if it doesn't work when others follow your advice, you help them...if you think you know what you are doing!"

owh.i was thought you forgot that line.

sir yes sir!. i'll quit asking **** from you from now on,i've had enough mentioning your name in the first place... only if somewhere on the forum you answer questions that you found out came from me i have nothing to do with it.

"Therizky, WHAT IS WRONG WITH YOU!

Can't you be happy standing in the shadow like the rest of the bunch. lol.gif"

i'm not hiding,i'm watching.

there's nothing wrong with me anyway.take a look. you'll know who attacks or who attacked. or maybe you already knew?

as for the each other duties,it just conflicts,it exists, can't avoid it. if someone ever complained why and how the "law enforcements" isn't there at the first place,who...who knows such thing is going to be happened? police always come after the bad guy got killed. but you have to figure out how to get out of **** hole. is that simple...for me.

as to the topic, hmf,don't mind useless posts, i have nothing more to contribute,(i am not a loser,if you want to reload your gun,i'll face you) psw obviously can take care all of you sustain seekers. don't give up,keep playing,keep rockin'.

but read back,be aware.

peace!!!

[Fresh Fizz]

Moderators do this purely on a voluntary basis, FF. We rely mostly on the forum users to report issues via the Report button as it would be both intrusive and impractical to "police" every thread. Our job isn't to force users into complying by some Big Brother overseeing of every keystroke, it is to keep the board on a reasonable track and address complaints as they are reported.

I understand. But what if a moderator gets acquainted with abuse on the forum in an alternative manner and not via some report button that's been pressed?

FWIW, my post wasn't directed at you (only the poking the animals bit) so I apologise if you construed it as being so. Must remember to proof my posts :-\

No need to apologise for a post that is perfectly understandable for an attentive reader.

O you mean make sure it's take-finger-not-the-whole-hand proof. Sorry.

I see that therizky is still around, of course you shouldn't be hiding, and you did nothing wrong. Sell as many sustainers as you can.

Sorry, but I don't understand the bad guy - **** hole thing, do I want to know this?

FF

[Prostheta]

I am sure that statistically, more posts under the banner of "sustainer threads" are totally off-topic. Just saying.

[Fresh Fizz]

I am sure that statistically, more posts under the banner of "sustainer threads" are totally off-topic. Just saying.

The next sustainer topic will be called Sustainer Builders Pub in the off topics chat sessions. Lower the level of expectation. Take the rants and BS for granted. Just behave like you're in the pub.

[Prostheta]

You really don't want to know how I behave in pubs. This doesn't help.

[Fresh Fizz]

You win

[therizky]

"Sorry, but I don't understand the bad guy - **** hole thing, do I want to know this?"

it's not important,i always use idioms and sarcasms in place of my mumbling english (in fact it's just foul languange) but somehow its just drown me to a more complicated situations.

anyway the point is just...**** happens,it just depends on each other person involved or those who watch the circus to take action.let 'em who fought become fanatic of their own ideology.as the third person needs to takes no side and neutral (which i suspect what you and your dude drak have did) to mod team i can only suggest to 'patrol' more often and always think positives. speaking about moderators i too have something to critize about this topic and how things work out here,but since i'm a fairly new member (look at my posts count and that big "mew member" label) and rarely get online and contribute ****,i wouldn't dare to do that (not to mention lines of people ready to kick my ass if i do that).but as someone has done that,i'm already feel represented.

"I see that therizky is still around, of course you shouldn't be hiding, and you did nothing wrong. Sell as many sustainers as you can."

thanks for the support dude.but unfortunately i myself don't know how the future of those project as i have other things to takin' care of,i have to finish my bachelor degree first,but thanks anyway.

peace!!!

[Joghurtgumi]

okay guys, i've started again. I've got me some proper 0.2mm wire, and i'll be winding it tomorrow, nice and neat, and potting it with a ton of glue. I have a question though: When i have the signal from my pickups split, and have 1 going to the sustainer amp(fetzer-ruby), and one going to my guitar amps, i get a loud, annoying buzzing sound from the guitar amps when the sustainer amp is on. what causes this? (I noticed that adjusting the trim pot in the fetzer-ruby amp reduces this, but only a tiny bit, and it's still very loud (louder than the sound of the guitar))

[psw]

I tried to send you a PM but it is disabled and you have no email address. I'd suggest sending me an email for a reply...psw

[Fresh Fizz]

okay guys, i've started again. I've got me some proper 0.2mm wire, and i'll be winding it tomorrow, nice and neat, and potting it with a ton of glue. I have a question though: When i have the signal from my pickups split, and have 1 going to the sustainer amp(fetzer-ruby), and one going to my guitar amps, i get a loud, annoying buzzing sound from the guitar amps when the sustainer amp is on. what causes this? (I noticed that adjusting the trim pot in the fetzer-ruby amp reduces this, but only a tiny bit, and it's still very loud (louder than the sound of the guitar))

So you have a sustainer driver coil in the neck position and the bridge humbucker split? If that's the case I would advice you to not split the humbucker and send its output signal to the guitar amp as well as to the sustainer amp. The humbucking functionality should reduce/stop the magnetic feedback, the buzzing sound that you're hearing.

cheers

FF

[Joghurtgumi]

Thanks, but i doubt that's the problem:

I don't have the humbucker split, and i don't have a fully working coil yet. I was just testing the sustainer amp, by hooking it up to a small 8 ohm speaker. By splitting the signal i meant sending it to both amps, not splitting the humbucker. So i got the buzzing without a driver coil, and even when i just replaced the guitar with an mp3 player, or when i didn't even have anything plugged in to the amps, with just the 2 inputs connected, so it can't be feedback.

I've wound my new coil today too. I have a headache from all the glue fumes, but i think it's the most promising of all so far, so it was worth it

If you have any more ideas for the amp, then i'd be grateful for any further help.

[psw]

Thanks, but i doubt that's the problem:

I don't have the humbucker split, and i don't have a fully working coil yet. I was just testing the sustainer amp, by hooking it up to a small 8 ohm speaker. By splitting the signal i meant sending it to both amps, not splitting the humbucker. So i got the buzzing without a driver coil, and even when i just replaced the guitar with an mp3 player, or when i didn't even have anything plugged in to the amps, with just the 2 inputs connected, so it can't be feedback.

I've wound my new coil today too. I have a headache from all the glue fumes, but i think it's the most promising of all so far, so it was worth it

If you have any more ideas for the amp, then i'd be grateful for any further help.

Then there is a problem with the amplifier circuit...do you get noise even when you just run the guitar through it?

A noisy circuit will have serious effects on performance...it might sustain a little but some strings fail or significant problems with getting enough power before EMI and squeal. Distortion is one thing (for crtics of teh LM386), but actual noise will be sent out as a signal that is only going to mess with the signal that you are trying to send, that tuned to the strings playing.

Glue fumes...PVA is a waterbased glue without harmful fumes...it is a primary reason for suggesting it along with long working times and gap filling properties. In all 150 odd turns should have only taken about 15 mins to complete...but I am glad if you ended up with a decent result.

More details and photos of what you are actually doing can help...for instance, how are you connecting things together, minimum length cables, shielded cables etc? Noise can easily get in from the usual sources, but it sounds like something is amiss in the construction or design of the circuit...which circuit are you using, how is it built, how is it connected, etc

[Fresh Fizz]

Thanks, but i doubt that's the problem:

I don't have the humbucker split, and i don't have a fully working coil yet. I was just testing the sustainer amp, by hooking it up to a small 8 ohm speaker. By splitting the signal i meant sending it to both amps, not splitting the humbucker. So i got the buzzing without a driver coil, and even when i just replaced the guitar with an mp3 player, or when i didn't even have anything plugged in to the amps, with just the 2 inputs connected, so it can't be feedback.

I've wound my new coil today too. I have a headache from all the glue fumes, but i think it's the most promising of all so far, so it was worth it

If you have any more ideas for the amp, then i'd be grateful for any further help.

I get the picture. The output (speaker) seems ok to me because it's buzzing. (You're using a battery, right? Not some unregulated net adapter.)

How about the input of the lm386? Any schematic here that resembles your design? Check if pinout 3 goes to signal (taper of trimpot) and pinout 2 to ground.

FF

[Guest Wasp]

First post here....just a quickie - I've wound my own pickups in that past but now fancy trying my hand at making a sustainer coil.

The tutorials more or less say wind a 'blocked off' strat bobbin with 0.2mm wire until you get to 8 Ohms - ok, but that 8 Ohms is so the LM386 amp is happy with the load - what's the best spec for the sustainer itself wrt to the number of windings?

Depending which of the multitude of threads you read, I've seen turns count quoted anywhere from 120 thru 200 ....that's a rather wild variation...which is ultimately going to yield very different results.

So, just what is the optimum target for the driver wrt 'number of windings/turns'?

Cheers.

[Fresh Fizz]

First post here....just a quickie - I've wound my own pickups in that past but now fancy trying my hand at making a sustainer coil.

The tutorials more or less say wind a 'blocked off' strat bobbin with 0.2mm wire until you get to 8 Ohms - ok, but that 8 Ohms is so the LM386 amp is happy with the load - what's the best spec for the sustainer itself wrt to the number of windings?

Depending which of the multitude of threads you read, I've seen turns count quoted anywhere from 120 thru 200 ....that's a rather wild variation...which is ultimately going to yield very different results.

So, just what is the optimum target for the driver wrt 'number of windings/turns'?

Cheers.

Hi Wasp,

That's a good question to start with, I wished my reply could be a quickie. There's some formulas in it, I hope it doesn't scare you off. But I understand your question as looking past the down-to-earth issues like "how do I build it" so this is the best I could come up with.

Power amp requirements

A certain amount of power is required to keep a guitar string sustaining. When using a battery the amount of available power is limited. So efficient use of the available power becomes very important. An lm386 will deliver the most power when the load (sustainer driver coil) is 8 ohms. Lower than 8 ohms will only heat up the lm386 more, higher than 8 ohms will decrease the current.

Sustainer driver coil considerations

How do you judge a guitar pickup? Not by the amount of turns of windings or the diameter of the copper wire. What matters is the sound of the pickup which is characterized by its resonance frequency which depends on the self-inductance of the pickup. There is a peak at the resonance frequency and above that peak the signal gets weaker and weaker (high-cut filter).

The story is more or less the same for the sustainer driver coil. The extra concern is whether or not the high-cut filter will prevent sustain to occur in higher fretting positions or in harmonic mode. As a matter of fact we're not talking about the same high-cut filter as in case of a guitar pickup. (The resonance frequency of the sustainer driver coil is very high.) The high-cut filter we're dealing with consists of the real component R (8 ohms resistance of the driver coil) and the imaginary component X(L) which is 'caused' by the coil. X(L) increases with the frequency, so the higher the frequency, the higher is X(L). And X(L) increases with the amount of windings.

And here we have to find a compromise namely:

1. The driver coil is most efficient at a certain frequency when X(L) is small compared to R.

2. More turns of windings on the driver coil makes it more efficient at low frequencies.

Or in the analogy of the guitar pickup, more windings give more output but you lose some highs.

Another issue is the rest of the stuff being used. It makes a difference whether you build a bare bones sustainer device (lm386 + driver) or a more sophisticated one with agc, eq, all-pass filters and so on.

I don't think there is an optimum target it's merely a matter of personal taste. Perhaps some minimum requirement, every note has to sustain?

This is how I measure the self-inductance of a driver coil. The oscilloscope is actually a simple HandyProbe.

(d) and (e) are the negative consequences of the self-inductance.

(e) Because the signal at the driver coil is somewhat out of phase with the signal detected by the guitar pickup the efficiency is reduced. This could theoretically be compensated by means of all-pass filters.

(d) The load is not 'ohmic', impedance Z is bigger than 8 ohms, less current (power amp requirements).

a. find resonance frequency F(res) (maximum voltage drop on oscilloscope)

b. calculate inductance L of driver coil (L in Henry, F(res) in Hertz, C in Farad)

L = 1 /(4π² * F(res)² * C)

c. Calculate reactance X(L) for a specific frequency ( X(L) in ohm, F in Hertz)

X(L) = 2π * F * L

d. Calculate impedance Z for that frequency (Z in ohm, R in ohm)

Z = √(X(L)² + R²)

e. Calculate phase shift for that frequency

ArcTan (X(L) / R)

So there are 2 ways to go. By ear, build a driver coil and if the behaviour for the high notes is still acceptable take thicker wire and use more turns of windings.

By spec, work towards a certain self-inductance.

Cheers

FF

[Guest Wasp]

Fresh Fizz - thanks for the eloquent & detailed reply.

I've not yet wound a driver, but I'm comfortable with the technicalities ....ie inductance, reactance, impedance etc (btw, I have a cheap chinese meter that I bought for winding pickups that saves a lot of that formulae!).

Seems to me that wrt DIY sustainers, there are a whole heap of 'variables'.....surely it's prudent to slim these down as much as possible?

IMHO, the final 'number of windings' for the driver is likely to be as important as the DC resistance ....because if there's not enough windings, then there won't be sufficient 'magnetic' drive, but too many windings & there'll be too much AC impedance.

So there are 2 ways to go. By ear, build a driver coil and if the behaviour for the high notes is still acceptable take thicker wire and use more turns of windings.

By spec, work towards a certain self-inductance.

The former needs a new DIY'er to get experimental & do some R&D.

The second would need someone to come up with the spec - to include a specific winding count.

I do like a bit of experimenting but just don't see the point of reinventing the wheel...(the sustainiac patent mentions 256 turns of AWG 30, which suggests they think stating the spec down to circa 0.5% winding tolerance is important!). If a 0.5% winding tolerance is important for people who make a living from these, then it's likely to be important enough for the DIY community to have a 'turns count' to shoot for too.

If everybody wound on the same bobbin type, using the same wire to the same tension at the same room temperature & in the same winding pattern, then a DC resistance would be all we need to shoot for. But obviously, differing sized bobbins, slightly different tolerances on the wires, different winding tension & style are all going to affect the final number of turns that makes up '8 ohms DC resistance' ...and like I say, the 8 Ohms is simply a ballpark target to aim for to placate the associated amplifier - not the main parameter for winding a coil?

So for example - 8 Ohms @120 turns, 8 Ohms @150 turns, 8 ohms @200 - which one is the reccomended 'target'? Becuase each one will surely differ in performance by a noteworthy amount.

Edited November 23, 2010 by Wasp

[psw]

If everybody wound on the same bobbin type, using the same wire to the same tension at the same room temperature & in the same winding pattern, then a DC resistance would be all we need to shoot for. But obviously, differing sized bobbins, slightly different tolerances on the wires, different winding tension & style are all going to affect the final number of turns that makes up '8 ohms DC resistance' ...and like I say, the 8 Ohms is simply a ballpark target to aim for to placate the associated amplifier - not the main parameter for winding a coil?

So for example - 8 Ohms @120 turns, 8 Ohms @150 turns, 8 ohms @200 - which one is the reccomended 'target'? Becuase each one will surely differ in performance by a noteworthy amount.

As it is, the bobbins are wildly different in particular the nature and size of the core. This accounts for the difference of a few windings difference to get to 8 ohms with a specific wire gauge. For all the maths people have at their disposal an alternative 'formula' is still not apparent.

I've always suggested to use resistance as a guide with a specific wire gauge and bobbin depth and on a wide variety of bobbin core types and size this seems to consistently produce the desired results.

Unless one were to say that a DIY'er "must use" a specific spec bobbin turn counts can't be used effectively. Even when examples of various types from the earliest to my telecaster that used an ordinary steel 3mm rail core on 3mm depth core...very few if any have chosen to duplicate this very simple scheme. If everybody did, and took care in teh windings...then the turn count could be a given (although would require checking for variables like wire stretch).

A machine wound commercial application where everything and the end application is consistent...then of course you can have turn counts...and this is exactly how the wafer coils are built...but then that is not DIY.

As for optimum...

I don't think there is an optimum target it's merely a matter of personal taste. Perhaps some minimum requirement, every note has to sustain?

Exactly as FF puts it...there is the minimum that one should judge if the project works correctly.

All notes sustaining, no squeal, low EMI or none at all and no noise, no loading of the guitars output, no alteration in sound from the original guitar are some of the obvious ones...

These kinds of things are the criteria that one has to set to gauge the success of any project. I have still more extensive criteria on my work...low mod to the original instrument (so, will require small circuits, the retaining of the neck pickup, minimal switching solutions, drivers that can be surface mounted or combined with the neck pickup some how, battery powered with decent life, reliability, etc)...but sustainiac and others perhaps have slightly different criteria or similar with different solutions (using the driver itself as an active pickup, electronic switching, etc)

The basic design and spec has been tested over many years with a variable turn count accounted for by the size of the bobbins core (what is the "optimum" size and material here??) and the skill of the winder. If built correctly, it does work fairly consistently despite such variances. I don't recall a winder to spec ever reaching 200 turns so I think the variances are a little overstated...where did these figures come from?...but with such a low turn coil, the bobbin size and how much it grows (winding style) makes a big difference on the final turns.

The main thing is that once has found that all these things have shown to work despite the variances...and by 'work' I mean meet the criteria that FF describes...when the formula is followed.

One can of course follow a completely different path than a simple single coil driver, use different wire, multiple coils...reinvent the wheel...and still meet the criteria of 'working'. If the work required to do this is 'better' or optimum is hard to say...not sure that I can hear that it sounds or behaves conclusively "better" or even that much different...though for some solutions the wider criteria might not be met.

I think the thing to do if this bothers you...is to make a few and count the turns. Otherwise, really hit the math and see if you can work out exactly what would be the most efficient...the thing is for all the tests and tools offered up like this, the "solution" seems still missing from such activities.

There used to be the same kinds of debates over the core material as well for similar reasons...

But hey, DIY project, there is going to be vast differences...sustainiac just simply order a specific design and count from a transformer company somewhere, it's just the inevitable result of commercialization and not a reflection that they have the 'optimal' design but are working to consistent product design.

[Fresh Fizz]

If everybody wound on the same bobbin type, using the same wire to the same tension at the same room temperature & in the same winding pattern, then a DC resistance would be all we need to shoot for. But obviously, differing sized bobbins, slightly different tolerances on the wires, different winding tension & style are all going to affect the final number of turns that makes up '8 ohms DC resistance' ...and like I say, the 8 Ohms is simply a ballpark target to aim for to placate the associated amplifier - not the main parameter for winding a coil?

So for example - 8 Ohms @120 turns, 8 Ohms @150 turns, 8 ohms @200 - which one is the reccomended 'target'? Becuase each one will surely differ in performance by a noteworthy amount.

One of the biggest arguments we had in the sustainer thread was about whether a what I call bare bones sustainer (fet + power-ic + driver) would do the job. (Too many dead spots to my taste, I don't expect miracles not even from the perfect driver coil.)

Some of the guys (me too) moved away from the bare bones sustainer: agc, agc and microcontrollers, fx pedals before the sustainer amp, hexaphonic sensors + drivers in combination with dsp. The sustainiac you've mentioned isn't exactly a bare bones one.

When one starts using agc not having enough magnetic drive isn't really an issue. I used 130 turns/1mH and 180 turns/1.8mH and both humbucker drivers performed well. (A more noticeable difference was caused by the difference in distance between the 2 coils of the humbucker.)

It seems to me that you fit in psw's school of thought. (0.5%, wow!) He's a firm believer in the bare bones sustainer. He did all the experiments with the various wire sizes. If someone knows the recommended target it should be him. Haven't received a pm from psw already?

cheers

FF

[Guest Wasp]

I take your point (& fully agree) that a basic approach to the circuit aspect is likely to yield a sustainer that'll perform patchy - I know from my past work with pickups, that the guitar's dynamic range is rather large & it will certainly need some 'smart' electronics aspect to interpret/control the levels.

I've seen talk of efficiency wrt making drivers on related threads on various forums - bearing in mind most sustainers will source their power source from a battery, I'm assuming by 'efficient', that folks mean the least current draw? Being of a very tight nature - and 9V batteries being comparitively expensive - the most efficient DIY driver from a power draw perspective has got to be the ultimate goal, hence wanting to know a more about the technical spec of the driver (No of windings vs inductance vs current draw for 'good sustain')...do you know if anyone has carried out 'current draw' tests for all the possible coil variants (series, parallel, single, dual) & established what the best perfoming coil is?

The commercial sustainer companies speak of 20 hours from a single 9V battery - that's impressive from a power source only capable of supplying 550maH....just wondering what the 'best in class' DIY sustainer gets out of a 9V battery?

[psw]

I take your point (& fully agree) that a basic approach to the circuit aspect is likely to yield a sustainer that'll perform patchy - I know from my past work with pickups, that the guitar's dynamic range is rather large & it will certainly need some 'smart' electronics aspect to interpret/control the levels.

I've seen talk of efficiency wrt making drivers on related threads on various forums - bearing in mind most sustainers will source their power source from a battery, I'm assuming by 'efficient', that folks mean the least current draw? Being of a very tight nature - and 9V batteries being comparitively expensive - the most efficient DIY driver from a power draw perspective has got to be the ultimate goal, hence wanting to know a more about the technical spec of the driver (No of windings vs inductance vs current draw for 'good sustain')...do you know if anyone has carried out 'current draw' tests for all the possible coil variants (series, parallel, single, dual) & established what the best perfoming coil is?

The commercial sustainer companies speak of 20 hours from a single 9V battery - that's impressive from a power source only capable of supplying 550maH....just wondering what the 'best in class' DIY sustainer gets out of a 9V battery?

I have a feeling that you are misunderstanding a bit in these assumptions.

It is not as simple as a reverse pickup for instance. Further, even if you follow this analogy, the idea that a driver couldn't produce 'sustain' on all strings and frets would be similar to suggesting a guitar pickup could not reproduce all those notew either because the guitars range is quite wide is it not?

As for efficiency, this is also a misunderstanding...it isn't about power draw in this context at all. This relates to the system and particularly the driver's design's ability to produce the effect with the least amount of magnetic output that produces unwanted effects such as EMI and squeal (oscillating feedback). You could make a system that drives the strings theoretically...but does so with so much magnetic output that the pickup is swamped by the signal of the driver over the vibration of the strings themselves.

Many times sustain is produced with a lot of noise and this aspect is not understood. Many times the proposal is to simply increase power seeking more powerful amplification, running little amps beyond their capacities, resorting to remote power as the limits of the battery are far outstripped...all this does is to try and overcome the inefficiencies of a system and making the problems worse. The aim is to provide the necessary energy with the most "efficiency" to mitigate any adverse effects interacting with the pickup driving the system. The main thing that allows this to work at all is the distance between the driver and the pickup...any attempt to move things closer together...such as a mid position driver...will require even more 'efficiency' to avoid adverse effects.

I can't tell you what the figures are on battery life...the estimates given by sustainiac can't be quantified either really. Every DIY design is different. One of the unique things about the systems I have proposed is that it only draws power when the sustainer is in use and the guitar operates regardless of there even being a battery. A Commercial systems cant and the guitar is disabled...this makes 20 hours a bit of a concern and certainly not great in that context.

With intermediate use, my sustainer guitar has had the same battery in it for some months now...but if I were to run the thing continually it would result in a significant loss of performance over time.

One thing that seems to be overlooked about the battery being a limiting thing...yes it is, it in itself provides some "limiting" to the system and so is itself a form of AGC and designed into the performance characteristics...it is the component of these simple designs. That a battery powered low powered amp can't produce unlimited power can actually be a good thing.

the most efficient DIY driver from a power draw perspective has got to be the ultimate goal

Clearly it is not because many rely on remote power to get the results they do with alternative systems. So, that is not the "ultimate goal" there at all, the goal is performance even if this requires external mains derived power sources. However, my early systems worked with a rechargeable 9v battery and still can and there are other options as well.

As to the performance thing being 'patchy' this is of course a preemptive presumption. There needs to be parameters set to make such a judgment. What are your criteria for performance? You can get powerful sustain and harmonics on every string with a simple design and circuit...audio examples abound. SO clearly it is not a requirement to go further to meet this criteria.

Every DIY system is and generally is quite different...the pickup input into the system for example and the quality and diversity of the build are major factors of diversity.

A basic system produces the effect of a very loud feedbacked guitar with predictability...this can be done of course acoustically regardless of the pickups under specific conditions. It will do so on all fret positions and strings regardless of the assumptions and poor preforming examples (we generally only hear about systems that are having problems and not built to spec). If you want a very even response or something that has a fully polyphonic kind of performance...then you are talking of a different beast. To do something like that, you would need to find a way of driving each string and preventing there being any interaction between the six drivers...but as I say, a completely different beast and beyond what something like these simple systems are designed to do....or indeed commercial systems such as the sustainiac.

It should be noted that earlier simple non-AGC examples of the basic systems of mine were compared directly with an example of a professionally installed sustainiac and while 'different' regarded as favorable...and many features and performance advantageous. Some of this is to do with what people want from such a thing and what is delivered. The sustainiacs advanced AGC and such makes for a fairly "tame" kind of sound compared to the more dynamic "alive" performance of the basic systems (words of the owner of the sustainiac guitar making the comparison) and advantages such as the system being completely independent of the passive guitar, choice of pickups, lower mod and more flexible application, smaller circuits and lower cost were seen as advantageous.

But these things are a matter or personal preference, my systems for instance accentuate this dynamic performance intentionally as a personal choice accentuating 'effects' such as harmonic bloom. Col went to extensive lengths to achieve a completely different performance that was very even and avoided much of this...as was his personal preference for sound and response. Both of us achieved the minimum criteria of 'sustain and harmonics' on all strings and frets. There is no "perfect system" or "ultimate sustainer" that seems to lie behind many of the disputes on this topic.

Really though, this is a DIY project and much of what you ask can only be done if someone actually does the work to make something and do such tests and set out the criteria for what they regard as "ultimate" in terms of performance and such. Things like the number of windings is nowhere near the variable range you have suggested and I don't know where you got those figures. For a given size of wire and core and depth of bobbin...the results will always be pretty much the same. As a highly variable DIY project, to get the "resistance" required (which itself is within a general range to get the most efficiency from the circuit proposed) there will of course be variables. The criteria is that it can produce the results required and this it can do regardless of these variables. When people go outside those specs of course they don't get the expected performance and the result is a lot of "I can't get this to work" posts and a reluctance to see that they have failed to a known formula and getting the results one would expect and reported from the development of the formula in the first place.

Also as A DIY project, all this research is also DIY and if this kind of data is required it will take the DIYer to do the work to produce it and set their own criteria for success.

[psw]

"Efficiency" isn't about the power draw or battery life...it is how efficiently the driver can drive the any of the strings with as little EMI and unwanted squeal fizz or noise effects it can put out with the distance between the driver and the source pickup.

Often people only make matters worse by increasing power as this only increases such effects generally and require something like a multi-coil driver to counteract some of these effects.

Mine tend to run on very low 'power'...watts. As a result they have remarkable battery life, especially compared to a commercial system that draws power even when the sustainer is not in use. However, If the circuit were running with more stuff like a sophisticated AGC or the like, it might pull more power and kill the battery sooner with the same driver...so an efficient driver is separate from power draw.

You can't have a figure across the board with the approaches so different and different circuits in use. I've been going to lower and lower power with mine and getting cleaner headroom, while others have been advocating more powerful amplifier circuits.

The "Ultimate goal" is not power draw as FF and others use remote mains derived power to get the effect they want and run the circuits and drivers...the goal is to produce the effect you want whatever your criteria is and for many battery power is not a necessary criteria.

I use a battery because for me it is, as is the ability for the guitar to remain passive and fully functional even with a dead battery or none at all.

But, the battery is also a component of the system...it is itself a limiting factor to any circuit and works as an AGC to stop things 'running away'. That's why I have always advised that people use a battery to test their work to be realistic. A wall wart might have a consistent voltage, but it allows an unrealistic current compared to a battery.

Not sure where you got your winding figures from, but for a given wire gauge and core size and bobbin depth and consistent winding style and potting method...the number of windings will always be the same for a given resistance. With such a low count coil, any factor that influences these things can have a dramatic impact on the number of windings. The basic design is able to tolerate a fair variance necessary for a DIY project though...but if you use a 3mm steel blade as I tend to like you it will be more 'compact' than something built on a single coil Pup with say a 5-6mm coil...it can make quite a bit of difference to turn count.

Turns though is only one small factor and one shouldn't compare the driver as if it were a pickup which has a different function. You might find that with maths and theory you come up with an 'ultimately' efficient driver that has not the range to drive all the strings as well because of resonant frequencies or perhaps is of some ohmage that it won't run off a common say 8 ohm amp circuit....it's all a balance and remember the basic project presented is for DIY which means it has to tolerate a lot of variances to be successful...which the basic design does. A fernandes system dictates the input pickup as well as the driver to keep conditions consistent and guarantee performance, in DIY systems the source signals are always different in power and frequency response because the pickup choice is limitless.

[Fresh Fizz]

...do you know if anyone has carried out 'current draw' tests for all the possible coil variants (series, parallel, single, dual) & established what the best perfoming coil is?

No I don't recall any tests on current draw.

Col, one of the guys over here, has come up with an agc that utilizes a feedforward sidechain. The agc regulates the signal level right at the guitar pickup. This way the swing amplitude of the string is being controlled. This will save energy. How to save more energy? Like you already said, more windings on the driver coil (it might well be that the sustainiac's spec is the optimal performance). It depends on whether the agc can deal with the behaviour in the high freqencies region, but it certainly would make your system more energy efficient for low frequencies.

Depending on how 'quiet' your driver and pickup are (humbucking?/shielding?) you can increase the gain in the pickup-amp-driver-string-pickup positive feedback loop and limit the swing amplitude even more.

And yes an LM386 or a TDA7231A which I use will get hot so class D would help.

The commercial sustainer companies speak of 20 hours from a single 9V battery - that's impressive from a power source only capable of supplying 550maH....just wondering what the 'best in class' DIY sustainer gets out of a 9V battery?

I'm afraid I skipped that class, mine is on 12V power supply.

Cheers

FF