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Sustainer Ideas


psw

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Where I left off my thinking about a sustainer driver a year or two ago, I had proposed the idea of taking a single coil pickup, cutting off the windings and rewinding with thicker wire, the consequence of needing to have lower voltages drive the necessary ampere-turns to move the string. I think it's in the archives over at ampage or DIY.

The ampere-turns of magnetic field is what determines the "grip" the driver has on the strings. Weak field, loose grip, poor transfer efficiency.

I pointed out that to use this as a pickup, you needed some serious amplification because it cuts the number of turns down dramatically, which cuts down on the output.

If you've found that a thinner coil works well, why not section a single coil pickup bobbin, putting a thin layer of driver windings up at the top of the pickup, and winding zillions of turns of thin stuff underneath? That lets you have both a driver and a real pickup on the same bobbin. It compromises the real pickup a bit, but you at least do get to have one.

Here's another one you might look into. The logical progression of drivers for this is to few turns of thick wire to drive the mechanics. No surprise, that's what happens in the motors world too. You want low inductance so you can build ampere-turns of Magneto-motive force (MMF) fast without having the inductance require huge voltages to make the magnetic field change quickly. At the same time you want high ampere turns for intense magnetic fields.

The logical conclusion of that is *one* turn of thick wire drive with a lot of current. That's probably not practical, but you could go to some fairly thick wire and high current if you used a step down transformer driven by the power amp and with the secondary driving a few-turns driver coil. More current, more agile, same driver grip on the strings.

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Oops, forgot.

One possible cure for your driver-to-pickup crossfeed problems is to put a big magnetic shunt between them.

The bleedover of the driver M-field outside of the string is presumably what you don't want, as that will squeal at whatever frequency the whole mess is resonant at, not the string frequency. You *want* feedback through the string.

The M-field feedback comes from the driver field getting over to the active pickup directly. While there are no magnetic insulators other than superconductors, you can make a magnetic shunt between the two pickups with some iron/steel. With a thickish piece of steel between the two, the steel will shunt excess drive field before it gets to the pickup. Ideally this would encircle the driver completely so that the fringing field was shunted on all sides and there was no air gap for it to overcome. That improves the efficiency of the shunt a lot.

Iron is several thousand times better "conductor" of M-field than air, so if you put an iron shunt around the driver, it potentially cuts the fringe field that the pickup sees by a lot.

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so what're you saying?

take a massive wire and wind it around just once?

but the extra current would make the battery life shorter, wouldn't it?

unrelated-

i was wondering if anybody's experiemented with the difference between tall drivers and shorter drivers? the shorter drivers would be more efficient space-wise, but is there any advantage to having a tall driver?

also, for the magnet underneath the driver, would a magnet from an old pup work?

also, i was thikning abuot taking out my volume and tone pots, just because i keep them all the way open anyways, so make room for the new knobs for the sustainer...well, the potential sustainer, i guess :D

Edited by BDRockStar
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Great couple of posts there RG...and welcome to the forum :D

Some of your ideas have been explored a bit, so he's a catch up...

If you've found that a thinner coil works well, why not section a single coil pickup bobbin, putting a thin layer of driver windings up at the top of the pickup, and winding zillions of turns of thin stuff underneath? That lets you have both a driver and a real pickup on the same bobbin. It compromises the real pickup a bit, but you at least do get to have one.

PD5.jpg

This is a single coil cheapo strat type pickup. The core has been replaced with a steel fin and a driving coil wound on top. The magnet goes below but the whole thing works well. The driving coil element is about 3-4mm thick. As the drive coil needs to be pretty close (read: very close) to the strings the pickup coil is not really that far away from where it would have normally been adjusted...I did a pictorial on making it about page 48 or so...

Ideally this would encircle the driver completely so that the fringing field was shunted on all sides and there was no air gap for it to overcome. That improves the efficiency of the shunt a lot.

Iron is several thousand times better "conductor" of M-field than air, so if you put an iron shunt around the driver, it potentially cuts the fringe field that the pickup sees by a lot.

Some of my "secret" hex drivers (most of the middle of this thread) were coated in super glue and dipped in pure iron powder for this purpose. It needed to have a lot of control so that it could be mounted near the bridge or close to the source...here's one of the last more advanced designs with a row of LED's on it...

drvlighton1.jpg

It sat within a thin aluminium case and was filled with magnetic "shunting" material...as you can imagine the six "driving elements" are very small...not exactly DIY (measured about 5mmx5mm side and depth)

I was an still am in two minds about the concept...one single string coil (not the best comparison as it turned out) worked extremely well with the coating totally encapsulating it. The coating also makes a decent heat sink (especially with the outer aluminium case) to protect the "driving elements" from ultimate destruction...also served to hold it all together and protect them from damage...

The Hoover/Sustainiac Patent shows adjustable "shunts" under the high b & e strings but they seem to be there to increas efficiency for thaose strings rather than any containment....

My ambiviance is that by shunting too much the field could be directed to remain more within the driving coil and thereby act less upon the string....

The bleedover of the driver M-field outside of the string is presumably what you don't want, as that will squeal at whatever frequency the whole mess is resonant at, not the string frequency. You *want* feedback through the string.

...Yes...one thing though is that some of the fluctuating magnetic field will travel along the metal string and effect nearby pickups....

Where I left off my thinking about a sustainer driver a year or two ago, I had proposed the idea of taking a single coil pickup, cutting off the windings and rewinding with thicker wire, the consequence of needing to have lower voltages drive the necessary ampere-turns to move the string. I think it's in the archives over at ampage or DIY.

I have tried that as have others with various amounts of success...generally we've found ).2mm wire and a very shallow coil (like the driving coil above the pickup coil in the above photo) seemed to be getting the best results...other advantages is that it is slimm enough to surface mount on some instruments or to be incorporated in a pickup design...but experiments have suggested that this design is more efficient.

This efficiency may also go back to your containment of the M-field ideas...perhaps the shape of the coil better achieves this...smaller coil, less EMI coming out of it to the sides....possibly

I pointed out that to use this as a pickup, you needed some serious amplification because it cuts the number of turns down dramatically, which cuts down on the output.

That's why I used a stock pickup and added the driver on top...a driver, even with the required amplification wont sound quite like a conventional passive pickup. Sustainiac do offer this in their stelth plus model and apparently the pickup doesn't sound too bad...or so it was reported....

Here's another one you might look into. The logical progression of drivers for this is to few turns of thick wire to drive the mechanics. No surprise, that's what happens in the motors world too. You want low inductance so you can build ampere-turns of Magneto-motive force (MMF) fast without having the inductance require huge voltages to make the magnetic field change quickly. At the same time you want high ampere turns for intense magnetic fields.

This too was kind of exploited in my hex drivers...six lower resistant coils...and precautions as described above to stop them burning out...

I have tried thicker and thinner wires with the more conventional designs but with the thicker wire you need to apply more power...while the driver can take it...the amount of power required limits it's practicality as an onboard battery operated device...It requires a balance I think that will only come from experimentation...thats really what this threads about BTW....

The speed of change of magnetic states though is really of concern and hampens the improvement of our simple drivers, I believe...

I have been trying to encourage people to explore alternative coil cores (rather than the coils themselves). I think that's where some real benifits lie. I've found a ferrite core reacts much quicker than a plain old chunk of steel. Likewise a laminated or epoxy/powdered iron core may result in similar benifits. Such cores may also serve to help "shunt" the field (ie keep the M-field centralized about the driver and strings) as well...

I sense that this is in part the problem with driving the higher strings (although higer tension and less magnetic material in these thinner strings are other obvious factors). At higher frequencies it's harder for the driver to change states that fast. With a core like ferrite, the speed of change available seems much higher...but it's practically imposible to work with.

Laminated cores (commonly used in transformers) seem to hold the best promise for the DIY'er as for some it may prove easier to work with than solid steel anyway.

Another idea is for the magnet to be the core...in the very slim designs tiny rare earth magnets would seem ideal, cheap and easy to work with...has still to be tested as the core but has worked as a compact magnetic source on a very slim coil design with a steel core. (Note though...the larger ceramic magnet did seem to work slightly better, I believe due to it's shape rather than it's strength...

Still...some interesting ideas not explored yet...lower resistance coils...more power...hmmm

Great stuff...welcome aboard...pete / psw

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OK, fellers, before we get all giddy at the prospect of more current from lower resistance drivers, let's look at some serious physical constraints imposed by the nature of the device. First of all, 8 ohms is about as low as the 386 (or any other chip power amp capable of running from a reasonably-sized battery) will handle without melting down. Second, a 9 volt battery (or anything similar, like say 6 AAA batteries in series) is not exactly an optimal supply for a power amp, so your output swing is going to be limited by your power rails, regardless of how low your output impedance is, and it's going to fall further the more you decrease output impedance. Has anybody tried a driver coil wound to about 8 ohms with 24 gauge wire? Yes, I know it's going to be quite large, but it should be both more efficient and lower in inductance, right? Seems to me that's what the target is - but I could be completely off base, so don't rely on my math skills. :D

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Quite right LK...hence...

I have tried thicker and thinner wires with the more conventional designs but with the thicker wire you need to apply more power...while the driver can take it...the amount of power required limits it's practicality as an onboard battery operated device...It requires a balance I think that will only come from experimentation...thats really what this threads about BTW....

You got to keep in mind the whole concept...there is only so much power you can supply without getting silly...or giddy for that matter...

I've run a 4 ohm driver pretty well with the LM386 and I've never actually melted one but I'm sure there is a practical limit...

I now do all my testing with batteries (usually rechargable 8.4 volts) because I'd get false results with the power supply as it could draw a lot of current if it wanted to but ultimately it wouldn't work in a practical battery powered design...

It does bring forth the notion of responsiveness though which is an interesting question...

I have been trying to encourage people to explore alternative coil cores (rather than the coils themselves). I think that's where some real benifits lie. ...

I sense that this is in part the problem with driving the higher strings ...  At higher frequencies it's harder for the driver to change states that fast. ...

Laminated cores (commonly used in transformers) seem to hold the best promise for the DIY'er as for some it may prove easier to work with than solid steel anyway.  ...

Another idea is for the magnet to be the core...

The coil is only one part of the equation...at some point you've got to put some restrictions on some elements and work with the others to progress...

So...a preamped LM386 seems the obvious choice...cheap, easy, battery powered, easy to obtain...perhaps you'd be better with a Class D amp but that's a whole other road...perhaps some AGC, phase shifting and tricky filtering would also be of benifit (as described in all the patents), but then again we are getting pretty good results without that and even the commercial systems seem to be developing the driver side of things more than some fancy circuitry...

BDRockStar wrote (while I was posting so I missed it)...

i was wondering if anybody's experiemented with the difference between tall drivers and shorter drivers? the shorter drivers would be more efficient space-wise, but is there any advantage to having a tall driver?

Now, for the coil...experimentation to this point, by a couple of guys here, seems to favor the slim coil design over the deeper, pickup like tall driver...for actual working efficiency. My thought on winding a driver on a conventional bobbing was to block up the lower half and just wind the top half...

A part of this is, I think, to do with the overlapping of the coil wires...A single wire does generate a small magnetic field...I experienced quite marked interferance from the wires going to the driver when too close to the pickups...I even went to the extent of threading them through ferrite beads to suppress this effect (works BTW)...Now, overlaping the wires, I think, increases efficiency as the single wire field are cummulative, each wires field is wraped in the others which increases efficiency...as we're not looking at a lot of turns (200 or so) the more compact coil design increases the effect...err..I think...

So...at least at this stage...0.2mm wire on a slim coil seems to be the go...

As for your other question...

also, for the magnet underneath the driver, would a magnet from an old pup work?

...most people are using old pickup magnets including me. One advantage of sticking it to the bottom of a core over putting the magnet inside the coil is the ability to continually recycle the magnet for future designs...

also, i was thikning abuot taking out my volume and tone pots, just because i keep them all the way open anyways, so make room for the new knobs for the sustainer

This exactly what I would suggest for a neat install (though a volume is pretty useful IMO)...for a strat you could lose the centre tone and make the other a master...an LP style, you could also have a master tone or a master volume or a single master vol & tone a sustainer control and a rotary switch to turn it on...

My test Strat is a bit different...I have a master tone and volume and the centre tone is already used as a centre pickup blender...hence the new cavity knob and eventual switch placement under the trem...I wouldn't advise that kind of drastic routing normally...although I dont think a small routing behind the trem would hurt for an easy place to fit the battery. The circuitry will easily fit within the guitar...the fetzer/ruby is particularly small and my new op-amp based 3 gain stage is not much larger....

Anyway...good to see some new comment on the whole sustainer thing...

psw

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OK, fellers, before we get all giddy at the prospect of more current from lower resistance drivers, let's look at some serious physical constraints imposed by the nature of the device. First of all, 8 ohms is about as low as the 386 (or any other chip power amp capable of running from a reasonably-sized battery) will handle without melting down...Has anybody tried a driver coil wound to about 8 ohms with 24 gauge wire?

Sorry, I wasn't being clear.

You're quite right. Any amplifier working from a limited voltage like a 9V battery is going to be power limited. A perfect amplifier can only get +/-4.5v out of a 9.0V battery, and into 8 ohms, you only get 4.5V/8 = 0.56A peak, 0.39A rms. That makes the max sine wave power 1.266W.

But if you want a smallish coil of thicker wire, you can use a transformer to convert that to a lower voltage and a higher current. Something like a 5:1 stepdown gets you to 0.9V peak and 2.8A. While this is the same power into the driver coil, you can now use 1/5 the number of turns in the coil and get the same ampere-turns of magnetic drive.

The inductance of a coil is proportional to the square of the number of turns for a constant form factor, so the inductance of the coil drops by a factor of 25. So now the coil is quite agile and can be driven to a given signal quite quickly.

That moves the problem from designing a critical pickup to designing an amp/transformer to drive it, which moves the design problem a bit away from the mechanically limited driver coil.

Actually, a strat pickup wound with #24 wire to a few ohms of resistance was my first suggestion for a sustainer driver.

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You know....apparently one sustainer (possibly an early Fernandes, not sure) did have a transformer, for such a purpose, I believe!

I'm not sure of the corresponding driver design though...and I did see somewhere (probably a rival patent) something about the transformer it'self puting out excessive EMI...! BTW...the Fernandes system uses two 9 volt batteries...

The detailed technical part (and math) is a little beyond me...but I'm willing to give it a try if you have some more concrete ideas on implementing them

Responsiveness is an issue....though...I and others have had really good results with the relatively crude designs developed so far. The sustainiac/Hover patent circuit details stretch for 6 pages as I recall...it's really a bit much for most and are they really gaining that much over these simpler designs...?

I still think more could be done with the drivers on this account. Especially core material...but...

Is it your suggestion that, with less coil "length" (number of turns) and more power (and thicker wire to handle it) you'd get a better response?

I think it would be hard pressed to get more power and if you did, the battery would have a fairly short life span, would it not?...Also, with the transformer...isn't power being "wasted" through the process of induction unrelated to the mechanical driving of the strings...or am I missing something...it seems that you're sacrificing turns on the driver for turns on the transformer....hmmm?

Anyway...all suggestions to do with any type of sustain device is welcome here...

My last post though is aimed partly at those who want to actually build a sustainer, now!!! I think the types of devices people (including me) are doing now are quite servicable...though not perfect. The fact that different people are getting slightly different resposes from the small design variations bodes well though as they promote a healthy evolution and cross pollenation of ideas and actual experiences...

In general the high string, especially the high e string response is disappointing. My high string does work but the response is slower and less sensitive...the patents suggest this is due to phase differences...hmmmm...this was discussed a lot early on but it didn't really come to much...and possibly rightly so!

If we were to consider a small basic practical amplifier design like a preamped LM386 (or similar) and a coil of between 4-8 ohms, as a given... there is still a lot of development that can be made in driver design...

For instance...the coil could be asymetrical, the core material could be played with, the orientation of the coil could be adjusted for phase differences...then there is the idea of multi-coils...

Sustainiac now uses two reverse-wound reverse polarity coils one under the top three strings, one under the bottom. Primarily this seems to be in an effort to contain the M-field (in a humbucker type configuration) but I had thought of driving each coil separately from two lower gained amps with appropriate filters for the strings they serve and maybe even different ohmages, wire thicknesses and such, once these things become apparent to be of benifit through peoples experimentation...

On the other hand...work with the hex drivers showed me that there is a complex interaction between near driver's pulsing magnetic fields that at least for now is unpredictable at best...it can work, but is it any better than these more crude designs...I've begun to think not!!

Anyway...another long post... :D ...

check you later

psw

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Yeah it reminds me of the early days...first ten pages or so...lot's of theories and ideas bouncing around...fascinating stuff...plus now we've got some practical stuff to build on...and best of all....more than just me making them so I can sit back a little and enjoy... B)

Thanks a lot for sticking around R.G. you'll find a few familiar people here I'm sure...

The sustainer technology is such a simple idea in principle...and it really is easy to get a fair way with it in practice...but to get it better, it's up hill...kind of like learning guitar really, not to hard to get a few chords and such happening but to get really good takes a lifetime... :D

Hope R.G. hasn't taken anything as a negative about his ideas on transformers and low resistant coils...there is something there I know...implementing it might be a little tricky...and the work/benifit has to be weighed up...look at all the work I did on my hex drivers :D

...the hex drivers were low impedance (about 1 ohm each by the way but chained together...they used ferrites and iron coatings and responded quicker than these big coils...some were unusual in that they drove the string from side to side, others had dual magnetic polarities so that the string was in a neutral zone between north and south that fluctuated with the signal...alignment became crucial and it got way out of the DIY realm...

Anyway...let's not lose sight of the fact that it's a great "effect" and a lot of fun to play with...it really is kind of addictive...and has a lot of musical potential, it's not just a novelty gadget...

psw

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I think a really useful thing to do is to try the magnetic shielding.

M-field is a square law thing. Each doubling of distance weakens the field by a factor of four. If you put a magnetic shunt covering the driver, it shunts the strong(-ish) field right at the driver and the strings get little driving. If the strings are closer than the magnetic shunt by a factor of two, they see a driver field of 4X the field that the shunt does. I'd put a soft iron shunt around the driver, but spaced away from the driver at least three times the distance from the driver to the strings. That would mean that the strings are still getting 9/10 of the driver field, and the shunt is working on 1/10 the field.

The shunt's job is to cut that fringing field down to unnoticeable over at the next pickup. Accordingly, the first shot at a shunt ought to be a ring of soft iron around the driver at 3X the driver-to-string distance from the outside of the driver. This should suck in the driver fringing field and shunt it away from the other pickup(s). You might get 40-60db of shunting. A shielding shunt around the other pickup as well should clean things up a lot.

I think of magnetic fields in iron like water ditches in dirt. The ditch carries maybe 1000 to 10000 times the water that just level dirt does, but some water always leaks out no matter how you dig the ditch. Without iron, M-field spreads out like water on level dirt.

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So, if I'm following this, what we're looking for as an "ideal" driver is a coil of fairly large wire, at a nominal 8 ohms or thereabouts, around a soft iron core and surrounded at some distance with a magnetic shunt, or alternatively (and perhaps preferably), a coil of much lower resistance with a coupling transformer to step up the impedance the amp "sees". Is that about right?

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Just popping in to say 'hi'. I've been following this thread, still, but it's like listening to Spock and Scotty talking to Jordy and Data. :D

Greg

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Hmmmm...... :D

My last try at shunting was with a 1cm wide blade cored coil (smaller than the 10mm bobbin) of 8 ohms (pictured with RE mags under it somewhere)...what I did was take a row of #10 staples (soft iron) and placed them to the back of the magnets so that thes fins on either side of the coil were the opposite polarity of the core...if you follow me...

The notion was (and had been used before on other prototypes) that these fins would draw back and contain straying M-fields...acting as a "shunt if you like...

Unfortunately....I found no difference in performance...

Using your factor of four however...would I not have to have my shunt 4cm either side (or 2?) of the coil...this makes the device a little large for practical purposes...

I'm willing to do some more experiments with some more direction...should I try a 2 ohm coil and see how it goes before the LM386 self-destructs?! BTW Does the lower impedance coil result in more or less power from the amp (does the amp run less efficiently, or run wild?)...why is it destructive to the amp not to show it it's desired impedance?

The ebow patent also proposed the six ebow idea and detailed a massive iron shunt...not entirely practical...

Another patent (possibly Hoover) suggests the coil be wraped in another coil (a "correction coil", I think they called it) which is wound in the opposite direction...would this not produce an electromagnetic "shunt" around the coil and, in the process...allow the main coil (around the core) to be of a lesser impedance, thus fitting your schema of a lower impedance coil...without a transformer. The patent was not really explicit, I may have misread it, or it might be my overactive imagination, but I have harboured this idea for some time but never actually put it into practice...

The magnetic field diversion tactics of metal fins and iron coatings has been explored a fair bit by me but it's hard to make any generalisations about it so I've kept the experiments fairly quite...things were getting complicated enough at the time...

All very interesting stuff...but what is it we are trying to achieve. Is it less interferance with other pickups so that we can apply more power to the driver before oscillation occurs...if so we do need to consider how we're powering this thing, battery life, etc. Or is it more efficiency so that we can continue with our low powered amps and get better results...

Afterall...less power but still enough to achive the effect is equivilent to "shunting" in that less M-field is emmitted, is it not?

Anyway...just some thoughts...I'll need to think about this some more...anybody want to add some thoughts and suggestions...

psw

Oh...and Transient/Emre...that's great...I'm not sure how piezo's will go as the source for the driver but there's no reason to think it wouldn't work. With the Ghost systems Hex pickup capabilities you may yet develop the first (known) truely hex driver....looking forward to seeing what comes of it....

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:D Hee Hee...no worries...we should take bets on when this thread reaches 100 pages...or maybe 1700 visits, or 1000 contributions....

Just popping in to say 'hi'. I've been following this thread, still, but it's like listening to Spock and Scotty talking to Jordy and Data.

:D Yeah...it's getting back to it's more wierder origins of the early days of the thread...but that's why it's been going for so loooonnnnngg I guess...it's craptastic, sheetoli, and totally wack! B)

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A few people from Aron's Stompbox forum asked where the Pickup/Driver Pictorial was...here's a link back to page 49...about a third of the way down and there were two installments....here's a the link:

PICKUP/DRIVER PICTORIALS PARTS ONE AND TWO

Now...

COMBINATION PICKUP / DRIVER PROJECT...Part 3

Got a little time and motivation to do a bit more work towards installing the sustainer permanently in the Test Strat...now that I've got a great big hole routed in it.... :D

So...now some more work on that driver...

Added some wires to the pickup coil and tested it...perfect...actually it will sit about the same distance from the strings as it was set anyway and no harm seems to have come of it's performance from the modification to it...so so far so good...

I carefully taped down the wires and coil and magnet with black electricians tape...

Then I cut and filed out the top out of the original single coil cover...

Here's a pic:

pup-driver1a.jpg

So simply pushing it all together it fits perfectly:

pup-driver1b.jpg

Looks like a kind of Charlie Christian thing...kind of spiffy as is...

For now I'll leave it...but the bobbin is not quite a perfect fit and the windings pushed the bobbin up a bit at the ends...in fact you can see a little of the windings as they go around the bass side of the blade. The blade is already showing the early signs of rust too...

The intention will to fill gaps with epoxy putty and coat the top in a layer of black epoxy...I might just simply fill the pickup cover with epoxy sealing the whole thing...but then it'll be there forever...no getting the magnet out then if it should fail...not that it will....

Anyway...there we are for now a tested but not yet fitted pickup/driver...success on the first go...

The pickup that it replaces by the way is the exact same design as this one so I'll be able to make another for my next project...a purpose built sustainer guitar...but for now it's on to making sure the installation process all goes well...

psw

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Hey,

I've been out of town and I just got caught up on what's happening in the sustainer thread. Reading this thing is full time job. Anyway, just wanted to post that I'm working on a new driver and hopefully I'll have pics to share in a week or so when I stop travelling.

Nothing special, just a short coil with a ferrite core (which I haven't tried yet) and hopefully some really strong magnets.

Everybody keep it up! It's great to see this discussion.

Mike.

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:D RG, can't get your link to work. All I get is a big "not found" error.

BTW, in case it hasn't been said, thanks for your interest and your contributions - it's nice having somebody involved who knows more about magnetics than the rest of us combined! :D

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R.G. ...sorry but that link doesn't seem to go anywhere...there's nothing on Geofex that seems to point to it either...want to check it out for us...cheer's

We'll it's 6am here and my 2y.o. has got me up to play trains again...so I can tell you a little of how the pickup/driver worked out so far...

The pickup is great...it may even be slightly "better" for the modifications...on the whole the pickup sound is nice and warm...unlike what you'd expect from a low impedance passive single coil pickup...the one it replaced has a similar sound, this just seems a little more "solid" but the difference is very subtle...The fact that the pickup/driver and the pickup it replaced were virtually identical makes the comparison quite clear...

The Driver...also working great...all but the high e responding great and working A-ok...I had thought I'd damaged it some how but a solder connection from the harmonic switch had become loose...

The Installation...not so great, so far...with the pickup connected up and the driver operating oscillation and/or cancellation and spluttering (depending on the phase of the pickup or driver) occurs...

Testing outside the guitar confirmed that the the driver and pickup still performed as they should but it was observed that when I touched one of the pickup coils to ground the problem would re-emerge....

I imagine that the pickup coil is having a voltage induced in it and is being sent through the guitar's ground to the output...I have yet to wire up the sustainer's ground lift bypass to the on off switch...perhaps this alone will solve the problem...but as only one lead of the pickup coil seems to need be connected and we're playing with phases, etc...this may not be enough to silence it and a more elaborate switching system needs to be devised...

The fact that my driver sits on top of the pickup or right next to an inactive pickup in Sustainiac type installations should make little difference to this effect so there will be a way...we'll have to see as the installation continues...

psw

BTW...Mike, great it'll be interesting to see how you managed to make a ferrite core...watch the magnets though...too strong and they'll pull the strings out of tune...really strong and they'll stick to the driver.... :D

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http://www.geofex.com/FX_images/Magdriver%20and%20shunt.pdf

here you go guys..

:D

Ohh psw, now that you have your driver/pickup combo, have you considered using it like a big e-bow; as in wiring the amp directly between the pickup and driver and not connecting anything to the guitar electronics (thus isolating the sustainer from the rest of the guitar circuit)?

Tim

Edited by onelastgoodbye
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Hi Tim....

Well even the ebow has to have some distance between the driver and the pickup... :D

However...and I was going to see if R.G. could put his mind to this...regular's will remember my hex driver's that sat on top of the pickup that was also it's source...or may be not...anyway, it had an effect which I called "induction drive" or something...Basically it's as you suggest...you get an incredible increase in gain as the pickup is being subjected to an amazing amount of fluctuating magnetism...now with the pickup to one side or the other it's less controlable but on top...perhaps there is a way to harness this effect...

I don't think that it would really work as an ebow but it's easy enough to test I guess...I'll try hooking it up and see what happens...if you don't here from me...send out a search party...

pete

now I'll go check that link, thanks...

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