Hank McSpank Posted March 20, 2009 Report Share Posted March 20, 2009 (edited) Just a couple of minor points (my loft beckons!). I wasn't suggesting for one moment you'd approached your sustainers will nilly (ie with my "Nike T Shirt - just do it" quip)....the comment came from your line... " I'm still not entirely sure why you don't just make a test coil of a known design and see how that goes, if only for a reference" that's my point...I'd rather think it through ad infinitum (beside my loft is too cold to "just do it"). Such is the written format - open to misinterpretation. (I also regret the boat analogy as it's allowed you to go overly wordy! lol) Re , your tele switching photo (which shows an awful a lot of interconnections). Well, without sitting down with a wiiring diagram & going through it wire by wire (& I've no intention of doing that even if you scanned one!), the more interconnections/wires, the higher the possibility for grounding problems....which might well have resulted in a failed simple micro switch scenario. Re the simplicity & my pursuit of hex...don't muddle the two towards scoring points! I've no wish to get complicated where simplicity will do...but from the outset, I've said there are major synergies with Variax & midi guitars...both of which I'm into in a big way (I also have a sexy little concept I wish to try which will yield any harmonic on demand ...3rd, 5th, 7th, 12th but this definitely necessitates a hex driver...all will be revealed once I've tried & failed!) - therefore my pursuit of hex, overides/negates the pursuit of a simple mono driver - I will however pursue simplicity whenever possible but only if it dovetails with my own particular requirements. Anyway ...thermal underwear & gloves on....to the loft & beyond. (on tonight's menu - getting my coil winder to drive some 7 segment LED displays, which aren't striclty need as the PIC turns off when it reaches a user predefined figure...but I'm @n@l that way...& you can never have enough LEDS - 7 seg or otherwise - on any project!) Edited March 20, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 20, 2009 Author Report Share Posted March 20, 2009 Re , your tele switching photo (which shows an awful a lot of interconnections). Well, without sitting down with a wiiring diagram & going through it wire by wire (& I've no intention of doing that even if you scanned one!), the more interconnections/wires, the higher the possibility for grounding problems....which might well have resulted in a failed simple micro switch scenario. Nope! btw that pic was in the early stages of wiring and it is extremely neat...it has nothing to do with ground loops or anything like that...the transformer effect is real...simple switching alternatives of all kinds have been tried with due care and workmanship. However, you will meet and hopefully solve or work around these problems when you get to them. There are things that Hex designs can address in various ways...unless you take that path, which very few have done, these things won't be available to explore...so again I applaud your efforts and they are not wasted. My/your boat analogy is still valid...just suggesting that making some rowboats and models are prudent exercises. This speaking from someone who has built a boat btw and dabbled in yacht design! Sorry about being overly wordy! Carry on! pete Link to comment Share on other sites More sharing options...
col Posted March 20, 2009 Report Share Posted March 20, 2009 (edited) Re the simplicity & my pursuit of hex...don't muddle the two towards scoring points! I've no wish to get complicated where simplicity will do...but from the outset, I've said there are major synergies with Variax & midi guitars...both of which I'm into in a big way (I also have a sexy little concept I wish to try which will yield any harmonic on demand ...3rd, 5th, 7th, 12th but this definitely necessitates a hex driver...all will be revealed once I've tried & failed!) - therefore my pursuit of hex, overides/negates the pursuit of a simple mono driver - I will however pursue simplicity whenever possible but only if it dovetails with my own particular requirements. The main thing holding me back from even considering a hex system is all the drive circuitry. I came to the conclusion a long time ago that for any real quality of sustainer you need some sort of AGC. This is not trivial circuitry, and a hex system requires a 6 channel drive circuit - thats 6 buffers, 6 channels of AGC and 6 power stages. I would need a semi-acoustic to find enough room for all that circuitry unless is was all SMD. Anyway ...thermal underwear & gloves on....to the loft & beyond. (on tonight's menu - getting my coil winder to drive some 7 segment LED displays, which aren't striclty need as the PIC turns off when it reaches a user predefined figure...but I'm @n@l that way...& you can never have enough LEDS - 7 seg or otherwise - on any project!) Thats the spirit . I'm jealous of your PIC experiments. I've looked at a few, but the ones I liked the look of are out of my price range. A decent DSP PIC should have enough power to process all your 6 channels, and condition them - including AGC, phase correction etc. so 'all' you would need would be the power stages. Are there any with that many ins and outs? I bet there are (I've done some DSP tinkering and lots of programming - assembly, C, C++ etc.). ============================================================ I have also been sustainer tinkering ! I had a first trial run to test out some of my theories. LM386 in current mode driving a 2.5ohm load WORKS! woohoo Parallel Dual core driver with 140 turns per coil of 0.28 wire WORKS ! woohoo I will have to do a lot more work to refine these, but for now I am feeling very positive. (after a bad start! I wired up the driver wrong and was worried the whole premise might be erroneous) The coils are wound on the guts of an old humbucker. There is no 'padding' so the coils are full depth, not 'thin'. The core is made from laminated steel. I used the steel from PC power supply casing - this seems to have very good magnetic properties, is readily available, nice and thin and you can cut it with tin snips. I have still to insulate and glue the laminates - figured I would wait until I'd run a basic test. The humbucker had rails, so the bobbins have slots in them, which is lucky for me, but a shame for the 'project' because these seem to be unavailable as parts, so it's a case of searching for an old pickup with rails (although a normal humbucker with pole pieces should work well with a few more turns of wire). With the laminations finished, I hope to get slightly better efficiency and less noise - right now the laminations are vibrating against each other lol. The thing DRIVES the strings! even with a knackered old battery 7v Its nice that it works without having to fabricate bobbins or mounting hardware - just winding some chunky wire onto big easy to handle bobbins, then use the magnet, wooden spacers and fittings that the pickup came with - nice and simple, and of course, it looks like a pickup!. I'm sure it would work with the cores the pickup had, but not as well - the inductance was too low, and eddie currents would also have been an issue. Testing this really brings it home how limited a non-AGC circuit is though. It takes a while to get a good drive started, then it tries to shake the guitar to pieces! AGC gives that hard drive at the start, then eases off when the strings are ringing.... anyhow - it's getting there. When I have finished the driver and installed it into the guitar. I'll be better able to appraise the 'simple' non-AGC version of the circuit. If I think this is good enough for starters, I'll post it. I have also been working on a more compact AGC, so I need to get that breadboarded and see how it compares with my old circuit. This new AGC is a feedback variant which is a compromise. Partly to minimise the part count and partly because its easier (for me) to build a feedback variant with a wider dynamic range based on some other circuits I've found. There are a some other things I'm trying out in this which might be nice. One idea is to roll-off everything above about 2kHz. The idea is that as I explained a while back, due to the space between driver and pickup, the sustainer actively damps the higher harmonics. The idea is that if we filter them out, the driver wont drive them so they won't get damped. When its all up and running, I'll play around to try and get the best frequency... Just now its just a simple RC filter in the power stage feedback. I haven't had much luck design wise with 2-pole active filters - they mess up the phase too much. ...enough for now.... When I get some more work done, and more tests, assuming its still working as I'd hoped, I'll explain the theories behind the amp and the design approach that lead to the driver design. cheers Col Edited March 20, 2009 by col Link to comment Share on other sites More sharing options...
al s. Posted March 21, 2009 Report Share Posted March 21, 2009 Hi. More news from the thin driver front. Nice to see a little excitement Pete. Although, its hard to imagine..... after three years of this stuff? I"ve been thinking about it for 6 months,working on it for 4 months and I'm getting burned out. So thanks for the encouragement. Anyway.. I was comparing some drivers side by side up above the neck pickup and on a whim I hooked them up in parallel. I"ll be damned! No EMI and much better defined Harmonic/ Sustain modes. The parallel setup also worked on the inside of the neck pickup. I couldn't go all the way to the center between the neck and the bridge because of the EMI became overwhelming. But now it is tantalizingly close. And this was just thrown together. I've been searching the forum.. and came across the Spazzyone era. Lots of discussion about dual rails and bi-lateral drivers. And yet here we are still with single pole drivers. Not that I don't like their performance. In fact I don't know that I even want a driver in the mid position... Seems like it might alter the harmonics, not to mention interfering with picking. But it does have advantages...ie. ease of installation, etc. So my question is: Why were dual rail and bilateral drivers abandoned.? Especially since we know that they can work cause this is the way the sustainiac does it. Am I just another lost soul in search of the holy grail??! AL Link to comment Share on other sites More sharing options...
al s. Posted March 21, 2009 Report Share Posted March 21, 2009 Hi Col. See. this is why I don't post more. Can't keep my foot out of my mouth... Your working with a dual core driver!. I missed your last post. It sure seems like it should work well....doesn't it? I' m glad you are taking it further. And watchin for your results. So many variables though. Wire gauge, impedence, polarity. power requirement. It boggles my mind. I was just thinking. Does anybody ever think about the pioneers of the sustainers? Just, guys like us tinkering in their garage.... No internet, no discussions, just plodding away by themselves.... yet and they came up with something we can barely duplicate. Hats off Mr. Hoover! Link to comment Share on other sites More sharing options...
psw Posted March 21, 2009 Author Report Share Posted March 21, 2009 Hey al s. good to see you are still about and experimenting...a bit more "air" in your posts could help with them being ledgable! I should say...some interesting stuff as well Col...not quite enough yet for me to make a corvus for this silly build-off...but I do see someone is proposing a ten-string version. I have my own idea that would use a sustainer...but we'll see...hahaha Anyway... So my question is: Why were dual rail and bilateral drivers abandoned.? Especially since we know that they can work cause this is the way the sustainiac does it. Am I just another lost soul in search of the holy grail??! AL No, there are a bunch of people that were working on that thing...things go in phases I suppose, people get hooked on an idea for a bit. There are worthwhile attributes though, and if you see Col's post above, he has made a new HB version and has pretty consistently used dual coil drivers. Col has always been an advocate of the dual coil system. And yet here we are still with single pole drivers. Not that I don't like their performance. Well...I tend to use single coil drivers because they are simple and I can get them to work! I can get dual coil and hex things to work too...but do they work "better"...well that's for the user to decide, in my experience no, and not for the amount of work involved. I have also found them to be more difficult to make and take up more space, so not so versatile...the result is often the complete removal of the neck pickup (note in cols new version the driver is the size of a full sized HB in the neck!). Some don't see that as a problem, and if I were to build a purpose built sustainer guitar that is probably what i would do...just a single pickup...but with other features, like momentary control switching if possible. However...there are places for them for sure, and they may indeed be "better" in some applications and intended response and performance. In fact I don't know that I even want a driver in the mid position... Seems like it might alter the harmonics, not to mention interfering with picking. But it does have advantages...ie. ease of installation, etc. Yes...this is an application where dual or even hex things may have an advantage in lowering EMI enough to put one in the centre position say on a strat. This is where I have tried rail and bi-lateral designs...but not with satisfactory results. I did find the things get in the way and the advantages of the ability to use the neck pickup not that great as to justify loosing the middle completely...or even of itself. It is still intriguing...but I also had a lot of problems with using both pickups at once, say with that bi-lateral tele idea from last year...I could get it working with either pickup...but it didn't like both for some reason. Anyway.. I was comparing some drivers side by side up above the neck pickup and on a whim I hooked them up in parallel. I"ll be damned! No EMI and much better defined Harmonic/ Sustain modes. The parallel setup also worked on the inside of the neck pickup. I couldn't go all the way to the center between the neck and the bridge because of the EMI became overwhelming. But now it is tantalizingly close. Yes...when i started doing this kind of thing I got some interesting and encouraging results...particularly interesting on my pickup/driver combos that share the same magnets too. However, I did have some installation and switching technicalities and decided in the end not to go with that kind of scheme. Purely from memory I think the neck pickup will need to be switched for harmonic mode along with the driver and that the core or the pickup if grounded also needs to be lifted...eddy currents build up in the steel that leak to ground. Testing the driver above the neck is always advisable...but there are still installation issues to contend with and I'd encourage you to start looking into this area since you have come so far. I think my strat which is on the bench has a sustainer coil on top of a stacked pickup...so three coils...and this could be interesting as well. Be sure that you are testing these things as clean as possible so you can be sure of results...remember also, if you are aiming the coil at the pickup from above, you have two magnetic fields at work there that can give false results that won't be duplicated with a proper installation. I expect with your thin drivers you will be able to mount the on the surface like I did my tele...so testing under the strings should be possible. Although, its hard to imagine..... after three years of this stuff? I"ve been thinking about it for 6 months,working on it for 4 months and I'm getting burned out. So thanks for the encouragement. Thanks, it's appreciated. Actually this thread started on May 1 2004, 04:57 PM, so that's about 5 years...but i had been looking at the thing for years before. And, as people may gather, I am more than burned out and so much has happened since that time in real life. Fortunately, you didn't have to start from scratch and have made significant and admirable progress...and already pushing things a little further. You've also coming to conclusions or proposition that I have come to I guess, is the single coil driver "good enough" for now or until the next big idea comes along. If you made a more complex design like a dual coil thing, but it worked just the same...which would you choose? The only times I have considered such things have been where the single coil drivers just won't cut it...in a centre position, improved polyphonic performance, compactness, EMI reduction, converting an HB pickup, ease of installation...so much more could be done with AGC and circuit design with the basic drivers before needing to venture further afield. But col could probably speak more to the benefits of the dual coil driver in practice. Anyway...some interesting results...and I'm glad it's all working for you so far. I'm sure I'm not the only one to want to see it installed and how you tackle that, maybe you'll find a way that I couldn't get to work... pete Link to comment Share on other sites More sharing options...
al s. Posted March 21, 2009 Report Share Posted March 21, 2009 ten string version...? Well it is a natural for a pedal steel guitar, and their quest for sustain....... Pete. I sent you an email. from albert105 please retrieve it from your trash. AL Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 21, 2009 Report Share Posted March 21, 2009 (edited) I came to the conclusion a long time ago that for any real quality of sustainer you need some sort of AGC. This is not trivial circuitry, and a hex system requires a 6 channel drive circuit - thats 6 buffers, 6 channels of AGC and 6 power stages. I would need a semi-acoustic to find enough room for all that circuitry unless is was all SMD. As it goes, I'm at the early stages of buying SMD related kit (or more to the point...making it where possible - eg a reflow oven out of a toaster oven - http://www.sparkfun.com/commerce/tutorial_...als_id=60!) Veroboard & breadboard is so last millennium! I completely agree about AGC being needed ...my initial tack wil be with a stereo AGC bestowed preamp (obviously 3 of those needed for Hex).For simplicity (there's that word again!) & to get me up and running fast, I'll likely use an LM386 as the power amp - I'll then get a string moving 'just the right amount' at each fret position & use a scope to get some handle signal characteristics across the driver coil - ultimately hoping to glean a power figure (for each string in turn)...I can then revisit the circuit design to tweak accordingly. You latest path is in synch with some thoughts I'd had myself - it strikes me that we should all be forcusing on current through the driver, not voltage across it. But it's a niche area & I'd be the first to throw my hand up & say "Dunno much about that guv"....but thankfully nowadays...there's a world wide reference library at my fingertips! (I completely agree about that recent comment - just how did anything get invented before the internet?!) The pursuit of hex opens up all sorts of *very* exciting possibilities. I'm not sure how much time I can actually dedicate to this (certainly not 5 years!), but I've all sorts of things in mind...which would *only* be possible with a hex driver. And with Hex, I'm very consicuous that 'fade' when bending a note will be a problem, so I'm envisaging a selectable 'solo' mode, where the note being played is fed to it's own string driver & the next lowest string - then when I player bends up & it moves away from the driver...it'll move into the zone of the next driver - since it'll be only solos, this oughtn't to be a problem. Also as I quickly mentioned... totally controlable harmonics 'on demand'. If nothing else great fun trying! Thats the spirit . I'm jealous of your PIC experiments. I've looked at a few, but the ones I liked the look of are out of my price range. A decent DSP PIC should have enough power to process all your 6 channels, and condition them - including AGC, phase correction etc. so 'all' you would need would be the power stages. Are there any with that many ins and outs? I bet there are (I've done some DSP tinkering and lots of programming - assembly, C, C++ etc.). PICs aren't in the least bit expensive - they're only about 2 quid apiece - for example, here's perhaps one of the most used variants http://uk.farnell.com/microchip/pic16f627a...equestid=404273 (but being a cheapskate, the PIC I'm using is a PIC16f690...it comes bundled with the Manafacturer's learning package ... http://www.rapidonline.com/Electronic-Comp...048/kw/pickit+2 ..I can heartily recommend it, though I now know that the PIC they bundle with that kit is not exactly a 'starter chip' - too many whacky 'gotchas' that a learner shouldn't have to get bogged down with so early on). It's taken me a fortnight to wrap my head a round the whole end to end process (which language to use, how to code it, what apps to use, how to program the PIC, header cards etc). I'm still at a fairly elementary stage - barely enough to get my coil winder going - but it has wet my appetite...I can see massive potential here (not necessarily for Sustainers). Edited March 21, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
col Posted March 21, 2009 Report Share Posted March 21, 2009 Here's the deal for the dual core parallel driver: # having two coils in this configuration helps to keep the field focused - so you don't have as much trouble with EMI getting to the pickups. # more efficient driver - more pull for the same power input! This second one needs some more explanation so here goes: For a simple electromagnet, the pulling increases with the current in the wire and the number of turns. Increase either and you get a stronger magnet. For a driver there are two problems with this: #1the amount of current we can provide is limited by the power amp and power supply. #2adding more turns to our coil increases the impedance as frequency rises Its easier to explain the next bit in relation to the current mode amp, so I need to describe that The current mode amp tries to provide the same current through the load even if the load changes - so as the frequency rises, it will push harder to keep the current at the same level - this means we get the same drive at different frequencies. ...so back to it... There is a point as the frequency rises where the amp can't push hard enough and starts to clip. This is the point where #2 meets #1. If you add more turns (or a better core), the frequency where clipping starts goes down – which is BAD. However, as you add more turns (or a better core), the magnetic pull gets stronger which is GOOD. What we need is the most powerful coil that still provides clipping free drive within our frequency range and power requirements. My idea was that if we decide what the highest frequency we want to drive fully. And choose a suitable maximum dissipation figure (de-rating to about 80%), and possible more... we can then optimise the driver by setting it up so that its Inductance is as high as possible without the clipping point dropping inside our desired response vs power range... Heres where dual core parallel comes in: Two parallel coils let us use two coils with double the inductance - wiring them in parallel halves the combined inductance, but also the current. So the circuit output sees 1 0.8mH 2Ohm inductor while the strings are being driven by 2 1.6mH inductors. Now, as we have wired in parallel, we can double our inductance, BUT we lose by halving the current through each coil... Overall we gain though because we have half the current going 4 times as many turns because we have two coils! In reality, We don't get exactly double the power, there will be other effects due to coupling between the fields. Its also important to get enough separation between the two coils otherwise the field doesn't reach over the strings enough – not enough projection. It may be that the best performance is with the power input much less than the maximum – this would be great to save battery, it would also mean changing the design of the driver somewhat – lowering the power rating means that the inductance can be increased while still keeping the clipping point at the same frequency. So thats basically the plan (working so far). Use a current mode amp to even out the current through the coil. Then tailor a dual core driver to maximise the magnetic drive within a set of desired parameters. Cheers Col Link to comment Share on other sites More sharing options...
col Posted March 21, 2009 Report Share Posted March 21, 2009 As far as PIC goes, it's not the chips themselves that I can't afford, its the programmer - the cheapest I can find that works with the chips I'd want to use is over £100. =============================== Current mode amp. I found a nice explanation of current mode a loooong time ago here I thought it was interesting and would probably have some application to the sustainer, but I was busy with other things and the article is theoretical - it doesn't give actual circuit diagrams, just simplified topology diagrams. Much later I was studying the Sustainiac patent, and realised that what they call a "current source" amplifier is basically the same thing as the current amp described in that sound.westhost page (patent speak always tries to make simple things sound dramatic and complicated). I decided to try and get a simple current amp working for the sustainer based on our existing circuitry. After trying lots of approaches and getting to the stage where I was giving up on a simple LM386 solution in favour of having to design a power stage from scratch (with all the extra hassle that that would entail - thermal issues, layout etc.), I had a brainwave! I checked the internal diagram of the LM386 in the datasheet - damn if this worked it would be a very elegant solution.... and it did The LM386 exposes some of its internals to allow gain control and bypass filtering. One of the gain control pins (pin1) allows you to connect a resistor or cap in parallel with the 1.35k gain resistor. What it also does as a side effect is give access to the 15k voltage feedback resistor. So I thought, what if we stick a tiny 'current sense' resistor after our driver, and feed the current back to pin1, that current feedback combined with the existing internal voltage feedback should give us a 'mixed mode' amp. well, I tried it and yes it does work - good ol' LM386 Here's the circuit. you can see the tiny (though physically big) 0.1 ohm resistor after the driver. the current is fed back to pin1 via a 10ohm resistor and a coupling cap (to keep out unwanted DC voltages). Its set up with lots of current mode and not much voltage mode to keep the current steady through the coil. It may be that a custom design could get this balance better and be more efficient, but you can't argue with the simplicity of the LM386 version. The 1.5k resistor and 133n cap form a low pass filter that rolls off frequencies above the clipping threshold... this has to be tweaked depending on the inductance and resistance of the driver. This isn't a stand alone circuit, it needs a pre-amp section, I have two in development, a simple one and an AGC one. Note also that this hasn't been road tested yet, its just been simulated and had a basic 'does it work at all?' test. It's possible that the LM386 could die quickly or deteriorate due to being used in this way, I hope not, but don't blame me if it does. I was worried that it might have some sort of protection not shown in the simplified diagram that would kick in and spoil things, but thats not the case. Oh, and don't mess around with the component values unless you know whats what or you'll probably toast your LM386. So folks, you saw it here first - LM386 in mixed mode! All rights reserved etc. ------------------- This might be good in things other than a sustainer e.g. a modified version could work well in a 'ruby' style small guitar amp - the westhost article explains how the technique is useful to give a more valve type sound to a guitar amp ! cheers Col Link to comment Share on other sites More sharing options...
psw Posted March 21, 2009 Author Report Share Posted March 21, 2009 Thanks for a couple of elegant posts there col. I don't know if I have the stamina right now to completely understand this in enough depth, but certainly the aims and principles seem like the way to go. Reserve power or power conservation through a more efficient circuit and or driver has lots of benefits, more clean headroom, longer battery life, more consistent performance. Readers should note that Col has championed the cause of dual coil drivers very consistently and for good reason. This thread can often get down to a "debate"...but that can be a healthy thing. It isn't always about opposing views (as in an argument) because I can't "fault" these aims or the results really. I have been working the single coil thing pretty hard in the last few years...I've tried a few dual coil things of course, and even the hex things for a long time. I guess there is a fair degree of "burn out" on my part...sustainer fatigue...at least on the construction side of things. I suppose my feeling about the single coil style is that it touches on a lot of my "auxillery" aims...things like the pickup/driver conversions, very compact surface mounted drivers, ease of construction, enhanced projection. I feel that the single coil style driver can be made to work well enough that some issues are less issues than they might seem. Of course, EMI reduction is an admirable goal, but it is a two edged sword. It is after all the electromagnetic radiation that leads to EMI that is driving the string. My dual coil experience has been that projection is low, the field so "focused" that I need more power or being excessively close drivers. The bi-lateral design is an interesting variation that might address this a bit, but this magnetic field does affect nearby pickup tone. A hex design, as many of mine were, that incorporates alternating rwrp drivers is effectively yet another variation on this idea in many ways. So...to me, swings and roundabouts...can a simple compact single coil driver produce the effect desired, I think it can. If a driver of any design is capable of producing the effect with sufficient EMI reduction not to distort up the signal (fizz), is it not producing the "effect" that a dual coil is doing? A lot of dual coil designs are not compact for instance, so breaking one of my primary aims...this new one is significantly larger prohibiting a neck pickup at all (breaking another personal primary aim), it requires bigger drivers of more turns and greater space between those coils for projection. The SC designs offer compact sizes, easier construction, better projection and enough EMI reduction to work...all decent aims as well. Anyway...my position is not a criticism of the dual coil design...just a different approach in the aim for the same of very similar effect. Where it falls down is where you try and get the things to do what they can't...like operating in the middle position...then you really do need to explore these more complex things. Who knows what possibilities are there should col or hank or someone else make significant inroads in this way. ... Also as I quickly mentioned... totally controlable harmonics 'on demand'. Yes...you have mentioned this kind of thing...but not entirely sure how you are going to achieve this. (I also have a sexy little concept I wish to try which will yield any harmonic on demand ...3rd, 5th, 7th, 12th but this definitely necessitates a hex driver...all will be revealed once I've tried & failed!) I can also understand why you may not wish to talk about these things...given my perceived negativity...some things need to be more explored. The immediate problem there is the aspects of the physical location and nodes (that shift with the fretting of strings)...but I can see where you are going I think with some "effects" like pitch shifting only really work monophonically. ... One aspect that I have had trouble getting my head around...as to why it should work though it does...is this... In harmonic mode...you are damping the fundamental and driving the harmonic. Once the harmonic is driving (which can often be immediately) you are using this signal/string vibration as the signal...so you would expect that a further higher harmonic to be produced, or at least this harmonic would be dampened like the original fundamental signal...and so on. One can only assume that it reaches a point in which it can't drive a higher harmonic or something. Intuitive, running it backwards you might expect and "anti-sustainer" much like the moog muting thing perhaps. Another aspect is that of playing a harmonic. Striking a harmonic in most cases the sustainer will try and pull it back to the fundamental. You would think that perhaps it would hear that harmonic note and continue to drive the string in that mode of vibration....but this is generally not the case. Another interesting harmonic effect that sometime can occur...if you sustain a note, switch to harmonic mode...you get a harmonic...switching back to fundamental the note will sometimes try and rise to an even higher harmonic. Generally it will then morph back to the fundamental over time. Anyway...just a few observations...the harmonic posibilities are as exciting to me as the prospect of "infinite sustain". ... If nothing else great fun trying!I can see massive potential here (not necessarily for Sustainers). Yes...that is the real benefit of exploring these things...it is fun, instructive and it engages you with things that you can see applications or offshoots into all kinds of other things. I have been able to use a vast number of skills that I have acquired through my work on these things and if nothing else, it gets you thinking and stimulates the brain! pete Link to comment Share on other sites More sharing options...
Akula Posted March 21, 2009 Report Share Posted March 21, 2009 Okay, another set of "you think this will work?" questions... I have a lot of strat pickups lying around. Do you think it would work if I took the polepieces that stick out the top of the pickup as the core for a driver, so I'd just wrap the wire around the tops of the pole peices, to have a driver on top of a pickup? (obviously use in the neck position, with the bridge pickup driving the circuit) Also, if I have the cheap ceramic magnet that you usually find stuck to the bottom of a strat pickup, and I coil the wire around that, perhaps that would work as a nice thin driver? My apologies if these questions are dumb. I've only got a 100m reel of wire, and my current guitar build is sucking up a lot of my money lol, so I'd rather ask dumb questions before winding Oh, and I'm sure it doesnt cost that much for a PIC programming circuit... Last year in a school project I made a PIC-powered clock, and I even built the programming circuit into my PCB. Most people in my class didnt bother, they just programmed their PIC's with a quick-n-dirty breadboard. Link to comment Share on other sites More sharing options...
col Posted March 21, 2009 Report Share Posted March 21, 2009 One aspect that I have had trouble getting my head around...as to why it [harmonic mode] should work though it does... I'm pretty sure about this and have explained it in the past (it's guesswork, but nobody's come up with a better explanation). The phase response of the system is frequency dependent - both electrically and physically (pickup driver gap). At a low frequency, an inverted signal cancels the fundamental promoting the octave harmonic and the chain reaction you describe starts. At some point though, the sum of the 180º invertion, the phase gap between pickup and driver* and the phase response of the circuit as frequency rises adds up to some figure closer to 360º than 180º... as you know 360º is equivalent to 0º in this application, so at the point when the phase sum is closer to 360º than 180º the chain reaction ceases and note settles at a harmonic. *remember that as the frequency rises, the gap between pickup and driver causes a bigger phase offset If you could have a system in which driver an pickup were in the same position and the circuit had no phase distortion, the signal inversion based harmonic mode wouldn't work ! cheers Col Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 22, 2009 Report Share Posted March 22, 2009 (edited) Oh, and I'm sure it doesnt cost that much for a PIC programming circuit... Last year in a school project I made a PIC-powered clock, and I even built the programming circuit into my PCB. Most people in my class didnt bother, they just programmed their PIC's with a quick-n-dirty breadboard. I know this isn't a PIC thread (but they offer a lot to the hobbyist!)... but I can confrim the programmers aren't expensive at all. Here's is a full get you started PIC kit - complete with PIC, Programmer & software ...http://www.rapidonline.com/productinfo.aspx?tier1=Electronic+Components&tier2=Integrated+Circuits&tier3=Pic+Microcontrollers&tier4=PICkit+2+Starter+Kit&moduleno=77048 ...or you could just buy a Clone (uses the same software/firmware as the original http://cgi.ebay.co.uk/Clone-Microchip-Deve...p3286.m63.l1177 ...to be truthful, knowing what I do now, I'd probably just buy a clone, grab a PIC chip off Ebay & a little bit of breadboard (you only need six connections from the header on the programmer to the PIC chip. Any, I digress...but once you have a dabble, there's a world of possibilities open up to projects such as sustainers. Plenty of free PICBasic Lite type programming apps about to. Edited March 22, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 22, 2009 Author Report Share Posted March 22, 2009 I have a lot of strat pickups lying around. Do you think it would work if I took the polepieces that stick out the top of the pickup as the core for a driver, so I'd just wrap the wire around the tops of the pole peices, to have a driver on top of a pickup? (obviously use in the neck position, with the bridge pickup driving the circuit) Yes...in principle...generally though there won't be enough room on the poles that are sticking out above your average single coil pickup to wind a driver and accommodate a bobbin to fit it all on. I take it you have seen my pictorial on this...Link... Also, if I have the cheap ceramic magnet that you usually find stuck to the bottom of a strat pickup, and I coil the wire around that, perhaps that would work as a nice thin driver? Possibly not...generally I have had great results with a coil around some 3mm steel with this type of magnet stuck below..see the tele driver for instance. The magnet is very wide and I have found this to be a problem...and I suspect there are problems with winding a coil equally around both n/s poles in internal magnet drivers equally which may explain why the magnet below works better. Unwinding a SC pickup, blocking up the bottom and winding a thin (say 3mm) coil onto that has proved a successful method...but then it doesn't work as a pickup anymore and generally takes it's place. ... Oh, and I'm sure it doesnt cost that much for a PIC programming circuit... Last year in a school project I made a PIC-powered clock, and I even built the programming circuit into my PCB. Most people in my class didnt bother, they just programmed their PIC's with a quick-n-dirty breadboard. I know there are some good kits about, but there are different PIC's and not all kits can exploit the full potential in these things. I just know the learning curves for me would be way too great to make the process worth starting...all that programming logic and language. I guess for the sustainer I was thinking of it mainly to address switching issues...but there is so much that could be done I imagine. ... Yes...I kind of know the "phase response" idea and there may well be an answer there...I'm not entirely convinced...maybe I need to sit down with the guitar a little more...perhaps there is something there as to how the harmonic response and the type of harmonic produced changes over the length of a string as it's fretted. May also have relevance to things like mid drivers, I know Dizzy didn't have harmonic drive and I have had some unusual things occur with harmonic drive as the driver gets closer to the source..much in line with your theory there I guess. pete Link to comment Share on other sites More sharing options...
Akula Posted March 22, 2009 Report Share Posted March 22, 2009 I have a lot of strat pickups lying around. Do you think it would work if I took the polepieces that stick out the top of the pickup as the core for a driver, so I'd just wrap the wire around the tops of the pole peices, to have a driver on top of a pickup? (obviously use in the neck position, with the bridge pickup driving the circuit) Yes...in principle...generally though there won't be enough room on the poles that are sticking out above your average single coil pickup to wind a driver and accommodate a bobbin to fit it all on. I take it you have seen my pictorial on this...Link... The poles stick up about 3mm from the top of the bobbin, on these pickups anyways, they're pretty cheap pickups lol. About how many turns do I need? 8 ohms needed, right? Link to comment Share on other sites More sharing options...
col Posted March 22, 2009 Report Share Posted March 22, 2009 Yes...I kind of know the "phase response" idea and there may well be an answer there...I'm not entirely convinced...maybe I need to sit down with the guitar a little more...perhaps there is something there as to how the harmonic response and the type of harmonic produced changes over the length of a string as it's fretted. May also have relevance to things like mid drivers, I know Dizzy didn't have harmonic drive and I have had some unusual things occur with harmonic drive as the driver gets closer to the source..much in line with your theory there I guess. The only part of my explanation I'm not fully convinced about is the chain reaction part (which is a remnant of someone else's explanation). Its more likely that the fundamental and all harmonics up to the point where the Phase gets closer to 360º (or to 0º) are quickly cancelled together leaving the harmonic at that tipping point to ring out. Yep that's more like it - otherwise we'd hear a weird sound as the note rises through the harmonics - which doesn't happen. You seem to have an aversion to the whole idea of phase response though ? There's nothing really complicated or special about it. Its just part of the whole system, and in the case of a sustainer, a very important part. Ignoring it doesn't make it go away (although not having a scope or software simulation must make it hard to get a handle on it. I'd like a scope to get a more accurate idea of what the physical gap is doing, but for now, at least I can look at simulated bode diagrams of the circuits phase response) ------------------- As for pics, I'm not interested in the weedy ones that work with the beginner kits or cheap programmers. I would want to use a dsPIC with decent specs to do some real DSP processing on, the kit for that is more expensive. I guess it would be possible to build a programmer, but I'm not interested in that and I have limited time, so that would 'cost' even more. It would also be nice to add some AI in there and you need some real grunt for that... I did spend some time researching whats available, so I do know what the options are, and I can't afford the stuff I personally would want to use. cheers Col Link to comment Share on other sites More sharing options...
psw Posted March 22, 2009 Author Report Share Posted March 22, 2009 The poles stick up about 3mm from the top of the bobbin, on these pickups anyways, they're pretty cheap pickups lol. About how many turns do I need? 8 ohms needed, right? The number of turns depends on the size of the core (or poles), how deep the coil is (how many overlapping turns) and how well you can wind them and such things. Generally you will need over 100 to 150...but honestly, you need to wind to resistance not turns. You can get away with a coil of between 7 to 8.5 ohms though. You need to be sure that your bobbin top will be able to support the coil...there is quite a bit of upwards pressure in a coil, especially on the ends and when squeezing them. If you have 3mm now, you are likely to loose 1mm (or a third) with the bobbin top and need to work out a way to keep it on there...simply gluing it on is unlikely to be enough. ... You seem to have an aversion to the whole idea of phase response though ? There's nothing really complicated or special about it. Its just part of the whole system, and in the case of a sustainer, a very important part. Ignoring it doesn't make it go away Yes...I can understand that perception, and there may be some truth in it. In fact there is some irony because in the early days I was accused of being obsessed with it...so I do understand it fairly deeply and intuitively and it does inform my work (or assumptions)...and much of what I have done has been to minimize the effect to avoid the phase compensation circuitry outlined in almost all patents. So, I really haven't ignored it. I suspect the 100uF output cap thing I use on the LM386 is a phase related thing. However, no being able to measure it is part of it (though i did try and get into software scopes and frequency analysis software for a while)...but the other thing was that the phase response must vary greatly with frequency and driver pickup distance, and length of a string...in the end, I put those issues to one side (not ignoring them in the hope they would go away) and set about designing around them. When I did that, I got far more progress towards those aims. Honestly, I thought in the early days, and it think there is evidence of that in the thread, and before the thread...that unless something was done to address phase issues, it was never going to work. That you would get at best sustain on some strings and fretting positions, and none at all at others...and unpredictable harmonics in fundamental modes as these things change...but in fact, with a driver or system that works...these things don't occur...with a driver or system that doesn't really work...these things do happen. It is this observation that has endeared me to the thin driver concept...some other designs did not cut it, presumably because of phase issues...but for some reason this style does work. Over the years many have come along and even built these things with access and expertise in these things...yet no one appears to have really tested it to provide a technical reason for why that design works where others don't or are inconsistant...so, I figure that if they can't do it, what hope will I have. ... pete ... Oh...I hope he doesn't mind...but I have had some mail and heard a clip of Al's driver and plans...the construction of the driver and other things is faultless...but I can not hear string drive in what he is doing and attempting. At least, not in the manner that we might think of a sustainer. The "effect" is perhaps a bit like the ansil thing, or spazzyones experiments and is running at a good 10 watts! It won't work in harmonic drive at all and the pickups isn't bypassed (which could be a big part of the problem). The strength of the neo magnets may also be pulling the strings intonation out as well and i misunderstood his parallel driver thing...he actually was taking about a stack of two drivers in parallel, not a neck pickup and driver in parallel. So, some fine construction, interesting and adventurous ideas, but perhaps not the kind of string driving sustain that we are looking for. The effect though isn't completely "squeal city" though...so maybe there is a musical use for this raw effect. I am thinking that at least some of the problems may be related to the lack of bypassing of the neck pickup...but 10 watts is a lot of power to be running into a driver without string rattling sustain! Link to comment Share on other sites More sharing options...
Akula Posted March 22, 2009 Report Share Posted March 22, 2009 Ok winding coils at 1:30 in the morning isnt a good idea, i messed up and ended up dropping and tangling an entire roll of wire. Whoops. And yeah I've glued a peice of plastic on top of the poles, so thats a permanent bobbin top, the coil isnt going anywhere. Link to comment Share on other sites More sharing options...
psw Posted March 22, 2009 Author Report Share Posted March 22, 2009 Hmmm...no, probably not a good time to do this kind of thing. Remember in the pictorial how I stressed the need for preparation and preplanning. You might want to post a pic of this bobbin...I'm a little concerned if the bobbin is "on top" of the poles...you want those poles sticking up at least to the surface othwise the bobbin will severely limit how close the driver and pickup can get to the strings and a 1mm effective cover is pretty big. Remember, the strings also need room to vibrate...so not the best idea. Also, don't forget the potting...the glue is vital to success...or whatever people use...and make sure you are prepared to squeeze in the coils and bind it up while it drys. Have a look at how Al or i did this kind of thing. Have the multimeter set up, on and something to bare the wires for testing resistance...once you start winding you can't afford to leave it to get something you forgot...go over the whole procedure in your mind. Good luck on the next try...100m should be enough to make a few coils...you may need to have a few goes before you have something just right. pete Link to comment Share on other sites More sharing options...
Akula Posted March 22, 2009 Report Share Posted March 22, 2009 The top of the bobbin is about a millimeter thick on top of the poles, I've measured it up to the guitar and its fairly unobtrusive. If this one goes well I may try an epoxy-potted coil of the same manner, which wouldnt require a bobbin on top of the poles at all. So where do you buy your .2mm wire? The only wire I can find is from ebay, which comes in a free roll, not coiled around a bobbin. And after last night's tangling incident, I'd rather have a nice clean bobbin to unwind the wire from. Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 22, 2009 Report Share Posted March 22, 2009 (edited) The top of the bobbin is about a millimeter thick on top of the poles, I've measured it up to the guitar and its fairly unobtrusive. If this one goes well I may try an epoxy-potted coil of the same manner, which wouldnt require a bobbin on top of the poles at all. So where do you buy your .2mm wire? The only wire I can find is from ebay, which comes in a free roll, not coiled around a bobbin. And after last night's tangling incident, I'd rather have a nice clean bobbin to unwind the wire from. I see you're in the UK ...Farnell have 35swg listed as 0.2mm... http://uk.farnell.com/pro-power/ecw0-2/wir...5swg/dp/1230974 As it goes, 35SWG is quite difficult to source, 36swg is 0.19mm (& as near as dammit) & marginally easier to find, http://www.rapidonline.com/Cables-Connecto.../62484/kw/36swg http://www.maplin.co.uk/module.aspx?moduleno=44 (though I'm actually using their 0.15mm variant, I can vouch for the maplin wire ...the enamel comes off with a soldering iron's heat relatively easily) Edited March 22, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
Akula Posted March 22, 2009 Report Share Posted March 22, 2009 Ahh thanks, much appreciated Link to comment Share on other sites More sharing options...
al s. Posted March 22, 2009 Report Share Posted March 22, 2009 Hi Pete. You just had to make me lug my guitar up from the garage didn't you? In defense of the tiny strong magnets AL Link to comment Share on other sites More sharing options...
psw Posted March 22, 2009 Author Report Share Posted March 22, 2009 Thank's Al... I'm hesitant to try and explain what you are doing, as I think people would be very interested in your approach to the project. I got similar results when I tried the same thing and it may well be musically useful. The ansil sustainer mod I believe aims to produce a similar effect (though I really did try it in various ways and no one else was able to get it to "sustain" as it was described). In other aspects it is similar to spazzyones experiments and results as well. Basically it seems (but it is hard to tell from the other side of the world ) like you are driving the pickups more than the strings. This is resulting in feedback of a kind, but perhaps not a lot of "string driving" and it would seem distortion of the type we have taken to refer to as "fizz", basically the pickups are sensing and amplifying the driver's signals. But perhaps others can comment on the sounds in the clip...thanks a lot for making and posting it. Whether it is the small magnets is hard to tell...it may well not be. The problem is more in the way the driver is being used which is quite novel. Here is a summary of what I think Al is doing. Al is attempting to run the driver remotely...from a box on the floor, with driver leads running up to the guitar and no bypassing of pickups. It is a concept that we have talked about before and is similar to the "test mode" of holding the driver above the strings to see if it works before installing. The drivers are thin enough to tape to the guitar. The amp driving it is 10 watts (I haven't heard, but I am curious if such power into a small coil doesn't generate a lot of heat, see my first post for similar experiences). The guitar is an SG with the driver between the pickups. Interesting results have come from paralleling two drivers. Reversing the driver does not produce the harmonic effect, possibly creating a muting effect (note I have had a muting effect with similar setups...but the strings are not so much muted but the signal to the pickups is canceled by the driver...although this too could be happening). ... I know others are interested in this kind of thing, not bypassing pickups, remote circuitry, portable devices and the like...I am also aware that I can come off as overly negative. So at the risk of any further comment at this point and closing down discussion, I'd greatly encourage others to participate here. ... Otherwise, Al has made some extremely well made drivers, driver building techniques, a remarkable housing for the amp like a stomp box and a very neat circuit and I commend him on his efforts and progress so far, and his willingness to venture into lesser explored areas of the project. pete Link to comment Share on other sites More sharing options...
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