fookgub Posted November 21, 2006 Report Share Posted November 21, 2006 Have you seen my pictorial on building my single coil pickup driver? pictorial Yup. If you'll remember I actually built a driver/pickup very similar to yours (here). That one is potted in PVA, and it is pretty solid (though sufficiently loud high frequency tones can be heard through it). I've also potted coils in epoxy, urethane, and loctite (didn't work at all). All my coils are/were thin and around 8 ohms (~100 turns of 32 ga. wire). The coil I did in CA actually turned out quite well. The CA doesn't attack the enamel, and the coil is very non-microphonic. It measures almost exactly 8 ohms, and is a little more compact than my previous attempts. If the amp is working all right through a speaker you should be ok there...so the driver is what is most likely where you need to look. Could you post some pics or something... I'll try to get some pictures tonight of the amp and my latest coil. The amp seems to be working fine. You are testing the driver above the strings and over the neck well away from the pickups, yes? A full installation should only be attempted after verification that everything else is working as it should. There are all sorts of variables to consider so they have to be eliminated one at a time... I've tried both. The problem is that even with everything disconnected except the driver and bridge pickup, I can't bring the driver within about 2 feet of the pickup before it starts to oscillate. If I crank the gain down enough to get it to stop oscillating when the driver is installed in the pickguard (neck position, of course), it will only sustain some notes on a couple strings (notably the G string). Even then, I have to coax it quite a bit. Link to comment Share on other sites More sharing options...
psw Posted November 21, 2006 Author Report Share Posted November 21, 2006 Hmmm.... I do remember that one now...looks very good, and you have made a few, but none are working for you?! CurtisA made a pickup/driver like yours and it has worked very well...he posted a clip a little ways back...CurtisA Sustainer Link You have also tried alternative pickups so it isn't that....hmmm I would simplify things back a little...go back to the fetzer/ruby design. Try putting a 10uf capacitor between pins 1 and 8 for max gain, or add a resistor to bring it down, and do you have the (10 ohm) resistor and small cap "zobel Network" happening on the output (pin 5) to ground...both of these are supposed to tame internal oscillations of the lm386 that might occur with our load... It does sound like excessive power causing EMI to get into the pickup...2 feet away is pretty far...you would think you would need to put out a lot of power to get that effect. You are using a battery to power the thing I trust? Power supplies can cause problems and confuse troubleshooting. They can also dramatically increase the power available...remember, we are trying to put out as little power as possible to get the effect...more power means more EMI. I run my LM386 flat out with a variation of this circuit for the power amp... I have omitted the resistor between 1 and 8 to give 200x amplification. A 1k trim there would provide 20>200x variation. However...the circuit is limited by the current it can obtain from the battery, while power supplies may give a stable current, they can allow a large amount of current to be drawn... So...work out a way to bring down the power to as little as you can to achieve some effect over the neck, bring it closer towards the bridge and increase gain...maybe tweak the basic circuit a little... Col's circuit is still in development, but he did try the basic circuit as well. I did succeed in testing this on my Les Paul without physically disconencting the neck pickup too, so I am not sure about the theory that HB pickups may be more sensitive. One other tweak is to raise the bridge pickup as close to the strings as is possible and be sure that there isn't anything loose in the mounting that could cause the pickup itself to vibrate... Keep trying, there must be something missing, it will work...I just had a great time playing blues riffs with the harmonic function on and it's great how the notes will peel off into harmonics on my guitar... I am looking forward to being able to make another sustainer guitar, trying out some of these ideas and coming up with some new ones. It will be interesting to do this again all the way through with a different guitar and working out how to solve these things...My guitar has been going strong for a long time and I really haven't done anything other than play it now for a year and a half. I have been through some really hard times, it will take a while before I can really get back into this stuff...I need a lucky break and it doesn't seem to be on the horizon just yet...just start to get my head above ground and I fall back down the well... Unfortunately, my move will be a little delayed but it will happen and I hope that the guitar will help me find a flat spot in the road, my bad luck steak is phenomenal thanks for all the best wishes, they really mean a lot to me...life will go on and better days will one day return... http://www.projectguitar.com/uploads/emoticons/default_biggrin.png' alt=':D'> ... pete PS...If the world were not such a big place, I'd come over personally and try and sort things out...perhaps there is some travel in my future, who knows... p Link to comment Share on other sites More sharing options...
col Posted November 22, 2006 Report Share Posted November 22, 2006 Just a quickie, I bought a TDA7052 chip yesterday - its a BTL chip, but not class-d AFAICT. Seems like a possible good replacement for the LM386. The most interesting thing is that while searching for a datasheet, I discovered one for a TDA7052A This looks extremely promising - it's the same as the TDA7052, but with the addition of voltage controlled gain. If this chip is easily available, it could let us have the same or similar AGC functionality in a much simpler and smaller circuit. Link to comment Share on other sites More sharing options...
psw Posted November 22, 2006 Author Report Share Posted November 22, 2006 Just a quickie, I bought a TDA7052 chip yesterday - its a BTL chip, but not class-d AFAICT. Seems like a possible good replacement for the LM386. Yep...I am sure that is the one I have somewhere and was thinking of using...smaller more powerful, no output caps and not tied directly to ground...all worth a look see. Voltage controlled gain... I didn't see that one, Is that one a DIP package too? This is the type of device that could be built into a driver...although that whole side of things needs to be tried out for it's true merits... My intention was a low to no gain (voltage follower) preamp to minimise distortion (perhaps the same for the guitar too) and controls (phase inversion, sensitivity) and an amp module at or near the driver. AGC or other clever circuitry could be inserted between these for a more advanced version if space permitted... The 7052 would provide more power and so better headroom and perhaps address the fizz by running cleaner... I have been wondering whether the fizz could at all be rellated to phase issues...could the vibration of the string itself somehow be distorted at the very high harmonics creating these sounds...as opposed to a high frequency EMI effect? pete Link to comment Share on other sites More sharing options...
curtisa Posted November 22, 2006 Report Share Posted November 22, 2006 I have been wondering whether the fizz could at all be rellated to phase issues...could the vibration of the string itself somehow be distorted at the very high harmonics creating these sounds...as opposed to a high frequency EMI effect? I think this whole phase distortion stuff is a bit of a red herring. Slight phase distortion (particularly in fundamental mode) would manifest itself in some notes sustaining better than others. Gross phase distortion (circa 180 degrees) does exactly what we want it to - harmonic mode. I think the fizz is nothing more than our high gain preamp/drivers being run at their limits, clipping away merrily, driving a very inductive load, in an unshielded (or at least poorly shielded) environment, inside an instrument that has a penchant for picking up all sorts of EMI garbage (ever played an amplified guitar while sitting in front of the TV?) I'll give you an observation from my sustainer guitar. When I'm running clean I get the fizzies. When I damp all the strings and then just take my hands away to let the sustain build naturally, as the sound gets louder the fizzies only start to appear at a certain volume level. If phase distortion was the cause of this the fizzies would be present no matter what level the string was being sustained at and they wouldn't get worse as the string vibrated more. Because the driver is in a fixed position, and the note I'm playing is also of a fixed position (for want of a better term) the phase has to be constant too, even if it is shifted by some degree. The fact that the fizz appeared at a certain output level and gradually got worse as the string vibrated more indicates to me that the fizz is due to clipping as the preamp/driver runs out of headroom and starts to "square off" the signal, causing lots of upper harmonics to be passed to the driver and being induced all through the guitar electronics. When I was doing the experiments with the compressor/limiter I could get much less fizz than with just the LM386 - I would think that this is because I'm simply running the system more efficiently with less clipping, and less drive when it wasn't needed. The fact that Col has built a similar system and got a similar result would indicate that it's "cleanliness" of the signal that's one of the major keys to reduce the fizz. I'm starting to wonder if we actually need a further level of improvement to the system - not only do we need to run the preamp more efficiently, but we may also need a more efficient driver - something that takes less drive to move the string just as much. Cheers, Curtis. Link to comment Share on other sites More sharing options...
psw Posted November 23, 2006 Author Report Share Posted November 23, 2006 I'm starting to wonder if we actually need a further level of improvement to the system - not only do we need to run the preamp more efficiently, but we may also need a more efficient driver - something that takes less drive to move the string just as much. Exactly what I have been saying...the driver is key...but, there may be a limit to the technology... Running a more powerful amp like the 7052 and less preamplification may indeed help, and using an AGC as col has devised may help even further to limit clipping... While the rail design is more efficient in reducing EMI I am not sure if it is more efficient at driving the string. Even if it is, is it enough... I am a little jaded because I have been pursuing the driver thing now for so long and tried very many strategies. With the single coil idea I reverted to a simple is best approach... The attraction of off board power and such is that it may provide for better headroom and thus a cleaner signal. Perhaps splitting a HB so it is sourcing the string from a single lower impedance coil would also help to provide a cleaner signal. Much of the problem with the mid driver is not so much squeeling EMI, but a transformer like coupling of the signal and driver...extreme fizzyness at least, and massive gain in some circumstances. The main thing that I found that helped was to make the device small (hence the thin driver and the Hex devices) to keep the forces as contained and as close to the string as possible. Shielding and such may help but from what I have tried, not a lot... More could be done, I guess, to get a cleaner signal to the driver, but perhaps the driver itself is causing distortion. How to best address something like this, if this is the case, I am not sure...certainly any coil will have resonant peaks and may result in some "clipping" that isn't apparent when testing it with a speaker...the driver itself is not audible (or at least shouldn't be). Perhaps more testing of our driver designs by puting wave forms through it and testing the response in some way is possible and appropriate, but I am at a loss at how exactly one would go about doing that... Perhaps I am just tired...interesting theories, and probably correct... pete Link to comment Share on other sites More sharing options...
unklmickey Posted November 23, 2006 Report Share Posted November 23, 2006 ...More could be done, I guess, to get a cleaner signal to the driver, but perhaps the driver itself is causing distortion. How to best address something like this, if this is the case, I am not sure...certainly any coil will have resonant peaks and may result in some "clipping" that isn't apparent when testing it with a speaker...the driver itself is not audible (or at least shouldn't be). Perhaps more testing of our driver designs by puting wave forms through it and testing the response in some way is possible and appropriate, but I am at a loss at how exactly one would go about doing that... Perhaps I am just tired...interesting theories, and probably correct... pete Pete, if you're not too tired, here's another interesting theory: in most applications driving coils for things like CRT deflection circuits and such, they use CURRENT feedback in the final drive. i am speculating this might be a VERY important avenue for experimentation in the sustainer arena. in it's simplest form, a small resistor is inserted between the "bottom" connection of the coil, and ground. this is used to sample the current through the coil. then through an appropriately sized resistor (to determine gain) this is returned the inverting input of the amplifier driving the coil. if you guys have not already worked in this direction, i strongly urge you to consider this. happy Thanksgiving everybody, see ya soon. unk Link to comment Share on other sites More sharing options...
psw Posted November 23, 2006 Author Report Share Posted November 23, 2006 Thanks Unk...I appreaciate some more input...unfortunately I think I am loosing my capacity to think at this time...I will have to leave the details in the good hands of my fellow sustainers here There could well be something there, but I am not at all sure how that would work...it is an interesting idea...any links so I can read up on the principle? I had also wondered about the use of the pickup coil in the pickup/driver combo to limit EMI in some way... The pickup coil has a very high impedance and lots of windings, could it be used to create a counteracting force to the EMI with very low power, even though it would not contribute to the drive? I am feeling very jaded...I have been let down very badly (again) and will not be moving for a little bit more unfortunately...All will have to wait for a little longer. I think I have had the longest run of bad luck in history and it seems to be continuing... Still, I still have my guitar, I took refuge in some playing today (even that is a little restricted) and earlier in the year I did a little solo performing...I think I will be looking to do something in the new year in playing if only for myself and I was surprised how a good 4 hours of playing can bring back some of the old chops... That is the real beauty of the guitar, it can take you to another place, and that I badly need at this point... pete Link to comment Share on other sites More sharing options...
col Posted November 24, 2006 Report Share Posted November 24, 2006 ... I didn't see that one, Is that one a DIP package too? Both the mail order places I checked had the TDA7052A in stock in a dip package at a reasonable price ~ £1.20 ...The fact that the fizz appeared at a certain output level and gradually got worse as the string vibrated more indicates to me that the fizz is due to clipping as the preamp/driver runs out of headroom and starts to "square off" the signal, causing lots of upper harmonics to be passed to the driver and being induced all through the guitar electronics. Yep, that seems to be the case, however we still donh't know how much of the fizz is due to electrical noise from the driver circuit, and how much is from crosstalk between the magnetic fields of the driver and pickup. It is likely that my current circuit _seems_ fizz free because the waveform of the crosstalk and noise closely matches that of the through signal, therefor it is masked. If I move the driver gets moved closer to the pickup, fizz returns - suggesting that at least some fizz is due to transformer action between driver and pickup, and that when you get closer than a certain distance, the voltage gained via the transformer action is enough to cause clipping. When I was doing the experiments with the compressor/limiter I could get much less fizz than with just the LM386 - I would think that this is because I'm simply running the system more efficiently with less clipping, and less drive when it wasn't needed. The fact that Col has built a similar system and got a similar result would indicate that it's "cleanliness" of the signal that's one of the major keys to reduce the fizz. My earlier circuit also allowed the system to run very efficiently, only providing just enough drive to keep the sustain going - unfortunately it had plenty of fizz ! I think that this is not because of the level of the signal but because the signal was being distorted - not hard clipping, but asymetrical soft clipping... So the real trick is to ensure that the waveform of the driver signal matches the guitar signal in all but amplitude - I would guess that even phase changes will give some level of woolyness to the sound - although in harmonic mode, this should only occur until the note has morphed to the harmonic... I'm starting to wonder if we actually need a further level of improvement to the system - not only do we need to run the preamp more efficiently, but we may also need a more efficient driver - something that takes less drive to move the string just as much. It seems that Pete has already done a lot of work in this area, I'm not sure how big a return we would get from doing much more, unless you have a radically different idea about construction or functionality. Maybe using laminated core materials or custom magnetic cores would help, but then it's getting further away from being an accessible diy project... or going to a hex pickup/driver setup so drive is only applied to strings that are undamped... or building a hexaphonic gravity drive from nanotechnology components - beam those strings up Scotty FWIW, I'm half way through building an installation circuit for my latest setup, if that gives the same percieved quality as the breadboarded version, I'll be happy with the functionality. The main reason for me to go on with development would be improving efficiency in order to reduce the battery drain. I reckon that the best way to make a noticable and repeatable improvement in that area is to switch over to class-d power amplification. I'm not concerned at this stage with a middle position driver - there's no middle position on my guitar.... it would be nice to have two driver/pickup combos.. so I could have bridge pickup with neck driver or neck pickup with bridge driver, but right now I would be happy with just a bridge pickup and a neck driver with reasonable battery life and no fizz. cheers Col Link to comment Share on other sites More sharing options...
psw Posted November 24, 2006 Author Report Share Posted November 24, 2006 It seems that Pete has already done a lot of work in this area, I'm not sure how big a return we would get from doing much more, ... or going to a hex pickup/driver setup so drive is only applied to strings that are undamped... or building a hexaphonic gravity drive from nanotechnology components Damn, you guessed my Hex driver technology The mid driver still tempts me for two main reasons... Choice of pickups Ease of installation (no bypass required) But...it is a very difficult task to be sure... There are still a few more areas to explore. I intend to try out some kind of bi-lateral device. I might even take this further and have 6 thin coil "disks" that alternate polarity under each string... There is the possibility of very small driver technology if I revisited my Hex drive ideas...the wave drive idea with up to 12 "coils", novel orientation and magnetics and magnetic shielding could work, it would be interesting to see... Some of my Hex designs may have failed as a result of installation problems and interferance between the driver and pickup that I simply did not understand at the time...perhaps I was closer than I thought to achieving something here... The sustainer thread has stimulated me to think of other things too. I was originally looking into pickup designs. I also did a bit of work on a bridge design that could allow alternate tunings, that would be really cool. I have been thinking of getting a new guitar and building a sustainer into it with minimal mods and looking at other improvements. In contemplating this, I am aware of the feeling that I really don't want a lot of switches and such sticking out of the guitar...I'd like to get the sustainer controls into a rotary selector if possible or perhaps some kind of outboard box or something perhaps... Here is a design I am thinking of doing, I know something similar has been done before, but this is my proposed method of achieving it... Take a cheap single coil, alnico pole pickup. Remove the winding and magnets. Cut it in half! Install the magnets on one half up side down Wind two coils, one on each half Glue the two bobbin halves with the coils back together... Put the cover back on... Result...custom wound humbucking pickup in a single coil sound with a "true" single coil sound, or at least more so than a rail design... Now...Push the magnets up a little further, wind two driver coils on top...bi-lateral driver and humbucking pickup... I have thought of, and explained, split blade rail pickups too...they could be interesting... Also, EMG seem to have a monopoly on Active Pickups...perhaps there is more to explore there with low impedance coils and onboard preamps... Perhaps a pickup could be developed for the bridge position that would allow the tonal diversity of a range of passive pickups and pickup positions from the selector switch, allowing the removal and replacement of the neck pickup with a driver... On the DIY side of things...during the course of doing this thread, I also built a servicable pickup winder (though I never quite worked out how to do make it automatically traverse the coil or allow for tension differences with the elongated coils found in guitar pickups). As I have a few guitars that will return eventually (a matching pair of left and right handed strats for instance...in pieces) there are a few cheap pickups to canabalise and work on to see what happens. At least, winding pickups does sound like a relaxing pastime....maybe a little theraputic even. Maybe a thread will emerge that will allow more people to get into this pastime... There is still the area of neodyminium magnets in pickups to explore. These are starting to be used a little (fenders new noisless wonders for instanace) and once a supplier can be found are pretty cheap compared to some of the specialist pickup magnets about, and no harder to get really. Their small size offer some interesting posibilities. Such magnets also offer the possibilities of shaping the magnetic field around pickups a little more, changing their sound. Perhaps there are new and valid sounds to be found in such work... Noiseless designs I think will be the order of the day...I think that as computer modeling becomes more the norm and digital recording (with it's own inherient electromagnetic radiation sources) become the norm...noisy guitars are going to be less and less acceptable... It is interesting to see that although the quality of inport guitars is getting quite amazing (all thoughs CNC production techniques give manafacturers less excuse) the pickups still remain the weak link. Given the cost of replacement quality pickups, it is a little odd that with essentially the same materials, these guitars couldn't be fitted with more acceptable equipment for the same or little more price than are presently being offered as stock...or that a machine made part like a pickup (wire around a bobbin with a magnet) could cost so much as an aftermarket replacement... The attraction of the top mounted pickups on that squier I saw recently was that, without the typical strat scratchplate, the pickups could be easily taken out and replaced....circuitry could be accessed from the back with the guitar still playable. To me it seems like quite a good test bed for such work and am still considering it as a pre-post christmas present to cheer me up a little... Otherwise, The way I am feeling these days, perhaps it is time to just play some guitar!!!! Perhaps Tim was right that by page 150 we would have completed a fully acceptable sustainer and ironed out a lot of the bugs...I still get a pop mind! pete Link to comment Share on other sites More sharing options...
bancika Posted November 26, 2006 Report Share Posted November 26, 2006 (edited) Hi! Today I've made a blade for my 2nd driver out of large 3mm ferrite sheet I found in the basement. It turned out really nice, I coated it with black acrylic paint after sanding it, but it just occured to me now that 3mm thick blade maybe isn't enough? What do you think, should I use this or make another one out of 5mm sheet I have? Also, do I need to make top radius on my blade to match string radius? My plan is to make bobbin out of thin 0.8mm plastic and cut it with laser to make everything look nice. Also, I got black plastic pickup cover to put driver in. Tnx Edited November 26, 2006 by bancika Link to comment Share on other sites More sharing options...
psw Posted November 26, 2006 Author Report Share Posted November 26, 2006 Wow...you can get 3mm ferrite sheet (but no wire!) and you have access to a laser!!! When I used ferrite it was really good but I couldn't find anything except that ariel rod and couldn't cut it without it breaking everywhere... I used 3mm steel for my blade... I was thinking about the stacked idea though, I am not sure if you wouldn't need the magnet between the coils, preferably internal...they need to be reversed to eachother and the polarity revresed too. If the magnets were internal, this may be ok...but if the magnet is between, the second coil is a fair way from the strings...hmmm My bobbin top is less that 1mm thick plastic...it really only protects the coil and held it together while the glued dried. The blade is flat so is further from the G string but get's a good response from most strings (my D string could be a bit better I guess)...so curving the blade is up to you. There may be something to having the coil as close as possible to the strings, not just the blade. A thick bobbin or too much blade or magnet above the driver...or a cover...may not be good. You could try Tim's jig for making bobbinless/coreless coils with epoxy... The blade design was used mainly so that you could get an even response when bending strings, and it was easier that separate poles to make. You could make 2 half sized 4ohm coils for a bi-lateral device...or full sized for a rail...perhaps one of your magnets could be used to power one north and the other south... Something different about my driver to others is that the blade is 10mm deep...the magnet sits on the bottom but there is a pickup coil between. I did however make a duplicte that was only 3mm thick and this worked fine, I also made some with separate pole pieces...I have tried different magnets (individual neo mags for instance) but my big ceramic pickup magnet seemed to work best... Good luck... pete Link to comment Share on other sites More sharing options...
bancika Posted November 26, 2006 Report Share Posted November 26, 2006 thanks for reply pete. Now I'm not sure what material is my sheet. It's not chrome, that's for sure, it was pretty rusty when I pulled it out from pile of garbage in my basement, besides chrome isn't magnetic. As for laser, I don't have access to it, but there's local company that has it and it's not too expensive. Take a look at what they made for me in wood, it's my ross compressor pedal Link My blade is also 10cm deep, but my first idea was to put coil(s) away from strings, like this. Also, Idea was to make stacked design with two 4ohm coils. Should I make 4 leads like on humbucker pickups and then just connect two of them or just solder two coils directly to bobbin and make 2 leads going from pickup? Now that you said that I consider cutting blade to about 5mm and moving coil towards strings. That would also mean not using pickup cover because it adds about 1mm to the distance between coil and strings. I noticed that my larger ceramic magnet (from those cheapo humbuckers) won't attract my blade on it's wider side (like this), but on narrower side (like this). I'm little confuzed by that Cheers Link to comment Share on other sites More sharing options...
psw Posted November 27, 2006 Author Report Share Posted November 27, 2006 Sounds like the magnet was from a humbucker...a compas will show you which pole is which, a magnet sould identify the magnetism of the magnet, as lnog as you know what the magnet is that you are using to compare it with... You want the coil as close to the strings as possible. The idea is to put all the energy where it is needed and to Limit the EMI to that part of the string...further distance will only require more power and spray the EMI further afield... I am not sure about the stacked idea with this arrangement at all and perhaps some others would comment. The reversed coils push and pull...the only thing that makes it not cancel out the force on the string to nothing, is the different polarities of the magnetic fields they are working with...I don't think this is going to work too well. Perhaps a rail design is more in order, but then maybe you wont be able to fit that into the guitar. Another option may be to make a bi-lateral driver. You will need two 4 ohm coils one for each of three string sets. You could perhaps make them from other magnets (craft shops) or remove your single coils magnets and turn one half of them in reverse, make new bobbins to suit...you may well get them back into a conventional cover. On my pickup...I cut the top of the strats cover out and what you see on top is the black bobbin plastic with the white cover protecting/hiding the edges so it looks neat. A spare cover came cheap and was very easy to cut and file... I am surprised that your driver didn't work as well as expected...perhaps this needs to be investigated further...BTW, any further pic's? Maybe you should try puching the magnets down more flush with the bobbin so the coil is closer to the top of the coil and closer to the strings (take off the cover)... It is always better to try and improve something that is working to at least as expected before stepping into the unknown. I have a feeling col does not support a stcked coil driver and I have my doubts too...I have not seen any patents along these lines so perhaps it simply doesn't work...hmmm Perhaps others could offer some suggestions...I gather you need a single coil sized driver for the squire strat... pete Link to comment Share on other sites More sharing options...
col Posted November 27, 2006 Report Share Posted November 27, 2006 (edited) ...the only thing that makes it not cancel out the force on the string to nothing, is the different polarities of the magnetic fields they are working with... .... I have a feeling col does not support a stcked coil driver and I have my doubts too...I have not seen any patents along these lines so perhaps it simply doesn't work...hmmm The problem with the stack is the way it works. Pickup wise, the core polarities are not opposite, they are the same - the reverse current flow in the two coils makrs the overall polarities opposite - the only reason it doesn't cancel all the sound is because one of the coils is much further away from the string than the other... remember that the strength of the feild changes with the 'inverse square of the distance', so if the lower coil is twice as far away from the string, the upper coil will collect 4 times as much signal from the string.... in other words 25% will be lost through cancellation.... fortunately in a real pickup, the near coil is probably closer than half the distance of the far coil from the string, so the losses are smaller. What if we use this as a driver... hmm the two coils are fighting each other, does this mean that the magnetic flux generated by the lower coil is kept away from the string and has little or no effect... therefor wasting about half of our input power ? Or is it just the reverse of the pickup causing us to lose something like 20% of our drive ? Not sure, but either way is not good Col Edited November 27, 2006 by col Link to comment Share on other sites More sharing options...
psw Posted November 27, 2006 Author Report Share Posted November 27, 2006 ...the only thing that makes it not cancel out the force on the string to nothing, is the different polarities of the magnetic fields they are working with... The problem with the stack is the way it works. Pickup wise, the core polarities are not opposite, they are the same - the reverse current flow in the two coils makrs the overall polarities opposite - the only reason it doesn't cancel all the sound is because one of the coils is much further away from the string than the other... remember that the strength of the feild changes with the 'inverse square of the distance', so if the lower coil is twice as far away from the string, the upper coil will collect 4 times as much signal from the string.... in other words 25% will be lost through cancellation.... fortunately in a real pickup, the near coil is probably closer than half the distance of the far coil from the string, so the losses are smaller. Now, I am not sure that this is quite true of a pickup. A stack coil has the bottom coil magnetised south the top north and the windings also reverse...the same prinicple as a humbucker. So, I would have thought that a coils did add up to about the equivilent of a single coil of about the same size rather than the difference between one coil and the other less distance...if you see where I am coming from....but may well be wrong. The problem with branislav's arrangement is that the magnet would need to be between the two coils so that one is north the other south...then you would have the problem as you have described... I thought the problem tone wise with stacked pickups was due to the cancellation of frequencies in this arrangement, much like those created in a HB by the distance between the coils vertically instead of horizontally and the typical overwinding used to compensate for these losses... All the same, as a driver design it has got a lot of problems with it and would be a risk to make except for experimental purposes...there maybe something of value in it...or nothing at all. The HB rail driver we know will have values in EMI issue addressing...but is it the best... bi-lateral and sideways drivers have some attraction too...and there are more but nothing that strikes me as being even more efficient as far as design goes. Using materials like ferrite may make the things more efficient so that is one area to explore...if you can find stuff to make it from... got to run now...very busy time ahead and I may be making a sudden move and will be away for a short while... keep on keeping on... pete Link to comment Share on other sites More sharing options...
col Posted November 27, 2006 Report Share Posted November 27, 2006 (edited) Now, I am not sure that this is quite true of a pickup. A stack coil has the bottom coil magnetised south the top north and the windings also reverse...the same prinicple as a humbucker. So, I would have thought that a coils did add up to about the equivilent of a single coil of about the same size rather than the difference between one coil and the other less distance...if you see where I am coming from....but may well be wrong. Surely its the direction of the magnetisation that is important - the polarization.... and that is the same throughout the magnet, therefor the cores of both coils have the same polarity. I thought the problem tone wise with stacked pickups was due to the cancellation of frequencies in this arrangement, much like those created in a HB by the distance between the coils vertically instead of horizontally and the typical overwinding used to compensate for these losses... My understanding is that the overwinding is to compensate for losses due to cancellation - ie humbucking of the guitar string signal. EDIT: From Wikipedia (I know, I know, not the most reliable source) "Instead of two coils arranged beside each other with both coils producing string signal as in a regular humbucker, stacked coils are arranged one on top of the other with the objective that only the upper one should produce string signal. However the desire to stop the lower coil producing string signal was never completely achieved, most pickup designers did not fully address the effect of magnetic coupling and mutual inductance interaction between the two coils. Consequently both coils picked up string signal and signal cancellation occurred between the two coils along with cancellation of hum signals. The pickup tone was once again changed and different from either humbucker or single-coil pickup. Stacked humbuckers have a higher than average pickup DC resistance as a consequence of overwinding the coils with extremely thin wire. This overwinding is done to raise the output to an acceptable level, but will cause the higher frequencies to be attenuated due to the increased impedence." Col Edited November 27, 2006 by col Link to comment Share on other sites More sharing options...
psw Posted November 28, 2006 Author Report Share Posted November 28, 2006 Well...you live and learn...certainly, Stacked humbuckers have a higher than average pickup DC resistance as a consequence of overwinding the coils with extremely thin wire. This overwinding is done to raise the output to an acceptable level, but will cause the higher frequencies to be attenuated due to the increased impedence." rings true with experience and I am not happy with the stacked pickup in my bridge position of the strat (or rails in general)... I believe the new fender noisless and kinmans have a fairly convincing sound... Ok...so I would not suggest making a stacked coil, but a bi-lateral or some form of rail does seem promising, especially if the coils can be kept close together. I think this is possible without too much trouble and the use of small neodyminium magnets also a posibility in this regard. The only driver that resembles a stacked coil is the old sideways fernandes driver, which would actually have both coils driving the string, as you point out... ---- On a personal level... Very difficult and stressful times lately. I was to move only to find the house withdrawn two days before moving in...I even had a truck booked and everything. Worse, my family law case is still going on and I am desparately trying to get some kind of shared custody of my children...and at least some of my belongings back. Just when this looked like happening, this and a few other things happen...and so I needed to find somewhere immediately before the case proceeds further in a couple of weeks. I think I have found somewhere and may move next week. If I have gone AWOL for a while, that is the reason. My health has suffered but all is recoverable and by next year, a new begining will have begun. That means I will be able to potter about in time with this project and put some of these ideas into practice. I hope to continue to encourage people to make this device and for others to develop it further. I have been really impressed by the work that has been put into this in recent months and we have made a fine team. This thread has a unique character that allows for a sharing of ideas and debate, where nothing is dogmatic and all have been welcome and have brought something to the table. The thread has been a valuable lesson for me and I count you all as friends...perhaps this kind of thing will transfer over to other endeavours I may wish to pursue in the future and should give heart to anyone wishing to enbark on some crazy obsession if they have the right attitude... Thanks to all and hope for some smoother sailing in the very near future... pete PS...I have just come back from a school concert where my daughter played violin...though I don't see my young son (4yo) as much as I would like, he sat through most of the concert till very late and was a real treat...I asked him if he would play the drums or violin...he wants to play guitar....brings a tear to your eye, don't it... p Link to comment Share on other sites More sharing options...
col Posted November 28, 2006 Report Share Posted November 28, 2006 (edited) I believe the new fender noisless and kinmans have a fairly convincing sound... from the reviews I've read, Kinmans are miles ahead of the pack. If someone were to attempt a stacked driver, it would make sense to follow Kinmans ideas and build two completely different coils - one designed to drive the string, the other to restrain the magnetic field while producing as little drive as possible - minimizing cancellation. Getting the balance right would take a fair ammount of experimentation, but could potentially provide a good result... Ok...so I would not suggest making a stacked coil, but a bi-lateral or some form of rail does seem promising, especially if the coils can be kept close together. I think this is possible without too much trouble and the use of small neodyminium magnets also a posibility in this regard. I'm not even sure if having the coils close together on a rail driver would be the best option. It would be more compact, and alow us to keep more distance between the driver and pickup, but it may turn out that a decent gap between the coils allows more of the flux circuit to cross the region of the strings - a very compact rail driver might be too good at restricting the field - difficult to say without more experimental results. ---- On a personal level... Really sorry to hear how bad things are right now, I hope you start getting it all sorted out soon. Good luck. Col Edited November 28, 2006 by col Link to comment Share on other sites More sharing options...
col Posted November 29, 2006 Report Share Posted November 29, 2006 Some good news to cheer Pete up I finally got my install debugged and working. Uploaded a new demo to soundclick sustainer clean demo starts with no sustainer, then normal, then mixed mode. I find that full harmonic mode is not so useful with a clean sound - maybe because of the dual rail, dunno. Anyhow, excuse the quality of playing and production, just listen to what the sustainer adds compared to the non sustainer sound. I have a pretty good stripboard layout for this circuit, but I need to edit it to point out where the connections are for input, output, power, switches etc. At one point, I thought that the fizz was back.. aaarrrggghhh Hoever, I discovered that it was being caused by my Amp sim being overloaded and in turn loading the unbuffered pickup signal... looks like I will have to be careful about what I plug into... no change there then... Right now, the pots are all internal, and I have a 4 way rotary switch on the face of the guitar - positions are off/normal/mixed/full harmonic. This seems good, but I may stick a pot on the front if there is enough variation in effect throughout the life of the battery. The switch on click is very quiet, but bad enough to be unacceptable in a recording. I don't think there is a way around this other than having the circuit powered all the time and just switching the poweramp on/off, or disconnecting the input.... Then minimum drain will be about 11-13mA. I'll have to wait and see if I end up using the non-sustained sound much... if the novelty doesn't wear off, then maybe I'll try that approach out... Thats all for now Col Link to comment Share on other sites More sharing options...
psw Posted November 29, 2006 Author Report Share Posted November 29, 2006 Some good news to cheer Pete up I finally got my install debugged and working. Uploaded a new demo to soundclick sustainer clean demo It certainly is clean...not as powerfull as effect as I'd like...but perhaps it needs a little dirt in the sound to get this flavour out of it. Any way to add a bit more gain to the driver perhaps? I find that full harmonic mode is not so useful with a clean sound - maybe because of the dual rail, dunno. I think with a clean sound the harmonic effect is subtle. With distortion these harmonics are brought right up. It is an interesting sound though to have notes fade out into a harmonic...a very subtle little detail, but nice all the same. Perhaps it does need a little more power to bring up the effect a little... I have a pretty good stripboard layout for this circuit, but I need to edit it to point out where the connections are for input, output, power, switches etc. I am really looking forward to seeing how you did the layout and how easily it will be able to fit into a standard guitar cavity... At one point, I thought that the fizz was back.. aaarrrggghhh Hoever, I discovered that it was being caused by my Amp sim being overloaded and in turn loading the unbuffered pickup signal... looks like I will have to be careful about what I plug into... no change there then... I have a similar problem. I find that some of my clean settings on my AX1G really bring out the fizz...I have found it happens with a straight amp too, so it isn't just the digital stuff...a clean setting with chorus really seems to bring out an ugly distortion squark fopr some reason, it does sound like the thing is overloaded or is processing sounds just too high for it to handle...not at all a natural distortion...hmmm Right now, the pots are all internal, and I have a 4 way rotary switch on the face of the guitar - positions are off/normal/mixed/full harmonic. This seems good, but I may stick a pot on the front if there is enough variation in effect throughout the life of the battery. Brilliant...this is exactly the control I am looking for in my next install...can't wait to see how it all wired up and if I can fit it in the guitar sucessfully. However...I don't think that you would be able to get the bypassing of other pickups happening with a multi-pickup guitar like mine with the rotary control...any poles left in it? Perhaps it needs an on switch (maybe push/pull) plus the rotary in this kind of situation...if a suitable switch could be found... The switch on click is very quiet, but bad enough to be unacceptable in a recording. Very mild if you ask me and could easily be edited out or masked by other sounds in recording situations. I think that sounds acceptable. Sometimes mind isn't too bad, but I wouldn't want to switch it live as it could create a sizable thump! I don't think there is a way around this other than having the circuit powered all the time and just switching the poweramp on/off, or disconnecting the input.... Then minimum drain will be about 11-13mA. This is an option and I suspect how the commercial units get around it...at least in part. (I did notice the sustainiac patent had a floating ground, don't know if that would help...) Thanks for your thoughts...looks like next week will be the start of my moving so the end of one era and the start of another... pete Link to comment Share on other sites More sharing options...
psw Posted November 30, 2006 Author Report Share Posted November 30, 2006 Oh yeah... I have been looking into some pickup designs... I mentioned a bi-lateral approach...here is the tele pickup I saw from Curtis Novak... A pickup construction such as this could be used for a similar driver with possibly better results... Also...for something different....the Lace Alumitone have a very different construction, bassed on current, it has a transformer under a simple amiminium frame with magnets in... check out...Alumitone Link... Could this kind of thing be adapted for a driver? Lots of interesting stuff out there in pickup land... pete Link to comment Share on other sites More sharing options...
col Posted November 30, 2006 Report Share Posted November 30, 2006 (edited) It certainly is clean...not as powerfull as effect as I'd like...but perhaps it needs a little dirt in the sound to get this flavour out of it. Any way to add a bit more gain to the driver perhaps? It is quite a strong sustain, but with a very clean pure sound. It is possible to make is a little stronger, but the stronger you make it, the quicker it takes over from the natural guitar sound. All things considered, I prefer it where it is. Of course, at this setting it's still powerful with some distortion in the sound .... There's also the option of adding a compressor into the signal chain, but I don't think that will make much difference really. And in adition, the louder you make the sustain 'effect', the harder you push the battery, so it runs out sooner, and it also is more likely to get 'tired' when you push it really hard. I find that full harmonic mode is not so useful with a clean sound - maybe because of the dual rail, dunno. I think with a clean sound the harmonic effect is subtle. With distortion these harmonics are brought right up. It is an interesting sound though to have notes fade out into a harmonic...a very subtle little detail, but nice all the same. Perhaps it does need a little more power to bring up the effect a little... there's no 'full harmonic mode' in that demo, just 'mixed mode'. The full harmonic mode is really pretty weak - I need to do some more testing to make sure I've not messed something up in the circuit. The mixed mode is more obvious with distortion, and it may need to be tweaked before its just right... a single resistor swap changes the transition point between normal and harmonic... I have a pretty good stripboard layout for this circuit, but I need to edit it to point out where the connections are for input, output, power, switches etc. I am really looking forward to seeing how you did the layout and how easily it will be able to fit into a standard guitar cavity... It will be tricky unless theres plenty of space... it takes up slightly less space than my old circuit install, so you can get a rough idea from that (until I post some images ) At one point, I thought that the fizz was back.. aaarrrggghhh Hoever, I discovered that it was being caused by my Amp sim being overloaded and in turn loading the unbuffered pickup signal... looks like I will have to be careful about what I plug into... no change there then... I have a similar problem. I find that some of my clean settings on my AX1G really bring out the fizz...I have found it happens with a straight amp too, so it isn't just the digital stuff...a clean setting with chorus really seems to bring out an ugly distortion squark fopr some reason, it does sound like the thing is overloaded or is processing sounds just too high for it to handle...not at all a natural distortion...hmmm Not sure that we're talking about the same thing. I'm talking about some fizz that is generated by the thing the guitar is plugged into 'loading' the guitar output (I think thats what is happening). Its not fizz thats there but quiet.. being magnified by an effect... the fizz really isn't there or is depending on the setting of the amp sim... I need to check that amp sim, I think its possibly faulty, or needs the input transistor re-biased or replaced. Right now, the pots are all internal, and I have a 4 way rotary switch on the face of the guitar - positions are off/normal/mixed/full harmonic. This seems good, but I may stick a pot on the front if there is enough variation in effect throughout the life of the battery. Brilliant...this is exactly the control I am looking for in my next install...can't wait to see how it all wired up and if I can fit it in the guitar sucessfully. However...I don't think that you would be able to get the bypassing of other pickups happening with a multi-pickup guitar like mine with the rotary control...any poles left in it? Perhaps it needs an on switch (maybe push/pull) plus the rotary in this kind of situation...if a suitable switch could be found... You can get some really chunky stacked rotary switches, it just depends on how much space there is in the cavity. The one I have used is a 3 pole 4 way, but you can get many more poles with a stacked switch, and even buy components to build your own custom switch. The switch on click is very quiet, but bad enough to be unacceptable in a recording. Very mild if you ask me and could easily be edited out or masked by other sounds in recording situations. I think that sounds acceptable. Sometimes mind isn't too bad, but I wouldn't want to switch it live as it could create a sizable thump! I don't think there is a way around this other than having the circuit powered all the time and just switching the poweramp on/off, or disconnecting the input.... Then minimum drain will be about 11-13mA. This is an option and I suspect how the commercial units get around it...at least in part. (I did notice the sustainiac patent had a floating ground, don't know if that would help...) Yep, I think the click I'm getting is just the electrical interference caused by the spark thats generated at the contacts when the power is connected. The best approach (for an SMD miniaturised board) would probably be some fancy chip that has very low standby current, and can (with some additional circuitry?) control the power supply to the rest of the circuit, turning it on and off slowly - e.g. in a few milliseconds. This lag wouldn't be noticable to the user, but may be enough to prevent any obvious pops or clicks. All sounds a bit vague, but there are solutions out there, I just haven't done enough research because my board is already too big ) Edited November 30, 2006 by col Link to comment Share on other sites More sharing options...
psw Posted November 30, 2006 Author Report Share Posted November 30, 2006 (edited) Col... I do have to congratulate you again on getting this thing up and running and perservering with your ideas... Such devices are a personal thing and depends on the type of music you wish to create... It is quite a strong sustain, but with a very clean pure sound. It is possible to make is a little stronger, but the stronger you make it, the quicker it takes over from the natural guitar sound. See...the sound in my head is not a natural guitar sound, it is one that increases in volume and power...that really accentuates that it is a sustainer, not just a really long sustain. I have gotten a real taste of this with my version, but it lacks the control and consistancy that yours provides, and that effect is good too! What I guess I am trying to get is a very "vocal" type of articulation, using lots of slides and trem articulations, dynamics (swells, etc), odd kind of ethnic sounds, even some fret buzz provides a nice breathy quality...the harmonic provides a kind of falsetto sound... with chords I guess it's more of an organ like pedal tone. These types of effects need a reasonably clean sound. I am getting hooked on the device and it is changing the way I play and approach the guitar. Even with the sustainer off, this emerging "style" is still present... I like the fact that these sounds can also be made at any volume and with control. It opens up some interesting posibilities with mixing the sustainer guitar and feedback sounds with acoustic instruments... Perhaps a different poweramp like the 7052(?) will offer some more options...then there is the modular idea...installation is still a problem and multi pickup guitars a special consideration. For what I am trying to do, the strat type guitar still provides the best scope for this kind of thing...it is easy to hide mods under that huge scratch plate and there are other spaces too, like in the trem cavity or jack plate, that could be used perhaps. I am wondering about those battery compartments that fit into the back of the guitar in a neat route. Could some of the switching or circuitry be hidden behind such a fitting solving both the battery and circuit space in one, as well as battery access and a neat install... The control offered by your circuit will be invaluable to developing a mid-driver (if it is possible or even turns out to be desirable )... I will definitely be looking at building one to test it out when everything gets back on track... Thanks again...I am sure that there will be some refinements and even if you were to leave the sustainer project as is, you would no doubt return to it... pete Edited November 30, 2006 by psw Link to comment Share on other sites More sharing options...
psw Posted November 30, 2006 Author Report Share Posted November 30, 2006 OK...stop press!!! I happened across this amazing Video from an amazing guitar builder that has featured elsewhere in this forum... He is known for his startling creations in a PRS mode in which he guts Variax guitar's for their electronics to bring that technology into a high quality instrument... Not only a geat builder, he is an impressive player (in a country vein) and this time he has something of interest for us here... Here is a video (8.8MB) to watch or download...http://www.guitaristjeffmiller.com/videos/..._variax_dc2.wmv This features a PRS Santana copy with duncan pickups, Fernandes Sustainer and Variax built into a floyd rose with piezo saddles.... A complete pictorial (lot's of pictures so beware if on dial up ) can be found here...http://www.guitaristjeffmiller.com/guitars13.htm There are lot's to note about the performance of the sustainer...the little bit of switch noise, the clean performance and how close we have come to getting a very similar performance with our DIY device... The Variax sounds are pretty good too...I do think that this device has legs, even if you have to cut out half of your guitar to get it in there ...and we thought we had installation problems... pete Link to comment Share on other sites More sharing options...
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