onelastgoodbye Posted October 5, 2006 Report Share Posted October 5, 2006 (edited) The mid-driver is probably already possible with the rail design. I didn't get EMI 'till I held it OVER the pickup and spazzy also had good results in the mid position. I'm holding off on building more drivers as I am currently Ruby-less and I'd like to do further testing with col's circuit when it's finished. I sort of consider the driver design itself to be in it's final stages, okay well maybe after the dreaded hiss issue is resolved. what i'm saying is that, sure, efficiency certainly still be improved, but driver-wise I think we're pretty darn close already, so maybe it's time we start looking at some problems that haven't been discussed as much, like implementation. Two things I would still like to tackle are a "side" driver, if only for experiments sake; and a rail driver with internal magnets, to get it as tiny as possible. The reason I'm so keen on internal magnets is because they allow for a very thin driver when combined with the bobbinless concept (which is very doable with the proposed jigs). a driver that's 2-3 mm thickcould be placed on the guitar without any need for routing or lowering pickups. you can put it on top of a pickup, on the pickup ring, between pickups, etc.. since the new jig facilitates the use of different cores, you could ultimately provide a kit where the end-user has the choice of using either the magnet core for a stand-alone driver, or an iron core for a pickup-driver combo. Two drivers in one package! (it's called modularity in design-terminology, psw ) Factoring in EMI-reduction, do-a-bility, efficiency, implementation, the rail driver is IMO our best bet so I'm gonna focus on that direction. btw, Jeez man, this thread is flying Edited October 5, 2006 by onelastgoodbye Link to comment Share on other sites More sharing options...
curtisa Posted October 5, 2006 Report Share Posted October 5, 2006 It is great that you got the thing to go so far. There is an improvement with the thing actually installed underthe strings as to holding it over the top. I did get the problem with the earth connectors and my switching required the disconnection of all but the bridge pickup completely to avoid such noise...though it wasn't squeeling as I recall. pete Admittedly I have yet to try the setup with the guitar plugged in to an amp. I was just testing the guitar/sustainer acoustically, so the squealing I was hearing was the driver, not the output signal of the guitar through the amp. I've got no idea what other noise nasties are in the signal yet! You are right about the Q and such. Although my lower output cap improved high string response, it is not at the sacrifice of the low strings sustaining...they simply sustain at an octave above their note. pete OK, so potentially you could shift the centre frequency up and down by decreasing or increasing the cap value respectively. I reckon you could also insert some extra series resistance in the output of the LM386 circuit to "flatten and widen" the response of the resonant circuit (ie, lower the Q) and potentially regain the "lost" low notes/high notes. The only drawback to doing that is that you lose some power to the coil and you'll need extra amplification to restore the lost gain in the driver. This is similar to the "mix" setting I believe on some units. It is a neat effect and can be heard on a lot of those sound clips if you listen carefully. (At some point I will make some test sounds of my guitar...promise) pete Now that could be an interesting alternative/addition to the normal/harmonic mode switch - different sized output caps could be switched in and out of circuit to changes the way notes sustain at the pitch extremes. Have you heard of a guy called Michael Manring? He's a bassist who's released a couple of solo albums where he creates a lot of interesting effects using multiple E-bows on his fretless bass. I only have one album of his, "Thonk", but it's got a piece callad "Adhan" where he creates multiple drones and melodies on different strings with lots of morphing harmonics in much the same way you've described above. Cheers, Curtis. Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 Hi psw (and everyone else) Just finished burning through all 120 pages of this monster thread, and got inspired enough along the way to build my own thin coil driver! I figured I'd join the discussion and contribute a few ideas and thoughts. I found an easy way to keep the windings nice and tight as I was winding them on was to pass the enamelled wire between a pair of books and draw the wire between them as I wound. The weight of the books applies a bit of pressure to the wire as it comes off the spool without gripping it too much, keeping the wire nice and taut. Got to be careful that you don't have too much tension, if you stretch the wire, you can increase the resistance of the wire (unevenly). I baked the assembled driver in the oven for 30 minutes with the oven set to the lowest temperature it'd do (50 degrees C in my case) to accelerate the setting time of the PVA - I noticed that some of us here had trouble with the innermost layers of PVA not setting properly and staying soft. "Baking" our drivers may be a good solution to preventing this from happening. If my wife caught me putting some gluey electronics contraption in the oven I would be in BIG trouble The other thing about resonant LC circuits is that they all have a "Q", which is the amount of peaking in the frequency response of the circuit. I am thinking that one of the reasons why some of us are getting better results with our drivers than others is that some of our driver/LM386 circuits have high Q's (very sharp, narrow response at the resonant frequency) while others have a much lower Q (wider, flatter peak at the resonant frequency). The amount of DC resistance in an LC circuit governs the degree of Q - more resistance = lower Q, less resistance = higher Q. Interesting point. could explain why reducing the cap value can help the high E a little. Is it possible that changing the cap alters the phase response in a way that helps the high E ? Also got to remember that the lions share of the problems with the E (and B ) string are due to its mass and tension. ...I wonder if there is such a way to run the driver in a balanced 3-wire configuration (ie, the coil driven by two equal and opposite signals swinging around a centre point) to reduce the extraneous EMI generated by the driver? All professional audio equipment uses this technology to reduce unwanted induced noise picked up in cables from being amplified at the input of the next connected device. The LM386 circuit feeding a transformer with a centre-tapped secondary would give you a balanced output, but the driver would need to be specially wound to accomodate this. I wonder if the transformer in the Fernandes sustainer is performing some similar kind of balancing operation here? I've thought a few times about using a transformer to isolate the circuit.... however, I'm worried about introducing yet another coil based component into the mix. I've also isolated the coil from the pickup in my setup both by using seperate batteries and by having a seperate pickup that is solely for the sustainer, so the guitars main pickup is not connected in any way to the sustainer system (I don't have a neck pickup installed right now). Neither of these attempts made any difference whatsoever to the crosstalk problems. The squealing EMI feedback can(tested and working) be dramatically reduced by using a dual rail driver in 'humbucker' configuration. Col Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 (edited) Hey there... Well I have been playing with the guitar a little just now... I have even quickly recorded a few samples and sent the to tim to host so they should be available soon! I found that by turning down the sensitivity control, much of the fizz, if not all, disappeared....but it lacked a bit of power. Part of the problem is that at such clean settings, and with this guitar especially, the sound is so thin that although it is sustaining, at those high frequencies you can bearly hear the sustain part of the notes. I have recorded with sustainer off, on low, and up hi so you can here the fizz I do get, when I get it. I also recorded something similar with a slightly overdriven sound. This gives the notes more body and the "fizz" is acceptable for me with this kind of sound... I put up another santana-ish distorted sound so you can hear the effect there... clips soon...or I could email if you wish... pete The mid-driver is probably already possible with the rail design. I didn't get EMI 'till I held it OVER the pickup and spazzy also had good results in the mid position. I suspect you may be right...I would be pleased as I could make a rail pickup/driver based on what I have already on the single coil. what i'm saying is that, sure, efficiency certainly still be improved, but driver-wise I think we're pretty darn close already, so maybe it's time we start looking at some problems that haven't been discussed as much, like implementation. Yes...implementation has it's own set of problems. I am keen on the mid driver thing, and rail drivers in general because it may help some of the problems I encountered...will be interesting to see... pete PS...PVA tends to soften with heat! you need to be careful not to melt the enamel insulation on the wire too. I think with the paper bobin and a bit of time it should hold together without doing that...mine has... p Edited October 6, 2006 by psw Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 Admittedly I have yet to try the setup with the guitar plugged in to an amp. I was just testing the guitar/sustainer acoustically, so the squealing I was hearing was the driver, not the output signal of the guitar through the amp. I've got no idea what other noise nasties are in the signal yet! Heh, thats what I did, took me a day or two before pluging it in. This is similar to the "mix" setting I believe on some units. It is a neat effect and can be heard on a lot of those sound clips if you listen carefully. (At some point I will make some test sounds of my guitar...promise) pete Now that could be an interesting alternative/addition to the normal/harmonic mode switch - different sized output caps could be switched in and out of circuit to changes the way notes sustain at the pitch extremes. Yeah, there are other possibilities as well, The top end sustainiac (i think its that one) has a knob that at one end is harmonic mode, the other is fundemental, and in the centre is 'off'. This is a circuit snippet I trawled up ages ago, and when I read the description of how the knob on the sustainiac works, it rang a bell (From David Medin) How about the simple single-transistor phase splitter? V+ | R V+ | | +---------+ 10K / | 0.1 uF | |/ P 0.1 uF IN>----||------+-------| 2N2222 O<--||---> High impedance output | |\E T (should be buffered) 10K \ | | +---------+ GND | R | GND The circuit uses the inverting properties of an emitter follower with a collector load. You have to experiment for a value of R and the pot that will keep the transistor's power dissipation within limits given the V+. The output stage should be buffered by another emitter follower stage, or an op amp, etc. Note that this circuit induces some loss in the p-p value of the signal, too. It is not completely distortionless, but reasonable if you do it right. The same topology can be employed with op amps: One inverting and one non-inverting with the pot between their outputs, buffered by a third op amp. here's a femm plot of a dual rail driver with ceramic magnet cores. It is surrounded by a cage/shield that is supposed to act as a conduit for the flux - to guide it back around the magnetic circuit and prevent so much from escaping in all directions. This is a detail - it was modelled in the vicinity of a pickup model. the gaps in the 'cage' are to help prevent is from saturating too quickly - the gaps store energy or something... These would have to be slots or patterns of holes in the 3d version. btw pete, if you're still interested, I found a simple op-amp circuit stage that can be switched from inverting to non-inverting (both at unity gain) with just a single pole single throw switch. (I plan to use this at some stage when I do a final install. I found a cool pot in a lucky grab bag - it has an on off switch, and a push momentary switch. So my idea is that i can puch it to switch harmonic modes, then release it when the harmonics are there... could be fun. the pot is 10k which is the right value for gain on my circuit, and even has fine click steps so it won't lose its position when pressing the switch ) cheers Col Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 (edited) btw pete, if you're still interested, I found a simple op-amp circuit stage that can be switched from inverting to non-inverting (both at unity gain) with just a single pole single throw switch. That is exactly the type of thing I was thinking of for my modular concept where the signal not the driver leads are reversed...well done. The cage looks cool...you know I called my things on some of my drivers a cage too? I have used a variety of things made of wire and even domestic staples (I have very small drivers...hehehe) for a laminated effect! Unfortunately, I did not find a whole lot of difference with these things, just another layer of complexity. I did find metal car body filling to be useful...it is a 2 part epoxy filled with iron filings. The end result has a lot of plastic to iron in it, but it dries hard and provides some shielding qualities.... I hope the clips I will post will add some encouragement to what I have been able to achieve with the simple driver and what could be done with a simple dual coil driver to improve things even more. Admittedly I have yet to try the setup with the guitar plugged in to an amp. I was just testing the guitar/sustainer acoustically, so the squealing I was hearing was the driver, not the output signal of the guitar through the amp. Well...something not right there...it shouldn't make any noise unless there is some kind of acoustic vibration should there? Perhaps you still have something loose in the windings or something if the driver is making a sound...hmmm Anyway...onward and upward... pete I found a cool pot in a lucky grab bag - it has an on off switch, and a push momentary switch. So my idea is that i can puch it to switch harmonic modes, then release it when the harmonics are there... could be fun. the pot is 10k which is the right value for gain on my circuit, and even has fine click steps so it won't lose its position when pressing the switch ) that is cool...I had an idea for a twist grip on the tremolo arm for a similar effect....hahahaha I love the surface mount momentary switches too...so very tiny...be great to have that kind of instant access some how to the harmonics. I'd love to have the same kind of option for the sustainer itself...maybe something will arise when people start to try to implement the systems into real instruments. On a single pickup guitar (without the need for bypassing) I guess it may well be possible...or your one knob idea. This is a detail - it was modelled in the vicinity of a pickup model. Interesting, I don't see any deflection...what happens if you omit the cage (give it the value of air)? Is there much difference without it? Edited October 6, 2006 by psw Link to comment Share on other sites More sharing options...
curtisa Posted October 6, 2006 Report Share Posted October 6, 2006 PS...PVA tends to soften with heat! you need to be careful not to melt the enamel insulation on the wire too. I think with the paper bobin and a bit of time it should hold together without doing that...mine has... p In an oven at 50 deg C won't hurt it. IME I have yet to melt the enamel insulation on copper wire with anything much approaching 100 deg C, and when you think about it some of our commercially available amps power transformers get pretty hot under normal operating conditions without showing signs of internal flashovers from shorted turns. It's the melting temp of the tape that will matter more, hence my low baking temparate and short time period. If my wife caught me putting some gluey electronics contraption in the oven I would be in BIG trouble Haha! The trick is to do it while she isn't at home Seriously though, once it's wrapped in tape there's nothing oozing out of it anyway...unless you go seriously overboard with the potting! And I certainly wouldn't do it with any solvent-based potting stuff like epoxy. Got to be careful that you don't have too much tension, if you stretch the wire, you can increase the resistance of the wire (unevenly). True enough, I'm pretty sure I didn't over-stress the wire as I was winding, just keeping the slack off the spool to make it easier to control. Besides, with such an elongated winding window it'll be nigh impossible to keep it too taut as there's so much slack in the longer part of the bobbin - that's what the potting's for. Interesting point. could explain why reducing the cap value can help the high E a little. Is it possible that changing the cap alters the phase response in a way that helps the high E ? Also something worth considering too I guess, and something no doubt that has been considered in the Fernandes Sustainer circuit - I seem to recall there being phase compensating networks. I've thought a few times about using a transformer to isolate the circuit.... however, I'm worried about introducing yet another coil based component into the mix. I've also isolated the coil from the pickup in my setup both by using seperate batteries and by having a seperate pickup that is solely for the sustainer, so the guitars main pickup is not connected in any way to the sustainer system (I don't have a neck pickup installed right now). Has anyone tried the DIY sustainer with an isolation transformer? If not, I have a bunch lying around at home that I can fiddle with to see what difference it makes. Neither of these attempts made any difference whatsoever to the crosstalk problems. The squealing EMI feedback can(tested and working) be dramatically reduced by using a dual rail driver in 'humbucker' configuration. When I mentioned transformer driving I was thinking two-fold: 1. To isolate the driving signal completely from the guitar's earth, preventing potential sources of induced earth garbage. 2. Driving the coil in a balanced fashion to self-cancel the mag field around the driver except at the point of origin, ie the blade(s). The driver would be a little more complicated to manufacture, but perhaps would have all the EMI cancelling advantages that we're searching for. In my (guff-filled) head I imagine our little LM386 amp driving a step-down isolation transformer with a centre-tapped secondary, maybe 4:1 ratio (to step up the drive current and force the driver to work harder without taking extra battery grunt to do it), and the driver would be a dual-blade contraption with one coil wound clockwise, the other wound anti-clockwise and the magnets mounted upside down in one of the blades. The transformer is connected with the outer-most taps wired to the outermost ends blade winding and the centre tap wired to the point where the two windings meet in the middle (don't have the ability to post a mock-up sketch at the moment, sorry!). Whether this would work or not in practice is completely beyond my thinking without the assisstance of a caffeine injection though! Cheers, Curtis Link to comment Share on other sites More sharing options...
curtisa Posted October 6, 2006 Report Share Posted October 6, 2006 Well...something not right there...it shouldn't make any noise unless there is some kind of acoustic vibration should there? Perhaps you still have something loose in the windings or something if the driver is making a sound...hmmm Anyway...onward and upward... Yeah, it's quite possible that my potting isn't great. It's more than likely the windings are rattling and carrying on and being generally antisocial. However, the fact that the thing works first time, and works quite well if positioned away from the pickups is encouraging! Cheers, Curtis Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 Has anyone tried the DIY sustainer with an isolation transformer? No...I had wondered wether the noise wouldn't be coupled magnetically anyway, or that the transformer itself could attract or generate noise or cross talk though... When I mentioned transformer driving I was thinking two-fold: 1. To isolate the driving signal completely from the guitar's earth, preventing potential sources of induced earth garbage. 2. Driving the coil in a balanced fashion to self-cancel the mag field around the driver except at the point of origin, ie the blade(s). The driver would be a little more complicated to manufacture, but perhaps would have all the EMI cancelling advantages that we're searching for. well if 1 worked, that could help with installation... 2 is an interesting idea...not sure that I quite get it in this application... Also something worth considering too I guess, and something no doubt that has been considered in the Fernandes Sustainer circuit - I seem to recall there being phase compensating networks. Yes...well, I have been trying to simplify things a fair bit by trying to run a sustainer with an improved driver design that aviods over complicated circuitry. Perhaps the Sustainiac or other such devices and circuitry is the ultimate conclusion of where we are headed here...hmmm For me, the pickup/driver is still a good concept for installation and functionality of the guitar. Loosing a pickup for a dedicated driver is a bit much unless it was a purpose built instrument for sustaining only. A mid-driver is attractive because it offers the possibilty of retaining both the main pickups and means only loosing or disabling the mid coil... I'd also like to keep the circuitry pretty small and compatable. I think a modular approach with the power amp stage incorporated or near the driver is a worthwhile concept. I still haven't abandoned the idea of remote power...but then that's me... pete Link to comment Share on other sites More sharing options...
curtisa Posted October 6, 2006 Report Share Posted October 6, 2006 No...I had wondered wether the noise wouldn't be coupled magnetically anyway, or that the transformer itself could attract or generate noise or cross talk though... The really good audio transformers come with intgrated shields to prevent, or at least minimise this sort of thing. 2 is an interesting idea...not sure that I quite get it in this application... Hehe, yeah like I said, it works in my head... Yes...well, I have been trying to simplify things a fair bit by trying to run a sustainer with an improved driver design that aviods over complicated circuitry. Perhaps the Sustainiac or other such devices and circuitry is the ultimate conclusion of where we are headed here...hmmm For me, the pickup/driver is still a good concept for installation and functionality of the guitar. Loosing a pickup for a dedicated driver is a bit much unless it was a purpose built instrument for sustaining only. A mid-driver is attractive because it offers the possibilty of retaining both the main pickups and means only loosing or disabling the mid coil... I agree, and was the main driver (pardon the pun) for me to pick your idea up and run with it. I like the idea of sustainers and their ilk, dislike the idea that I have to sacrifice a pickup for it (particularly one like the neck pickup), and prefer not to be tied to a special handheld doohickey to generate these effects, particularly if it's only monophonic (E-bow). Cheers, Curtis. Link to comment Share on other sites More sharing options...
curtisa Posted October 6, 2006 Report Share Posted October 6, 2006 Here's a quick sketch of the balanced blade driver idea that I was talking about: You're looking at the driver side-on. The two dots at either end of the transformer indicate the polarity of the transformer secondaries. The two magnets are the cores, and the wire is wound around one clockwise, and the other is wound anticlockwise. The magnets/blades are opposite polarity. The induced magnetic field at the point where the blades are exposed to the strings is enough to move them, but as soon as the distance from the blades increases the two mag fields start mixing together and cancel each other out as they're equal and opposite. I've got absolutely no idea whatsoever if it'd work, it could just be another crazy idea bound for failure, but I'm hoping this'll help explain what's circling through my head at the moment. Cheers, Curtis. Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 The induced magnetic field at the point where the blades are exposed to the strings is enough to move them, but as soon as the distance from the blades increases the two mag fields start mixing together and cancel each other out as they're equal and opposite. It does actually take me a bit of a while for these things to sink in...how is that different from just a HB driver in which the two coils are putting out equal but opposite amounts of radiation but operating as one because of the reversed magnetic polarities... It is quite possible that the transformer in fernandes designs was to step up the driver coil to make it a more effective pickup...I have never had an explanation, and it seems to be absent from the current designs... Interesting idea though... I think Tim may be right, the rail driver concept may be good enough....it could be the quality of the constructionas much as anything that is eefecting performance... Playing my guitar today, I do think that col's AGC would be a real asset to giving the device some refinement and something along those lines should be encouraged. I think also that Tim's point that discussions move toward installation options is a valid one too. It should be possible for people to get a basic functioning sustainer into their guitar with the current art. I'm not sure, but mine and primals seem to be the most developed of these and mine the only one with multiple pickups...hmmm, not the best strike rate. Lot's of people have made it to the stage that they have had the strings singing with the device, but few have gone all the way with it...that's a shame. I think that the "system" is adaptable. I think that the modular scheme is attractive because you can always build a better driver, improve EMI, make a better or more refined circuit...all kinds of things may and will happen...but, the way this thread goes, it will be quite a while before the "definitive" DIY sustainer is specified...I don't think people should or need to wait to get into this thing... pete Link to comment Share on other sites More sharing options...
curtisa Posted October 6, 2006 Report Share Posted October 6, 2006 It does actually take me a bit of a while for these things to sink in...how is that different from just a HB driver in which the two coils are putting out equal but opposite amounts of radiation but operating as one because of the reversed magnetic polarities... Errr...good point...dunno! Like I said, my idea could've been a red herring! In that case, the only real advantage is that the wiring from amp to driver would no longer be a source of EMI, which has caused havoc for some of us. But you're right, the costs of employing a shielded audio transformer and specially-wound driver will probably outweigh the benefits. Can't deny the potential to step-up current into the driver by using a transformer though. The weekend is approaching - I shall experiment and get back to you all. Cheers, Curtis Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 Can't deny the potential to step-up current into the driver by using a transformer though. Well, I could if that part had sunk in...worth a shot... A little concerned that this could slow the driver down and use more of col's power savings....since you have one, why not...but I don't think it will help with the high end response. Try the output cap thingy...see if that helps, you maybe pleasantly surprised...or perhaps plan a new driver with less vibrations in it... Unfortunately...or perhaps not with these huge posts of mine lately....the kids are with me and I work the weekend...looking forward to progress... pete PS...I had a lot of fun playing with the thing today. I think the battery was suffering cause after giving the thing a bit of a rest it really came alive. I think the battery consumption thing is a little misleading...it is the current that is really killing it...after a rest it recovers. Either that or my wiring needs attention....I live in dread that the thing will need repair while I am without a soldering iron and such. Boy...when I get settled again you will see a fantastic rail driver and if the thing will run in the mid position...modular circuitry...who knows what!!! p pps...nice to see another australian on the thread...we live in the same time zone!!!! Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 Can't deny the potential to step-up current into the driver by using a transformer though. Well, I could if that part had sunk in...worth a shot... A little concerned that this could slow the driver down and use more of col's power savings....since you have one, why not...but I don't think it will help with the high end response. Try the output cap thingy...see if that helps, you maybe pleasantly surprised...or perhaps plan a new driver with less vibrations in it... Take another look at the quote I posted (post#1754) - an inductor (so I guess transformer) really doesn't impart any delay to the signal... issues could be impedence and/of phase distortion. IMO the two biggest problems with using a transformer are bulk and cost. Of course as Curtis says, a good audio transformer will be very well magneticall shielded, but they are EXPENSIVE . and even tiny transformers are chunky when compared to the other components in the system - the whole circuit including AGC could be smaller than a transformer once its all done with SMD tech I can't see why a transformer set to give a higher current can help us - this would mean using an even lower impedence driver potentially increasing the crosstalk problems (parasitic transformer multiplier would be even higher) Maybe going the other way and stepping up the voltage could help ? so we could have a higher impedence coil... dunno... not good for efficiency?... PS...I had a lot of fun playing with the thing today. I think the battery was suffering cause after giving the thing a bit of a rest it really came alive. I think the battery consumption thing is a little misleading...it is the current that is really killing it...after a rest it recovers. Yes, prolonged use at such a high current draw will kill a battery much more quickly. I've looked at graphs from some battery manufacturers, and they show much higher total miliAmpHours rating when the current drain is low. So 20 mA might cause the battery to last quite a bit more than 5 times longer than 100mA. It also depends on the type of battery - the more high tech alkaline stuff and the Lithium stuff will cope much better with a heavy current drain - still not as good as with a light drain. I forgot to mention earlier that I've done some experiments with the coils from my dual rail driver. I tried out different configurations of one or both coils on its side, with magnets in different positions. So far, by far the best level of EMI noise reduction comes from the basic original 'humbucker' config. About that femm plot, There _seems_ to be very little interaction between that driver model I posted and the nearby pickup model, however if you make even the tiniest changes to sizes and positions, or move either the pickup or driver even a little, you can get on of those flux lines joining up... I really fell that the flux lines are a red herring, they are really there to help you visualise the field, the best way to tell if there is going to be interaction is to look at the shape of the field overall, not if there are lines joining the pickup and driver... in this model, the field of the pickup was slightly deflected away from the driver at the top and bottom(see below) - this means that there will be interaction ( no surprise there). The trick will be - and femm can help here - to try an design the driver so that the areas where the deflection is visible are in a region with very low flux density - so when comparing and tweaking designs, it is imperative to look at the numbers in the key rather than the colours (they are misleading because they are normalised per plot). @pete: Its interesting that you mention trying 'cages' and having dissapointing results. This is why I was talking about the significance of materials data - the magnetic properties of the material used for the cage are so important. e.g. if the air gaps are too large or too small (differences of only one or two mm), the functionality will be compromised. The thickness of sheet to use, air gap width and positioning, and gap to leave around coils, and particularly the gap to leave open to focus flux on the strings are all dependant on the specific properties of the material used - so a design may work with one type of 1mm soft sheet steel, but not work with another seemingly identical metal, because it saturates at a different rate or something... Of course if we can get the data for a usable available sheeting and some magnets, then we need to learn how to use it . But at least the femm plots would become a lot more meaningfull as we could be modelling with exactly the right parameters instead of guessing 'US steel type 2' or 'carpenters electrical iron' etc. cheers Col Link to comment Share on other sites More sharing options...
spazzyone Posted October 6, 2006 Report Share Posted October 6, 2006 When you guys refer to a "cage" are you talking about covering the whole driver? when i played around with the thin laminated core driver i found EMI to be uncontrolable untill i tried differant thoughts on sheilding and found that using the same material as the lams (the metal from a transformer) bent around the "coils" only. worked well i did not try covering the whole driver though (Maybe a better idea) but i could get real close to the middle position with no problems same goes for the rail (wich is already factory copper tape sheilded) but never connected the braid to ground though. only i could get even closer to the bridge pickup than the middle position with no EMI im not trying to sound ignorant.. but i found that it was the coils facing each other that was the problem (maybe why the original fernandes coils were on their side?) not the magnetic feild im no where near the "Electronic" gurus you guys are im just trying to keep myself on the same page Link to comment Share on other sites More sharing options...
onelastgoodbye Posted October 6, 2006 Report Share Posted October 6, 2006 (edited) It is quite possible that the transformer in fernandes designs was to step up the driver coil to make it a more effective pickup...I have never had an explanation, and it seems to be absent from the current designs... There's a thread somewhere on diystomboxes. com on installing a fernandes sustainer that said the transformer was to step up the battery supply voltage when they went from 18 v to 9 v. Can't seem to find it now though... mehh.. From the sustainiac site: (17) Q. What is a BILATERAL DRIVER AND WHY IS IT SO SPECIAL? A. The Bilateral Driver is the new Maniac Music development for the Stealth magnetic sustainer. This driver is a patented design that virtually eliminates magnetic crosstalk into the instrument pickups. When the sustainer is installed into an existing instrument as a retrofit, a special MAGNETIC BALANCE PLATE is moved back and forth carefully by the installer to the position that gives the best magnetic null. You can hear when the positionis best, because "grunge" that is radiated by the driver and sensed by the pickups goes away at the null position. Why is this important? It is a breakthrough, because now the gain can be turned up to a level never before possible with magnetic sustainers. This results in very robust sustainer performance. It also results in being able to use the Sustainiac Stealth sustainer with any bridge pickup. Even a single-coil bridge pickup. This is a first for magnetic sustainers. (18) Q. Since the STEALTH sustainer runs on a single 9-volt battery, is it as good as an 18-volt sustainer? A. This is another question that we are getting lately. This has been going around in email chat groups. The Sustainiac Stealth sustainers produce more intense sustained string vibrations than any other magnetic sustainer, including our old Sustainiac GA-2, which ran on 18 volts. There is an understandable lack of knowledge about sustainers out there, because they are still kind of "underground" devices. Here is how magnetic sustainers are designed to be intense: By putting less (not more, but less) turns on the driver coils, you transfer more energy into the driver from a given battery voltage. This lowers the impedance. More current is drawn from the battery. This results in stronger, more intense sustained string vibration. We tried this with our old Sustainiac GA-2 sustainer, but the single 9-volt battery wore out so fast (supplied high current) that we couldn’t use the design. So, we had to add turns back on to the driver, and get the energy we needed by adding another battery to make 18 volts. That is why some competitor’s sustainers use two 9v batteries. They all copy certain critical aspects of the GA-2. Here is one of the really cool things about the new Sustainiac Stealth: We always wanted to design a sustainer that was even more intense than the GA-2, and still have decent battery life. The only way we could think to do it was to add still more batteries. Here is how we solved the problem: We discovered how to design a digital power amplifier that was four (4!) times as efficient as a conventional power amplifier when driving a magnetic transducer. With this revolutionary design, we were actually able to double the amount of energy that we deliver to the Stealth driver, but with half the battery energy that we used before in the GA-2. It's true! The Sustainiac Stealth sustainer actually puts more energy into the driver (STRONGER SUSTAIN) than any other sustainer out there, even " 18-volt" sustainers. Compare the Stealth to anything else on the market, and put a current meter in series with the battery to verify these statements. Edited October 6, 2006 by onelastgoodbye Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 (edited) ....a special MAGNETIC BALANCE PLATE ... has anyone come face to face with one of these? is it a permanent magnet or a sheet of steel/iron or some more complex magnetic structure ? is it connected electrically? or just stuck to the guitar body ? is it a sink, a conduit or some sort of flux alignment doohickey ? does it rely on the bi-lateral configuration or could it work with a rail or single core driver ? does it go close to driver or pickup? heh, gotta love the stuff about revolutionary battery consumption and that they are implying that class D(assuming thats what it is) is some new invention of theirs lol. btw, today I was managing to get crosstalk with the driver away from the guitar, behind the bridge etc. so at least some of it is related to wires and circuit being influenced by the magnetic feild rather than direct from pickup to driver. I also tried two seperate bar magnets - one per rail - instead of a single magnet. Much worse ! Don't know why - maybe due to crappy magnets, probably because there is less surface to make a good magnetic connection on the bottom of the rail compared to the side. So I've decided to bite the bullet and install the circuit in the guitar cavity - with shortened leads etc. to see if its better/worse/similar. Then its time to search the house for as many sheets of magnetic metal and permanent magnets as possible . Also going to scavenge some chunky toroid ferrite inductor cores from my old PC power supply (it burned out making a very horrible smell acouple of days ago :-| still worked, but I wouldn't have trusted it to not cause a fire). cheers Col Edited October 6, 2006 by col Link to comment Share on other sites More sharing options...
axe_2_grind Posted October 6, 2006 Report Share Posted October 6, 2006 wow 122 pages!! Good Going guys!! It's been slow going on my end (well, actually it hasn't been going at all). I've been having to deal with band stuff over the last few weeks, so I haven't really had time to mess with this project at all. I do still need to rebuild my Fetzer/Ruby circuit. Anyway, looks like I've got some catching up to do on this whole Bi-lateral driver thingy. Keep it up!! Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 wow 122 pages!! Good Going guys!! It's been slow going on my end (well, actually it hasn't been going at all). I've been having to deal with band stuff over the last few weeks, so I haven't really had time to mess with this project at all. I do still need to rebuild my Fetzer/Ruby circuit. Anyway, looks like I've got some catching up to do on this whole Bi-lateral driver thingy. Keep it up!! Mind you, ours is more of a bi-longitudinal driver than bi-lateral I've raked up some info on the Sustaniac 'magnetic balance plate' It seems that this is some sort of flux conduit - like a partial 'cage' designed to control the flux at the area between the two halves of the sustainiac - heres a diagram from the installation manual: So maybe there is some value in persuing 'cage' technology. I threw together a few pics of my as yet unfinished install - the modular circuit in the guitar cavity, with inset pics of the driver and that fancy pot I found (is even has a long threaded shaft - perfect for guitar installation now I don't know wether to play with cage ideas or work on the installation. cheers Col Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 Like this on the side coil...I believe that these side plates are for better high string response by narrowing the window around the b and e strings (at least from the patent information)... This type of thing is why I still advocate a thin core (though not to thin....) pete Link to comment Share on other sites More sharing options...
col Posted October 6, 2006 Report Share Posted October 6, 2006 (edited) Like this on the side coil...I believe that these side plates are for better high string response by narrowing the window around the b and e strings (at least from the patent information)... This type of thing is why I still advocate a thin core (though not to thin....) pete My understanding is that the plates reduce the flux fringing on the more responsive strings not on the b and e . At least, that fits with the drawings and my experience modelling cages with femm? Problem is that it kills efficiency, although if your having to turn it all up until the top e rings, then I guess it makes no difference.... This approach to balancing the output would be equally valid with the thin driver I think. If you decided to use off-board power, this would be a viable alternative to the AGC circuit (at least string-to-string balance, it won't help with high fret / low fret balance) I've been looking at my guitar while doing this install, and I can't believe I've not realised before how close the tips of the screws that hold the trem spring mounting plate must be to the neck position and driver. Given that neither the driver or pickup have magnetic shielding beneath them, I wonder how much of a flux conduit this is ? If this is causing issues, it could explain why some folks don't get the same problems - guitar hardware is very variable - some don't have trems, others will be mounted in different ways, and different positions and made of different materials. If this does turn out to be an cause, it could certainly be helped by using a cage - the underneath of the driver is the easiest part to deal with I'm having problems with harmonic mode on my install (its hard wired, so i've not tried fundamental yet) theres lots of crosstalk - maybe because the circuit and wiring are much closer to pickup and driver (and trem hardware) - interestingly, with the extra bad crosstalk and EMI, its easier to notice the effect of putting slabs of steel in different places near the driver. It can make a noticable difference, so I will definately be going further along this line of research cheers Col Edited October 6, 2006 by col Link to comment Share on other sites More sharing options...
psw Posted October 6, 2006 Author Report Share Posted October 6, 2006 ok...thanks again for Tim hosting some sound clips I did 3 quick mp3's of my sustainer...very rough, but you get the idea... noodling1 this is a ultra clean sound. I found if I turned the sensitivity control down the fizz largley went. I start with the bridge pickup with the sustainer off so you can here the natural sound...then the sustainer turned down...then turned up...you can hear the fizz in there particularly in the harmonic mode... Are we talking about the same sounds guys? noodling2 this is a slightly overdriven (echoy sound) that I tend to favour...still be regarded as fairly clean by some. This brings out the harmonics and gives the sound a little more body and effectively hides the fizz. Note that this guitar is badly in need of some work. The action has got fairly low and there is a bit of fret buzz...once the sustainer kicks in, a lot of those sounds are the strings crashing into the frets... europish Ok...so a bit of santana style, more distortion...shows with this kind of thing how it mimics traditional feedback sustain and brings out controlled harmonics. Unfortunately, I think the battery was kind of dying a bit cause later, the guitar was a lot more responsive...grrr Anyway...got kids to look after...but perhaps we can see if your experiments and EMI problems are similar to the fizz I get...or wether such sound quality as these clips show are acceptable, or could be improved. Bear in mind this is a very poor quality POS $50 guitar... got to run...thanks TIm pete Link to comment Share on other sites More sharing options...
spazzyone Posted October 7, 2006 Report Share Posted October 7, 2006 (edited) Col that is what i was refering to in the my last post (about the cage) the EMI seems to me to becoming from the coils not the magnets i tried my thin driver coil with no magnet and still got EMI ill have to do another comparison test to see how much worse it is with and without the magnet and ill post another soundclip tomorrow Edited October 7, 2006 by spazzyone Link to comment Share on other sites More sharing options...
col Posted October 7, 2006 Report Share Posted October 7, 2006 (edited) Col that is what i was refering to in the my last post (about the cage) the EMI seems to me to becoming from the coils not the magnets i tried my thin driver coil with no magnet and still got EMI ill have to do another comparison test to see how much worse it is with and without the magnet and ill post another soundclip tomorrow That seems likely. Although I'm starting to think that EMI is coming from everywhere in the system. I'm getting worse crosstalk now that the circuit is in the control cavity. I've built a 'sardine tin' style box for the driver in an attempt to control the flux, but its not made much of a difference - I'll try to refine it when I have more time. Will have to try building a bi-lateral driver to see if there really is some magic there ok...thanks again for Tim hosting some sound clips I did 3 quick mp3's of my sustainer...very rough, but you get the idea... Good stuff. Its the same issue, but it's much much worse on my setup. Even if i take out the AGC it's still a lot worse than that. As I've mentioned, it seems to be worse now the system is fully installed - closer proximity of circuit and driver I think. Maybe I'm sheilding the wrong thing - worrying about the driver and pickup, maybe the circuit need protection - a possible downside of the extra circuitry in my setup... anyone know how much 'mumetal' costs and where to get it ? cheers Col Edited October 7, 2006 by col Link to comment Share on other sites More sharing options...
Recommended Posts