psw Posted June 14, 2004 Author Report Share Posted June 14, 2004 So here's my next brainwave... build a PUp into this new drive element... Now I've got an idea of how to do this but I have a limited supply of these components on hand, and while I can get more, I don't wan't to waste them...not to mention my eyesight making these tiny things... What I'm expecting will happen is that the drive connected one way will cancel the signal so that nothing will happen...or...connected the other way, feed off itself into an uncontrolled oscillation, probably at the combined resonant frequency of the device... So, is there a way for a driver and pickup to share the same magnetic field and not simply pickup on itself...would an effective humbucker PUp arrangement help...that is, identical pickups, sensing opposite magnetic poles... Put your thinking caps on that if you could cheers psw Link to comment Share on other sites More sharing options...
lovekraft Posted June 15, 2004 Report Share Posted June 15, 2004 ...is there a way for a driver and pickup to share the same magnetic field and not simply pickup on itself... I think that's pretty close to the textbook definition of a transformer - the driver's magnetic field would swamp out the signal from the string, and you'd wind up with a simple oscillator at the resonance of the dominant component in the system (probably the driver and/or pickup coil). I've given it a lot of thought, and I don't see any way to avoid separating the driver from the pickup unless you don't use a magnetic pickup. My guitar pickups will sense the field from my headphone speaker coils at a fair distance, even with the strings muted by hand. There may be a way around it, but I can't see it. Andreas, any input? Link to comment Share on other sites More sharing options...
psw Posted June 15, 2004 Author Report Share Posted June 15, 2004 OK LK So it's not possible to consider there being three elements - the pickup --- the driver --- and the string and that the string is the dominant resonant frequency in this sytem? I have had trouble with squealy terimin type sounds as I have said before. Hence the development of designs like the CP6x which seeks to contain and neutralize emitted radiation. Would a piezo pickup - magnetic driver system fair better as far as this feedback loop? The idea of an internal pickup/driver was to islate everything from the guitar circuitry and, as far as possible, contain this radiation. Of course I cant contain the pickup/driver from it's own magnetic fields. My only thought was to arrange the sensing and driving elements at right angles to each other. This could work as the cp6x has a circular, cycling field, a bit like a toroid transformer (no larry it's not a toroid transformer...). I could also arrange two sensing elements on opposite sides so as to be effectively N/S so that when the drive gain is cycling north more will be sensed by the south and visa versa. Perhaps some tricky switching circuit that alternately senses on the positive and responds on the negative could be arranged? This is purely speculation of course and I don't have the where-with-all to design such a circuit! Meanwhile, I'm exploring a few refinements to the driver design. I havn't given up driving it from the bridge either and this could perhaps incorporate a hex bridge piezo system as well to drive each element. I was reading a little on active crossovers. In fact there maybe some chips for this purpose. This would be useful to send an appropriate signal and gain to each string driving element from the guitars pickup using a single amplifier. Another idea is a simple common signal to each diving element as I have been trying, but I fear this wil not be refined enough. The 1st string (high e) is particularly difficult to get to respond... the g string consistantly good...hmmm Anyways, thanks for the consideration of this stuff, I hope it is of interest and not too taxing on the brains trust psw Link to comment Share on other sites More sharing options...
GregP Posted June 15, 2004 Report Share Posted June 15, 2004 "The G-String Driver" That would have limited but effective use. Link to comment Share on other sites More sharing options...
Biohazard Posted June 15, 2004 Report Share Posted June 15, 2004 And that name would mean that the driver would sell worldwide. But probably for the wrong reasons lol. Link to comment Share on other sites More sharing options...
lovekraft Posted June 15, 2004 Report Share Posted June 15, 2004 So it's not possible to consider there being three elements - the pickup --- the driver --- and the string and that the string is the dominant resonant frequency in this sytem? No, but to make the string the dominant component you have to remove the magnetic feedback between sensor and driver I have had trouble with squealy terimin type sounds as I have said before. Yes, that's the result of direct feedback between driver and pickup Would a piezo pickup - magnetic driver system fair better as far as this feedback loop?That would eliminate any magnetic interaction between sensor and driver -it just adds complexity, but that's not necessarily a bad thing. I'd still tend to use the guitar pickup(s) as sensors, but that's provbably because that simplicity and elegance appeals to the "boy engineer" in me. A simple FET follower will electronically isolate the driver circuit so as not to add any inductive load to the pickup circuit. The idea of an internal pickup/driver was to isolate everything from the guitar circuitry and, as far as possible, contain this radiation. Of course I cant contain the pickup/driver from it's own magnetic fields. My only thought was to arrange the sensing and driving elements at right angles to each other. I'm not sure - I do know that if you place the power transformer in a tube amp too close to the output transformer, it induces a loud hum regardless of their angular relationship. I was reading a little on active crossovers. In fact there maybe some chips for this purpose. This would be useful to send an appropriate signal and gain to each string driving element from the guitars pickup using a single amplifier. You've got the right idea there, I think - a simple steep slope bandpass filter for each string driver between the sensor and the gain controller/driver amplifier. Since you can limit the bandwidth of each string to just over two octaves, your amplifier becomes much more efficient, having only to amplify those frequencies that are useful. With bandwidth reduction and gain control, you should be able to drive the string like a Georgia pack mule with minimum power. And as for you other two guys, there are vibrating G-strings currently available from your favorite local adult novelty store, complete with remote controls, but that's a whole 'nother kind of electronics! Link to comment Share on other sites More sharing options...
Biohazard Posted June 15, 2004 Report Share Posted June 15, 2004 LOL, sorry, just decided like adding in a joke back there. Link to comment Share on other sites More sharing options...
psw Posted June 16, 2004 Author Report Share Posted June 16, 2004 yeah yeah yeah...of course I'd thought of that...then I stopped thinking..and then... So, great stuff LK, but electroics don't come natural... So, can you point me in the direction of A simple FET follower Will this isolate the circuitry from the ground also? I suspect I'm getting interferance through the ground wire. Simply lifting it and connecting it to -V causes quite a racket... how about the amp - one 386 enough? Now, for active filters Do you happen to know the frequency range of each string? How about filter circuits - any sites you can suggest? I'm not familiar with these chips, any numbers you can suggest? I like the idea of a simple setup. I want this thing to be a natural extention of the instrument. The more drivers and pickups, amps etc the more complicated and expensive it becomes. The more time also it takes. While I'm prepared to investigate anything in this quest, it is the distilled ideas, the elegant solutions that are always the best, it's a shame you have to go through all the bad ideas to get to the gems...oh well Same thing with humour I suppose...keep trying cheers psw Link to comment Share on other sites More sharing options...
lovekraft Posted June 16, 2004 Report Share Posted June 16, 2004 Just 'appen to 'ave one, roit 'ere! source follower That may need some tweaking, but it's a basic building block, and it'll work with most any audio N-channel JFET. I'm not sure about ground noise, we probably need to ask Ansil (hint, hint). I don't think you need a 386 for each driver, I think a single discreet transistor amp (perhaps like this one), would probably drive the "coil" sufficiently, and be a lot simpler (and cheaper) to implement, since you're still going to need 6 of 'em. Bandpass filters can be implemented fairly simply with opamps, and the filter and gain reduction functions can be integrated into the same block with a little clever trickery. Check RG's excellent article on filters here, and DGB Studio has a chart of guitar fundamental frequencies from open to 36 (!!?!) frets. Now the only hard part is kludging all these together into a working system, but that's why people like Edison ended up rich! Hopefully that helps clear up the items I mentioned a little - maybe we're not boring everyone else to tears. I guess if they get tired of these incessant ramblings, somebody'll say something. Link to comment Share on other sites More sharing options...
psw Posted June 16, 2004 Author Report Share Posted June 16, 2004 WOW...great source material...now you're the man... I knew about dgb studio for a while now...in fact I was wondering why it wasn't posted in answer to all those PUp wiring questions...(didn't realize freq stuff was there, ta) ...but those low voltage circuits are amazing and will be really useful on the drive signal when I finally get this thing going! Now i've been doing some research and come up with this magic formula : C = 1 / 39.5 x Fsq. x L or L = 1 / 39.5 x Fsq. x C F is frequency value in hertz C is capacitor value in farads L is inductor value in Henries 39.5 is approximately 4 phi squared Now my maths is crap...so...plugged it into a spreadsheet...(still working on specific calculations...) Given the frequency ranges for each string from dgb studio and knowing the inductors value...the series capacitor required to tune the resonant frequency of each driving element will be given...well thats the theory! Now, I think that the resonant frequency of the driving elements are potentially crucial to efficiency. I do believe that there is room to move and that this resonance need not be exact. My hope is that a resonant frequency of the average for each string will provide an adequate window for this efficiency to occur. This research brought up this: RESONANCE : Capacitive reactance decreases as the applied frequency increases, while inductive reactance increases along with the applied frequency. At some specific frequency for every combination of a capacitor and an inductor, the capacitive and the inductive reactances will be equal. This frequency is the resonant frequency, and it results in a unique circuit condition called resonance. ... At resonance, the impedance in a series LC circuit will be detirmined solely by the dc resistance. The impedance is at it's minimum value at the resonant frequency. So...what does this mean? Well it suggests that you can tune a given inductor to a resonant frequency by a simple series capacitor, based on the formula above and that the full power of the circuit will only be achieved (impedance at a minimum) around this frequency. Now...present sustainer devices use a single driver and pickup system. This cuts through the patent BS we have been debating . What designers have been trying to achieve is a frequency follower that switches in various capacitors in series (hi-pass filters) and parallel (lo-pass filters) to adjust the resonant frequency to the signal. Some problems here are that they receive a complex signal from all strings and attempt to drive the strings with a driver driven at a resonant frequency of the sum of these complex waves. Inevitably, inconsistant results, such as notes winning out over others will occur. The idea here is to tune each driver to the likely resonant frequencies found on a given string (I'm not sure how it will deal with harmonics) overcoming this problem and dispensing with the variable circuit...well I hope Ultimately, a hex pickup / hex driver system would be the go but may not be necessary and just add complexity and expense$$$$ Somewhere on the sustainiac site they alluded to this but the cost of manufacture would be high (say 6x their current system + development) Hopefully with my driver element idea, this cost can be brought wayyyy down and much, much smaller. In fact, My latest refinement (still undergoing testing) is even cheaper, easier to source, allows for some adjustment of L and hopefully less radiation still. My driving element is based on magnetic balance. It is suseptable to problems with string bending. This problem gets worse the closer to the neck as the bend pushes the string out of alignment with the driver, comprimising this balance. The closer to the bridge I can get it, the less this is a problem so I'm working on that and on tuning the drivers So LK, that should scare off most people... - maybe we're not boring everyone else to tears. I guess if they get tired of these incessant ramblings, somebody'll say something. This thread has had over 1200 views...I think it's become something of a saga...perhaps it's like some poor soap, people just keep tuning in! If you're following this thread...perhaps you could let us know! Vote A : if you want to see psw overcome his obsession with phases and get this thing going on a real guitar Vote B : have Lovekraft dismantle psw's obvious fraud with the CP6x driver Vote C : if you think Larry has already patented the CP6x just in case Vote D : if you think psw should give up and seek professional advice see you on the next installment... psw Link to comment Share on other sites More sharing options...
lovekraft Posted June 16, 2004 Report Share Posted June 16, 2004 (And the hits just keep on comin'! ) Ok, just to see if we're all on the same page, here's a preliminary system flowchart: The red blocks represent bandpass filters, the dark blue are gain control blocks, and the light green are the driver and associated power amp. If everybody's happy with this architecture, we can get down to business implementing the blocks - if anybody sees a problem with this layout , I'm sure they'll let us know. Link to comment Share on other sites More sharing options...
Biohazard Posted June 16, 2004 Report Share Posted June 16, 2004 How much research did it take you both to come up with this knowledge? psw whats your background and how did you get into this. Lovekraft again, what is your background and how did you aquire your knowledge for this. I am certainly enjoying reading it but unfortunately it is over my head, but i'm trying to understand as much as I can. Link to comment Share on other sites More sharing options...
lovekraft Posted June 17, 2004 Report Share Posted June 17, 2004 The hard way, almost without exception! I've been taking things apart since I was a toddler, so eventually I had to learn how to put some of them back together (or my parents might have killed me). That and reading everything I could find on anything that catches my interest over 40 years, and asking stupid questions whenever I ran into an expert, has given me a little knowledge about a lot of subjects. And I spend way too much time on the internet! I got into electronics as a teenager trying to make HAM radio stuff and graduated to PA, amp and effects repair when I was playing with a road band (there just aren't any all-night amp repair shops in places like Screven, GA or Jacksonville, NC, or at least there weren't in 1979). Most of what I know I've learned from people like Perry, Wes, Jeremy, et al, who were kind enough to help me out when I was over my head, but before online forums existed, so I picked the brains of every builder, repairman, engineer and player who would talk to me for years (what an obnoxious little git I must have been). And I still don't know much, but I've learned where to look for solutions to specific problems, that's all! Link to comment Share on other sites More sharing options...
psw Posted June 17, 2004 Author Report Share Posted June 17, 2004 Bio - I'm just full of...err...ideas. Sometimes I just can't let go! Actually, I'm self taught though I went to University I studied Music after leaving school early ad playing in some bands...glory days....sigh Much like Lovekraft, I guess, but I wasn't such a pest...more of what we call a smart-arse...I'd find out what little information I needed to prove that I could do it. Actually I don't really know much and really struggle...but I'm not one to let that stop me Unfortunately not a good life strategy these days, I know many things but am a master of none. The guitar has always been my consant companion... Anyways, enough of this revelry....................................................... That sounds reasonable LK I was thinking: Buffer ---> amp ---> current dividing resistors to portion out gain and bring up impedance ---> series capacitors (to the values indicated by the magic formula) ---> driver element (cp6x) I have just finished a new version of the cp6x (cp6.1x ?) which is about 1cm square by 8mm high. This has a little more magnetic power but works out cheaper and even easier to make than the original! The main aim in the redesign was to cut radiation so as to move it closer to the bridge. Initial tests with a very primitive set up showed tremendous sustain driving it up to the harmonic, mid way between the bridge and the bridge PUp. Still working best on the G (heh, heh..) but I think that this must be close to its resonant frequency. So things look positive cheers psw P.S. Mrs psw and psw's 1 & 2 have requested I spend a litle less time on this, more on them...fair enough... Link to comment Share on other sites More sharing options...
lovekraft Posted June 17, 2004 Report Share Posted June 17, 2004 Mrs psw and psw's 1 & 2 have requested I spend a litle less time on this, more on them...fair enough... OK, I can take a hint... I'll take a couple of days and find some circuits that might work in place of the pretty colored blocks, and report back. Like they say around here, "If Mama ain't happy, ain't nobody happy!" . Link to comment Share on other sites More sharing options...
psw Posted June 17, 2004 Author Report Share Posted June 17, 2004 LK No panic, there's always a work around! My whole life's been catch as catch can!!!!!!!! Working on a preamp and typing at the same time! it's getting there...we'll get this thing working yet...whatever it is! cheers psw Link to comment Share on other sites More sharing options...
ansil Posted June 17, 2004 Report Share Posted June 17, 2004 i like what you have done psw and LK. and think you should continue on with it. i dont' post too much in this thread cause i am still trying to get in the shop and work on my octave circuits at present moment. but i try to catch up and read when its slow and i can do some reading. Link to comment Share on other sites More sharing options...
psw Posted June 18, 2004 Author Report Share Posted June 18, 2004 We'll, I'm done screwing around with the primitive circuit (386 and an outpu cap). I've put together a 0.5 watt 386 based amp kit and a little two transistor preamp kit hard wired to the double adaptor in the guitars output. I'm getting very encouraging results with a regulated wall supply (was eating batteries something shocking) with only 6 volts. I'm getting no weird noises (a product of the battery losing power - put-put sounds) and eliminated some of the shorts. The amp is set to a gain of 32db (gain of amp x41 - my previous to x200!) and the preamp about 40db. At the reduced voltage the power is possibly half that!!!! (The amp can run on up to 16volts and the load is about 4 ohm instead of 8) Running the CP6.1x all but the high e string could be driven (high string has less mass being thinner and possible phase problems) from a sweet spot about 1cm from the bridge pickup and the bridge on a strat, roughly in line with it's angle. The unique ability of this system (except the Model C which is a slightly different principle) to drive and sense different pickups is really neat and the system should be sensitive to the guitars volume control in a musical way. Several new designs in the X series drivers don't seem to be improvements but obviously the principle is sound. The CP6.1x is cheaper and easier to make as well. The height of the driver element is about 8mm and must be placed very close to the string. However there is no string pull or noise should the driver come in contact with the string. So, should there be any practical problems with these dimensions, let me know. Also, if people have ideas for the control of this thing, now would be a good time to contribute... For instance, should the device be attached to the outside of the guitar rather than being inbuilt...should a slider pot be used for sensitivity...pushbuttons or toggles...LED's anyone...what color...inbuilt drive effects...rechargable...??????? Don't feel intimidated by LK, Andreas, Ansil and me...join in and contribute...what do you want this new generation sustainer to be? psw Link to comment Share on other sites More sharing options...
lovekraft Posted June 19, 2004 Report Share Posted June 19, 2004 For instance, should the device be attached to the outside of the guitar rather than being inbuilt...should a slider pot be used for sensitivity...pushbuttons or toggles...LED's anyone...what color...inbuilt drive effects...rechargable...??????? Whoah, there, Sparky, let's not get all Microsoft and start adding features before the operating system works! I want flashing lights!!! Seriously, let me make sure I'm up to date; The CP6.1x is an 8 ohm load, you're currently using a 386 running at 6 volts with no compression or filtering and getting good results on 5 out of 6 strings at about +32 dB (does that include the voltage gain from your preamp?).The driver element is approximately 8mm tall (5/16" for us ignorant yanks), and has to be fairly close to the string. Will it drive the high E string if you place it closer to the neck?Do you have schematics for the preamp and amp you're using? OK, I'm through asking stupid questions - please feel free to resume intelligent conversation. Don't feel intimidated by LK, Andreas, Ansil and me...join in and contribute...what do you want this new generation sustainer to be? I don't know about intimidated - but they should be afraid..be very afraid! Link to comment Share on other sites More sharing options...
GregP Posted June 19, 2004 Report Share Posted June 19, 2004 If it's sucking batteries like mad, make is able to use and transform phantom power so that we can use standard XLR as a power source. Link to comment Share on other sites More sharing options...
psw Posted June 19, 2004 Author Report Share Posted June 19, 2004 Firstly, Greg P - I'd rather not use phantom power - I rather want to keep the instrument stock. Sustainers in general suck up a lot of juice, but I'm running with very basic electronics and if the driver were "tuned" as LK and me are suggesting it should be really efficient. I had been testing with a rechargable 9 volt. I think people wouldn't mind charging their guitar like a mobile phone. LK - actually I do have an LED or I wouldn't know it was on when the thing doesn't work I don't think it is too soon to look ahead, but yes, lets get the thing going. It may inform the design process. For instance the 10mm square shape won't fit on my Les Paul...should I develop a more versatile driver? Both circuits are from the Magazine Silicon Chip. The Amp is called the Champ preset at 32db. The preamp is called the PreChamp and is set at a 40db gain. The CP6.1x (very microsoft!) has a 4 ohm impedance while the amp wants 8 so is not running efficiently. Maximum power for the amp is 0.3 watts at 6 volts. There is no filter or compression although adding various series capacitors had an encouraging effect. Driver from the neck - No, it doesn't seem to. The X series devices are very sensitive to alignment to the string and are specifically designed to run from the bridge end (possibly even in the bridge!). While I recognise the mechanical advantage, the wider throw of the vibrating string appears to be actually detrimental to the driver's electromagnetic efficiency. I don't have the schemetrics in a postable form but I can tell you that it's the usual LM386 with appropriate filters (220uF output and 100uF supply decoupling for instance) and a 10k volume control on the input. The preamp was built as a means to isolate the drive circuit from the guitar as you suggested but does add some gain. All in all there's no electronic hocus pocus here. As I've indicated before with my WCS test plank, if it will work with this stuff, imagine what it could do if I knew what I was doing! I have to say that it isn't running without it's hiccups - nothing comes that easily - but the fact that it works at all is amazing. Being able to drive it from the bridge end without modifications to the instrument, is remarkable - even if I do say so myself! Now, I got up at 3:30am to work on this while the family were sleeping (and I'll be back at real work for the next couple of days) so I've had to work fast. I had made a driver CP6.2x but it failed. People reading this should probably be told that although it may look as if I'm just dreaming this stuff up - and I am - most of what I dream up does not work or is impractical in real life. I have quite a little collection of failed drivers all sticking together in a little miniture, magnetic sculpture. The lesson here is that, until you've tried it you wont ever really know if you're being stupid or clever. Also that only via stupidity will the real gems be discovered Case in Point. While trying to put together CP6.3x I accidently misaligned the polarity of my little tiny magnets. Let me tell you, these little buggers will stick to anything and are not so easy to get in place. The magnetic fields are invisible and the effect of multiple magnetic fields somewhat unpredictable. Well, having to work fast as dawn was approaching and I had to turn back into Family Man, I did'nt check my work and plugged it in anyway - the squeal woke the 2 year old and I had to abandon it for a while. I checked it out, found the problem, but there was no improvement over the CP6.1x so was I up a blind alley...hmmm. So, I carry around a notebook and draw little doodles and have got quite good at the logic behind these 3D animated magnetic fields (which are now lodged in my brain) and played around with my mistake. The result is...drum roll... ...................................CP7x It looks as if the squealing was because of the extra power efficiency. I could tell you the logic of it but of course I would then have to kill you Anyway, further testing will be required but it loks hopeful Hope everyone is enjoying this warts-and-all account of the invention process...feel free to chip in cheers psw Link to comment Share on other sites More sharing options...
Biohazard Posted June 19, 2004 Report Share Posted June 19, 2004 Cool, good stuff. I like the idea of a slide pot for sensetivity changes, that would be a good idea and a cool little feature. Link to comment Share on other sites More sharing options...
psw Posted June 19, 2004 Author Report Share Posted June 19, 2004 Yeah, I kind of liked it. What about a tailpiece arrangement with battery and everything inside (no digging into your axe to install) and the slider across the back of the bridge. Easy to see where the sensitivity is at before you switch on. Could be worked like a violin bow, or adjusted with the heel of your hand... Oh, and I like a blue LED but a little expensive...also found some push-on/off 6PDT switches with built in LED...thought that could be neat... Anyway, back to the experiments... psw Link to comment Share on other sites More sharing options...
Biohazard Posted June 19, 2004 Report Share Posted June 19, 2004 Not that I have a guitar with built in stuff (yet) but I don't mind built in stuff in a guitar as long as not all the body has been routed lol . However, if your sustainer could be made so people could choose to either fit it inside their guitar or not have to route then it will appeal to a whole load more people and that would be great for it. Link to comment Share on other sites More sharing options...
lovekraft Posted June 19, 2004 Report Share Posted June 19, 2004 Blue LEDs aren't really expensive any more - check LSDiodes. High intensity (4000 mcd) blues for $.45US each, and worldwide shipping $2.00 for up to 30 items. Link to comment Share on other sites More sharing options...
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