psw Posted March 26, 2009 Author Report Share Posted March 26, 2009 I think that is a shame - a version of this technology affecting all the strings, but using an integrated p/up and with it's own psp, sold at a similar price to the e-Bow would be likely to find a good number of players willing to shell out for one. If the e-Bow affected all the strings at once, I might even be willing to sacrifice my right hand picking in order to use it from time to time..... I know this has been explained before... An ebow has a pickup and driver very close together...it is able to do this because it needs less power to drive a single string, is extremely close to the string, and they make a feature of the pickup hearing the driver as it gets closer. They also use other precautions like both the pickup and driver encased in a metal sleeve. You would expect that an ebow big enough to vibrate all strings would have 6 times the output. To cope with that, it would reasonably be assumed that you would need six times (at least) the distance between the driver and the internal pickup. Coincidentally, this is very much the distance between the bridge pickup and a neck driver! This needs to be considered also with a Hex system where it is trying to drive all six strings of course. Link to comment Share on other sites More sharing options...
TheEdge Posted March 26, 2009 Report Share Posted March 26, 2009 wow, seems like I've missed some pages here.. does anybody could tell me what is going on now? new schematics? new ways to build this? Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) This occurs when there is excessive drive signals (so my circuits and the F/R can display this at the higher gains quite easily...cols heavily AGC things far less if at all I suspect). but that wouldn't be the case when the battery is dying (when youve said fizz is especially prevelant) You get fizz when there's hard clipping. This occurs with too much gain. It also occurs when the battery is very low - As the battery drains, the voltage drops and the headroom is reduced so clipping occurs with lower voltage signals than when the battery is fresh. cheers Col I'd say that fizz could possibly be better defined as distortion as seen on the signal across the driver vs the input signal .....this could be either Hard clipping (driving the output signal past VCC) or soft clipping (VCC is fading away below that of output stage's normal working 'region)....OR any other other form of interference on the driver signal. In short it's distortion...but even though fizz seems a bit of a girlie description...it's very apt! Re the 330hz - a different tack tonight ...& a whole different ballgame...no matter how I tried last night (using a sig gen as an input), I could not rid the guitar output of the most dreadful EMI (just an overpowering sound of the sig gen's frequency). Out of desperation, I quickly knocked up a TL072 based preamp...fed my guitar bridge pickup into that...then onwards to a TDA7053A (stereo amp with DC volume control).....sustain was sweet, with EMI relatively easy to eliminate. The outputon the scope was as pure as the driven snow too...none of the ugliness of the LM386. I want to revisit the sig gen approach, as it's the best way of control conditions, but for now, I need to crack on & start taking some reading. Sadly, I ran out of time again...but with my 8 ohm single coil, driving the Low E, A, D, G strings was very easy - the B String was troublesome, the high E just about do-able. This is a conundrum...why should the B string be such a problem (it's thicker than the high E...& the high E sustains - anyway needs further pondering! Tonights obs... 5V-6V seems fine as VCC ...certainly into 8 ohms at least...though I intend knocking up a variety of coils with different impedances to test (I had my missus peeling an old pickup tonight to get me enough 0.063mm wire!) The TDA7053A seems viable - I like its elegant DC volume control, which could be ganged to control all 3 ICs needed for 6 strings (ie for sustainer intensity), there's also no visible distortion on the scope trace - but being two channels, it's not really an obvious choice for the single driver clan though! I'm noticing that a fundamental frequency is easier to 'excite' with the driver near the middle pickup location (I can get about 1.5cm from the edge of the middle pickup, before squeal becomes a factor)...the harmonic is the most predominant 'excitable' frequency between the neck & the neck pickup (but I'm sure you all already knew this!) One quick number, for this 8 ohm coil (400 turns of 0.15mm ...1cm deep, core of 5mm mild steel), there's 300mV peak to peak needed for the G string to 'sustain' just past what I call 'the edge' (about 25mA AC current measured with my DVM). This figure tails away as the strings get thicker (eg the A String at the 12th fret needed approximately 180mV & 15mA This last point is where I personally think a major win of the hex approach lays....tailored coils (& current) per string. I also very much like the idea, of having tailored the coils to each string, a circuit which will yield a constant current into the coil. I could be wrong (& I'm sure Pete will chime in that he's already tried & the reusults weren't good), but I'm hoping with the right 'tailored' coil per string, coupled with the absolute minimal but constant amount of current needed to get the string sustaining *just* past the 'edge', that inter string driver interference will not be a major source of problems. Imagine each strings driver wielding supreme control of its own string...strum a chord & hold...no dominant string...bliss. Anyway, bed beckons. Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
Truth_David Posted March 27, 2009 Report Share Posted March 27, 2009 Different tack tonight ...whole different ballgame...no matter how I tried last night (using a sig gen as an input), I could not rid the guitar output of the most dreadful EMI (just an overpowering sound of the sig gen's frequency). Out of desperation, I quickly knocked up a TL072 based preamp...fed my guitar bridge pickup into that...then onwards to a TDA7053A (stereo amp with DC volume control).....sustain was sweet, with EMI relatively easy to eliminate. THE output was pure as the driven snow too...none of the quirks of the LM386. to be contined (moving PCs!) That new setup sounds familiar.....could it be that our friend zfrittz6 actually was not so far off track after all? David L Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 Well...I am glad that you plugged it in and also that you tried running a properly preamp/amp circuit from the actual guitar's signal (bridge pickup) into your driver and got good results. The TDA7053 was one of my previous suggestions when this was being discussed and something I did try and held (and still do) hold hopes for to replace the venerable LM386. Without meaning to be patronizing , by doing this (plugging the guitar in, trying the guitars output and a good stable circuit (your very simplified lm386 thing didn't include zobel or other stabilization suggestions for the chip)) you seem to have come up with similar results as I have described. One could extrapolate that if your driver were bigger and trying to cope with the complexities of multiples strings (or if you were running six of them), that there might be less efficiency and greatly increase EMI effects which may cause some concerns or require extra measures. Again, this would be pretty much the kind of effect that the more simplified approaches seem to exhibit. I sincerely meant that while sustain is possible acoustically, you will not be aware of the side effects of EMI and related issues till you plug it in and so risk false positives. It was for this reason that I abandoned signal generator experiments...as I was trying to say...in my own unfortunately offensive way ... wow, seems like I've missed some pages here.. does anybody could tell me what is going on now? new schematics? new ways to build this? Good question... hmmm...people may have to speak for themselves...how much have you missed? Col is working on current amps using the LM386 in this way and a new HB sized dual coil driver to match this kind of thing. Hank is pursuing the "ultimate" sustainer by actively experimenting with single string drivers with a view to a hex system. David has several different approaches that he is conceptually exploring or discussing...personally I think there are a number of things being overlooked that would scuttle these ideas practically. Donovan has been having trouble with high string response with converted single coil pickup drivers. A couple of members have been having trouble with faulty fernandes sustainers...so there is some work to fix and understand them a little better. I appear to be engaged in digging my own grave in an attempt to contribute or help, and largely failing at that! I continue to promote the simple single coil driver and simple circuit as a practical and workable way of producing sustain and harmonics....others have a different approach, desires or doubt the results perhaps. A little further back MRJ posted a layout for the F/R circuit with improvements that are advisable for better performance. Some internal magnet driver building techniques were demonstrated by Al that look promising. ... In this summary am I in anyway trying to speak on their behalf, just my understanding of what seems to be at play and why the thread is so active at the present time. There have been some healthy (and perhaps unhealthy) debate along the way as has often been the case from time to time. Just offering the summary as a bit of a catch up, I see there has been a lot of non-menber visits and it is a bit confusing I'm sure! pete Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) Well...I am glad that you plugged it in and also that you tried running a properly preamp/amp circuit from the actual guitar's signal (bridge pickup) into your driver and got good results. The TDA7053 was one of my previous suggestions when this was being discussed and something I did try and held (and still do) hold hopes for to replace the venerable LM386. My reason for going 'non real world' initially, was purely to get a controlled enviroment. I'm actually quite shocked at the night & day results. ...I certainly cant account for why feeding a standalone sine wave into the driver vs the guitar string (which very soon morphs into a sine wave anyway!) should yield *massively* different amounts of EMI. I'd really like to be able to explain that one away! Without meaning to be patronizing , by doing this (plugging the guitar in, trying the guitars output and a good stable circuit (your very simplified lm386 thing didn't include zobel or other stabilization suggestions for the chip)) you seem to have come up with similar results as I have described. One could extrapolate that if your driver were bigger and trying to cope with the complexities of multiples strings (or if you were running six of them), that there might be less efficiency and greatly increase EMI effects which may cause some concerns or require extra measures. Again, this would be pretty much the kind of effect that the more simplified approaches seem to exhibit. Non patronising tone gratefully accepted! I'm viewing it the other way...once I have all drivers in place, each 'tuned' for minimum current...there ought to be less 'reach'/sprawl of EMI. Yes, there'll certainly be more EMI activity in the immediate vicinity of the driver...but like I say...I'm hoping its reach will be less. This could be the one massive kick in the pants...all this work I then eventually assemble it together down the line only to find & it's EMI Central! I sincerely meant that while sustain is possible acoustically, you will not be aware of the side effects of EMI and related issues till you plug it in and so risk false positives. It was for this reason that I abandoned signal generator experiments...as I was trying to say...in my own unfortunately offensive way to be truthful...what I got was a false negative...the sig gen was much *much* worse (like 100 times) than using the guitar signal as an input (& who'd have thought?!) It was so bad, I was genuinely puzzled how anyone could have a working sustainer without EMI! I was getting EMI with the mini driver located up at the machine head lol. This is troubling me, but I haven't got time to investigate this right now ( I've only so many CPU cycles in my head I can dedicate to the issue-ettes this project throws up!). If you get a minute & want to have your head messed up, download test tone generator...plug the output of your soundcard into your driver circuit's input...prepare to don radioactive underpants due to the shear amount of EMI bounding about! Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 That new setup sounds familiar.....could it be that our friend zfrittz6 actually was not so far off track after all? David L David...With all due respect...I am not sure if you were around at the time of zfrittz6 but his circuit and drivers (at least to good extent) were tried and failed. His response was that the circuit had error, in fact as presented these errors failed for it to work as an amplifier at all. As I recall his results were not all together verifiable...but for all we know maybe it worked in a fashion once the bugs were worked out. I have already explained how the switch idea while clever may in fact have fundamental problems and as far as I am aware failed to be built or shown to actually work! However, what would be most instructive would be if you were to attempt to replicate his work and prove it for us. Otherwise, I am putting on the patronizing attitude I can tell...some of your suggestions are really wishful thinking. I often do this, and I come up with ideas and even experiment with them. There seems to be some misunderstanding about the ebow for instance or aspects that keep getting overlooked. Scaling the device up for instance means scaling up everything including the distance between the internal driver and pickups...that could be up to six times the size of a conventional ebow right there! You will find somewhere my attempt to build an ultra miniture ebow with one of my single string hex drivers and a similar thing as an internal driver and an off board or surface mounted circuit and battery box for instance. Not bad ideas, worth you having a go at them too if that is what you are seeking...personally I cam up with a lot of problems and shelved the idea in favour of pursuing the direction I did (no point having a successful sustainer and such a device really). I was particularly taken with the idea at one point as exploiting one of the aspects of one of my hex driver approaches that created harmonic effects depending on alignment. The intention was that in a hand held device such harmonic effects may well be created by simply twisting the little ebow in relation to the string. But honestly...there are significant problems to be overcome, practicalities involved and all kinds of issues. That does not mean that these things couldn't be solved...but it would take a lot of time and dedication, and motivation to do so. The whole sustainer to my mind is deceptively simple. At it's most basic it really is just regenerating the signal into a coil that excites the strings...but always the devil is in the details...and this is where the real work and challenges are. It is a bit of a balancing act. One way of getting a feel for some things is to take things to an extreme. For instance, a completely sealed driver would potentially eliminate all EMI (this was part of zfrittz6's tin can enclosed drivers) but in doing so, it could completely eliminate the EM forces that drive the string! Another approach would be to create something that focuses the field...dual coil drivers are a strategy but can suffer from a lack of projection...one way to help this as col is doing is to widen the gap between the coils. A sound idea, but enlarging the driver. Perhaps it is a better way, or something similar (bi-laterals, alternating hexs) but with some other sacrifices. Col and the commercial guys have taken or embarking on this route and in part overcome the sacrifices by allowing the driver to act also as a pickup...either through pre-amplification or transformers to help with impedance matching. Not a bad idea at all really, perhaps a low impedance driver could be built to equal or better the tone of an active or passive pickup (the sustainac I heard wasn't at all "bad")...but for others the need to always have power for the guitar to work and no choice of neck pickup might be too much. That's not an advertisement of my approach, I too have made many compromises, it does what it does in that form. To take it further, you will see that I have had to resort to things like multicoils and magnetic shielding...the mid pickup attempts for instance. ... So in short it can come off as patronizing or "shooting your ideas down in flames" when someone, usually myself, tries to show the shortcomings in them. Then I find my comments (which with all due respect have a fair bit of practical experience behind them) are dismissed in quotes from other unacknowledged parties, and then their apparent shortcomings dismissed as off hand remarks. pete Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 Thanks Hank...it is appreciated... Non patronising tone gratefully accepted! I'm viewing it the other way...once I have all drivers in place, each 'tuned' for minimum current...there ought to be less 'reach'/sprawl of EMI. Yes, there'll certainly be more EMI activity in the immediate vicinity of the driver...but like I say...I'm hoping its reach will be less. This could be the one massive kick in the pants...all this work I then eventually assemble it together down the line only to find & it's EMI Central! Well...one thing that is in favour for hex coils (though I did not find it a solution) is that they can all be wired alternating RWRP which might help matters. EMI is unavoidable...it's what makes the strings go...the trick is to balance the power and the efficiency and the distance between the driver and pickups to get something that works under practical conditions. My hex drivers did seem to work much closer to the pickups than some things, and they also were capable of miniaturizing that helped a lot as well. Whether you are able to make something that fits your requirements can only be had by trying. I did "settle for less" in the end I suppose, but it did strike a balance of goals quite effectively and exceeded them in some areas to my satisfaction as I say. Others may want more...the commercial systems are a little more elegant and sound a bit different, and most likely a cheaper solution for many. I suspect col has o is well on the way to a similar response. There are lots of other areas to explore as well...like the harmonics thing. There will be limitations and compromises I am sure, the sustainic guitar that I encountered had a variable "mix" control that I thought was more effective and was somewhat envious of. I think my circuit could do with a much better AGC for most things. One should not underestimate techniques as well with these things...they do tend to require the development of skills to get the most out of them even when they do work! anyway...thanks and good hunting for the solutions and the explanations you seek pete Link to comment Share on other sites More sharing options...
col Posted March 27, 2009 Report Share Posted March 27, 2009 This occurs when there is excessive drive signals (so my circuits and the F/R can display this at the higher gains quite easily...cols heavily AGC things far less if at all I suspect). but that wouldn't be the case when the battery is dying (when youve said fizz is especially prevelant) You get fizz when there's hard clipping. This occurs with too much gain. It also occurs when the battery is very low - As the battery drains, the voltage drops and the headroom is reduced so clipping occurs with lower voltage signals than when the battery is fresh. cheers Col I'd say that fizz could possibly be better defined as distortion as seen on the signal across the driver vs the input signal .....this could be either Hard clipping (driving the output signal past VCC) or soft clipping (VCC is fading away below that of output stage's normal working 'region)....OR any other other form of interference on the driver signal. In short it's distortion...but even though fizz seems a bit of a girlie description...it's very apt! Hmm, so fizz is a girlie term... I guess next you'll be calling magnetic pull gay ? Fizz is a particular type of sound that is produced by the system that is a SYMPTOM of some type of distortion of the signal. I use the word fizz because: #1 everyone can understand it - it obviously not a low frequency rumble or a musically usefull crunch, or even a soft breathy fuzz. #2 if I start talking about distortion artifacts in the range 1.5k - 4k (or whatever it really is) then I'm going to go crazy and most of the people here are going to get confused and misunderstand my posts even more. What's seen across the driver is not as helpful as you think - altough it would be a nice coup for you - you know none of us have scopes, so if we agree that we can only make worthwhile comment based on measurements taken accross the driver, we'd all have to shut up and listen to you. :-p What would be more useful to see is measurements taken across the pickup (we have to depend on your scope for this). We only care about distortion that gets to the pickup so that's where to start IMO. In that context it would be worth seeing if those match the distortions in the driver - is your scope dual trace ? fizz could be caused by distortion in the driver circuit fizz could be caused by flux being transported via magnetically saturated strings to the pickup fizz could be caused by transformer coupling between pickup and driver generating voltages in the pickup high enough to cause clipping there. fizz could be caused by high frequency distortion generated by the shitty LM386 getting into a badly designed ground configuration fizz could be caused by eddy currents in the driver core fizz could be a symptom of the phase gap between driver and pickup 'selecting' some small atonal bands of high frequency noise to promote I would guess its at least two of these things that cause the high frequency nasty sizzling artifacts, so by far the most sensible name for them is fizz - which is why its ended up as the defacto term here. I agree that a systematic approach to discovering which are the significant causes would be the best way forward - I spent some time promoting using a test rig to work on this, but I took a long break from the project at that time because I got sick of pissing into the wind Sadly, I ran out of time again...but with my 8 ohm single coil, driving the Low E, A, D, G strings was very easy - the B String was troublesome, the high E just about do-able. This is a conundrum...why should the B string be such a problem (it's thicker than the high E...& the high E sustains - anyway needs further pondering! Don't forget that the response of your guitar will have an impact on which notes sustain easily. My guitar significantly favours the G string over all others. Unless you can use a range of different guitar shapes to test on , your systematic approach will be weaker in this area. If you can, you will probably find that to get the full intended value (per string tailoring of drive) from your hex approach, you will have to make the cores adjustable or just accept that each new install will require a custom hex driver design. One quick number, for this 8 ohm coil (400 turns of 0.15mm ...1cm deep, core of 5mm mild steel), there's 300mV peak to peak needed for the G string to 'sustain' just past what I call 'the edge' (about 25mA AC current measured with my DVM). This figure tails away as the strings get thicker (eg the A String at the 12th fret needed approximately 180mV & 15mA If you hold down the A string at the twelfth fret, it will be physically closer to the driver and therefor need less power to drive the sustain. This issue is worse for me because I like quite a high action, so the difference is very noticeable. So improved performance in this case may be related to the string gauge, or it may be completely down to gap from string to driver. (dead horse flogging time: the field strength drops off with the square of the distance, so a small change in the gap from string to driver can be significant, particularly if you are taking scientific measurements to base a theory on) This last point is where I personally think a major win of the hex approach lays....tailored coils (& current) per string. I also very much like the idea, of having tailored the coils to each string, a circuit which will yield a constant current into the coil. I could be wrong (& I'm sure Pete will chime in that he's already tried & the reusults weren't good), but I'm hoping with the right 'tailored' coil per string, coupled with the absolute minimal but constant amount of current needed to get the string sustaining *just* past the 'edge', that inter string driver interference will not be a major source of problems. There will be coupling between the coils. That they will affect strings other than their own is not really an issue I would guess, but the change in inductance of the coil when it is stacked with two other coils either side will be if your not ready for it. A coil that has optimum inductance for you system when stacked with other coils will not be optimal when used stand alone. My guess is that the math and physics involved in calculating this effect would be a major chore and not accurate due to not having specs for core materials etc. so the only way to get this 'just right' will be through iteration. Just as well you've built a winding machine hehe. cheers Col Link to comment Share on other sites More sharing options...
chops1983 Posted March 27, 2009 Report Share Posted March 27, 2009 Hi Chad and fellow aussie You are not likely to be able to inlay it on a fretboard...have a look at my recent tele driver (see blue link in sig). On such a coil the blade is just wider than the width of the string spread...but the coil needs to go around that...much like and for the same reasons that a pickup is wider than a neck. There would be other problems implimenting it as well if you think through how you would go about this... pete yes...completely agree col... Fair call! I knew there would be some reason why you guys have not done it yet! So why then does vibes say to move it up the fretboard? Their design is obviously individual drivers for each string or much more compact. Is there a link to vibes sustainer so i can have a look? Chad. Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) Hmm, so fizz is a girlie term... I guess next you'll be calling magnetic pull gay ? We need 'MAN' terms here ....eg inductance, resonance, distortion, EMF, EMI, flux ..........but 'fizz'? (I'm jesting here....ok?!) What's seen across the driver is not as helpful as you think - It is if you've got [dons a skirt] 'fizz' & you can't figure out where it's coming from! [parks girlie 'fizz' jokes for the foreseeable future] What would be more useful to see is measurements taken across the pickup (we have to depend on your scope for this). We only care about distortion that gets to the pickup so that's where to start IMO. In that context it would be worth seeing if those match the distortions in the driver - is your scope dual trace ? Yes it is....and it has storage capability too (handy for transiential sounds like guitar strings) - but have you ever scoped a guitar magnetic pickup signal? It's very small & certainly on the scope, not all that 'clean' to look at. I'm fairly convinced that fizz is reasonably easy to identify across the driver...to replicate I cranked VCC both up and down & could hear it on the guitar output - for the fizz I'v heard, the signal across the driver either visually clips or changes it's attack/release element (when VCC drops below the chip's normal operating range) fizz could be caused by distortion in the driver circuit fizz could be caused by flux being transported via magnetically saturated strings to the pickup fizz could be caused by transformer coupling between pickup and driver generating voltages in the pickup high enough to cause clipping there. fizz could be caused by high frequency distortion generated by the shitty LM386 getting into a badly designed ground configuration fizz could be caused by eddy currents in the driver core fizz could be a symptom of the phase gap between driver and pickup 'selecting' some small atonal bands of high frequency noise to promote They're all plausible, but it the light that I have no fizz when the VCC is set for correctly for a decent output stage (ie not an LM386!), then we can probably place less significance on a good few of those. I agree that a systematic approach to discovering which are the significant causes would be the best way forward - I spent some time promoting using a test rig to work on this, but I took a long break from the project at that time because I got sick of pissing into the wind The wind does seem to be quite blustery. If you can, you will probably find that to get the full intended value (per string tailoring of drive) from your hex approach, you will have to make the cores adjustable or just accept that each new install will require a custom hex driver design. I'm coming round to the idea of adjustable cores - but it'll likely hard to find sutable non galvanised steel screws (in fact non galvanized anything) this is disheartening, as I'm faced with threading my own rod. In fact. It's readily apparent I'm flying solo when it comes to sourcing parts. I tried ringing B&Q and asked for some suitable bobbins with a thread hole for a hex sustainer project...he sold me some decking. (if only I lived Stateside There will be coupling between the coils. That they will affect strings other than their own is not really an issue I would guess, but the change in inductance of the coil when it is stacked with two other coils either side will be if your not ready for it. A coil that has optimum inductance for you system when stacked with other coils will not be optimal when used stand alone. My guess is that the math and physics involved in calculating this effect would be a major chore and not accurate due to not having specs for core materials etc. so the only way to get this 'just right' will be through iteration. Just as well you've built a winding machine hehe. Completely agree...rather than try & work it out on paper, I'm just gonna have to suck it and see... & yes, wasn't my auto coil winding machine was visionary?! lol !! Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
TheEdge Posted March 27, 2009 Report Share Posted March 27, 2009 thanks for the summary Pete, great as always! Link to comment Share on other sites More sharing options...
Leppard84 Posted March 27, 2009 Report Share Posted March 27, 2009 Just some points I wanted to make before I head out for work today, gotta load those boxes... I've been keeping up on the 386 discussion and thought I'd chuck my 2cents of knowledge into the mix. The LM386, if that is what anyone is using, is the junkiest form of the chip. We can get them at Radio Shack here in Toledo, Ohio. Made a Ruby amp for my friend with one of those and sounded crappy at best. I ordered a NJM 386-D from mouser electronics and the gain control and overall sound improved dramatically IMHO. I understand they're appealing only because of thier simplicity but I thought I'd throw that out for everyone else to give a try. And my Fernandes circuit board is getting mailed out this weekend to a company that will repair it for me! A little beyond my capabilities and equipment. But I looked up the op-amp in it, a NJM 062-D. Just a plain dual op amp, no FET input or anything, which kinda surprised me. 1Mhz gain bandwidth (I have no clue what the relevance of that or the slew rate are, yet...) and a 3.5V/us Slew Rate. Maybe you knowledgeable types can figure something out with some of specs of that, but I was thinking about trying a TLC2272 (low noise rail to rail) as my op-amp, with a FET input buffer infront, and test out a ruby stage with my good 386 (only got one NJM here) and my driver. Will let you know how it goes after I get back and start boarding again. Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) Just a thought...in the previous 300 pages, has anyone experimented with 'Y'-ing off the power amp input signal ....& then feeding this duplicate signal 'inverted' to a say a 'blocker' coil placed somewhere between the driver & the middle guitar pickup? (& at a slightly lower level towards cancelling the EMI) Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 Just a thought...in the previous 300 pages, has anyone experimented with 'Y'-ing off the power amp input signal ....& then feeding this duplicate signal 'inverted' to a say a 'blocker' coil placed somewhere between the driver & the middle guitar pickup? (& at a slightly lower level towards cancelling the EMI) Me, Me...oh, pick me.... I haven't got a word in edgewise, but being 4:16 am .... I didn't do a lot of this kind of thing, but I did propose the Idea and try a few things to a lack luster response. My idea was to have a coil around a core (like now) but another coil around this coil of an opposite polatity. I think I called it an "active shield". However, others probably could see it straight away, while I took a while to come to see the falicies (ohh, is that a gay word?) ~ The outer coil or similar "active shield would require power to run it....something in short supply. ~ It would also be putting off it's own EMI potentially adding to the problem as without a core, it wouldn't be very focused ~ Probably a whole lot of other things that I can't think of at this time of day...like lowering efficiency by canceling drive forces in the driver Anyway...this is really what the dual coil ideas are doing...except, that the secondary RWRP drive coil also uses the power to drive the string and creates a kind of magnetic shield that is identical to that of the driver (as it also has a core) So...to that extent I have tried stacked coils, side coils, bilateral coils, alternating hex coils. I did try some active shields, etc... This kind of thing would likely be fundamental to a mid placed driver for instance in which there was a fair amount of work with little or no gains yet. You may find that you are simply going to have to provide adequate distance and remove the other pickups from circuit in any practicable driver or set of drivers... I still see some fundamental flaws in your experiment setup there...your driver is suspended right next to and over the neck pickup on the bridge side (so close to the middle as well) In addition to the fizz thing (in which I think col missed some more possibilities) there are other very similar effects that sound just like it or are related...many of them to do with incorrect bypassing for instance. BTW...the technical term that Sustainiac use in their manual for fizz is grunge! Col and me and most others do tend to agree that one fundamental aim is to provide completely clean sustain...so any distortion is a bad thing. So things like "fizz" is often pretty mild and completely hidden if you use any kind of distorted, even mildly crunchy amp tone...but still "not acceptable" given that aim. Clean amp headroom is a great help, but not a total solution. Also..."fizz" type disortions can sound radically different on different guitars. Most "fizz" to my ears also sounds like string rattle. Given the ferocity that you can move these strings it can often be mistaken. Many people play guitars with light strings and a very low action and don't have a problem with a bit of string rattle. Like col, my action is reasonably high with 10's...some sounds can sound a bit "fizzy" when driven to extreme's but is in fact this string rattle effects...more AGC would aid in this. I can also get fizz (especially with a low battery) but it can be avoided to a very large extent even without dual coils and complicated circuitry...but you do need to take precautions! Anyway enough from me for now...the conversations seem to be returning to something more productive and I guess we are all learning along the way. ... Oh...I did try some piezo things in working towards separate signals for each driver. However, much of my hex things worked on using all the coils simultaneously but "tuned" for each strings response as a starting point. Various reasons for that...most concepts were tested as a single string driver then expanded to six...but the physical size of the things made a big difference to performance, EMI, etc and these were getting ever increasingly more difficult and expensive to make. There were a lot of failures much of the work having to be done with a big magnifying glass! As col said...at some point you feel that chilly wind Pete Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 However, others probably could see it straight away, while I took a while to come to see the falicies (ohh, is that a gay word?) ~ The outer coil or similar "active shield would require power to run it....something in short supply. ~ It would also be putting off it's own EMI potentially adding to the problem as without a core, it wouldn't be very focused ~ Probably a whole lot of other things that I can't think of at this time of day...like lowering efficiency by canceling drive forces in the driver Hmm...convinced that any of those should dissuade (yet!) Re needing power... the EMI 'level' obviously drops off as the distance from the driver increases...therefore it shouldn't need as much current (in comparison to the power in the driver coil - which isn't that much anyway!) Re the blocking coil putting out it's own EMI ...well, that's the whole point!. If you get the balance/ratios right, the EMI eminating from the driver should exactly be cancelled by the blocking coil. RE 'cancelling forces in the driver', again, the blocking coil should be at such a low EMF level (& sufficient distance from the driver) not to figure in this equation. Since there hasn't been that much exploration down this avenue, I'll put this one for the 'to try' soon list. (btw, I can prove/disprove zfrittz6 switching solution sometime over the weekend hopefully) Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) However, others probably could see it straight away, while I took a while to come to see the falicies (ohh, is that a gay word?) ~ The outer coil or similar "active shield would require power to run it....something in short supply. ~ It would also be putting off it's own EMI potentially adding to the problem as without a core, it wouldn't be very focused ~ Probably a whole lot of other things that I can't think of at this time of day...like lowering efficiency by canceling drive forces in the driver Hmm...I'm not convinced that any of those should dissuade further investigation (yet!) Re needing power... the EMI 'level' obviously drops off as the distance from the driver increases...therefore it shouldn't need as much current (in comparison to the power in the driver coil - which isn't that much anyway!) Re the blocking coil putting out it's own EMI ...well, that's the whole point!. If you get the balance/ratios right, the EMI eminating from the driver should exactly be cancelled by the blocking coil. RE 'cancelling forces in the driver', again, the blocking coil should be at such a low EMF level (& sufficient distance from the driver) not to figure in this equation. Since there hasn't been that much exploration down this avenue, I'll put this one for the 'to try' soon list. (btw, I can prove/disprove zfrittz6 switching solution sometime over the weekend hopefully) I still see some fundamental flaws in your experiment setup there...your driver is suspended right next to and over the neck pickup on the bridge side (so close to the middle as well) Please, you need to gather some facts before you start finding 'flaws'. My intention (at this stage - until proved otherwise) is never to have the sustainer driver active when the the neck or middle pickup are selected ...hence the driver's position relative to the neck/middle pickup matters not a tot ...what does matter of course, is the driver's position wrt to the bridge pickup....but last night I established that the EMI is sufficiently low up until about 1cm from the middle pickup...at this point squeal from the bridge pickups erupts (as it goes, that video is out of date...the neck pickup was taken out of the guitar early last night & the 0.063mm wire peeled off the pickup pending further driver coil experiments!) Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 Since there hasn't been that much exploration down this avenue, I'll put this one for the 'to try' soon list. (btw, I can prove/disprove Since there hasn't been that much exploration down this avenue, I'll put this one for the 'to try' soon list. (btw, I can prove/disprove zfrittz6 switching solution sometime over the weekend hopefully) Hahaha....you guys wont let sleeping dogs lie...seriously though, It doesn't seem like you are anywhere near getting a handle on the factors that make this a problem. This thing has been tested any number of times really. All that concept is is that the bridge pickup is selected and the circuit switched on. Everyone who has ever tested as I suggest before installation has done exactly this...if simply switching it on were a solution that generally worked I surely wouldn't be spending $7 plus just for the switch to turn the thing on and all that wiring stuff. But...maybe you have something that works "crystal clear" no fizz hanging over and between the middle and neck pickups with no interference at all...in which case it may well work. It occurs to be though that zfrittz6's driver was pretty big and he may not have been using multiple pickups at any point...but hang on, no one actually tried it because that switching on by connecting a battery with the bridge pickup failed...and then zfrittz6 disappeared with translation difficulties. I still get a feeling though that it would be instructive (not and end to your quest) to build a thin coil design (20 minutes) since you have the rest of the system down (circuits, guitar etc) and see what happens. Then at least you will have a basis to see how to improve or diverge from this and maybe get some more insight into what problems are there with the most basic approach. As I recall, col did this and then went straight on to a dual coil approach...at least by doing so there is something to compare it with. That is not saying that this would halt work towards a hex design or anything that would improve performance...it didn't stop col for instance or curtisA or many others. One approach would be to remove other pickups from the equation then add them back in...when I did the sustainer strat (my first complete rewire/install) this is exactly what I did to find a solution and identify where the problems were coming from. I used to work from the other way...if it didn't work with these pickups in here, then that's not working. I doggedly pursued this course because I couldn't see where the problems were coming from or dismissed them. Even if the end result required is that the pickups must not be bypassed for your aims...then finding out what is the problem with that is crucial. But...maybe you have found a way...a single string driver can be extremely deceptive. I had one working within 2cm from the bridge pickup on the b string with the other pickups installed in some manner (ultra tiny device)...but there was no way when scaled up that these devices could be operated in such a way. I was also using some fairly exotic ways of creating these things...transverse orientations, iron epoxy shielding and heat absorption, balance magnetic fields, very tiny focused components...all in the same devices. Still, I could not get that kind of performance or overcome the problems that I didn't at that time know existed. Later, I was kicking myself that I didn't bypass those pickups because in all likelihood on some designs that would have fixed a lot of not all the problems with some of these things. Sometimes I even think of returning to them (I had to by some components in bulk so I got too many that are useless for anything else) but then I remember how much work went into creating them and how so many of my aims have already been at least partly satisfied by the simpler approach, and compensated for in other ways. Might give myself a kick anyway though... pete Oh...I was wondering...have you tried reversing the driver wires to get the harmonic effect with your set up? There are times that I have been able to get pretty good results (like a mid driver or close pickup driver thing) but all hell (squeals, etc) breaks loose when the thing is reversed. Hmm...I'm not convinced that any of those should dissuade further investigation (yet!) No...I still like the concept...you will find a heap of drawings around about the thread from me somewhere...I even found a neat way of making them...hahaha However...the big difference is that I had something to compare it to. I have made all kinds or wacky designs including "active shields" (not all for sure) and most worked in one way or another...but they did not work better! One particularly interesting one was a three bladed miniture stack thing...it wasn't working too well, till I dropped it on the strings by accident and it fell on it's side and all manner of sustain goodness came out of it. Unfortunately, the coil wires broke after a bit of handling and couldn't be fixed. Such designs have not been discussed too much here. A lot of "failures" I never posted due to embarrassment after a while. I did get pretty obsessive after a while...so close, just a little more work and...nope, try something else. We are talking hundreds and hundreds of hours of practical work and a fair bit of money I dare say (hate to think)....and I'm not the only one who has been doing similar work over the years in exactly the pursuit you are after. You may well crack it! But...the active or passive shielding approaches won't eliminate the "issues" completely unless it eliminates the EMF for which EMI is the natural byproduct. The most effective thing is to move the things further apart it would seem. Less power will only work with greater efficiency, negligible phase differences and ideal circumstances...IMHO...obviously something to be aimed for. Col's approach to only put out power as required and then cut back is perhaps a better approach to the power thing...which of course is a circuitry thing and outside of my skill set Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 Please, you need to gather some facts before you start finding 'flaws'. My intention (at this stage - until proved otherwise) is never to have the sustainer driver active when the the neck or middle pickup are selected ...hence the driver's position relative to the neck/middle pickup matters not a tot ...what does matter of course, is the driver's position wrt to the bridge pickup....but last night I established that the EMI is sufficiently low up until about 1cm from the middle pickup...at this point squeal from the bridge pickups erupts (as it goes, that video is out of date...the neck pickup was taken out of the guitar early last night & the 0.063mm wire peeled off the pickup pending further driver coil experiments!) Sorry, can only go by what I know of what you are doing...my fact gathering ability is limited entirely to what you reveal. Still...there is an assumption that complete bypassing of pickups is not necessary despite the evidence that it apparently does matter. The presumption seems to be that your hypothesis is correct and the experience that it does can simply be dismissed. You may have found a solution, or you just may not have yet come up against the problems that at least would appear to be likely...so I raise your tot, till proven otherwise (and I hope you do)! Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) But...the active or passive shielding approaches won't eliminate the "issues" completely unless it eliminates the EMF for which EMI is the natural byproduct. The most effective thing is to move the things further apart it would seem. Less power will only work with greater efficiency, negligible phase differences and ideal circumstances...IMHO...obviously something to be aimed for. Col's approach to only put out power as required and then cut back is perhaps a better approach to the power thing...which of course is a circuitry thing and outside of my skill set Like most things in life, there'll not be one simple solution...but likely a combination - a hybrid outcome. Putting out power only when it's needed is good (& I raised this point after the sustainer circuit was posted up yesterday), but I'd say that applying only the bare the miniimum of power and only when it's needed is even better - see .....a hybrid in it's embryonic stages! This is why I'm more focused on getting some meaningful data down (power required per driver, per string etc). I tried sourcing some 0.2R resistors today (to no avail!), as I do think a constant current through the driver coil approach is a better than trying to compensate voltage vs frequency using filters earlier in the circuit...hey ho, the hunt continues. PS Re reversing the signal to the coils (for harmonics) ...well, I'm on breadboard & at this stage don't have a switch in cct (& being late, couldn't be bothered to reverse the wires manually!) - I did notice that when I flipped the driver coil a full 180°, the bridge output squealed like a good pig with a septic trotter. Harmonic switches are way further down the line (& 'if at all' - as my approach to harmonics will likely take a different tack). I actually seek clean fundamental frequency sustain evenly applied across all the strings over all else. ....especially in these early stages. PPS I'm not presently geared up to make your standard issue prescribed driver on my pickup winder - yet. My traversal system feeds copper wire onto metal rod held/turned by a drill chuck holding arrangment. I'll need to make a bobbin holder to go into that holder (which I will do soon, as it gives me more options) Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
col Posted March 27, 2009 Report Share Posted March 27, 2009 I tried sourcing some 0.2R resistors today (to no avail!), as I do think a constant current through the driver coil approach is a better than trying to compensate voltage vs frequency using filters earlier in the circuit...hey ho, the hunt continues. hehe, not so easy eh? I got 0.1 and 0.22 from a little local independent shop, but they are big chunky wire wound jobs. If I had a meter that could measure very low resistances reliably, I would probably make one. If you trust the manufacturer to make the winding wire with close enough tolerances, you could wind one yourself by working out what length of wire you would need and wrapping some suitable bobbin with a few turns. I even though of using the final few turns of the driver coil as the low value resistor, but decided that it really needs to be on the circuit board and mounted in a sensible position to prevent parasitics effecting the functionality. Re your thought about using a reverse polarity coil to reduce coupling between driver and pickup, there was an interesting idea proposed a while ago (can't remember who by), but I tried out some variations. what you do is take a loop of wire from just before the driver - some single core bell wire works - and bend it into some shapes putting it between driver and pickup or even in a loop around the pickup (leaving an inch or two gap all round). This is an interesting experiment, and results were occasionally surprising but for it to provide a practical solution it would have to be researched a lot more. Definitely something you should try out though because its quick and easy to play with. Re Petes suggestion that a dual core driver works in a similar way - I don't think that correct (although I will have to double check at some point). The sustainiac does work this way (I think?) but suffers from weak sustain near the centre where the two coils meet. A humbucker style config just has way too much cancellation. What my coils are doing is both pushing at the same time or both pulling at the same time - this shrinks and expands the permanent field. The reason this gives better performance with reduced fizz is because: # the permanent field is more contained and focussed # you get twice(roughly) the magnetic pull from the same level of drive signal, so you can reduce the gain more. # (possibly, but not sure) more core material means core saturation may be less of an issue. It is possible to contain the field better with a single coil driver, you need to use side (and bottom) plates - basically external core pieces - these focus the field much more tightly. However, they will also increase the inductance, so the coil would need some tweaking in order to achieve similar drive performance. I have tested this and it does improve things - my old single core driver was almost able to match my old dual core driver fizz wise (the old dual core driver was not wired in parallel, so does not benefit from the 2x magnet power thing) I wonder if a hex driver could be improved by using an open topped E core (similar to what I just described for the single core driver). The outside plates would between the coils, with a small air gap between each unit - might this help to minimise losses due to coupling between the cores ? cheers Col Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 27, 2009 Report Share Posted March 27, 2009 (edited) I should quantify... I can locate 0.2Rs but only in larger wirewound 3-5W varieties (Farnell have some in 0.5W, which are SMT, but since they'll be bigger than normal, they're likely to be useable) Re the blocking coil (or active shield, if we want to go all Trekky!)....it's not clear what's being fed into the bell wire? what you've decribed would obviously have a very low DC resistance & therefore pull a whacking amount of current! Also was there any inverse driver signal being channeled into it? Thanks for the heads up wrt placing cores between hex coils...I'm still a way off observing how several hex coils interact yet, as I'm still dicking about trying to get the approximate 'starter for 10' coil (I'm hoping to get the windings down to something in the order of 150, as it's seems the 0.15mm wire at 400 turns on my bobbin - to make 8 ohms - results in a coil to 'perky' for its purpose)....smaller seems to be the name of the game here - & not easy to get bobbins for what I'm intending doing. (* my previous attempts at winding have illustrated all too clearly that some form of bobbin is needed to wind a coil!) Edited March 27, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
psw Posted March 27, 2009 Author Report Share Posted March 27, 2009 PS Re reversing the signal to the coils (for harmonics) ...well, I'm on breadboard & at this stage don't have a switch in cct (& being late, couldn't be bothered to reverse the wires manually!) - I did notice that when I flipped the driver coil a full 180°, the bridge output squealed like a good pig with a septic trotter. Harmonic switches are way further down the line (& 'if at all' - as my approach to harmonics will likely take a different tack). I actually seek clean fundamental frequency sustain evenly applied across all the strings over all else. ....especially in these early stages. I mention this as a primary indicator of the complete bypass necessity...reversing the magnet/coil is the same effect. This may need to be explored a little more. PPS I'm not presently geared up to make your standard issue prescribed driver on my pickup winder - yet. My traversal system feeds copper wire onto metal rod held/turned by a drill chuck holding arrangment. I'll need to make a bobbin holder to go into that holder (which I will do soon, as it gives me more options) Generally better results are made by good hand winding than with any kind of winder...as in the pictorial...with the glue potting and everything it is generally not the best. Even my tele driver was effectively hand wound as my winders battery was flat but discovered only when I had the epoxy ready to go and the wire tensioned...d'oh...but we are talking less than 200 winds, not much really Link to comment Share on other sites More sharing options...
col Posted March 27, 2009 Report Share Posted March 27, 2009 Re the blocking coil (or active shield, if we want to go all Trekky!)....it's not clear what's being fed into the bell wire? what you've decribed would obviously have a very low DC resistance & therefore pull a whacking amount of current! Also was there any inverse driver signal being channeled into it? No worries about current, because its in series with the 8ohm driver coil. Think of the bell wire as the first turn of the driver coil, but detached and moved. Remember, you don't need to invert the signal and split it, just turn the loop over and the current is going the other way so the polarity of the magnetic radiation flips. (all that RWRP talk is bogus, it's either RW or RP that you need, both together would get you back to where you started!) In this case, using RW gets you what you need for your "simple loop of wire test". Thanks for the heads up wrt placing cores between hex coils... That idea (a brainstorming - may be nonsense one) will only work if the permanent magnets all have the same polarity - if you try to do some sort of alternating NS SN NS SN deal, it will fail. although, it seems to me that you might be as well using just one big old full width permanent magnet to magnetise the strings with your individual coils siting on top ? cheers Col Link to comment Share on other sites More sharing options...
Hank McSpank Posted March 28, 2009 Report Share Posted March 28, 2009 (edited) No worries about current, because its in series with the 8ohm driver coil. Aaah, I just revisited your post... what you do is take a loop of wire from just before the driver - some single core bell wire works - and bend it into some shapes putting it between driver and pickup or even in a loop around the pickup (leaving an inch or two gap all round). This is an interesting experiment, and results were occasionally surprising but for it to provide a practical solution it would have to be researched a lot more. Definitely something you should try out though because its quick and easy to play with. there wasn't enough detail! - but in series makes complete sense now! My only thought here is that we're trying to fight EMF that was created using 200+ turns on the main driver - is a simple one or two turn reversed loop up to the job? (also, it's not exactly the most concise, aesthetically pleasing solution ... but nevertheless worth spending a short while toying with) I've had a totally frustrating night dicking about with a chip with AGC built into it (a TDA7284 - another one of zfrittz6's circuits...I do rate some of the stuff he came up & I'd like to eliminate them from my enquiries first) ...I can't get a peep out of it when I feed it a guitar signal. I now suspect it needs a a buffer opamp between the guitar output & its input (it's actually meant for a tape recorder AGC....the datasheet is awful...also, I feel I should be wearing big flares, with massive hair & listening to music by Howard Jones as I construct the lash up). It's the most embarrasingly simple of circuits too... http://www.ea4nh.com/articulos/alc/fig06.htm....some Google-ated translation splurge about the chip from a user too... http://www.tinyurl.com/c5azq7 hey ho. Edited March 28, 2009 by Hank McSpank Link to comment Share on other sites More sharing options...
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