psw Posted February 13, 2008 Author Report Share Posted February 13, 2008 It has nothing to do with sounding like a violin, (not a goal of mine anyway...) No, that's not what I meant either...it is just that the sound of the guitar once the sustainer takes hold is different from that of a simple plucking of the note. Not that a violin tone is sought, just that as with a violin, the act of plucking a string results in some "distortion" of the strings vibration not wholly associated with standing waves and simple models... around post #3481 I think...I said... Certainly it would seem that, besides all that is said above, the shear physical vibration of the strings in such an unnaturally powerful way will cause some distortion, if only in the physical way in which the string vibrates. ...to which I was trying to elude to the fact that the string is vibrating in a complex manner and that the way it is excited (plucking, magnetic sustaining, etc) 'distorts' it from the simple standing wave model....that is why I mentioned the 'physical way in which a string vibrates' not distortion in the sense of signal sqaure waveing, simply eluding to the complexity of the vibration outside of the normal expectation of standing waves by the way it is played and that the driver action will be different again. I am not seeking to sound like a violin! Hibert transformers appear to be some kind of multiple tapped transformer to create different phases...hmmm...errr...no, I don't! Well, there are other ways to create the effect but it is a lot of work if it can be done in an easier way, and the standard coil of wire seemed to be more successful and approachable. I am still astounded about this secondary coil effect of the pickup windings...everything like this that comes along sheds new light on some of the failings...and new opportunities. I still don't know why I am getting noise when turning down the guitars volume in harmonic mode or why it responds so poorly on this guitar...another mystery perhaps! Still, even this has encouraged me to seek alternatives that may turn out to be more fruitful in the longer run... pete Link to comment Share on other sites More sharing options...
col Posted February 13, 2008 Report Share Posted February 13, 2008 It has nothing to do with sounding like a violin, (not a goal of mine anyway...) No, that's not what I meant either...it is just that the sound of the guitar once the sustainer takes hold is different from that of a simple plucking of the note. Not that a violin tone is sought, just that as with a violin, the act of plucking a string results in some "distortion" of the strings vibration not wholly associated with standing waves and simple models... around post #3481 I think...I said... Certainly it would seem that, besides all that is said above, the shear physical vibration of the strings in such an unnaturally powerful way will cause some distortion, if only in the physical way in which the string vibrates. ...to which I was trying to elude to the fact that the string is vibrating in a complex manner and that the way it is excited (plucking, magnetic sustaining, etc) 'distorts' it from the simple standing wave model....that is why I mentioned the 'physical way in which a string vibrates' not distortion in the sense of signal sqaure waveing, simply eluding to the complexity of the vibration outside of the normal expectation of standing waves by the way it is played and that the driver action will be different again. Ok, this may seem a little pedantic, but first you said that: the shear physical vibration of the strings in such an unnaturally powerful way will cause some distortion(my emphasis) And now you seem to be saying that the "shear physical vibration of the strings" IS the distortion... these statements have quite different meanings, the firsts suggesting more traditional distortion as normally understood when discussing a guitar sound. The second seems to be re-stating the obvious fact that for any sound to occur, the physical string must be distorted. Complex vibration is what you get with a guitar when the strings are 'excited' by plucking bowing sustaining - whatever - you don't ever get pure standing waves. Personally, I don't think 'distortion' is a suitable synonym for 'complex vibration' Hibert transformers appear to be some kind of multiple tapped transformer to create different phases...hmmm...errr...no, I don't! A Hilbert transformer is a particular arrangement of all-pass filters that give a controlled phase response. I have a bunch of questions about the details and how they can be used that would need someone with experience of them (or a much better grasp of electronics theory than me to answer. Well, there are other ways to create the effect but it is a lot of work if it can be done in an easier way, and the standard coil of wire seemed to be more successful and approachable. I don't see how you can suggest that it is 'more successful' when you have no experience of some of the other possible approaches ? The 'standard coil of wire' as you put is certain to have a bunch of side effects that at this stage are poorly understood, at least by the folks here. You certainly can't reasonably expect to gain full control over phase shift by using some parasitic effect of whatever pickup coil is available on the target guitar. On some setups, you might get a good effect, on others it may be terrible. Its not predictable, so its not possible to design for - assuming you want something that can work on different guitars ? One possibility is that you are experiencing some interesting response with the extra coil because your 'thin' coil has a far from ideal inductance for use as a driver - if this is the case, then moving to a higher inductance would be a much better solution than relying on parasitics from the host pickup. I am still astounded about this secondary coil effect of the pickup windings...everything like this that comes along sheds new light on some of the failings...and new opportunities. I still don't know why I am getting noise when turning down the guitars volume in harmonic mode or why it responds so poorly on this guitar...another mystery perhaps! But you just said that its easier, more successful and approachable... now, there seem to be a bunch of problems ? :-p Whatever, it certainly IS an interesting effect that you have discovered, but before you can safely use it in a commercial product, you're going to have to understand it much more thoroughly and solve the side effects. Personally, I feel that in doing so, you will find that it is actually more of a problem than a solution - that it is one of the difficulties of creating a good working 'piggyback' solution. It would be really useful to get some measurements from it - that way understanding lies If you can work out what its doing to efficiency, what its doing to the inductance etc, then its going to be easier to work out how to control (or use) it and how to avoid or limit the associated problems. col Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 13, 2008 Report Share Posted February 13, 2008 Pete and Col, thanks for replying Maybe it was a bit much for a first post. Maybe it was better first to say what I was aiming at. The way I see it the production of a driver is to pass a series of test procedures. So actually you should think of a ratrace, the drivers and electronics are the rats. Failing a test the rat dies. This is the way how you've been improving your drivers, Pete. You could tell everybody that 0,20 mm copperwire works best because you've experimented with various thicknesses of copperwire. My first post was to show you a manner of how to measure the electrical properties of the produced driver. This would give some indication of the quality of the driver (it's eveness of frequency response). Col, when I spoke of the ideal conductor, I ment it as electronic component, not as driver coil. The 90 degrees phase shift will only occur at very high frequencies. Indeed the power transfer is 0. That's not what we need, we need energy to move the strings. What we need is 0 degrees phase shift. But that's exactly the problem. Building a driver is finding the best compromise. Pete knows all about that. For o degrees phase shift we could stick a big resistor underneath the strings? Nice to keep your picking hand warm, but no magnetic flux at all. Col, you were quick to point out that the core materials, the whole construction, dimensions matter. That's true, that is the quantitive aspect of the driver. We should have a test procedure for measuring the strength of flux produced by the driver. Anybody? How about revolting e-strings? I don't think you can blame the driver for e-strings being so skinny. This has to be solved electrically (eq, agc, overdrive, more power). Threaten to turn it into a f# or g-string! Combining both test procedures would enable us to experiment with coil, magnets, core material and improve the driver design. And I wouldn't rule out the option to include test procedures to tame down EMI. It only looks a bit more complicated to me because it could be driver dependent but how bad the EMI is can only be experienced and evaluated after a complete installation. Col, thanks for the information of strings motion and so on. The clip reminds me of a Pantera video clip. But I don't see why the Heimholtz motion is that important to the functioning of the DIY sustainer. Let me try to convince you. A complex sound consists of multiple frequencies. According to fourier (analysis) a sound can be broken into it's separate frequencies (sine waves). Al these sine waves can have their own life span and phase shift compared to the fundamental. Even a picked guitar string can be considered as a fundamental (standing wave) and harmonics (even heimholtz motion) superimposed on top of it. The harmonics can be so dominant that because of subtraction from the fundamental there appears to be an out of phase situation. But the out of phase situation only counts for the harmonics. Because it's out of phase it won't feed back at all. The fundamental that was buried underneath this powerfull complex of harmonics is in phase and will feed back. Maybe your design experiences some complication because of use of agc. Right after the attack your design limits the signal. It uses the louder higher harmonics as reference. As a result the fundamental is attenuated and slowly released after the higher harmonics have died out. I'm more in favour of using overdrive for sustaining. Better chop off the attack! Having said that I like the low battery sound clip. There are more ways that lead to Rome! The link shows that things aren't as bad as they look. Signal seems to have the wrong phase, but as you can see, the fundamental is completely healthy! (second picture) http://www.geocities.com/SunsetStrip/Studio/2987/fatts.html Link to comment Share on other sites More sharing options...
psw Posted February 13, 2008 Author Report Share Posted February 13, 2008 Thanks fresh fizz... The way I see it the production of a driver is to pass a series of test procedures. So actually you should think of a ratrace, the drivers and electronics are the rats. Failing a test the rat dies. This is the way how you've been improving your drivers, Pete. You could tell everybody that 0,20 mm copperwire works best because you've experimented with various thicknesses of copperwire. This is where the rats go to die... This is the failure bucket only of the latest design and only some of them at that... The box contains a bunch of older designs and novel versions of stuff...their failures reside in some other bucket somewhere... I have made all kinds of drivers, probably well over a hundred, all kinds of designs singl coil, dual coil, stacked coils, six coils, side coils, lateral coils.... Similarly, and within my limitations I have made many circuits...compressors, preamps various different poweramps... Obviously, and I have said it before...I suggest 0.2mm because that is what I have found to work...but only after some trial and error to get there from thinner to thicker. Col and I seem to have some communication problems...that is not unusual with me, especially at the moment...if I could get a bucket big enough, I'd join the rats above... I don't see how you can suggest that it is 'more successful' when you have no experience of some of the other possible approaches ? But you see, I have tried many, many different approaches, probably more than any other and I have done it for years now and at a reasonably high enough quality that every chance has been given to those ideas that I could give them. No one can have tried every possibility, that is the beauty of this stuff, but I surely have tried a whole lot... A measure of success is that it works. How well it works is a degree of that success. But in addition I have a overlaid a number of other goals onto my work, especially in the recent years that restrain some avenues of exploration. Mostly to do with practicality and real world application. I don't pursue the "piggyback" idea because it is the "best" approach necessarily, but it is one of my more successful approaches both in the way it works and within the restraints of practicality. It was a good application of the thin driver design, but that design was not built to go on a pickup...it proved to work better than other ideas. The design has proven itself further in recent times with an even thinner design. Ok, this may seem a little pedantic, but first you said that: Yes...I do think it is pedantic! I simply tried to say earlier that the act of plucking a string 'distorted' its vibration...over-and-above the guitars complex set of vibrations. It is most likely a confusion in terms or language, but not a fruitful debate I would suggest... One possibility is that you are experiencing some interesting response with the extra coil because your 'thin' coil has a far from ideal inductance for use as a driver - if this is the case, then moving to a higher inductance would be a much better solution than relying on parasitics from the host pickup. I respect your goals to develop an ultimate driver configuration and to test and prove this to be true. For a long time all I did was follow this pursuit with little regard to how it might eventually make it onto real work instruments. You are right, taking control of the inductance and whether by experiment or by measurement (which is pointless if you don't know how to interpret them, which I don't) or any other component of the driver is ideal. I have not ever relied on "parasitics" (quite what that means in this context I'm not sure) but if they serve a purpose, which it would appear they do have an effect, possibly on inductance, then if that is advantageous, I will use them. If they cause noise or distortion or generally increase the bad EMI, I will try to eliminate this. If they enhance the response...I will exploit it. I am as curious as the next person and would like to know why things work, however in that abscence I will continue with the laborious task of continued practical experimentation.... I am still astounded about this secondary coil effect of the pickup windings...everything like this that comes along sheds new light on some of the failings...and new opportunities. I still don't know why I am getting noise when turning down the guitars volume in harmonic mode or why it responds so poorly on this guitar...another mystery perhaps! But you just said that its easier, more successful and approachable... now, there seem to be a bunch of problems ? :-p I have consistently said that I am having trouble with the harmonic mode in this guitar and installation. It is odd as I have done something almost identical with the same guitar and pickups only 2 months ago. However, what I am getting is a range of steller normal mode effects with true fundamental vibration at lower gains and harmonic bloom in higher settings. While it may be a failing that the harmonic mode doesn't work so well, it is also an "opportunity" as I discussed. Reversing the phase is pretty crude and continues a escalation of the harmonic response... I am pretty sure I posted recently on this, but can't find it to quote on it. Basically...the string is sounded, the reverse phase of the driver cancels out the fundamental and drives the harmonic. However, now it is hearing the harmonic that the string is vibrating at and so the reverse phase is attempting to kill that too... If you have the device working in normal mode and pluck a harmonic, most often this harmonic will continue to ring (octave harmonics though often fall back to the fundamental). So...when the setup I am testing now produces a harmonic it is loud and clear and noiseless. The tendency for these harmonics to exist can be suppressed by altering the load on the secondary coil, or lowering the gain of the amplifier. These harmonics sound better to me and evolve better without transition from the initial sounded note. They also have a degree of touch sensitivity that makes them more expressive. They seem to be more predictable and intuitive on the whole sounding at the first harmonic, which of course is an octave... However, at this early stage they are not present across the board. Interestingly, they are not so much frequency dependent. The note a on the d string may be a harmonic while the note a on the g string may not. There is a particularly good harmonic on the high e string around the 12th fret area over several pitches. This would seem to indicate that these effects are in part influenced by the distance between the pickup and driver or most likely, the location of the driver in relation to the length and characteristics of each string. I'm more in favour of using overdrive for sustaining. Better chop off the attack! I think you are in part right, the original sustain-o-strat had a lot of gain in the preamp and so was overdriving the signal. Much better harmonic response, etc. My present design has no preamp gain. However, it has plenty of gain and so eventually will start clipping...unfortunately, there is a tendency to introduce distortion into the signal if it is too much. Interestingly, with a small cap shorting my secondary coil, the high frequency distortion goes and a much better overdrive kind of distortion at these levels is produced. While col admirably aims for no distortion, and mine will do that at moderate levels and still produce infinite sustain and some harmonics...this effect also has it's appeal. I think some degree of overdrive in the drive signal is producing the harmonic effects too. Perhaps I should further explore this area. ---------------- I am seeking to make something that works for me and for others. I am looking for a device that can add avenues of expression and musical exploration. I am seeking to take the electromagnetic string driving technology further in this direction. I am seeking to make this happen as simply and as practically as I can. I am seeking for this to happen without limiting the instrument on which it is installed. I am seeking to improve the installation and practical real world application of the technology. I don't use a simple single coil on my present designs except that it suits the application...a guitar with single coil pickups, and retaining those pickups. My aim is to do the best I can within that limitation that works. I have tried many different approaches, many worked quite well...however, they do not fulfill the promise of this in this application. Once this is more sorted, I will make a dual coil version for HB pickups...because it suits that application. While we can get bogged down in various string vibration modes and technical measurements, the fact is that there are a lot of ways of approaching this and many work quite well...including mine. I am seeking out the window of compromise that works well enough to be useful. When I have a window large enough, it may well become a commercial proposition...that is the intention for reasons I have stated. I am getting strong sustain from the lower strings to the highest to just shy of directly above the driver (with a slide)...obviously the window of what can work is pretty wide. It may be a little different on each guitar, this does always seem to be the case, but it will work still, so obviously some details are more important than others and getting bogged down in them is only going to hold things up and add doubt that might prevent experimentation that may well be fruitful one way or another... later... pete Link to comment Share on other sites More sharing options...
col Posted February 14, 2008 Report Share Posted February 14, 2008 But you see, I have tried many, many different approaches, probably more than any other and I have done it for years now and at a reasonably high enough quality that every chance has been given to those ideas that I could give them. No one can have tried every possibility, that is the beauty of this stuff, but I surely have tried a whole lot... I was talking about a specific issue (phase correction) in relation the recent discussion here - in which other possible ways of handling this problem have been suggested - you _seemed_ to be dismissing these ideas out of hand. I know you have tried many many variations of your system, but I also am pretty sure that you have not tried the ideas that have been suggested recently, so why be so negative ? You may have tried using thicker wire, or heavier cores, but as I have explained more than once, this would have been very likely to fail without using measurements and some basic math to tune the circuitry. You have just discovered the existence of all-pass filters, but have not tried using them yet... etc. ...I simply tried to say earlier that the act of plucking a string 'distorted' its vibration...over-and-above the guitars complex set of vibrations. It is most likely a confusion in terms or language, but not a fruitful debate I would suggest... Well, it would be silly to waste a lot of time arguing over it, but I feel that it is not just a matter of the definitions of words, it deeper than that. The sound of a guitar as we know it includes the extra harmonics that are created by the plucking action - to call those a distortion is to suggest that they are somehow not part of what we think of as a natural guitar sound. I think that is a mistake. Thinking about a complex system like a sustainer in a creative way, and coming up with useful ideas and solutions depends on having a good mental model of individual parts make up the whole. One of the 'parts' that makes up the natural characteristic sound of a guitar is the overtones created by the act of plucking. For me it is very important that these overtones are considered as an intrinsic component rather than an extra additional effect. When you used the term distortion (and then defended its use) in this context, it made me think that your understanding or mental picture in this area is at odds with mine. Now, I am thinking that its more down to a misuse (IMO) of the word distortion. What this whole mess does highlight is that when words are all we have for communication, it is very important to be precise, and not to bend their definitions - or to mix and match different definitions of a word in the same discussion, otherwise, there will be misunderstanding and that often leads to arguments. I have not ever relied on "parasitics" (quite what that means in this context I'm not sure) Parasitics are 'effects' that are not the primary function of a component... so for example at very high frequencies like on a PC motherboard, the 'parasitic' inductance and capacitance of the circuit board traces becomes important. Closer to home, the transformer effect between driver and pickup is parasitic because it is not the primary intended function of those components - it is a side effect. In this case I'm using parasitic to refer to the effects that the pickup coil is having on your piggyback driver. These were unexpected and as the primary function of the pickup in this system is as a 'core donor', the term parasitic seems entirely appropriate . Of course, just because an effect is parasitic, doesn't mean you can't take advantage of it. I have consistently said that I am having trouble with the harmonic mode in this guitar and installation. It is odd as I have done something almost identical with the same guitar and pickups only 2 months ago. However, what I am getting is a range of steller normal mode effects with true fundamental vibration at lower gains and harmonic bloom in higher settings. While it may be a failing that the harmonic mode doesn't work so well, it is also an "opportunity" as I discussed. Reversing the phase is pretty crude and continues a escalation of the harmonic response... I have a very good idea as to why you are having problems with 180º harmonic mode and at the same time getting great fundamental mode performance - the two things are closely related (this is not something I've thought about as a response to your problem, it's something I wrote up before then in my notes). Unfortunately, its all tied up with (my) understanding of the phase response of the different components of the system, and I seem to be having trouble explaining my ideas in that area at the moment. ...However, at this early stage they are not present across the board. Interestingly, they are not so much frequency dependent. The note a on the d string may be a harmonic while the note a on the g string may not. There is a particularly good harmonic on the high e string around the 12th fret area over several pitches. This would seem to indicate that these effects are in part influenced by the distance between the pickup and driver or most likely, the location of the driver in relation to the length and characteristics of each string. This is explained by what I've been saying about Helmholtz motion. The cancellation due to the combination of how the string really vibrates and the gap between driver and pickup... The same note will have a different driver/pickup phase relationship depending on which string/fret it is played on. This is because on a shorter length of thicker string, the 'kink' moves slower, and therefor spends more time per cycle in the cancellation zone between driver and pickup. For any single note frequency, an overall system phase difference that optimizes for one string/fret combo will be less effective for another. I'm more in favour of using overdrive for sustaining. Better chop off the attack! I think you are in part right, me too, with caveats (of course . While col admirably aims for no distortion, and mine will do that at moderate levels and still produce infinite sustain and some harmonics...this effect also has it's appeal. Thats not quite true. While I certainly aim for no grunge/fuzz leaking from the sustainer system, I can see great benefits from using a clipped signal to drive the strings. If we could find a way to prevent the fuzz becoming audible, then I would most certainly be using clipping of some sort... possibly even using a comparator to create a pulse wave. (I suggested that a very long time ago) So far the only way to prevent the fizz is to prevent clipping in the drive signal - this is unfortunate because it has a number of negative side effects. I am seeking out the window of compromise that works well enough to be useful. Understanding how the strings vibrate and taking technical measurements could help you find a better window more quickly. Do not dismiss lightly! It may be a little different on each guitar, this does always seem to be the case, but it will work still, so obviously some details are more important than others and getting bogged down in them is only going to hold things up and add doubt that might prevent experimentation that may well be fruitful one way or another... Without properly understanding these 'details', their implications and how they fit into the 'big picture' of the complete system, it is impossible to know which ones are important and which ones are not. If you want to ignore some detail and be in no doubt about its insignificance, your gonna need to understand it well first. cheers Col Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 14, 2008 Report Share Posted February 14, 2008 This is where the rats go to die... This is the failure bucket only of the latest design and only some of them at that... They look so slim, they must have been starved to death! Col and I seem to have some communication problems...that is not unusual with me, especially at the moment...if I could get a bucket big enough, I'd join the rats above... Don't Pete. We still need you. Maybe you could even reanimate some of the rats for further testing. I was wondering if it's the best choice to use coils with a dc resistance of 8 ohm. In operation the driver works with currents of 350mA (1W output). So the coil must getting hot. How hot? If the coil gets hot the resistance rises. Think of lightbulbs or heater in electronic valves/tubes. So how much? This could be tested with a 9V battery and a resistor in series with the driver (preferably a lab rat). With a 18 ohm resistor in series with the 8 ohm driver we would get a initial current of 350mA. It's nice to see if that current drops when the driver gets hot or melts (no more current anymore). Measure the voltage over the driver R_driver = V_driver / I = V_driver / (9 - V_driver)/R If the result is a lot more than 8 ohm we could try to use thicker wire, but same amount of windings. That's why I like to talk about test procedures. At which current do we test? Bye Link to comment Share on other sites More sharing options...
col Posted February 14, 2008 Report Share Posted February 14, 2008 Maybe it was a bit much for a first post. Not at all - it was an excellent first post! My first post was to show you a manner of how to measure the electrical properties of the produced driver. This would give some indication of the quality of the driver (it's eveness of frequency response). Understood, and I agree that some sort of metric could be very useful. However, do you accept that evenness of frequency response and power of electromagnet are opposing attributes? And that the best practical driver is going to a compromise between these two things (and other factors). So any metric that doesn't take both into account will not provide good results. Col, when I spoke of the ideal conductor, I ment it as electronic component, not as driver coil. The 90 degrees phase shift will only occur at very high frequencies. Indeed the power transfer is 0. That's not what we need, we need energy to move the strings. What we need is 0 degrees phase shift. But that's exactly the problem. Building a driver is finding the best compromise. Pete knows all about that. Thanks for clearing that up. Col, you were quick to point out that the core materials, the whole construction, dimensions matter. That's true, that is the quantitive aspect of the driver. We should have a test procedure for measuring the strength of flux produced by the driver. Anybody? In the absence of an accurate precision gauss meter, we can use some simple formula to calculate the flux - this will not be wholly accurate due to the losses in our system, and the wide tolerances in our measurements, but it will be pretty good for explaining which changes will increase the flux and which will reduce it. Fm = Magnetomotiveforce I = current (we can measure this) N = number of turns in coil (we can count this - if we remember - and the kids don't distract us) Φ = magnetic flux Rm = reluctance L = inductance (we can measure this) Al = inductance factor (this is a characteristic of the core material and its dimensions) L = 10^-9 x Al× N^2 Rm = N^2 / L Fm = I x N Φ = Fm / Rm so Φ = (L x I) / N so Φ = I x 10^-9 x Al× N We can calculate a rough value for Al (inductance factor) by measuring the inductance and plugging the result into a twiddled version of the first equation above. (unfortunately this will not take into account hysteresis which can be more or less significant depending on the formulation of the core material - I guess we could come up with a method to get an estimate for this as well if we wanted) In the end, the important thing that this tells us is that flux is proportional to the number of turns, the current and the core specifications. Of course, there are other important factors e.g. flux density. It is important that as much of the generated flux as possible is acting on the strings - we can get a good idea of how this might be achieve by modeling in femm, and while this is more of a trial and error process, its a damn sight quicker than building coils and trying to analyse their fields using a gausse meter and paper covered in iron filings Most of the stuff above was learned from this fantastic website - worth spending a few evenings looking through these pages ! Maybe your design experiences some complication because of use of agc. Right after the attack your design limits the signal. It uses the louder higher harmonics as reference. As a result the fundamental is attenuated and slowly released after the higher harmonics have died out. Very good point. My gut reaction suggests that the harmonics will only be dominant for a very short time after which the fundamental will take over, but gut reactions are often wrong when fueled by ignorance. Do you have any data on the amplitudes of the different harmonics and the fundamental during the attack phase of a guitar note? If this is a significant effect, it should be easy enough to deal with by filtering the control signal. cheers Col Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 14, 2008 Report Share Posted February 14, 2008 I suppose it's the amount of posts that sets the forum regulars apart from the newbies. ...However, at this early stage they are not present across the board. Interestingly, they are not so much frequency dependent. The note a on the d string may be a harmonic while the note a on the g string may not. There is a particularly good harmonic on the high e string around the 12th fret area over several pitches. This would seem to indicate that these effects are in part influenced by the distance between the pickup and driver or most likely, the location of the driver in relation to the length and characteristics of each string. A tone around the 12th fret has a belly right above the driver. At the 20th fret the driver is close to a node, but on the other hand the string is much closer to the driver. And there is a symmetry, driver and pickup are as close to a node. You could argue that in such case the driver gets the ideal type of sound to keep the string moving. Lower on the neck, like the 3rd fret, means more room to swing, less stiffness. But then there is some kind of split personality thing. Both fundamental as 2nd harmonic (or 1st harmonic, depends on how you count) are in phase. So in feedback both tones may occur. It will depend on sound characteristics of the guitar and eq (output elco of f/r as low-cut) which tone will feed back. I think it's very difficult to reason why some notes feed back and others don't. This is explained by what I've been saying about Helmholtz motion. The cancellation due to the combination of how the string really vibrates and the gap between driver and pickup... The same note will have a different driver/pickup phase relationship depending on which string/fret it is played on. This is because on a shorter length of thicker string, the 'kink' moves slower, and therefor spends more time per cycle in the cancellation zone between driver and pickup. For any single note frequency, an overall system phase difference that optimizes for one string/fret combo will be less effective for another. I still am not buying the stuff about Helmholtz motion. I am convinced that this motion happens, but I don't see what it has to do with the fundamental. When you pick a string you get a lot of harmonics and even sounds that have no mathematical relationship with the fundamental. The fundamental is masked by these harmonics. These harmonics and noise could cause the diy-sustainer to set in slowly, but don't blame the fundamental for it! Col, what I understand you are saying is that the Helmholtz motion is causing the fundamental to do strange things. But how on earth would that be possible, the nodes of the fundamental are fixed points on the guitar (nut/bridge or fretted position/bridge), they even make traveling kinks bounce back. I think that you find the solution for your problem in pre-agc eq, taming the highs. Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 14, 2008 Report Share Posted February 14, 2008 Of course, there are other important factors e.g. flux density. It is important that as much of the generated flux as possible is acting on the strings - we can get a good idea of how this might be achieve by modeling in femm, and while this is more of a trial and error process, its a damn sight quicker than building coils and trying to analyse their fields using a gausse meter and paper covered in iron filings Most of the stuff above was learned from this fantastic website - worth spending a few evenings looking through these pages ! Ok, I understand. It's flux density that matters. So what I actually want is some kind of device I can stick my driver onto that will measure the driver's flux density. Even if it is only to get a rough idea. If I have a driver and then modify it has it become a more efficient driver or not? Now it is like modifying, installing into the guitar, listening en guessing if it's a real improvement. Very good point. My gut reaction suggests that the harmonics will only be dominant for a very short time after which the fundamental will take over, but gut reactions are often wrong when fueled by ignorance. Do you have any data on the amplitudes of the different harmonics and the fundamental during the attack phase of a guitar note? If this is a significant effect, it should be easy enough to deal with by filtering the control signal. Let me tell you first that I have been working a lot on my very own Ross compressor modifications. It works with a CA3080, a predecessor of the LM13700 you're using. Actually it's a limiter. I understand that you want the notes to go into sustain quicker? I think that you have to distinguish two things, how the limiter works and eq. I agree with you that harmonics only wil dominant for a very short time, but even so what can happen? When hitting the strings hard the compressor starts limiting the signal. If the attack time of the compressor is short it means that signals at the very beginning of the tone (let's call it attack) will be used to limit. Compared to the attack the fundamental is relatively weak, assume it is -20 dB then if the attack is used as a reference for limiting the fundamental will still be 20 dB below the attack level. It can be that this attack is only very shortlived but what if the release time of the compressor is long? Say the attack only lasts 20 mseconds and the release time is 200 mseconds. Right after the attack you will experience a softer signal (sagging). So it is important to have a short release time. Rapid reaction is more important than whether pumping or not. Eq (taming the highs) can make the attack softer what makes that the fundamental is relatively louder after limiting. The data you are asking depends on the guitar, type of pickups, position of pickup. Maybe it's better to soundcheck and listen if the compressor sags. Cheers The Fizz Link to comment Share on other sites More sharing options...
col Posted February 14, 2008 Report Share Posted February 14, 2008 I still am not buying the stuff about Helmholtz motion. I am convinced that this motion happens, but I don't see what it has to do with the fundamental. When you pick a string you get a lot of harmonics and even sounds that have no mathematical relationship with the fundamental. The fundamental is masked by these harmonics. These harmonics and noise could cause the diy-sustainer to set in slowly, but don't blame the fundamental for it! Col, what I understand you are saying is that the Helmholtz motion is causing the fundamental to do strange things. But how on earth would that be possible, the nodes of the fundamental are fixed points on the guitar (nut/bridge or fretted position/bridge), they even make traveling kinks bounce back. I think that you find the solution for your problem in pre-agc eq, taming the highs. erm, where on earth did I 'blame the fundamental'? or say it is doing strange things ? I have no problem with the fundamental any more than any other feature of the spectrum of the sound. I'm interested in 'Helmholtz Motion' because it is what actually happens when you pluck a string, and - at least for me - it is a more intuitive way to visualize what is happening when you pluck a string, and the different relationships between the physical distance between pickup and driver, the phase difference, different notes on the neck, different forms of drive signal etc. I figured that it would be interesting and useful for others on the board because it might help to understand some of the more complicated aspects of the process and maybe suggest some interesting ideas. As far as there being problems with my own system. I would say that for what it is, it works extremely well. However I am a perfectionist, and there are some weaknesses with my system (as there are with any non-ideal solution to this kind of project). I have a very good understanding about what those weaknesses are, and I know that many of the are not fixable, they are inherent characteristics of that particular solution. The most significant being that there is no drive when the input signal is high - which in some ways is good, but it does mean that some effects possible with other sustainers are not available. The other major issue (and for me this is more important) is that my system tends to sustain only at one frequency - there are fewer of the overtones that characterize a guitar sound than you get when you drive with a clipped signal. This is a side effect of removing the fizz from the sound. So as I've said, we (or at least I ) need a different way to deal with the fizz/grunge. So far the most likely solution seems to be some variant on utopian Isotopes loop idea. I just haven't got around to working on that yet unfortunately. Ok, I understand. It's flux density that matters. So what I actually want is some kind of device I can stick my driver onto that will measure the driver's flux density. Even if it is only to get a rough idea. If I have a driver and then modify it has it become a more efficient driver or not? Now it is like modifying, installing into the guitar, listening en guessing if it's a real improvement. I don't think flux density is any more important than the sheer 'amount' of flux. As far as taking a measurement, the place to do that would be where the strings would be above the driver (obviously). I googled DIY gauss meter and the first page I got was this, which seems to be a discussion about building a gauss meter from parts of a cd rom drive motor. However, the important thing is not the actual value of density (what would we use that for?). Rather more useful to us is working out which arrangements of coil, magnet and core give higher density in the right place, and which give lower, and it seems like this is a good. I agree that it would be very useful to take actual readings from a working coil, but we can get a pretty good idea without that. Let me tell you first that I have been working a lot on my very own Ross compressor modifications. It works with a CA3080, a predecessor of the LM13700 you're using. I gave up on the LM13700 a long way back - it had a great response, but the fuzz problems were terrible - the circuit I was using just imparted too much distortion to the drive signal. Additionally, it was too sensitive to very low signals, so prone to squeal (fixable, but not worth it in light of the fizz issue). My most recent completed circuit was based on this FET based fast peak limiter. I ended up changing it massively, and it mutated into something way less elegant and much less precise, but what I ended up with does limit an extreme amount, is a feedforward topology, imparts very little distortion to the signal over the guitars range, has a very even frequency response and a fast attack and decay envelope. The decay time is as short as it can be before distortion is introduced at the low frequencies. I spent some time trying to improve this. Maybe your suggestion about the frequency spectrum of the attack will improve things - I'll certainly give it a go (assuming I can find room on the board to hack something in). FWIW, the release of my AGC is ~50ms, the attack is ~10ms Unfortunately, the release of the sustainer system as a whole can be much slower because it takes many cycles of full drive to get the string up to acceptable volume, and on some string/fret/ combos, the takeover 'battle' from natural sound to sustain can be noticeable. Fortunately, most of the time, the only downside is that certain swell effects that are available with some sustainers are not with my current system. And it takes a bit longer for harmonics to bloom (sounds more natural this way, but it's still a limitation) Playing a note or a chord in a normal way gives a good effect that moves smoothly into strong sustain (you've listened to the demos). Where the real downside (I think) is between my system and some others (my previous version for one) is that because there is no clipping on the drive signal, the sustain quickly removes most of the interesting harmonic content from the tone and leaves mostly just fundamental... this is great for washes of ambient colour, or glassy echoing stuff, but it doesn't have the 'balls' of a freshly plucked string. I think that is the next stage - find some way to take the fuzzy but more ballsy result of using a squared off drive signal and prevent the fuzz getting to the ears without getting rid of those characteristic guitary overtones. The data you are asking depends on the guitar, type of pickups, position of pickup. Maybe it's better to soundcheck and listen if the compressor sags. As noted above, the attack and release of the compressor are pretty quick (the release gets back to almost full output in about 25ms, 50ms to full) What I have on the drawing board is a pure limiter version much more closely modeled on the circuit from that page linked above, it will always have drive when the input is above the lower threshold, it will be less good a balancing the output levels, but might offer a slightly more lively response. It is important to note that my existing system is not just a limiter. When the input exceeds an upper threshold, much of the drives is removed. The idea behind this was two-fold, let the guitars natural attack sound be free without the sustainer acting on it... and more importantly save the battery. The drive only kicks in when playing long notes or chords. When playing faster more choppy rhythm stuff, the battery gets a rest. Without this, the battery will be worked much harder, causing its performance to suffer after even a few minutes. It also means that I can get a good effect from a nearly dead battery because it isn't being constantly loaded by a high current drain - it gets regular rests So lots to think about gotta go cheers Col Link to comment Share on other sites More sharing options...
psw Posted February 14, 2008 Author Report Share Posted February 14, 2008 I think it's very difficult to reason why some notes feed back and others don't. I am getting very good sustain and strong drive all over (a little less on the lower strings ironically enough compared to previous versions...maybe a treble bias in the circuit) and the drive is pretty consistent along the neck. The harmonic mode is pretty much an anti-sustainer actively suppressing notes (doink, doink) excet for the low e string primarily. In higher gain modes where the drive signal gets a little fuzzy...you get these beautiful harmonics. So...now I am looking at alternative ways of enhancing the harmonics that I am getting... And...looking into how to integrate all these things back into a fully functioning guitar...the installation process, primarily on this one hooking the neck pickup back in without pops or other noises... Something fresh fizz wrote a little while back caught my attention and had concerned me previously too...something about a kind of a signal back from the driver into the circuit at certain phase angles? I had been trying to find an amplifier type that did not tie the driver directly to the ground. Obviously if there is any back signal from the driver a part of this will be sent into the ground of the circuit and directly to the guitars ground and signal chain. This could be a more significant cause of distortion and fizz than the EMI...any thoughts, it is also relevant to the off "pop" syndrome that some have experienced where a backlash of energy is restored to the ground when turning off the device (not when turning on)...well at least that is the theory. I am not in the least adverse to experimentation into the areas col is exploring but I am somewhat limited in my skills and time and have a bit of a different approach. I am seeking a simple elegant solution that minimizes the need for compensation and such. I have also tired of chasing the "perfect" driver design, rather settling on a workable practical design and trying to optimize that. With a driver and circuit being in testing now since august last year, it is difficult to make too many radical changes to the concept without losing some of the relevance of my testing to this date. Occasionally I have ventured into something a little different, like the concentric coil driver, but generally unless I had a design drawn up for an all-pass filter, it would be difficult for me to develop it and incorporate it into this particular version. Rather, I am concentrating on getting the most of this and then looking at those options to enhance what I have when it reaches it's fullest potential. I was listening to the guitar without an amp and there is a little vibration in the driver. Obviously the cover is not quite enough to hole the thing still, so I will be taping it in to stop this vibration. Possibly there is vibration in the pickup coil that I previously thought was not relevant if it were unconnected but I now see is potentially critical. Try as I might though, I have detected no heat from the coil or the pickup in general...certainly the magnets remain cold. Part of the beauty of the ultra-thin coil design is that it is a great heat dispersal design with very little mass to retain and store heat (it is only 1mm thick). I suspect heat in this design has little impact...though in others perhaps, my 3mm thin driver did create a little warmth over extended use. Oh...and something that I have not mentioned is that the driver is a conventional pickup with alnico magnet poles (fender strat) but there is very little loss of drive when bending strings between the poles...a reason for the blade design previously. ok...back at it... pete Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 15, 2008 Report Share Posted February 15, 2008 Try as I might though, I have detected no heat from the coil or the pickup in general...certainly the magnets remain cold. Part of the beauty of the ultra-thin coil design is that it is a great heat dispersal design with very little mass to retain and store heat (it is only 1mm thick). I suspect heat in this design has little impact...though in others perhaps, my 3mm thin driver did create a little warmth over extended use. I only mentioned it as a way of improving efficiency. It could be that when in action the driver coil measures much more than 8 ohm. The F/R amp performs best, gives most power, when driving an 8 ohm load. If the load is higher, than lower current, lower power. Like a 50W lightbulb. When the lightbulb is on the restistance is about 1000 ohm, but cold the resistance is much lower. This could be a more significant cause of distortion and fizz than the EMI...any thoughts, it is also relevant to the off "pop" syndrome that some have experienced where a backlash of energy is restored to the ground when turning off the device (not when turning on)...well at least that is the theory. When a high current is abruptly switched off a huge induction voltage is being created. That's why the coil of relays are bridged (?) with a diode in opposite direction of the voltage supply to suppress that induction voltage. Fizz Link to comment Share on other sites More sharing options...
col Posted February 15, 2008 Report Share Posted February 15, 2008 Ok, I understand. It's flux density that matters. So what I actually want is some kind of device I can stick my driver onto that will measure the driver's flux density. Even if it is only to get a rough idea. More thoughts on this. A gauss meter like those DIY ones at the link I posted would work ok assuming we just use a DC current through the driver for testing. To get a more accurate idea of the flux when theres an ac drive signal, I guess you would need to use the sort of technique described here (heh its that same site will all the info). That approach would also be interesting because we could check out the hysteresis graphs of some of the available cheap core materials. It would be nice to know if this is something we can ignore, or alternatively if it is having a critical impact on the functionality of the sustainer. Are hysteresis losses causing a significant efficiency hit? How much of an effect are they have on phase? cheers Col Link to comment Share on other sites More sharing options...
psw Posted February 15, 2008 Author Report Share Posted February 15, 2008 When a high current is abruptly switched off a huge induction voltage is being created. That's why the coil of relays are bridged (?) with a diode in opposite direction of the voltage supply to suppress that induction voltage. So...just as I thought... Can you explain further how I might do this with a driver like this...if I were to put diodes on the output surely it would short it out...or have I got the wrong idea. It is one of the more significant problems. Putting one across it would surely short one make a half wave rectifier of the AC signal...possibly also creating a harmonic response. I attached the neck pickup into the circuit but my switching idea with a dpdt switch didn't quite work (didn't attach the bridge pickup in neck position) and makes a pop turning on and off that is unacceptable. I am getting some good sounds out of it all the same but hardly a fully installed instrument... I have mapped an alternative with a 4pdt that looks promising...the last one i did with 2 pickups with this kind of switch was pretty quiet. ------------ Perhaps it needs some kind of "referenced ground" separate from the signal ground that could allow the return of this induced current while switching to the signal ground...is there such a way of doing this? ------------- Also...I have finally got to play a sustainer equipped guitar today...very impressive, it is going to be hard to match. However the circuit is 4 times the size of mine. Particularly impressive was the mix control which dials in harmonics probably with an all pass filter or something. Also, they have a small cap, probably 10uF on the harmonic switch. I believe this is to compensate for the phase difference that is adversely effecting performance on this guitar of mine for instance. However, the mix control provided fairly similar response and so made the harmonic thing a little obsolete The mix thing did not have any effect when switched to harmonic mode. The neck pickup/driver is active and the "coil" next to it simply a dummy. This guitar did not have coil taping on the bridge HB, whether because it couldn't (simple lever action five way (no superswitch) or because the sustainiac couldn't handle it I don't know. The on off switch was a dpdt. It provided exactly the kind of sustain that I suspect col is after...very clean and controlled and the switching was dead silent. I suspect that the sustainiac is a better deal than the fernandes unit with better support and instructions, a smaller board and off board switching. The board is heatshrinked but I could see some massive capacitors on there . I was assured that the guitar would work without the battery though the neck pickup wouldn't function...it being the driver and so requiring preamping and I suspect electronic switching...wasn't able to test the theory though. ------------ It was a little disheartening to see how good it was, but mine also impressed with a different range of sounds. As it is it is pretty good so I think I had better concentrate on how to interface it with the guitar..it is a shame to even have to use a 4pdt switch as I was really hoping for a dpdt solution. Anyway...any help curing the swtich pop would most greatfully be appreciated. pete Link to comment Share on other sites More sharing options...
col Posted February 15, 2008 Report Share Posted February 15, 2008 Also...I have finally got to play a sustainer equipped guitar today...very impressive, it is going to be hard to match. However the circuit is 4 times the size of mine. Particularly impressive was the mix control which dials in harmonics probably with an all pass filter or something. Also, they have a small cap, probably 10uF on the harmonic switch. I believe this is to compensate for the phase difference that is adversely effecting performance on this guitar of mine for instance. However, the mix control provided fairly similar response and so made the harmonic thing a little obsolete The mix thing did not have any effect when switched to harmonic mode. The neck pickup/driver is active and the "coil" next to it simply a dummy. This guitar did not have coil taping on the bridge HB, whether because it couldn't (simple lever action five way (no superswitch) or because the sustainiac couldn't handle it I don't know. The on off switch was a dpdt. It provided exactly the kind of sustain that I suspect col is after...very clean and controlled and the switching was dead silent. I suspect that the sustainiac is a better deal than the fernandes unit with better support and instructions, a smaller board and off board switching. The board is heatshrinked but I could see some massive capacitors on there . I was assured that the guitar would work without the battery though the neck pickup wouldn't function...it being the driver and so requiring preamping and I suspect electronic switching...wasn't able to test the theory though. Thats great news - at last you've had a chance to try out an off the shelf unit. I'll have to try and find one somewhere in town and try one out myself. Was it a Sustainiac ? More detailed descriptions please ) What was the sustain level like, what about the harmonic modes, was the mix mode very obviously different from standard mode, or just more tendency to bloom ? Was standard mode giving pure fundamentals right down to open low E? was the tone quite pure - more like a sine, or was it more like the initial guitar tone with plenty of harmonic content ? (assuming a clean sound here) (if it was a fernandez - we've see a sustainiac in pieces) Did you get a chance to have a good look at the coil dimensions? It was a little disheartening to see how good it was... Thats a shame, although it good to know that theres more to come - it's not pointless to try for improvements ! cheers Col Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 15, 2008 Report Share Posted February 15, 2008 As far as taking a measurement, the place to do that would be where the strings would be above the driver (obviously). I googled DIY gauss meter and the first page I got was this, which seems to be a discussion about building a gauss meter from parts of a cd rom drive motor. However, the important thing is not the actual value of density (what would we use that for?). Rather more useful to us is working out which arrangements of coil, magnet and core give higher density in the right place, and which give lower, and it seems like this is a good. The "this" link looks interesting. Thanks Col, I'm gonna take a look at it. A gauss meter like those DIY ones at the link I posted would work ok assuming we just use a DC current through the driver for testing. To get a more accurate idea of the flux when theres an ac drive signal, I guess you would need to use the sort of technique described here (heh its that same site will all the info). Very theoretical. I'm just a simple guy. I've thought of a way measuring the efficiency of the driver by using a sine wave generator connected to my diy-sustainer amp into the driver (installed on guitar) and measure the output of the guitar pickup in the bridge position. Tune in to a specific tone on a selected string and use different voltage levels. It's a lot of work but it can be done. I gave up on the LM13700 a long way back - it had a great response, but the fuzz problems were terrible - the circuit I was using just imparted too much distortion to the drive signal Yes the input of the CA3080 as well as the LM13700 are easy to overdrive. I can keep my CA3080s clean only by attenuating the signal. The LM13700 uses biasing diodes which for me makes things only more complicated. When a high current is abruptly switched off a huge induction voltage is being created. That's why the coil of relays are bridged (?) with a diode in opposite direction of the voltage supply to suppress that induction voltage. So...just as I thought... Can you explain further how I might do this with a driver like this...if I were to put diodes on the output surely it would short it out...or have I got the wrong idea. It is one of the more significant problems. Putting one across it would surely short one make a half wave rectifier of the AC signal...possibly also creating a harmonic response. But I don't know if this takes place in our driver coil. There is no DC current going through the driver coil (blocked by output cap). But when switched on there is half the supply voltage on the + side of that cap. When switched off that voltage goes to 0. Maybe that is causing the popping noise. Could a voltage divider solve this problem? (2 resistors of equal value, one from + voltage to + side of output cap, one from + side of output cap to ground) 2 x 4,7 kOhm would "cost" you about 1 mA. The extra 2,35 kOhm load is a piece of cake for Ruby! Like you reasoned diodes wouldn't work. I'm installing the driver and amp in my guitar so tomorrow I will do some testing. It's a bit ridiculous to act the wise guy when I myself don't even have an operational sustainer! If everything works (more or less) I'll let you know. Wish me good luck! Link to comment Share on other sites More sharing options...
col Posted February 15, 2008 Report Share Posted February 15, 2008 A gauss meter like those DIY ones at the link I posted would work ok assuming we just use a DC current through the driver for testing. To get a more accurate idea of the flux when theres an ac drive signal, I guess you would need to use the sort of technique described here (heh its that same site will all the info). Very theoretical. I'm just a simple guy. hehe, me too, I would have to do some reading and bodging to use that stuff as well. The reason I linked to it is because there would be a few problems for us using that simple gauss meter. In our sustainer drivers, the field strength of the permanent magnet is overwhelming compared to that of the inductor (at least I think so? *) So unless removed the magnet, or have a very accurate sensitive DMM, the readings wouldn't be very useful. *This is suggested by femm models that show very little variation in the permanent field caused by the comparatively weak electromagnet. The explanation as to why this is necessary is that the permanent magnet needs to be strong enough to align the magnetic domains in the strings - with this done, the very small variation of the fields strength caused by the electro magnet is enough to get the strings moving. The hysteresis of the hall effect sensor in the gauss meter would cause problems with accurate readings when an AC is driving the coil. I'm not sure how easy it would be to calculate, or measure how much of an impact this would have. Using a DC drive for taking measurements is bad news, because all the frequency dependent things we want to have mix would be ignored, so the measurements would be pretty useless. All that aside, I've already ripped apart one cd drive (only to discover no hall sensors - it was a very old slow drive) Link to comment Share on other sites More sharing options...
psw Posted February 15, 2008 Author Report Share Posted February 15, 2008 Wish me good luck! Good luck...are we looking at a multi pickup installation by chance...would be interesting to see what you com up with... But I don't know if this takes place in our driver coil. There is no DC current going through the driver coil (blocked by output cap). But when switched on there is half the supply voltage on the + side of that cap. When switched off that voltage goes to 0. Maybe that is causing the popping noise. Could a voltage divider solve this problem? (2 resistors of equal value, one from + voltage to + side of output cap, one from + side of output cap to ground) Will the resistor from the +ve of the output cap to ground not cause problems...it is effectively tieing the +ve and -ve of the driver output around the cap...or does the other resistor nullify it. Will it cause problems with the input. You may be right though...not sure...will build it into the testing circuit I am working on. I was thinking that perhaps these big output caps in the sustainiac were perhaps absorbing the switch shock. Interestingly, on the guitar I am working on, I get a switch on pop that I wasn't previously getting. The switching I used didn't effectively work though, it didn't bypass in the neck selected position. I was using the ground to switch the power on. The Sustainiac... Was it a Sustainiac ?...yep! Well...I had the guitar for about half an hour while talking to it's owner. It was a homemade jem copy (down to the monkey grip) a non-split HB single coil middle and sustainer in the neck, effectively an active single (with fake blank coil in HB size). I wasn't able to take it apart but the control cavities were made of perspex so you could see but not touch! One thing I was able to see is this alteration to the harmonic switch... This might fix mine by altering the phase perhaps and was something I had thought of just prior to seeing the thing (in line with the adjustable output cap thing). It is also as I recall mentioned in their literature. The wiring was such that I can't exactly verify this typical X phase wiring but it seemed to be the case and makes sense. Also the value was obscured...the 10uF comes from my memory of reading it somewhere (though I thought they were talking about the mix function at the time so left it in the backlots of my memory)... There is a lot of wiring to be hooked up but the entire board is about 4inches long and covered with heatshrink. There are a few obvious through hole components, mainly what look like capacitors, one about 20mm high by 1-15mm round. They use connectors on each end of the board which would help to wire this thing up as getting the circuit board into a guitar and working on it will be tricky without them though they add more "size"...it is about cavity depth and runs on it's side through the cavity that on this guitar needed to be routed out to fit it in. What was the sustain level like It was pretty controlled and in line with the output of the guitar. It didn't bloom like mine so much in that it never goes into "overdrive" so obviously well 'limited' to retain the natural clean sound. That is not to say it didn't do the "violin" attack thing from 0-full by tapping, but it didn't do the bloom from fundumental to harmonic quite like mine does for instance...staying pretty much as setted...if that makes sense. what about the harmonic modes The harmonic switch bypassed the harmonic mix control and sounded like you would expect...harmonics with the usual octaves and fifths and such. Perhaps a slight hint of the "tinniness" you sometimes get, but only very slight and the levels again pretty consistent. was the mix mode very obviously different from standard mode, or just more tendency to bloom Yes...this was the surprise control and very much like I was hoping to achieve in many respects. It sounded a lot like a rotary harmonic switch with pretty defined fundamentals to harmonic at the other end. It wasn't so much a "bloom control" as I have with mine, but a pure harmonic selection tool. Was standard mode giving pure fundamentals right down to open low E? Yes...it seemed to...perhaps one of those huge caps is for the output to ensure this. There were a couple of notes that seemed to break into a mixed harmonic but as I recall I only really caught it out on the high e a few times. was the tone quite pure - more like a sine, or was it more like the initial guitar tone with plenty of harmonic content ? (assuming a clean sound here) I only played it clean as that is the test right! The guitar and neck were made of solid queensland maple and was pretty heavy and non resonant. The pickups were nothing special and lacked character and warmth. A pretty bright guitar but fairly "cold", sharp attack without a lot of "colour" IMHO. Good for shredding I'd expect, fairly low action good sound for a lot of fast picked runs. To that extent, the sustained sound reflected the sound of the guitar...it did kind of "hum" along there, but there was no obvious character change as the sustainer took over. Mine does this too on low settings, but when driven hard, it certainly does change the character...the sustainiac did not. Unfortunately, without a lot of natural tonal character to begin with, it is hard to tell...I suspect that something with more character would reveal the change a little more...I am not sure how it couldn't given the way the string is being excited. It certainly was a more "smooth" sound lacking any remnants of a pick attack if that is what you mean. It did also sound a little "unnatural" to my ears. It does what it claims...infinite sustain...however it doesn't sound like 'natural feedback' which does tend to bloom and evolve. (if it was a fernandez - we've see a sustainiac in pieces) Did you get a chance to have a good look at the coil dimensions? No...sustainiac, and I couldn't really see anything of the driver...up close and personal other than the cover. I suppose I didn't get a lot of time with it but the overall impression is of something very tamed and in control. In that it didn't "bloom" in a tonal character sense and in that way to me, sounded a little lifeless. On the other hand...totally predictable in response, no noise or pops. The mix control could be seen and probably is some kind of "tone control"...perhaps if I had played with it a little more I would have discovered some settings that "bloomed" but generally it responded immediately with the harmonic response expected. There appeared to be some interaction between the tone control and the sustain system also...effecting the signal to the sustainiac and the guitars signal...probably a little difficult to avoid I guess without going fully active. It was a little disheartening to see how good it was... Partly it is because mine wasn't working so well 'on the day' and I have still failed to get the switching fixed. That morning I had decided to wire up the neck pickup and of course, all great plans...pops both on and off and the neck pickup selection failed to bypass. I also shimmed the neck and so the action had gone a little skew-wiff...ironically, half an hour after my guests had gone, it came back to some significant improvement with a little TLC. Thats a shame, although it good to know that theres more to come - it's not pointless to try for improvements ! Yes. However...if someone wanted a good sustainer with this very controlled response and features, the sustainiac really does fit the bill. It has advantages over the fernandes particularly in board size and shape and switching. It is likely to require a little routing in most guitars I suspect. The driver as an active pickup sounded pretty good too, better than I would have expected. Very much a single coil sound though...not a fake HB or anything. I believe the cost down here to be about A$360 (possibly A165 wholesale) but is sold direct from sustainiac. They do pretty good service and have an installation service too. It is not something that the complete novice is going to be able to install (this was installed professionally) and I strongly suggest that it would be difficult (but probably not impossible) to get it into a lot of guitars without modification and cavity enlargement. The dpdt switches mean it would be possible to operate with push pull pots. I suspect it would have some trouble coping with an overly complex wiring scheme with coil splitting and such...still I don't know?! So...perhaps looking at $A500 installed, so not cheap. As for improvements...well it depends on expectations of what you want the thing to do. I have sought not to replicate these devices but to extend the technology and sound. If I had built this I would be happy, but since it exists already...that is what is a little disheartening. If this response is what is sought, then "improvements" could be made by retaining the passive pickup choice (though this is minor really I guess), smaller size perhaps and maybe a better price. On the brighter side...there are other effects that have been tamed that this appears not to do. It doesn't sound particularly like "natural feedback" with a tendency to bloom (particularly harmonic bloom). It doesn't seem to add any "distortion" which of course is frowned upon generally, but there is some good distortion effects possible without going into fizz territory. Ans while there is "dynamics" that drive the strings from nothing (say a tapped note) to the guitar's normal volume...it doesn't exceed that and so will not overdrive the amp as mine can do. Also, perhaps it lacks some of the organic touch sensitivity that mine generates...certain pick attacks and strength will elicite harmonics and bloom more naturally and with a character that thins thing seemed to lack. To me then, if I could make "improvements" it would be to enhance these features often seen to be disadvantages or failures to the system to create a more organic and expressive device. What was "disheartening" was how well it integrated into the guitar, no pops, no noise. This has been forever plaguing me with all of this and it is really wearing me down. I could tame mine a little more...perhaps tweaking the AGC a little more or making it adjustable...I could play with all-pass filters (which is most likely what the mix control is?) or output caps or add something to make the harmonic switch work better as illustrated. There will be ways to get it further towards the performance of this. However, what we haven't got is a convincing method of installing and operating it at anything like this level...correction, I haven't! I did get the last one to work without clicks...well at least while I was testing it...but I used a 4pdt on a 2 pickup guitar to do it. Obviously the scheme I tried with the dpdt on this is either wired wrong or has failed in concept. (as a side note, when in the neck position without a load, you can hear a very fizzy, tinny sustained sound with no squeal!) Every evening lately I try and devise different schemes...I am treating them like logic puzzles. Last nights 4pdt seems promising...but only real world testing seems to bring out the faults in such plans. ok...took some time to draw it out... The idea in this kind of scheme is to exchange the entire selector with the bridge pickup. It won't deal with split HB's or anything (doesn't control the series connection), but the intention is that it will deal with multiple pickup schemes and combination switches by switching out the entire selector and replacing it with the bridge pickup. This one is also interesting as I was able to get a free pole from the circuit ground connection and so perhaps there is a possibility of having some kind of slow release pop prevention strategy on this...any ideas that won't send the battery flat? I think this would also work for a two pickup toggle switch, typically a sp3t switch with a common ground. On a typical strat switch, with a master tone, you free up the other side of the switch so you could connect individual hots to one side and grounds to the other...the bridge pickup and any combinations would be switched out in bypass mode...sustainer off is shown down in the drawing above. I haven't quite worked out the toggle switch version but I think it can be done. Of course...it is not tried yet and it still uses a 4pdt switch grrrr.... Problems, improvements? As for the performance of my device...I really like some aspects of it, the expressiveness of it seemed to impress the owner of the sustainiac a bit (though I wasn't feeling too well and the device was not working as well as it could) but I am sure that bad switching made a bad impression. I think I will continue to foster these "expression" aspects of it in my work. With my system... At high gains there is distortion and and the strings "hum" along obviously being "driven"...but this driven sound is kind of attractive. I am not talking about a really fizzy sound and I am not even sure it is an EMI issue. The driving forces seem to create an interesting almost "overblown" kind of effect that is pretty expressive. It has a wide and touch responsive dynamic range that the sustainiac seemed to lack...it has more life, but then is harder to "play" (get the most of it) if you understand. A lot of the distortion is created by the wide dynamic range...the thing "sounds loud and rich in harmonics at the upper range of gain. I might switch to a linear pot and see if I can explore more shades of this BTW. The lower range of the drive control is very clean and controlled. In the lowest setting there is the natural pick attack and some decay before settling to a quiet infinite sustain. I have noticed some interaction with the volume control...a little distortion to the drive on lower levels but it sustains well even when turned down to 0. The distortion at higher levels can have a sax like quality, kind of grainy but attractive, more apparent is that it overdrives the amplifier with the increased output as the notes "expand" and bloom. I started testing with a valve amplifier now, over the little test amp I normally use. This is a fender hotrod deluxe and capable of a superb clean valve sound. Like all good valve amps, it will break up with picking strength and it seems to like my device. How it would perform in a digital domain is hard to tell...normally computers and such don't like things with this broad a dynamic...I have yet to try and record it. Anyway...that is my report and contribution for now... pete Link to comment Share on other sites More sharing options...
col Posted February 16, 2008 Report Share Posted February 16, 2008 Just a quick note to say that this evening I tested Utopian Isotopes 'loop' technique. It does work exceptionally well as a way of removing/controlling squeal. As is, the basic loop doesn't seem to have any impact on fizz/grunge. cheers Col Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 16, 2008 Report Share Posted February 16, 2008 Good luck...are we looking at a multi pickup installation by chance...would be interesting to see what you com up with... Nope. A single humbucker Seymour Duncan TB5 at the bridge position of my stratocaster. The sustainer circuitry fits in the middle pup hole position. I use a frankenstein pickguard. It's been cut in 2 pieces. So we have one piece with driver and pup fitted in and a part to fit in the controls. This way it's possible to open the guitar without removing strings all the time. I only had to add to screws for the part below, that makes 13, but we're not superstitious (?). Will the resistor from the +ve of the output cap to ground not cause problems...it is effectively tieing the +ve and -ve of the driver output around the cap...or does the other resistor nullify it. Will it cause problems with the input. You may be right though...not sure...will build it into the testing circuit I am working on. It's a way of keeping the voltage at the cap at 4,5 volt. The driver's load is 8 ohm so the 2 resistors (4700 ohm) won't have that much effect on the working of the ic. I suppose that you have a main power on/off switch to which the voltage divider can be connected besides a switch that only switches off the f/r. But to be honest I don't know if this addresses the problem. With the testing I did I only experienced problems when switching on my sustainer circuit. (Pfffeeewww in dutch, don't know in english) Switching off seemed to be quiet. So I am back om my feets again. It's a lot easier to do the theoretical blaba than to really get a sustainer system to work and be really satisfied with it. The good thing is that I've got the sustainer working. I'm using an overdrive (fet with diode clipping) into a tda7231a chip. It has tremendous overdrive and power and I get good sustain on all of my strings and all positions. At this moment I'm only using the fundamental mode which is free of squeal. The bad thing? FIZZ!!!!!!!! After closer investigation I came to following conclusions. Maybe you could tell me if you share my opinion, Pete and Col. 1. When I say that there is no squeal I notice that there is sensitivity point, a specific frequency band, where the system would like to sqeal if it only had enough energy/volts/whatever to feedback. When I listen through a compressor in front of a distortion/overdrive into headphones I imagine I can hear that frequency band in the background. When I switch off the sustainer it's gone. When I hit a low note on the low e string it seems to waken up this monster. Like it's thinking: "finally enough energy". But there's not. So it's like a short colorization of the sound (emphasizing that particular frequency band) and then going into string feedback. This is a very unpleasant sound effect (not musical sounding) 2. Crosstalk of harmonics generated by the overdrive. This is something I can live with because it doesn't sound unmusical. Surely I will try to diminish this effect as much as possible but it's like balancing off efficiency and sound quality. I'm thinking of what is the next best step Cheers The Good Fizz Link to comment Share on other sites More sharing options...
jamforthelamb Posted February 16, 2008 Report Share Posted February 16, 2008 Just a quick note to say that this evening I tested Utopian Isotopes 'loop' technique. It does work exceptionally well as a way of removing/controlling squeal. As is, the basic loop doesn't seem to have any impact on fizz/grunge. cheers Col Hi Col, and everybody. What is this technique? I tried looking for it and didn't find it. Recently got my sustainer guitar together, and I have a squeal. The sustainer worked fine outside of the guitar, so now I'm a little frustrated. Any help you guys could give would be great. Thanks! -Kevin Link to comment Share on other sites More sharing options...
col Posted February 16, 2008 Report Share Posted February 16, 2008 1. When I say that there is no squeal I notice that there is sensitivity point, a specific frequency band, where the system would like to sqeal if it only had enough energy/volts/whatever to feedback. When I listen through a compressor in front of a distortion/overdrive into headphones I imagine I can hear that frequency band in the background. When I switch off the sustainer it's gone. When I hit a low note on the low e string it seems to waken up this monster. Like it's thinking: "finally enough energy". But there's not. So it's like a short colorization of the sound (emphasizing that particular frequency band) and then going into string feedback. This is a very unpleasant sound effect (not musical sounding) It sounds like you have the gain set so it is nearly squealing. When you hit a note or chord, the extra signal level (more square signal wave shape with more harmonics?) is enough to start the build up to squeal, however, this is quickly cancelled as the fast decay of the guitar removes energy faster then the squeal can build up... so you get a small attempt to squeal during the attack of each note. ? Does that sound about right? 2. Crosstalk of harmonics generated by the overdrive. This is something I can live with because it doesn't sound unmusical. Surely I will try to diminish this effect as much as possible but it's like balancing off efficiency and sound quality. I can only live with this if it's unobtrusive enough so that you have to be searching for it before you can hear it I don't like the weak fizzy distortion in the background - why spend years trying to get your sound 'just right' then compromise it by adding a low grade quiet fizz to everything. I'm thinking of what is the next best step Two effective ways of dealing with the fizz are using a dual core driver - either in bi-lateral (sustainiac patent) format, or bi-longitudinal (lol) dual rail format - this reigns in the field dramatically, and you can move the driver much closer to the pickup before there will be any squeal (There are some possible efficiency concerns though). Or the loop trick. Utopian Isotopes recently discovered method using a simple loop of wire really does work really well for reducing the squeal. For the fizz, well, the first thing we need to do is narrow down the probable culprits. Depending what is causing it, there may or may not be solutions. I don't think it is caused by the phantom parasistic transformer stepping the voltage of EMI induced signal up until it clips - this would not be removable by avoiding distortion in the drive signal. I don't think it is electrical interference or magnetic radiation from the circuit or leads - I'm pretty sure I checked this a while back - but it needs re-checking I suppose. If it were caused by direct coupling between the driver and pickup, then surely the same tricks that fix the squeal would have at least some easily noticeable impact on the fizz. (this maybe a part cause, but not the worst culprit ?) That leaves coupling by magnetization/flux reaching the pickup via the strings (tricky to solve - although there are possibilities) And loading through shared earth - either directly from the driver -ve, or possible via the battery or circuit if a BTL output is used (just guessing there) of course, it could be something else, but these are the first things to eliminate (or not) Whatever the main cause is, its going to be tricky to fix, but at least if we can narrow it down to one or two things, we can focus out R&D in the right direction Most of these issues can be isolated by moving things around on a test bench - I'm going to rig up something when I have the time. The guitar will just have a pickup with a longish lead to the test rig... the rig will have its own pickup and the rest of the system allowing me to move driver, circuit, pickup and strings around in relation to each other without worrying about the trem getting in the way etc. I'll have to set up some 'fake' strings on a block as well, and a variety of different 'loops', this way I should be able to listen to just the fizz as well ! Simple process of elimination should do the rest. (of course, I won't get infinite sustain either, so there will be lots of annoying twanging to do) Any other ideas or suggestions about how to narrow down the causes of fizz ? cheers Col Link to comment Share on other sites More sharing options...
col Posted February 16, 2008 Report Share Posted February 16, 2008 Just a quick note to say that this evening I tested Utopian Isotopes 'loop' technique. It does work exceptionally well as a way of removing/controlling squeal. As is, the basic loop doesn't seem to have any impact on fizz/grunge. cheers Col Hi Col, and everybody. What is this technique? I tried looking for it and didn't find it. Recently got my sustainer guitar together, and I have a squeal. The sustainer worked fine outside of the guitar, so now I'm a little frustrated. Any help you guys could give would be great. Thanks! -Kevin here is a post he made with links to pictures. You can search a page or 2 before and after that post to find the other related posts. Basically, the idea is that you make a loop from some single core wire - I used shielded copper 'bell' wire. You remove the 'hot' side of the driver lead and solder this loop between the driver circuit output and the driver lead. Then stick the loop flat between pickup and driver... make sure you have it the right way up (trial and error is quickest), then mess about with positioning. I found the best (I didn't try all possibilities) was with the loop squared off somewhat, one side near the driver and the other near the pickup. Simple and effective ! Utopian Isotope has refined it by using aluminium foil so the shape is more controllable and it looks better. I'm sure there are other options, And I have some ideas about some possible changes that might help with other problems, but at this stage they are just pie in the sky, so the less said the better cheers Col Link to comment Share on other sites More sharing options...
utopian isotope Posted February 16, 2008 Report Share Posted February 16, 2008 (edited) Just a quick note to say that this evening I tested Utopian Isotopes 'loop' technique. It does work exceptionally well as a way of removing/controlling squeal. As is, the basic loop doesn't seem to have any impact on fizz/grunge. cheers Col Hi Col, and everybody. What is this technique? I tried looking for it and didn't find it. Recently got my sustainer guitar together, and I have a squeal. The sustainer worked fine outside of the guitar, so now I'm a little frustrated. Any help you guys could give would be great. Thanks! -Kevin Hello jamforthelamb. I looked back, and it started at page 230. ---------------------- Addition: Instead of aluminum sheet, brass or copper is better, because you can solder wires to it, when using ordinary soldering tin. Edited February 16, 2008 by utopian isotope Link to comment Share on other sites More sharing options...
Fresh Fizz Posted February 16, 2008 Report Share Posted February 16, 2008 It sounds like you have the gain set so it is nearly squealing. When you hit a note or chord, the extra signal level (more square signal wave shape with more harmonics?) is enough to start the build up to squeal, however, this is quickly cancelled as the fast decay of the guitar removes energy faster then the squeal can build up... so you get a small attempt to squeal during the attack of each note. ? Does that sound about right? Yes, I think it has to do with the dynamics of the sound. During the attack there is a tendency to squeal. Because the fundamental is masked by all those higher harmonics string feedback doesn't happen immediately. Only after the attack the string feedback starts to build. If you mean the fast decay of higher frequencies (attack) I'm your man. I have holding back some valuable information. I use a treble booster inside my guitar (1 fet, 16 dB high boost). It serves as input signal for my sustainer. It's only after the overdrive I cut the high but overall there is still high mid boost. On my guitar there are no extra controls for the sustainer device. There is only a 6,3 mm female connector for the 12V power supply. I have 2 grounds (?) one for the pickup ,treble booster, guitar cable and another one for the sustainer device. Both are interconnected through a 100 ohm resistor. My volume pot serves as sustainer drive controll as wel. Cheap My driver is a humbucker with 2 blades, it looks a bit like those dual rails pickups. The overall impression I have of the driver is that it's good higher up the neck sustaining with a fat sounding fundamental but a bit thinnish lower on the neck. And that is almost the same on all 6 strings. Maybe a peculiarity of my driver? It could well be that I use too much gain. When I set the drive lower there is still good sustain. Some tweaking is going to happen. I'll try to get rid of the overall high boost. Fizz Link to comment Share on other sites More sharing options...
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