Fresh Fizz

Actually, can't count me in that list... I consider my project a failure on hold at the moment. I burned myself out from messing with that circuit and probably won't try another sustainer circuit until I learn A LOT more than I know now. I've been reading this thread on a regular basis, hoping to get up to speed, but Col and Hank are getting into some unchartered waters. With any luck, they'll have it sorted before I break down and buy a Fernandes or Sustainiac system. Too bad to hear that from you. So what's the hurdle you can't take? I myself had to build 3 different drivers before I finally was satisfied with the result. The poweramp (IC) was a case of building according to instructions. That's the point were I got stuck messing around with all sorts of preamp designs. Even with a well-built driver and poweramp I got lousy sustain. Poor performance on B and E strings. Notes that strugle to build up sustain. It could be that your guitar is in the need of performance-enhancing Uber-compression like mine. Cheers Fresh Fizz

Thanks for the kind words. But if you have your system up and running it will be a cathedral compared to that shed of mine. 1. There's a highboost preamp built in my guitar that operates on 12 volts. See the first image R1 and 4.7uF cap are built into my guitar preamp, the MPF102 in the guitar The 12 volts power supply I built can also be used for my guitar preamp. For that purpose I use a gutted Boss flanger with only 2 resistors and a cap inside. There is an extra resistor that grounds the cap (without the resistor that side of the cap "floats"). 2. Apart from the LM386 the TDA2731A was the only one I knew! When I started thinking of building a sustainer the TDA was mentioned on the diystompbox forum to be used as headphone amp. I have actually built a headphone amp with 2 TDA2731As. Performs really well. The sound quality equals my old Pioneer amp. I only had to weaken the output signal, that was way too loud! Mind you, I use a 120 ohms - 1 ohm voltage divider. I did some tests with the headphone amp at max volume through two 8 ohms loads. Headroom (clean output power) was pretty close to what was expected. The ICs got hot but were still touchable maybe thanks to the chameleon tongue shaped heatsink. I have to say that the first time I tried my headphone amp one channel didn't work at all. After some investigation it appeared that one of the TDA7231As was dead and had to be replaced. It must have been dead when I bought it! My soldering skills can't be that bad! I read that you are a bit disappointed in the LM386's performance, it could be you have problems with a lousy LM386, a bad apple. I have plans to build the LM386-BS170 thingie with some modifications, see how that works out. @ hank mcspank & zfrittz6 as well I don't know if you're familiar with this. The sustainer device's output is inverted (180 degrees phase shift). That will improve stability, it's mentioned in the sustainiac's documentation as well. If your grounding is not ideal (not zero ohm) there could be some output signal fed back into the input which could lead to oscillation. (The output impedance is very low, 8 ohms - in case of a non-inverting sustainers output there is a positive feedback loop). I once thought of inserting a resistor to diminish the risk of oscillation (& fizz). For fizz it didn't make a difference and the oscillations were caused by emi (and solved with a new driver). The resistor is still in my guitar but it could be the cheapest mojo on the planet! http://i268.photobucket.com/albums/jj18/Ma...er_earthing.jpg 3. Maybe I shouldn't have called it fizz in the first place. This is what I think is happening. When I pick the E and A string both strings want to build feedback. But you know that in the end only one string will feedback. Maybe is a bit like sumo wrestling, each of the two signals wants to push the other from the mat. It's not static fizz, there's a bit of dirt on the tone. Like when you hit your fat E-string and hold the tip of your finger close enough to the strings to touch it slightly but not close enough to dampen it. It could be that my setup is too aggressive (much compression, 1 Watt output) and in your edit you mention something important, namely the equalization of the signal. With humbuckers the signal is too bass heavy. In the original Ross compressor there is some treble boost applied. I have removed the high boost because it introduces phase shifts that will diminish sustaining efficiency at least for the fundamental mode. I think that purely for the sustainer's functioning it would be best to slant the pickup (close to the strings on the treble side, further away on the bass side). But soundwise a slanted pickup doesn't combine well with the high boost I use. Maybe a hexaphonic pickup is the way to tackle this particular problem. I prepared another document how to do some testing: Steady Steed Info 3 What other sustainer devices I built? Drivers: magnetless see below copper wrapped around bar magnet - flux gun - lots of EMI hexacoil humbucker 6 rod magnets in N-S-N-S-N-S orientation - no EMI but insensitivity spots in between poles amps: class B powertransistor for magnetless driver - the idea: as soon as signal is being applied to the transistor half of the signal will be sent to the driver and the iron core of the driver will magnetize. No revolutionary breakthrough, no nobel prize. sustainers with an overdriving preamp - not too bad for the overdriven channel but too fizzy when playing the clean channel Old but not so gold Cheers Fresh Fizz

Hi everybody, There's a lot happening at the moment (simulations, hexaphonic pups, new schematics). I like to comment on some of the ideas proposed. But first I show you my sustainer. I wouldn't advice people with less experience in electronics to build my sustainer. (No print available, need to do a bias setup - with oscilloscope-). Ofcourse I don't mean the hank mcspanks, zfrittz6, col and donovans of this world. Piece of cake for you guys Steady Steed The schematic Info 1 Info 2 Cheers Fresh Fizz

So how would you go about that ? cheers Col Welcome in Babylonia! You mean how I was supposed to reduce the power consumption at rest. From what I understood from the article the power consumption has to do with the real dead time setting and switching frequency. I wouldn't be surprised if the voltage was the determinant factor, but that's not what the article says. Only one way to find out. Swap capacitor and see what happens. Cheers Fizz

I still find it a strange design. (I posted the version I knew with a cap at pin 5 of LM386, not the aussimart) To me it seems that only one of the can work. The signal that goes from pin 5 into the MOSFET gate is not DC decoupled. I understand that a positive voltage is needed to properly bias the MOSFET. But when the battery decharges and voltage drops the bias setup is changed. Maybe it's been done with a purpose and I don't get it. There are not that many more components required to mix AC from pinout 5 and DC from the battery. AC: cap to resistor (the 4.7k one) to variable resistor (10k) DC: + of battery to resistor (new one #1) to zener diode to ground. junction (new resistor #1 - zenerdiode) to resistor (new one #2) to variable resistor (10k) With an extra resistor it would even work better, but then I have to draw a picture. Now it's already not that clear. Cheers Fizz

I saw the following schematic in the Dutch Elektor may 2009 (Power in the pocket - eenvoudige PWM-versterker by Ton Giesberts) Is not included in the english release of may, it might well appear a month later. schematic components print layout Self-oscillating PWM amp 1W / 8 Ohm, 1.7W / 4 Ohm Power supply: 6...9 Volt L1-C5: low pass filter to filter out oscillation frequency D1-D2-R4-R5: Dead time setting to prevent both MOSFETs to be opened at the same time. The oscillation frequency varies with applied voltage According to Elektor's info: 9V - 660 kHz - quiescent current 44 mA 6V - 510 kHz - quiescent current 10 mA (4 x AA penlites!) 5V - 450 kHz - quiescent current 6 mA, but according to Elektor too little voltage for the MOSFET's gates. A modification to reduce the power consumption at rest would make the amp more suited for the sustainer. The power consumption could easily be tested with a small resistor in series with the 9V battery. Measure the voltage across the resistor and then apply Ohm's law to obtain the current. The resistor should be big enough to give a result on your multimeter, but not so big that it influences the measurement too much! (And don't forget to connect your sustainer driver while testing!) Just apply Ohm's law, for a desired output of 250 mVolts at the expected 44 mA you need a 5.6 Ohm resistor. It's a bit like biasing your output valves in a balanced AB amp. The oscillation frequency depends on R3 and C4 (and R2 and the output impedance of whatever is connected at the input I reckon). To lower the oscillation frequency and quiescent current increase C4 and run the test again. Cheers, Fresh Fizz

@psw & col I want to share with you the schematic of the mosfet compressor I have. I've found this one on the diystompbox forum some time ago. Could it be that this one is the original and that the ones that zfrittz6 and psw have posted are derivatives? That could possibly be toxic? Maybe zfritt6 only wanted to be helpfull and posted the schematic. But has he actually built that compressor or has he obtained the schematic from somebody who stated that he had actually built it? For instance have seen schematics for starved plate tube amps (with ECC83s) that couldn't possibly work. How do I know? Because I've have been messing around with ECC83s with low plate voltage. That schematic must have been the result of a thought process and not a reflection of something that has been constructed in reality. Back to the schematic I posted. In this schematic there is a cap in between LM386 output (pin 5) and the rectifying diode. Which means that the anode side is at a zero volt potential, just like the cathode side. In zfrittz6' and psw's the cap is missing, anode side is at half-battery voltage (4.5V) times attenuation (depending on 4k7 resistor and potmeter) , and the diode is conducting (?!) Which means positive voltage on the gate of the mosfet. (Resulting in which resistance measured between drain and source of the mosfet?) Anyway, the cap at the gate can only be charged more when the voltage at pin 5 goes above 4.5 volts. Now to me it seems that the cap has to be included. And it has to be big compared to the cap at the gate of the Mosfet. At least I would bet that of the three schematics the one I posted should be the correct version. And if the frittz6 and aussimart are functioning hey should be two completely differen beasts compared to the one I posted. But I HAVEN'T built it, so I'm not sure. But has anybody really built one of the other versions? Cheers, Fresh Fizz

The problem with your design is that fets are not that consistent, specs can vary a lot. That's why I haven't posted my design, based on the Ross compressor. Fet needs to be biased properly, not all ca3080s work exactly the same(bias, transconductance), transistors have different hfes. What we need is a design where all the calculations can be made based upon component values like with the THATS. Could be as simple as this one Looked it up in the dictionary, still think I ment exotic Cheers Fizz

Of course I want it! Thanks, Hank. So you caught me telling the untruth. I've been looking for that THAT before, today I did only a quick search and I couldn't find it.

There have been some contributions by others. But it's logical to see the F/R amp and the driver as step 1 in building a sustainer device. Inserting a compressor could be seen as the next step to improve performance. Limiting or compressing, both will do. Using a stompbox makes a lot of sense to me. A. You could do some outboard testing B. Out of the box solution C. Is designed to work on 9 Volts. Small circuitry. Could be transplanted into the guitar. D. If info/schematics/print lay-out found on the internet it could be cloned. (Here is where the trouble starts) And we need a design without exotic parts. The CS-3 is not a good example I'm afraid. No info on the That2159 available. Difficult to buy I guess. Fizz

You don't have to go that far. All you need is a compressor/limiter, a small poweramp and a driver. For the poweramp even the F/R (lm386) will do - I use a tda7231A - has a little bit more power. Pete has optimalized his drivers for these run-of-the-mill (13 in a dozen, we say) ICs. So build according to Pete's instructions and it'll work. No need for phase-compensation or stuff like that. I think my sustainer performs as well as the commercial ones. Not as energy efficient, though. I think that Pete is reluctant to post and endorse a compressor/limiter is because so much tweaking is required. If he says, this is what I use he can expect a 1000 questions about compressors and how to do the setup. Even if you explain it well enough the person has to test with an oscilloscope and design the print layout by himself. For an experienced builder this is not a problem but for the inexperienced one a design is needed that works out-of-the-box. Even if you clone a sustainiac you have to test it with an oscilloscope. You just can expect to solder everything error free. Fizz

Hi Pete and others, I don't think the F/R (LM386) is that bad. But without a compressor/limiter there is a headroom problem. And because of that there is a big chance of ending up with notes that don't sustain well while other notes generate fizz. Pete, I've heard your clips, and the fizz sounds indeed musical to me. But that also depends on the other equipment a guitar player uses. For instance, I'm using a strat with a humbucker. Because humbuckers have more mid and I like a bit more highs I use a high boost. Using a high boost also affects the headroom problem I mentioned. My humbucker is positioned at even distance from bass and treble side, not slanted. This compensates for the use of the high boost. But the high boost is not used as a part of my sustainer device setup. Therefore if I set up my sustainer device in a way that I have sustain on my bass strings without fizz the treble strings are underpowered. If I boost the highs or cut the lows the even response is gone (phase shifting). So in a sole F/R setup I have to live with the fizz. But in my setup the fizz that's being created by the sustainer device goes through my high boost! Result: harsh sounding fizz, NOT musical! So my conclusion is: the sole F/R can indeed give good results but it depends on what other equipment is used. An optional limiter should be offered to prevent fizz for those setups where it's not sounding well. Fizz

So far I'm only familliar with one configuration that works: compressor/limiter - IC amp - driver. I've tried to use some sort of overdrive device instead of the limiter but that gives a lot of fizz through acoustic feedback (via the strings, not emi). Without limiter I wasn't able to get a steady operation of the sustainer device al along the neck and on each string. I don't consider manually adjusting the sustainer device (sustainer volume pot) to be an option. With the F/R that's basically what you have to be prepared to do. When playing chords, tame the sustainer otherwise you'll get lots of fizz. When hitting the high e-string, boost the sustainer otherwise it takes the sustainer ages to accelerate into feedback, but be carefull, at some point you might want to ease back a bit because of the danger of fizz. I get good results with a modified ross compressor. But like col says, it's a bit a one dimensional sound. Almost as soon as the sustainer sets in you end up with a single sinus (fundamental most of the time). I was thinking of using a simple phase shifter atter the compressor or maybe a dynamic filter in front of the compressor in order to change the feedbacked tone. Or maybe you need a compressor with a superfast attack and a slow release for a more violin type envelope. Even if it's theoretically possible at all, there's hardly any space left inside my strat. Cheers Fizz

Pete, have you ever tried a sustainer device as following: A driver with an iron core built into the guitar. No magnet is being used so this way it will not work at all. But now if we put/place a magnet above the driver there will be a magnetic field and the sustainer will work. (I hope) It could be a small but strong magnet in some way attached to the picking hand to achieve some interactiveness (what col wants). By moving the magnet the magnet field would change (weaker, stronger, different strings). And it's cannot be that difficult to come up with a construction to mount a bar magnet above the driver. (In order to have the old functionality back) So we end up with the strings in between driver and bar magnet. Just an idea of mine. Please evaluate! Fizz

Hi Pete, It's been a long time since my last post on this forum. I only want to tell you that I've finished building my sustainer device and I'm totally happy with it. Some things stayed the same: power ic tda7231 and the 12volts outboard power supply While others changed: I took my old dual blade humbucker-type driver and filed off the piece of iron core that was protruding from the bobbin. That helped to decrease the difference in sensitivity between low and high fret positions. So a built-in distortion wasn't a good idea. I've replaced it with a compressor. I built a slightly modified Ross compressor with a ca3080 IC. I kept the EQ flat. Which means no high boost before and high cut after the ca3080. There is plenty compression (it actually works as a limiter) about 34 dB. At about 40 dB the poor thing can't take it anymore and starts distorting. The result: I have strong sustain on all strings and fret positions. And I hear almost no fizz at all! I've set up my sustainer device in such way that a minimum of distortion is generated. My power ic uses all the headroom there is but doesn't distort. I always thought that the fizz occurred because of magnetic crosstalk. Apparently not in my case. My driver is in the neck pickup position and my power ic in the mid pickup position of my strat. That could be an explanation. It seems to me that the fizz came from an acoustic action=reaction thing. The distorted signal on the driver made the string vibrate in such way that it was perceived as a distorted sound at the guitar pickup. Something that supports this theory (Colin: read hunch ) is the fact that with chords I can hear sometimes a little bit of fizz. Should be one string interfering with the string vibration of another string or so. It's hardly noticeable with the blade, my pseudo-hexaphonic driver had more problems with it. The lesson I learned is: avoid any distortion and use strong compression and listen to Pete's advice So my sustainer project has come to an end. I would like to thank everybody (especially Pete) who has helped me. This forum was a confidence building environment to me. The final step for me to start building one sustainer myself. I go back into lurk mode. Good luck to the other builders. Fresh Fizz

I think that is the easiest way. Now it depends on what you really want. Do you want the switching to be active? The sustainiac mid driver version needs current even when the sustainer is switched off. What type of switch does your tele have? Same as strat without the in-between positions? If so, how about modifiying this old one? You need to insert the 2 buffers for bridge and neck (before S2a). Mid on S1a is the in-between position of the to pups. S1b shortcircuits bridge-only and neck-only to ground. No more need for S2a (?) Just a quick reply, don't know if it's entirely correct. About my own device: the Ross compressor is ready to be installed. Cheers FF

How about this: The bi lateral driver generates a loop of flux. Where the strings are above the poles, the flux is more vertical, where they are between, it is more horizontal. The electrical signal applied to the driver only can attract or push away the string. When the string is in between the 2 cores, or in my case 2 rod magnets, there is mostly horizontal flux. This also goes for the flux created by the driver coil. But the fields of the 2 cores (magnets) work in opposite direction! Both cores attract or push away the string at the same time. So the horizontal component of the flux field is canceled, leaves only the smaller vertical component. Cheers FF

I've installed my new sustainer driver. It has 6 strat-type rod magnets with alternating orientation (N-S-N-S-N-S) and 6 copper coils. I don't know how you call it, hexalateral perhaps? Another thing I did was to use more windings for the higher strings. But I wanted to keep the maximum humbucking effect so it's done in pairs, 90 turns for E and A string, 110 turns for D and G, 145 turns for B and E. Good guesswork from my side, I ended up with a total of 8,5 ohm. When it comes to throw this new driver is a big improvement over the previous one ( with the blades). The new driver is much more sensitive in the lower fret positions and increasing the amount of turns for the higher strings improved string balance. The biggest drawback is what is mentioned by Pete. When bending the string in between two magnets the efficiency drops. In the worst cases the sustain stops. Not so good! I think there has to be iron core or magnet underneath the string to make it work. Make the gaps as narrow as possible, leave only enough room for the copper I would say. My configuration with lots of overdrive doesn't seem to work well. I hoped that a more sustainiac-like driver would diminish the fizz, but that's not the case. At least I could remove my dummy coil without getting the squeal back! I'm afraid that the overdrive is on its way out. Cheers Fresh Fizz

If saturation was the case wouldn't I also experience fizz when keeping the magnet still above the pickup? It wasn't even my intention to generate fizz. I was thinking of mounting a magnet above my sustainer driver to create a more homogenous flux field to get more "throw". So I was checking how the bridge pickup performed with the magnet above it. I didn't notice much difference except when waving the magnet. True, I can get fizzless sustain high up the fretboard but then it's impossible to get good sustain in low fret postions. Maybe my current driver is a lousy piece of crap in a kramer barettas disguise. Doesn't matter. There is a new baby coming. I think that the metal piece in the kramer serves as magnetic shield. FF

@captainstrat This change of tone is explained in the sustainer patents. The sustainer in operation pushes away the magnetic field of the pickup towards the bridge. Because of this the tone thins out. I haven't experienced it myself but I've read about it. @psw I'm only referring to the switch that switches on the power of the sustainer amp, the fetzer-ruby. The one that connects/disconnects the battery. You could try to bridge that switch with a diode in opposite direction of the current flow. This is also being done in circuits with relays. Well, if I could move a magnet that fast Yngwie Malmsteen should better quit playing the guitar. No, I mean 1 or 2 times per second. And because of that movement I hear overtones of the string when played. What I was saying is that when it's fizzing you don't hear tones from the driver that bleed through. It's more that the driver causes the magnetic field of the pickup to fluctuate. And because of this fluctuation there is fizz. I don't think there is anything revolutionary about my remark and in some way we have to live with the fizz but I think that the magnet experiment shows that there is no qualitative relationship between the sounds the driver produces and the overtones that are heard as fizz. It's more the quantity of the flux produced by the driver that determines the fizz. @col and @psw My humbucker driver in single coil format looks almost like a Seymour Duncan Cool Rails. It has 2 thin blades and ,yes, maybe the gap between the blades is too narrow for a sustainer driver (only 7mm). I could modify the driver but I like its looks. First build the new driver, then test it and then I'll decide what I do next. Cheers FF

Have you ever tried bridging the sustainer current on/off switch with a diode in opposite direction of the current flow? This should help against induction voltages. I'm still working on a new sustainer driver. My complaint with the current one I have is what I believe Pete calls a lack of throw. High up the fretboard it's sustaining beautifully. My sustainer seems to be capable to do what I haven't heard in the clips of you, a Jimi Hendrix or Adrian Belew-like reversed volume swell. I need to play more staccato because the strings are swinging so fiercely while sustaining. But low down the fretboard is a different story. It seems that the strings are a bit out of the magnetic field - I have a dual blade driver in single coil format - and the sustain is weaker (on all 6 strings). My new driver won't improve the throw. At least that's what I think. I hope that it will reduce the amount of fizz I'm experiencing. By the way I found out that I could generate the fizz phenomenon by slightly moving a rod magnet à la strat above my bridge pickup. (Closer to pup, away from pup, sustainer not active) This would mean that the change of magnetic field is responsable for the fizz. What I mean is that while moving the magnet with a frequency of 1 or 2 Hz I hear harmonics of the string in the kiloHz range. This means it is not enough to prevent the sustainer amp + driver to distort, the output level needs to be as low as possible to avoid the fizz phenomenon. Cheers Fresh Fizz

Yes! Allways open one mosfet switch before closing the other one. I read it somewhere in the patent. I don't think you need lower resistance drivers. The lm386 with the current source trick could still be applied but now with thicker wire and more turns of copperwire. Available headroom is indeed a problem, the current source trick should be combined with the drive current limiter. FF

One way to deal with it is to sandwich the pickup in between two driver coils which are out of phase with each other. What I understand from Pete is that some extra conditions have to be met: 1. 3 pickup configuration 2. when sustainer switched off the 3 pickups function all passively (no power supply needed) I can remember that we spoke about a sustainiac that used a (step-up ?-)transformer to turn the driver into a pickup. If the transformer is used for that purpose than the schematic of this particular sustainer device could solve this problem. The question is, what transformer is needed, can we buy it, could it be a DIY project? There must be some sustainer schematics with ordinary output stages, no fancy D-amp. How do they switch on/off the sustainer? Nice driver Curtisa, must have a decent self-inductance! Fresh Fizz

That's exactly what it has been designed for, to avoid switching noise. If we look at Q1 it's source is connected with the output of IC1 which has the same potential as V1. That's the floating ground, half of the available voltage, 4.5 volt. You could see the floating ground as bias for the IC. Thanks to this bias the IC can deal with the positive as well as the negative half of an AC signal. The gate receives it signal from 3 of U5a. It's some sort of binary logic so the output of U5a can be low (<4.5 volt Q1 open) or high (>4,5 volt Q1 closed). The point I was trying to make is that the best way to proceed is to go through the patents and figure out how the switching functions. Maybe you're pushing yourself too hard and are you trying something that even the sustainiac guys couldn't solve! There must be a schematic somewhere that solves your switching problems. FF

Maybe it's best to take a closer examination of figure 11 of patent 5932827. For the switching of the pickups and driver when used as pickup fets are being used. Notice the middle gate, neck gate, bridge gate filter. The make use of RC filters. The cap is charged and decharged smoothly through the resistor. The mosfet pair is not switched on and off. There is allways voltage across the mosfets even with the output jack disconnected! When the sustainer is off the comparator supply is switched off (V4 across C28). When switched off C28 will be decharged through the comparator, when switched on C28 will be charged smoothly through Q8. Fresh Fizz