Members Reaganomics! Posted July 12, 2011 Members Share Posted July 12, 2011 So, I bought a chinese fx55c Supra Distortion for $20 vaguely remembering that it got a good word here. In retrospect, I think only Devi talked about really liking it, which sort of makes sense because I found it to be a really harsh ice-pick near fuzz, distortion. After searching for mods I found Wampler modded it back in the day and there were a few rave reviews about it making it a Plexi in a box. Most of the info I found pertained to the older USA made FX55B, but I figured it out enough to get it sounding pretty good. Basically, all there is to it is changing the clipping diodes (D1,2,3,4) from 1n4148 to a mix of 1n4001 and LEDs and switching out two caps (C3, C23) to .1uf. I couldn't find any info about which caps were which, just the numbers which could be different on any different version of the fx55. I found that on the Fx55c, changing C3, which is 120pf, which was parallel to the two clipping diodes closest in the circuit to the gain knob, took almost all of the gain out of the circuit and made it a clean boost. I'm sure it's possible to play with smaller cap values and tune it to the right amount of distortion you want. I put it back to stock, and felt like it sounded O.K., but I might go back and change it later if I can learn more about what value would sound good. There is another mod pertaining, as far as I know, only to the fx55c version. This involves putting a .01 uf cap parallel to C31. This can be done without taking the board out if you want to just solder the cap to the corresponding leads on the component side. I think this just gives you more bass (or less highs?). I'm not sure if that alone would make a big enough difference that the pedal would be useful without having to take it apart to get to the diodes/caps. Link to comment Share on other sites More sharing options...
Members Reaganomics! Posted July 12, 2011 Author Members Share Posted July 12, 2011 Link to comment Share on other sites More sharing options...
Members Reaganomics! Posted July 12, 2011 Author Members Share Posted July 12, 2011 Ok, so here are the sound clips. I recorded everything on the bridge (JB Jr) on my Strat into the clean channel of a Traynor YCV50 w/classic 30 speaker. Master and Channel volume where up 1/4 of the way, all the EQ controls were the full way up, bright switch off. I used a Sennheiser e 835 S, which is not ideal for guitar, but it's all I have. That went straight into a M-Audio MobilePre, then into garageband. In the first two clips the Supra's Level is between 10-11 o'clock. Tone and Distortion are just under 9'o clock. This was about the only reasonable setting stock before it turned really harsh. It doesn't sound ideal modded, but it gives a sense of how it changed with the same settings afterwards. In the third clip I just messed around with the tone and gain. Stock Supra Modded Supra Comparison Messing around Link to comment Share on other sites More sharing options...
Members Reauchambeau Posted July 12, 2011 Members Share Posted July 12, 2011 I have one and look forward to hearing some clips. Link to comment Share on other sites More sharing options...
Members less_cunning Posted July 12, 2011 Members Share Posted July 12, 2011 i wish that the feedback were more ballsy & that you could chord with it; otherwise, you can put me in the "i like the DOD Supra Distortion" camp. Link to comment Share on other sites More sharing options...
Members cmog Posted July 12, 2011 Members Share Posted July 12, 2011 Doesn't Spencer mod these under a Supra Zombie name? Edit: Yes he does... http://www.spenceramps.com/modz.html Link to comment Share on other sites More sharing options...
Members spentron Posted July 12, 2011 Members Share Posted July 12, 2011 ^^-- well someone remembered . I do some wonderful mods, maybe not what you're looking for. The Supra "C" is a good hard distortion except for needing the amp set specially for it, due to its tendency to make the sound brighter and thinner even with Tone set to minimum. The gain does go all the way down to clean, although it doesn't really boost anything then. I don't see a C23 on my 55B schematic and C3 is the same. I don't see anyplace .1's would improve the tone where they aren't .1's already. Possibly C2 would make tighter bass, but that part of the 55C version is changed, the closest is C4 1uF, but the resistance in series is so much lower it's more a case of wanting to increase it (the B uses the gain control on the ground circuit, the C has the gain in the feedback with a fixed resistor to ground). Sticking to the C version, the tone circuit consists of a fixed 10 dB bass boost and a variable treble boost (no cut, so you can turn it all the way down) (you can actually simulate it with Tone Stack Calc. by adapting the Vox model). So why is it so bassless? C4 and C31 both cut bass pre-dirt or in-dirt around 300 Hz, which is a lot. The stock unit has extremely tight bass and allowing more through decreases that. One could try increasing the post-dirt bass even more, but how far can that go? So I tend to trade off a little tightness of bass against actually having some.... You could try a large value for C4 to change that stage (post-dirt amp to drive the tone control) from a slight treble rolloff to a fixed shelf filter (with C4->infinity, the gain of the stage drops from 4 to 1). I see R3 is 470 ohms on yours, that should mean the early version with 500K gain control. The later one had 1K and 100K, for 1/10 the maximum gain! (the 1K does cut less bass, but the higher gain does fill it in some). However the gain taper is terrible with the 500K, I've even seen them use reverse audio taper for it which is even worse. If you want to easily dial in low gains, change it to normal audio taper. I'll give away the only real "tone tweak" I came up for it: change the 470K resistor next to C22 to 100K. This makes the signal hit the second diodes about 5% lower, for a slightly smoother tuning (NOT necessarily better, different). I messed with the resistors, attenuation/boost etc. through there quite a while, and believe it or not, the circuit is tuned to a "sweet spot" where changing almost anything degrades it, it's just not a very sweet choice of sweet spots. Another known mod is remove D1/D2, with the "B" version this becomes identical to their Classic Fuzz. Link to comment Share on other sites More sharing options...
Members less_cunning Posted July 12, 2011 Members Share Posted July 12, 2011 the Zombie mod seems interesting. Link to comment Share on other sites More sharing options...
Members DylanWilde Posted July 12, 2011 Members Share Posted July 12, 2011 Very cool stuff. I've never played a supra distortion, but I have heard that, in terms of circuitry, it's fairly close to the FX50B "Overdrive Plus", which, apart from being my first dirtbox, was, strangely enough, the best overdrive/fuzz pedal I've ever played. Link to comment Share on other sites More sharing options...
Members Reauchambeau Posted July 12, 2011 Members Share Posted July 12, 2011 Very cool stuff. I've never played a supra distortion, but I have heard that, in terms of circuitry, it's fairly close to the FX50B "Overdrive Plus", which, apart from being my first dirtbox, was, strangely enough, the best overdrive/fuzz pedal I've ever played. I believe it's the FX-55B that's really close to the FX-50B. I own a FX-55C and a FX-50B and they're quite different. Link to comment Share on other sites More sharing options...
Members Reaganomics! Posted July 12, 2011 Author Members Share Posted July 12, 2011 Top because I put some clips up in the third post. Link to comment Share on other sites More sharing options...
Members Reauchambeau Posted July 12, 2011 Members Share Posted July 12, 2011 that's a big improvement alright, sounds great. where'd you find the mod? Link to comment Share on other sites More sharing options...
Members Reaganomics! Posted July 12, 2011 Author Members Share Posted July 12, 2011 one of the mods was on gearpage, and the other was alluded to on wampler's indyguitarist forum as he had done a mod for it back in the day. Through a lot of searching around I was able to find a link to the member page on indyguitarist, which is sort of hidden now as it seems everything got screwed up in a redesign or something. However, the page is still up on the server and it has descriptions of the mods he used to do, although they seem really vague. They just give you cap values, but not which circuit they go to so it was trial and error for the 55c. I think my recordings don't do it a lot of justice because I don't have a very good mic for this. It's got a lot of thickness and chunkyness to it now, and is a little bit more touch sensitive. The gain knob has a little more play than before, It used to go from silent to hair metal distortion with a little bit of a turn. Now it has some lower gain settings, but you would not be able to use it as a clean boost. The Tone knob works a lot better too. It's as transparent as it can get with it around noon, and it's really effective almost as a filter knob since adding more gain gives it more treble. The tone knob used to have to be all the way to the left for it to be even bareable, now you can dial in a good balance of bass/treble wherever the gain is. It also takes a tubescreamer like a champ. IMHO I think this totally kills the Rat i had modded with all of the bells and whistles; I'm not sure if it's as good as a Keeley DS-1 as I never had one but I'd guess it might give it a run for your money. Link to comment Share on other sites More sharing options...
Members Reauchambeau Posted July 12, 2011 Members Share Posted July 12, 2011 one of the mods was on gearpage, and the other was alluded to on wampler's indyguitarist forum as he had done a mod for it back in the day. Through a lot of searching around I was able to find a link to the member page on indyguitarist, which is sort of hidden now as it seems everything got screwed up in a redesign or something. However, the page is still up on the server and it has descriptions of the mods he used to do, although they seem really vague. They just give you cap values, but not which circuit they go to so it was trial and error for the 55c. I think my recordings don't do it a lot of justice because I don't have a very good mic for this. It's got a lot of thickness and chunkyness to it now, and is a little bit more touch sensitive. The gain knob has a little more play than before, It used to go from silent to hair metal distortion with a little bit of a turn. Now it has some lower gain settings, but you would not be able to use it as a clean boost. The Tone knob works a lot better too. It's as transparent as it can get with it around noon, and it's really effective almost as a filter knob since adding more gain gives it more treble. The tone knob used to have to be all the way to the left for it to be even bareable, now you can dial in a good balance of bass/treble wherever the gain is. It also takes a tubescreamer like a champ. IMHO I think this totally kills the Rat i had modded with all of the bells and whistles; I'm not sure if it's as good as a Keeley DS-1 as I never had one but I'd guess it might give it a run for your money. son, I am impress RATs have never impressed me, altough I use one for really low gain in my bass rig. I have a Keeley SEM/Ultra DS-1 and it's pretty cool, I think your Supra would give it a serious run for it's money. Link to comment Share on other sites More sharing options...
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