A DS-1 Mod I am working on

JakeAC5253 · Post by **JakeAC5253** » 16 Dec 2011, 21:09

Here is a DS-1 mod that I am working on. Had a stock DS-1 in my drawer for a few years untouched because I didn't like the sound and I didn't know what direction to take it. Yesterday I had another look at the schematic and I started getting ideas, so I hit the iron and this is what I've come up with so far. The sound is nice and clear, but it gets very dark when the gain knob is rolled back, a problem which I have been unable to source. The 220pF cap? Anyway, thought someone might think some of this is cool or useful, so here you go.

Here is the Mod schem:
http://dl.dropbox.com/u/8838613/DS-1%20 ... %20Mod.JPG

Working from this stock schem:
http://dl.dropbox.com/u/8838613/DS-1%20 ... 0Stock.png

Also the part of the mod paper that is cut off says D1 is a Blue water clear LED and D2 is a Green water clear LED.

JakeAC5253 · Post by **JakeAC5253** » 17 Dec 2011, 20:43

Alright, got to test the pedal just now, doesn't sound at all like what I had intended it to sound, which is both good and bad. Bad because I didn't get my result, good because I will learn something. I ended up changing the emitter resistor for the signal path common emitter amp from 100Ω to 1k bypassed by a 2.2µF cap to help clear some low end. The unit sounds like a fuzz pedal now, sounds starved and overdistorted. I thought this would have something to do with the bias voltages, but they seem to check out on all counts. The common emitter amp biases at about ~5.5-6v, but I've biased common emitter amps in that range before and not had any problem, but it might be different this time because the output is unclipped. Might try to get that bias down to 4.5v in the meantime, but I honestly don't think that's the main problem just going by intuition.

JakeAC5253 · Post by **JakeAC5253** » 19 Dec 2011, 17:35

Think I just pondered the reason for muddy low-gain sound, and it is due to the fact that the gain trimmer pot sums with the RC resistor when the gain pot is rolled down, so anywhere below the full gain mark and the RC reactance means nothing from a tone shaping point of view. I've put the project aside for now so I am not working out the bias issue currently, but if anybody has anything else pertinent to add/comment on, feel free to do so.