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rump roast question

Started by 9Lives, February 28, 2012, 11:52:46 PM

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9Lives

Home etched, came out ok. It's clipping pretty bad when I give it any volume past hmm I'd say 11:00. Of coarse it cleans up when I turn the volume down on the guitar but I wanna try and get around that. I accidentally used a 10k trimmer on one of the fets but it still reaches bias. So ok right? The only other part I subbed was the 680pf. I used 1n (close I had laying around). Is this a headroom issue or do I just need to mess with the biasing some more?

madbean

Are you sure it's the circuit clipping (ie hard clipping) or is it your amp overdriving? It's supposed to cook the crap out of the front end of your amp, so if it's not hard-clipping or nasty sounding then it's doing its job, I'd say.

9Lives

ok that explains some. This is a solid state :/.. When we talk about hard clipping are we talking an attempt at a shitty wanna be rat-ish type hard clip? It's definitely not doing that but even at perfect 4.5 bias there's still a small bit of weird subtle slipping. It goes away if I bias the fet on the left (looking at components, input side.. I think) when I lower the bias back down it gains more volume and the louder it gets the more it clips. I can definitely see that it is designed to crab a tube by the short curlys (i just don't have a tube amp :( yet!) the clip also goes away with decrease vol on the compressor infront of it. Unfortunitly this comp suffers from and vol decrease.. I'm tellin ya, this is one of those things SOMEthings gotta sacrifice I guess. I failed to mention this thing is still not enclosed. It's in my crappy radioshack experiment thingy. I find that once I enclose and ground every thing correctlyalot of these issues fix them selves. That's what I'm hoping for.

madbean

Okay, got it. Have you tried putting a volume control on the end? That should make it more palatable to a solid state amp.

Hard clipping of the circuit would sound more like a fizzy square wave type distortion. The RR will produce really smooth overdrive in front of a tube amp, but adding a volume control will let you use it more like an actual overdrive with an SS amp...basically "fake" the tube amp part by attenuating the output gain.

9Lives

hey brian? I have SO much cramed in this tiny enclosure that I'm not sure I can fit a pot :(. I had to sub the 680pf cap to a 1n I think...? It the cap with "102" it was the closest I had. Is that ok? Also if I just ad like a 10k resistor to the out put will that serve  the same purpose as the pot in  a fixed sort of way? I wish I could make this thing cleaner at low volume. When it's cranked it sounds great at lower volumes it sounds ok. Also what do recommend as the bias? 4.5 sound like sht on mine. I have to raise the voltage on the first fet to tame it a lil.