Bad Odie

[Wild E]

New member, new builder.some electronics knowledge, extensive electrical knowledge (commercial construction electrician).My first build was a Ruby, worked great right off the bat, maybe too great but that's another story.My next build is an Odie.Built the circuit, set the trim pots then hooked up my guitar & amp.It made a sort of buzzing noise and the volume pot did nothing. I removed the pot and shorted the leads to lugs 1 and 2 together and set that issue aside since the volume didn't matter if it was making noise.I played with it and it sounded good aside from the buzz.I narrowed it down to the first FET stage.Made an audio probe and the noise seemed to start at the junction between drain,trimpot and output cap for that stage.I thought the FET might be bad/cooked but the circuit did work.I took voltage and resistance readings on the FET and they seemed reasonable.Then I turned volume up a bit on my amp and used the probe again and noticed a faint noise at the junction between source, cap and resistor.Could it be that the cap is letting DC pass and be amplified by the FET? I'm using 2N5457 FETs and have another one to use for the second half of this build but can get more.If you want my readings or more details please let me know.This forum has already been a great help and I thank you all!

[Wild E]

OK, here's an update on my odie project. I breadboarded the first fet stage so I could sub some parts. No luck with caps. I saw a thread on noisy pots & didn't like the trim pot so I measured it and replaced it with a comparable resistor, no help. Then I went to rat shack and got a mpf102 dropped it in and got the same noise. I measured the voltage at drain and it was only about 1.5 volts. I adjusted the trim pot for 1/2 supply voltage and bingo, no noise!The gain was way lower than the massive gain of the 2n5457 biased at 1/2 voltage , but it was quiet. I dropped in the 2n5457 without adjustment and it behaved similar to the mpf102. I measured the resistance of the trim pot and split the difference and it had more gain but slight buzz. I haven't had a real chance to play it yet as it was kind of late and cops seem to have a bad attitude at that time of night, but for now I would think of it as a clean treble boost with a tone knob. it's still on the breadboard so maybe I'll try the clipping diode trick with my extra fet's.I'll post another update after I've messed with it a little more.

[Ben N]

Just logging in here to let you know that someone is paying attention. Pretty cool that you are figuring it out.

[Wild E]

thanks Ben. I saw views but I guessed not too many people had experience with this ckt. I just played it for real today and cranked it and got some good sounds out of it. I still want to try a few things. Thanks also to everyone else who wrote what I have read so far.It has helped me a lot.