EQD Crimson Drive - noisy

[Kinki fuzz]

Just built this one from the layout at tagboardeffects. The thing turned out quite well, nice fuzzey overdrive... but it has too much background noise, any idea where it could be coming from?

http://tagboardeffects.blogspot.com.es/2013/05/earthquaker-devices-crimson-drive.html

[Kinki fuzz]

The circuit includes a germanium transistor, I wonder if that could be the source of the hiss... I will try with another one

[Kinki fuzz]

The b***h got me confused. I attach the circuit in case anyone has a clue. PNP germanium wasn't the guilty, I tried some with same result. Read at fsbx, that it boosts eléctric noise easilly so I tried a battery, a little better, but that wasn't the solución either. I'm pissed rigth nos.

I followed the signal, and found that noise starts at the base of q2. But no clue about how to fix it. I'm going to forget the damn thing until tomorrow

[midwayfair]

What kind of noise? Hiss, high-pitched whine, ocean sounds, low-frequency hum, motorboating, ... there are many types of "noise".

What's the gain and leakage of your transistor?

What are your voltages?

Have you tried replacing the germanium transistor with a silicon transistor to eliminate leakage as the source of the noise?

Have you used/heard the real pedal that you know whether this sort of noise is normally present in the circuit (if maybe not at this level)?

FWIW, upside down germanium transistors always sound like noisy pieces of crap to me, so there's that.

[Kinki fuzz]

Yeah, tried several germs, makes little diference. Also tried a silicon, with no improvement. I'm very into fuzzes, so I tolerate noise to higher levels han most , but this is not normal.

Loud hiss + some high pitch component that is more present at low gain setting. At higher levels mostly hiss.

[midwayfair]

Remove Q2 and audio probe where the base would be. Is the noise present? (Hopefully you're using a socket.)

Assuming that the circuit is still outside of the box, put a 100R in series with your power supply and a 100uF after that to ground.The high pitched noise should go away.

The hiss is a completely separate issue. I'll see if I can think of anything.

[Kinki fuzz]

Hi Jon, the power filtering is bigger than most effects, with 200u, but there's no resistor, so I will try that. Great tip.

Pulling out Q2, the signal in the base pad is quite clean, it gets nasty when you put Q2 in place, no matter Ge or Si, the result is similar. Does that mean something to you?.

[Bret608]

For what it's worth, this circuit is known to have background noise. Jamie at EQD posted at ILF when he originally discontinued it that he did so because he was unhappy with the noise level, especially with a power supply. It's since come back with an added tone knob, so maybe he found a way to deal with it. But the layout at Tagboard is for the original version.

[Kinki fuzz]

Uh! Didn't know that... I'll have to check that

[Kinki fuzz]

The new version uses a OC139, a NPN if I'm not wrong, so that's a major change I think. The one I'm working with uses AC128 (the same type I'm using).

Other than that, it's strange that in the schem the 1n4148 is there for voltage protection and the 1n4001 for clipping. They seem just misplaced...