Acetylene

[MAO]

Just curious, I've had a few BS170s with drain voltage readings way out of expectations in the past.
My vero layout build of the Acetylene is working, but I'm getting a ton of hiss. Very similar issue I had with my Azabache builds, which I was never able to resolve.

Getting 4.74v on Q4 and 5.06v for Q2. Thanks for the info.

And false alarm, must have been an impedance mismatch causing the noise/hiss as it sounds correct feeding the input on the amp. (Was originally testing it plugged directly into the power amp, found that adding a buffer between the two solved the noise as well with this setup)

 

[Chuck D. Bones]

Runoffgroove introduced a design in 2012 called the Azabache that's sorely overlooked. It's a great OD that broke some conventions at the time by using JFETs as 'clean' amplifiers, diodes for clipping and tacking on a primitive cab sim at the end.
Subsequent designs from them built on this, but IMHO, the Azabache is the real gem of the bunch.

Another pedal design goes into the breadboard queue.

 

[MAO]

Another pedal design goes into the breadboard queue.

If you do build the Azabache, please let me know how you make out. My 2 builds had way to much hiss. Only noticeable when not playing, but it was crazy loud. Pedal did sound great...until I stopped playing.

 

[Chuck D. Bones]

Hmmmm. I ran some sims and the gain is not that high. I would not expect it to be noisy.
How clean is your power and did you use any carbon comp resistors or disk ceramic caps?

Trimpots can be noisy. ROG recommends replacing the trimpots with fixed resistors once you find the desired value.

 

[MAO]

Hmmmm. I ran some sims and the gain is not that high. I would not expect it to be noisy.
How clean is your power and did you use any carbon comp resistors or disk ceramic caps?

Trimpots can be noisy. ROG recommends replacing the trimpots with fixed resistors once you find the desired value.

Hey Chuck, thanks for checking into this. All metal film and mylar or monolithic caps. Also used fixed resistors. When probing the circuit, the hiss increased through each gain stage. This is where I was at troubleshooting when finally throwing in the towel:

"I built a 2nd one with all new components except the pots. Same issue with hiss!!!

Anything above 7 on the volume control and the hiss is very apparent (when not playing). Not an issue with higher gain settings and moderate volume, but with lower gain settings and higher volume, way to much hiss.

I find it strange no one else has mentioned this, which leads me to believe there is something wrong with my builds, but I can't figure it out.

So I ended up adding a 3-way "hiss reduction" toggle switch. The center position is the original unmodded circuit, which sounds great as long as I keep the volume below 7. Switch up adds in a 1n from the gate of Q2 to ground, this removes a good bit of the hiss. Switch down also increases a low pass filter I have at the output.

Been using it for a few days now, the added switch seems like a good countermeasure when the hiss becomes annoying."

 

[ALK2MT]

I bought one too. Until the Build Docs are published, the silkscreen on the board IS the build doc. Being the A/R person I am, I make a spreadsheet for each build that includes a parts list, which can double as a shopping list. Haven't done that yet for this board.

How’s it going??

 

[Chuck D. Bones]

No progress yet.

Build docs were posted a couple of months ago.