Fuzz Aldrin hfe question

[lespauldoc]

Hey all--- I'm going to build the "holy trinity" of Skreddy based on other reports I saw in this forum: Lunar Module, Screw Driver, Hybrid Fuzz Driver. Yes, looks like we can build all 3 with the Aldrin board! I have the HFD, so will be awesome to compare the 3 builds to!

So easy question, maybe. What hFE are we looking for in the Si, and especially the Ge? I have tons of Soviet/Ruskie transistors so will be fun to socket and experiment.

Thanks!

 

[Chuck D. Bones]

HFE is not the important factor. Leakage is the important factor with Ge transistors. You want something leaky for Q3 in the SD & HFD to get the correct tone. I tried MP38A, 2N1308 & AC127 in my HFD. The MP38A was fairly close, but only the AC127 had the correct tone. In the end, it comes down to what sounds good to you.

I recommend building the Screw Driver first. It's tone is somewhere between the Lunar Module (Aldrin) and Hybrid Fuzz Driver. If the SD is too "hot" for your tastes, then you probably won't like the LM. Also bear in mind that Marc Ahlfs (Mr Skreddy) designed the LM & SD to work best with single coil pickups and the HFD was specifically designed to work with Humbuckers. Doesn't mean that you can't change it up. It does mean that the LM & SD are more bottom-heavy.

 

[lespauldoc]

HFE is not the important factor. Leakage is the important factor with Ge transistors. You want something leaky for Q3 in the SD & HFD to get the correct tone. I tried MP38A, 2N1308 & AC127 in my HFD. The MP38A was fairly close, but only the AC127 had the correct tone. In the end, it comes down to what sounds good to you.

I recommend building the Screw Driver first. It's tone is somewhere between the Lunar Module (Aldrin) and Hybrid Fuzz Driver. If the SD is too "hot" for your tastes, then you probably won't like the LM. Also bear in mind that Marc Ahlfs (Mr Skreddy) designed the LM & SD to work best with single coil pickups and the HFD was specifically designed to work with Humbuckers. Doesn't mean that you can't change it up. It does mean that the LM & SD are more bottom-heavy.

I'll build up the stock first (Lunar) then the Screw Driver.... they already are done up with sockets for the Ge parts. I have a HFD I bought from Skreddy around 2015, so will be interesting if I can get close tones with that mod.
Just playing around to see if there's a ballpark before I just plug and play. But I'll plug and play

 

[Chuck D. Bones]

I too have a Skreddy HFD. I traced it and built a replica on an Aldrin board. I hooked the two up to an A/B box so I could compare the tones. My A/B box has a stomp switch and no indicator, so it's pretty easy to lose track of which of the two pedals is connected to the guitar and amp.

Using an MP38A for Q3, I was able to nail the Skreddy HFD tone, but the knob settings were a bit different between the Skreddy pedal and the clone. When I changed Q3 to AC127, then the tone and knob positions matched.