Mk1.5 hfe and leakage

[Johnnyorange500]

Hi,

Anyone got any advice for transistors for a tone bender mk1.5 and good hfe and leakage values? I’m guessing you have to get close to a fuzz face in terms of hfe and leakage but I’m not sure?. Any suggestion would be great.
Thanks

Johnny

 

[Coda]

You want Fuzz Face specs, you you can afford to be a bit leakier than a FF. I just built a 1.5 ( best sounding fuzz I’ve ever heard), and I believe my numbers were something like q1: 78/30u, and q2: 118/120u, or something like that. These would work fine in a FF, and most likely be an especially gated FF…

 

[Johnnyorange500]

You want Fuzz Face specs, you you can afford to be a bit leakier than a FF. I just built a 1.5 ( best sounding fuzz I’ve ever heard), and I believe my numbers were something like q1: 78/30u, and q2: 118/120u, or something like that. These would work fine in a FF, and most likely be an especially gated FF…

Nice one! Thanks, I’ve got quite a few transistors to go through so will look out for those specs. Have a oc75 but it’s hfe 79 and leakage is 0.45 so maybe too much leakage? What transistors did you use?

 

[Coda]

Russian: Q1: MP20, Q2: GT402B (BART)…

 

[Coda]

My build is in the Build Reports forum. I’d link it but it keeps giving me an error…

 

[Johnnyorange500]

My build is in the Build Reports forum. I’d link it but it keeps giving me an error…

Ok mate. Will try and find it. Cheers

 

[andare]

You want a lot of leakage to get Q2c between -7V and -8V otherwise it'll sound like a bassy Fuzz Face. The Higher voltage makes it treblier.
For gain I would shoot for the usual FF values.

Your OC75s are exactly what you need.

 

[Chuck D. Bones]

Something to keep in mind with Ge transistors in a Fuzz Face is that the bias of both transistors is governed by the hfe, leakage and Vbe of Q1. If any of those drift, the bias drifts. Best to have low leakage for Q1. If Q1's operating point is stable, the whole circuit is stable.

This is why Jimi Hendrix would audition many Fuzz Faces and pick the few that sounded right.