TRI DIRTY BOOSTER Muff clone Hfe?

[Gristlepig]

Hey folks,

I'm whipping up a clone of the rare Hohner Tri Dirty Booster on Turretboard.org's vero layout and the schem from Kit Rae's page.

Scored a bag of NOS 2n5176 TO-98 package, but they all test between 100-180hfe. Bmmr.

I can't find anything regarding trannies for this unit, aside from the part number.

Am I correct in assuming this circuit will sound best with 400-600hfe trannies, like the Triangle it's based on?

Thanks

[John Lyons]

Try the 180s. 400-600 is going to be too buzzy.
300+/- is what I shoot for. Anything will work really.
See what you think.
A lot of the those old triangle muffs were not with high gain devices.
I'd say 100-300 if even that high.

[Gristlepig]

Thanks John.

[PRR]

hFE for the 2N5172 part noted is 100-500.

180 is right down the middle of that range.

In 1973, transistors with gain like 600 were VERY uncommon. Not something a pedal-maker would want to use. Instead you would use an extra low-gain part to get overall jack-to-jack gain. Since this pedal has 4 (Wow! FOUR transistors!!) it should not need a heap of gain at each stage.

[Gristlepig]

Finally built it up....

Used a quad of 2N5172 Hfe between 180-250

Doesn't sound nearly as nice as the clips of the Basic Audio unit. Though the lower gain sounds are def nicer than on a standard muff.

Mine sounds very scooped. I used the schem from Kit Rae's site and triple checked my build... hmm.

Any ideas?