Bass Fuzz vs. Big Muff Pi (modified stage)

Started by mac, February 16, 2014, 08:51:11 PM

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mac

A comparison between a Bazz Fuss and a Big Muff Pi modified stage.
The Bazz Fuss plot shows two curves, one with one diode and the other with a pair of back to back diodes.
The BMP-like stage has almost the same topology and working voltage.

As I noted in one post long ago, the diode in the Bazz Fuss can't clip and bias well at the same time, so it's better to add a Vcc to base resistor given by Rbase = hfe*Rc, and then fine tune Rc until Vc=Vb, which is the Bazz Fuss tuning condition.
Arsenio Novo's desing has the same tuning condition. It's a kind of Bazz Fuss.

But instead of fine tuning a Bazz Fuss oftenly, I tried the BMP way and found out that results are... well, quite similar.
Breadboard and have fun!

BF schem


BF plot


BMP schem


BMP plot


mac
mac@mac-pc:~$ sudo apt install ECC83 EL84

thehallofshields

Mac. I'm a little confused... I know you like to bias the base with a resistor, but here I see that blocked with a diode.

Can you explain the graphs? Are we seeing that the bazz fuss soft-clips the positive and nearly square-waves the negative? Does this account for the synthy tones the bazz fuss occasionally produces?

mac

#2
QuoteMac. I'm a little confused... I know you like to bias the base with a resistor, but here I see that blocked with a diode.

Note that the modded big muff has a R7=1000k resistor from C to B ;)

QuoteCan you explain the graphs? Are we seeing that the bazz fuss soft-clips the positive and nearly square-waves the negative? Does this account for the synthy tones the bazz fuss occasionally produces?

Not much to add, you answered yourself :)

The BF has two simulations, think Rs as a on/off switch:
- Rs almost zero, both diodes connected, yellow trace, which is similar to the BM.
 (Note that BF has no negative feedback resistor as the BM)
- Rs almost infinite, only one diode working, blue trace, soft clipping up, hard clipping down.

mac


mac@mac-pc:~$ sudo apt install ECC83 EL84