Bonamassa Fuzz Face Mini - Polarity ?

[Mcentee2]

The JBFF comes with a AC power jack, and hte manual states it can be used wih the MXR Brick (non-isolated) so it can be daisychained ok on negative ground power, so as compared with the big one (battery only) Dunlop must have:

1) Used different transistors in the mini NPN vs PNP for the large one ?

2) Added a voltage inverter to the PCB of the mini ?

3) Just ploughed ahead with a negative ground wiring scheme for those Russian PNP trannies ?


Does anyone have any idea which Dunlop have done for the mini ?

[Mcentee2]

Quick follow up for anyone in the future:

I got my hands on a mini, the transistors are the same as the big one,

Q1:MP39B
Q2:IT308V (this is the military version of GT308V, and also not to be confused with the 308B, Russian "capital B" is our "V")

Q1C: 1.53v
Q2C: 4.63v

Voltages are referenced to the 9.06v battery supply "ground", ie Q1C is sitting 1.53v away from 9.06v, if you measured this referencing the "0v positive rail" it would read 7.53v - easy eh!?)

Only that one obvious trimmer for Q2C.

I'm not 100% sure of the whole circuit, even though I have had it apart and inspected it!

However, I can't see any obvious inverter, and I can trace the +ve battery/PSU input directly to Q1E, where it sits at about 8.74v from a 9.06v supply through an SMD resistor or two on its way, and also to the Fuzz pot.

So it looks like it wired like the AMZ scheme: http://www.muzique.com/lab/fuzzface.htm

One departure from that scheme is the fuzz pot bypass cap. One end connects to the fuzz pot wiper through a small resistor (100r or 10r?) and sits at 8.4v, the other side of the cap isn't connected to the +ve supply like the fuzz pot end is, it is connected to real -ve and oriented -ve this way, just hte same as in a silicon -ve ground circuit.....not sure if this is weird or not, I suppose it should be agnostic to polarity of the DC biasing whichever way round it is.

There are fair few smd components that I haven't been able to fully trace (not an expert at that!), so cannot tell if they are anything added to the FF audio or otherwise separate for some reason. they seem to be part of an input/output switching system, the transistors seem to directly connect to the input and output caps as well as and in parallel to the normal in/out path to jacks.