MKI tonebender - SMD tweaker layout

[JustinFun]

I've been wrestling for a few weeks now with various MKI tonebender builds, read reams of forum posts from the contradictory to the enigmatic, and finally thought 'screw it, I'm going to make an easy tweakable SMD layout that will work with almost any germanium transistors!'

No idea if it really does do that, but suffice to say that I etched and built the first one yesterday and it worked right away with minimal tweaking and 3 AC176 resistors - I love it!

It's the Gary Hurst tonebender schematic, with 1M trimmers added between collector and base on all 3 transistors (to add 'leakage') and 1k trimmers on the emmitters of Q2 and Q3 (to tame the oscillation and chirping that plagued most of my earlier builds).

Thought I'd throw it up here in case anyone else fancied a go. It's not a purist's MKI, obviously (where are the axial caps!), but it's an easier route to Mick Ronson-style fuzz-god status... 

[Dingus]

Does that leakage imitation actually work? I hadn't heard of that method before.

[JustinFun]

It's worked for me so far - can get to mki bias for most transistors including ultra-low leakage Russian germs. I have found, however, that the seriously low leakage transistors need more taming from the emitter resistors, leading to less saturated fuzz overall.

[Digital Larry]

Theoretical question - for taming squealing etc. you recommend adding an emitter resistor.  How about reducing the collector resistor instead?

[JustinFun]

Theoretical question - for taming squealing etc. you recommend adding an emitter resistor.  How about reducing the collector resistor instead?

From messing on the breadboard, It doesn't seem to work that way. The emitter resistors act as more subtle max gain controls - you generally just need a few ohms to stop the noise.