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I traced this one way back when it first came out and I found some better gut shots to confirm values. I'm surprised I didn't see a topic on it. Really nothing new going, just a fixed MKIII/MKIV Tone Bender variant with the tone control fixed. I know a lot of guys like the DAM stuff. In my opinion it's a more useful two knob version rather than the 2 knob Park Fuzz Sound which has the gain fixed rather than the tone control. Modifying a pre-existing layout should be a breeze for it.

Rock on and enjoy.

I think that schematic is correct. Can post some gutshots one of the latest purple Grease when I'll back home. I think also have layout somewhere...

First units has 10nf input cap instead 15nf in GB-80.

Grease has really nice clean up, its sounds like blend between drive and fuzz - its not so gainy comparing to others MKIII/IV circuits, so I believe last trannie hfe should be around 60-80.

here is board from copper side - this jumper in read is one of Q1 leg

Nice! I'll compare it to my schematic.

beedotman wrote:- this jumper in read is one of Q1 leg

this is Q1 emiter

Can you check the pot values? I just went with normal mkiii/iv values.

and this is layout.
sorry for shitty work - I've done this in excell when I was bored at work
i think its pretty much ok

phibes wrote:Can you check the pot values? I just went with normal mkiii/iv values.

Citec 100KA for both

and little more gut shots

Yeah that layout matches what I drew up. Thanks for the pot values! Consider this one verified.

trannies:
Q1 - Motorolla metal can OC75
Q2 - CV7004
Q3 - OC71

phibes wrote:Yeah that layout matches what I drew up. Thanks for the pot values! Consider this one verified.

cool!

awesome stuff! i love the MKIII design, so it's always cool to see variants.

redrawn layout

I have finished prototype with transistors on sockets and it sounds really nice.

I think Q3 should has little higher hfe - 85-105 to get proper bias on collector which is around 2.5V in orginal units.
For Q1 and Q2 I have used "standard" gains (50-60 and 70-80 respectively with medium leakage) but this circuit is quite elastic so there shouldn't be problems to get good sounding trio.

Very fun and highly recommended circuit!

BTW... In latest batch AC125 trannies were used with 15K instead of 20K on Q3 collector.

beedotman wrote:redrawn layout

Nice Layout, thanks!
I just noticed that C1 and C2 have to be turned 180°! Or the shaded side is "+"

G5120fx wrote:

beedotman wrote:redrawn layout

Nice Layout, thanks!
I just noticed that C1 and C2 have to be turned 180°! Or the shaded side is "+"

Yup! You're right! "+" should go to ground, I haven't noticed shading before.
Will redrawn it again and post soon.