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Carl Martin - Crush Zone  [traced]

Posted: 05 Dec 2016, 15:16
by Manfred
I traced the Carl Martin Crush Zone distortion and measured the voltages at the transitors.
CarlMartinCrushZoneShot.jpg
CarlMartinCrushZoneSchematic.JPG

Re: Carl Martin Crush Zone Schematic

Posted: 05 Dec 2016, 18:03
by Intripped
i assume the original pedal is not true bypass, there's a DPDT switch fitted in it, but i see a 3PDT switch in your schematic.
so probably you've already modified it, that's ok, but what i don't like are the pulldown resistors: they are always on the signal, and this is not good; you should put the 2M2 res after the 3PDT switch, and the 100k res before it.

thanks for your work, rock on!

Re: Carl Martin Crush Zone Schematic

Posted: 05 Dec 2016, 18:23
by Manfred
Intripped wrote:i assume the original pedal is not true bypass, there's a DPDT switch fitted in it, but i see a 3PDT switch in your schematic.
so probably you've already modified it, that's ok, but what i don't like are the pulldown resistors: they are always on the signal, and this is not good; you should put the 2M2 res after the 3PDT switch, and the 100k res before it.

thanks for your work, rock on!
Thank you for pointing that out, no I didn't modify the circuit, that was my mistake.

Here the corrected schematic:
CarlMartinCrushZoneVoltagesCorrected.JPG

Re: Carl Martin Crush Zone Schematic

Posted: 06 Dec 2016, 06:55
by Manfred
I found a modded schematic in my schematic library, and add the mods to my schematic.
I have no idea how the mod affects the sound.
Who knows more about?
I am not sure whether the 39k and 1uF values are right, because the original schematic is small sized and blurred.
CarlMartinCrushZoneMod.JPG

Re: Carl Martin Crush Zone Schematic

Posted: 07 Dec 2016, 14:11
by EddieTavares
The input cap is 220p, is it correct?

Re: Carl Martin Crush Zone Schematic

Posted: 07 Dec 2016, 16:20
by Manfred
EddieTavares wrote:The input cap is 220p, is it correct?
Yes, it is correct.
The added image shows the input capacitor C10,
you can find the imprint "221".
C10.jpg
C10.jpg (37.53 KiB) Viewed 2166 times