Pete Cornish - CC-1 Crunch

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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aion
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Post by aion »

The CC-1 is an original circuit by Pete Cornish, or at least as original as you can get with op-amps and diodes, but not a clone of anything else.

He had said the OC-1 was an original design, and he was definitely correct to say so, so I decided to take a chance that the CC-1 was worth tracing too. Expensive... but someone had to do it!

Schematic:
Cornish CC-1 Schematic
Cornish CC-1 Schematic

Full tracing journal here:
https://aionelectronics.com/blog/tracin ... nish-cc-1/

PCB available here:
https://aionelectronics.com/project/cep ... overdrive/

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andy-h-h
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Post by andy-h-h »

I knocked out a quick layout this morning - keen to get building.

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Ben N
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Post by Ben N »

Nice. Looks like a worthwhile build. Might NE5532/NE5534 be a good substitution for TL072/TL071?

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Post by aion »

Ben N wrote: 14 Sep 2020, 19:32 Nice. Looks like a worthwhile build. Might NE5532/NE5534 be a good substitution for TL072/TL071?
Yep, will be a little higher current draw but on paper it’s a better audio chip. Should work fine!

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Post by Ben N »

Cornish says this:
"The CC-1™ features two fixed low gain Soft Clipping Stages preceded by a variable gain (maximum +22dB) linear preamp to compensate for low output pickups and provide extra drive to the soft clipping stages if required."

Huh? Looking at the schematic, where is this +22db linear preamp? All I see upstream of the first clipping stage is an emitter follower, aka "my well established Class A input buffer".

Also interesting is that the first clipping stage is non-inverting, while the second is inverting. This, along with the inverting EQ/output stage makes the output in phase with the input, but I guess there is more at work, such as not letting the clean signal all the way through unmolested the way non-inverting soft-clipping opamp stages, with their floor of unity, do.

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Post by mireg »

Schema Aion has fault bass section resistors R22 and R23 must be 11kohm. I pointed out this error to Aion and it's already been corrected in his schematic

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Post by aion »

mireg wrote: 27 Oct 2021, 17:08 Schema Aion has fault bass section resistors R22 and R23 must be 11kohm. I pointed out this error to Aion and it's already been corrected in his schematic
This is correct, we went back and measured them and it turns out that those two were in fact 11k - which has the same 5-band color code as the much more common 1k2, which is also used elsewhere in the circuit. The Cepheus build docs were updated awhile back to reflect this, but I haven't posted a new trace schematic yet.

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