Pete Cornish - SS-3 Soft Sustain  [traced]

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aion
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Post by aion »

Okay, so I've been keeping a secret - I actually traced two Cornish pedals this summer, not just one. (The other is the OC-1 Optical Compressor.)

The SS-3 is an update to the earlier SS-2, which had been sort-of traced by way of the Skrydstrup ODR-2 which was rumored to be a clone of the SS-2. But that means that the SS-2 schematic was in fact based on a trace of another alleged trace, then with the Cornish buffer from the G-2 added on the front. So the level of confidence wasn't necessarily great on that one.

I had the opportunity to get an SS-3 for a decent price (well, for a Cornish anyway, but outlandish otherwise), so I thought I'd get this one tackled for good by dissecting an original to the source. According to Pete, the SS-3 is the same as the SS-2, except for the addition of a low-cut control since the SS-2 was a bit bass-heavy.

Schematic:
Cornish SS-3 Schematic
Cornish SS-3 Schematic
The good news: the SS-3 is in fact very close to the ODR-2, so we haven't been too far off the mark even though it was a bit of a telephone game. The claimed SS-2 schematic has a couple of errors, either with the FSB trace of the Skrydstrup or else the Skrydstrup trace of the SS-2 - I'm not sure. Either way, though, it's nothing drastic, fortunately for everyone who has built one.

Full tracing journal here:
https://aionelectronics.com/blog/tracin ... t-sustain/

Imgur gallery with all the tracing photos:


PCB available here:
https://aionelectronics.com/project/som ... overdrive/
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cornish-ss3-trace-schematic.pdf
Cornish SS-3 Schematic (PDF)
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Post by andy-h-h »

Well it was either do this or clean up the back yard in 34 degree heat (that's 93 for you foreign folks)

Unverified, will probably build over the weekend. I didn't add VC as it seemed a little OTT, you could squeeze it on another row if you really wanted it.

Thanks for the trace aionios :thumbsup
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PETE CORNISH SS-3 V1.png

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Post by andy-h-h »

updated - it works, but I did have mistake in the previous vero, with pins 1 & 2 of hi cut being joined

I also ran a separate power supply to the collector on the buffer in the end, but this version should be fine.
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PETE CORNISH SS-3 V1.png

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Post by Ghandi »

Thanks!!!
How sure are you about the IC‘s both being TL071 and the diodes 1N34A?

Why would Cornish make such a strange dualpot “bass cut“ poti?
If it‘s all the way CCW it not only reduces bass but increases highs, so the frequency respond becomes more toppy allaround and if you turn it CW it returns bass and removes highs...

BTW: On my old build based on the Tagboard Lay-out from IvIark I added a switch to the 10nF cap after the diodes that you’ll add 47nF or 200nF to increase the body and make the sound more bold since the build was to thin sounding, seems that was a mistake / difference to the real SS-2.

Peace, Love and Bananas!
Ghandi

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Post by andy-h-h »

Have you had a look at the tracing blog with pics? Looks like the guy was pretty thorough, I trust the results. If you look really hard at the pics you can just make out that one IC is a national semiconductor TL071CN (at least I think so). In terms of diodes, I was in a bit of a rush when I was making the layout and build (have since cleaned up the layouts above), and I just dropped in some Russian d9k diodes that were sitting right in front of me on the breadboard, and it sounds good to my ears.

I quite like the Lo cut. I didn’t find it a problem at all - can really dial it in to a sweet spot.

I’ve built the SS-2 which I really liked. Have to say that after building the SS-3 that I like this one more. I’ll probably experiment with the gain a little to try and reduce the loss of bottom end when the gain is cranked, which is common on distortion +. Apart from that, this does a great job on low to mid gain, so the loss of bass is not a big deal for me anyway. Highly likely that I’ll play around with it for hours and then just leave it as is....

It’s a keeper for me. :thumbsup

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Post by Frank_NH »

I built an SS-2 from the original veroboard layout at Tagboard Effects. What I discovered is that it sounded much better with the Cornish buffer at the input. Looks like the SS-3 has that incorporated into its design, so I'm sure it will sound better than the bufferless SS-2.

BTW - I used my SS-2 experience to experiment with putting a Cornish buffer in front of a Klon circuit, and voila the Unicorn Drive was born. :D

http://guitar-fx-layouts.42897.x6.nabbl ... 44433.html

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Post by Ghandi »

Jup, I have a cornish Buffer in front of everything except the Fuzz Effects because it is in my P19 klon which comes as the last fuzz in the row...

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Post by Satch12879 »

One small snag; the output jack is missing the 10n/1kV ceramic capacitor from ring to the ground lug. The same on the OC-1 schematic.

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Post by andy-h-h »

I had a bit more of a play and ended up making a layout with an additional soft-clip mod on the first op-amp - sounds cool. Just some diodes over pins 2 and 6 of the first op-amp. Works best with an option to turn off either set of diodes as they don't sound great together at tiger gain settings. Naturally play around with diode combinations to see what works best for you. I've gone for silicon for soft-clip and left the hard clippers as germanium.

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Post by Ben N »

Why not just use a dual?

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Post by Ben N »

Why not just use a dual?

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Post by andy-h-h »

Ben N wrote:Why not just use a dual?
You certainly could if you wanted to. Too many knobs for me :) (assuming by a dual, you mean two circuits in one box).

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Post by Ben N »

No, I meant a dual opamp--a TL072, instead of two 071s. I get that layout would be a tad trickier, but no harder than many other overdrives.

And sorry about the double post. Too late to edit.

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Post by andy-h-h »

Ben N wrote:No, I meant a dual opamp--a TL072, instead of two 071s. I get that layout would be a tad trickier, but no harder than many other overdrives.

And sorry about the double post. Too late to edit.
Ohh - yes of course... dual opamp. That should have been obvious, must have been half asleep. Thought you were referring to using different diodes. :slap: I used the single opamps as that was what was in the schematic. You could most certainly use a dual opamp if you wanted to.

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Post by luix »

Hi guys,

I've routed a PCB but as for the OC-1 I'll not be able to test it until april.

As usual my design is not tidy and some components have not the same number as the schematic, dimensions are 73x38mm.
Buffer is on board.

If anyone want to try, images are attached.

regards
luix
Attachments
SS3_BOTTOM_MIRROR.pdf
bottom and mirrored pdf of the pcb, 1:1
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SS3_BOTTOM.pdf
bottom pdf of the pcb, 1:1
(23.67 KiB) Downloaded 143 times
top image of the pcb
top image of the pcb
you can find some of my creation on instagram @ luixanalogdevices

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Post by Ben N »

andy-h-h wrote:
Ben N wrote:No, I meant a dual opamp--a TL072, instead of two 071s. I get that layout would be a tad trickier, but no harder than many other overdrives.

And sorry about the double post. Too late to edit.
Ohh - yes of course... dual opamp. That should have been obvious, must have been half asleep. Thought you were referring to using different diodes. :slap: I used the single opamps as that was what was in the schematic. You could most certainly use a dual opamp if you wanted to.
Right, so I guess more to the point I am really asking why the original uses two singles. Seems odd, no? Kevin, Andy, or anyone else--any thoughts on why Cornish (or Kevin) would have done it this way?

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Post by andy-h-h »

At a guess, I think Cornish may have used single op amps as it worked for his usual board layout. He seems to have a particular style which is common across his work. Maybe there’s a technical reason, who knows???

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Post by luix »

Looking at the lowCut A pot, actually it is a variable lowpass filter so it cut the high not the bass.

@aionios are you sure of the dual gang of this pot? I think that the dual gang pots are those named LowCut A and HiCut as those two pot form a lowpass filter and cuts treble from the signal.
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Post by andy-h-h »

luix wrote:Looking at the lowCut A pot, actually it is a variable lowpass filter so it cut the high not the bass.

@aionios are you sure of the dual gang of this pot? I think that the dual gang pots are those named LowCut A and HiCut as those two pot form a lowpass filter and cuts treble from the signal.
I've built this, and it definitely works well as a lo-cut. Someone with more experience re electronics will have to explain how, as I see what you mean re opposing filters on A vs B. :hmmm:

PS - I dropped an old LM308H in as the first op amp, and it really changed the character of the drive in a smooth squishy kind of way, but still sort raw (what an explanation). Got pretty noisey with the gain cranked, but that's not where this pedal shines. I would also suggest that if anyone does use one of my layouts posted above, that they seperate the power to the buffer. :D

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Post by aion »

luix wrote:Looking at the lowCut A pot, actually it is a variable lowpass filter so it cut the high not the bass.

@aionios are you sure of the dual gang of this pot? I think that the dual gang pots are those named LowCut A and HiCut as those two pot form a lowpass filter and cuts treble from the signal.
Very, very sure. We went over this thing in great detail three or four times, with multiple sets of eyes independently confirming the schematic without seeing the work of the others, so it's definitely right.

Best guess is that the low cut also implements a high cut at the same time in order to improve the functionality of the control. Pete would have done the simpler method if he felt it did what it needed to do, but he must not have felt that.

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