PETE CORNISH: P-1

I'd created a layout for the Pete Cornish P-1 about four years ago, based on best guesses as to what this said to be - a Rams Head Big Muff.   I was kind of close, but here's a layout from a very reliable Aion FX trace.  If you want to see where it sits in the spectrum of the Big Muff, check my BMP components table.

Interestingly, the circuit matches the 1976 Rams Head circuit #2, despite stories of it being based on a 74 model.  Who knows?  It's quite possible this was the case for the original P-1 with Pete changing values at a later date.

PETE CORNISH: P-1 VERO LAYOUT

Yes it's a very big layout for a Big Muff.  I included all of the buffers on the board, and left room on the corners for mounting.  I'm sure the multitude of standing resistors will throw a lot of people off too.  I clearly don't mind them.

I wasn't all that concerned about size, as I intend to drop this into an old big box BMP enclose, as beat up NYC ones seem to be going pretty cheap, and of course they already have cool graphics, pots and a hardware ready to go, so job done in that respect. 

PETE CORNISH: G-2, 2012, Battery Free Version (Aion FX Trace)

There's been so much speculation about the G2, over many many years.   Aion FX has traced two versions of the Pete Cornish G2, so hopefully this is the end of some very long threads on various forums.  

Long story short, one version is very close to all of the mods that everyone has been doing for years.  Here's the battery free version, which uses a mix of germanium and silicon diodes, and has smaller caps in the required places to fixe the darkness issue.   

I will come back to this at a lter date with more details and a larger layout incorporating the second buffer.  This is it for now...  

PETE CORNISH G2 - AION FX TRACE, 2012, BATTERY FREE VERSION

PETE CORNISH: GC-1 (Aion FX Trace)

Another from the recent Aion FX Pete Cornish traces - this time it's a variation of the CC-1 Crunch, the CG-1.  Same layout, just a few value changes here and there.  It will sound a little different to the CC-1, but not substantially.  

I quite like the CC-1, especially with an added mod to dial in the diode clipping.  Combine this with the active EQ and you have an extremely versatile overdrive.

PETE CORNISH GC-1  -  VERO LAYOUT

This layout has a simplified power supply to reduce board size.  

PETE CORNISH: NG-3 Fuzz (Aion FX Trace)

Aion FX recently traced a few more Cornish pedals - and the NG-3 trace was was a real surprise package.   It was thought to be a NG-2 with an external bias control.  It's nothing like the NG-2 trace by Pedal PCB - not even close.   

I did have a vero layout for the NG-3 based on the NG-2 - I've taken them down, as they're clearly not the same thing.

PETE CORNISH NG-3 FUZZ  - VERO LAYOUT

I've not built this one yet, but I have checked over it a few times.  So if your feeling brave, let me know how it works out.  I'll definitely be building this at some stage.

Ignore the text explanations in the video - they've used the marketing spiel, which are said to be not based in reality.

PETE CORNISH: P-2 (Aion FX Trace)

So the mysterious P-2 has finally been traced, care of Aion FX (thank you).   I had previously posted a guess as to what this might be, and I wasn't too far off.   Here's the same layout with confirmed values.

PETE CORNISH P-2 - VERO LAYOUT

PETE CORNISH: TB-83 Treble Booster, Point to Point Layout

I followed a vaguely similar layout to the one pictured at the bottom of the post for the Pete Cornish TB-83 Treble Booster.   

This is a straight treble boost using a silicon transistor - it's going to sound horrible into anything apart from a cranked valve amp, or maybe a valve based pedal.  Given this was in Brian May's rig, think normal channel of a cranked AC30, with this hitting it.  Well maybe you aren't running nine AC30s at once, all running so hard the border on catching fire, but you get the idea.

PETE CORNISH TB-83   POINT TO POINT LAYOUT

PETE CORNISH TB-83 - LTSPICE

I used the schematic from Fryer Guitars - link here.  

GUILD: Brian May Box

The layout is for the Guild Brian May Box, which on the Guild schematic is marked as designed by Pete Cornish, but he has disputed this.

There's a massive write-up here on Fryer Guitars, including photos of inside Brian May's Pete Cornish built pedal board, and inside a pretty vintage looking Pete Cornish treble boost, which also happens to contain a buffer.  Given that Fryer rebuilt AC30's for Brian May and has a few of his own treble boosters, I think the man knows a thing or two.

Either way it's a buffered treble boost.  You can either wire this up as buffered or true bypass, whatever you prefer. 

GUILD BRIAN MAY TREBLE BOOSTER - VERO LAYOUT

GUILD BRIAN MAY TREBLE BOOSTER - ORIGINAL SCHEMATIC

GUILD BRIAN MAY TREBLE BOOSTER - LTSPICE

Not much to see here.

And one difference to other treble boosters from the Rangemaster family is the 10n input cap vs the standard 4.7n.   

CORNISH: SS-3 Modded Diode-Compression Opamp

Details of this project can be found here - as I started with a modded Pete Cornish SS-2 using the Joe Davvisson diode-compression op-amp, and then moved on to this.  Essentially the same as the SS-2, but with the addition of a lo-cut.  

After a bit of testing, I’d suggest a C50k for the sustain pot, followed by B50k, and A50k if you have none of the previous.

CORNISH SS-3 WITH DIODE-COMPRESSION OP-AMP - VERO LAYOUT

The layouts works - I added a buffer on top of this build.  

CORNISH: Modded Cornish SS-2 using Diode Compression Op-amp

This is a Pete Cornish SS-2 using Joe Davisson's diode-compression op amp.  It sounds pretty good - a lot like the regular SS-2, but without any distortion artifacts on sustained notes as it fades outs.  It's also quieter in terms of noise.  This one is getting boxed up, and now I want to try a SS-3 version.

For my ears it sounds best at 18v, and with a Cornish buffer in front.  You can notice the buffer on cleaner sounds in particular, as the high frequencies are a little brighter. 18v sounds more open with better string clarity.  9v still sounds good, but it's more compressed and less dynamic in my opinion - may be a tad thicker sounding as a result of this, which some people may like.

Being based on the MXR Distortion +, higher gain settings roll off bass and treble to provide more of a mid-hump.  It also sounds pretty good with the tone control wound all the way back.  Low gain settings sound pretty nice too, as the frequency response flattens out.  

The tone control is definitely needed as the treble can need a bit of smoothing out on some settings.  It works well for a simple tone control.

I tested it on a transistor and valve amp - both had their own charms.  Could not say which one I preferred.  The valve amp liked it more when it was just breaking up, and then pushed with the SS-2 - but then again when doesn't a valve amp not like being pushed on breakup?

Things to tweak if you feel like playing around with the tone;

• C2 - definitely increase to 22n (input cap).  10n forms a 66hz HPF with R8, 22n forms 30hz HPF

• C8 - 10n capacitor paired with diodes to ground (forms a 1.5khz LPF with R11)

• C5 - 10n capacitor from clipping section into tone 3, rolls off some bass (I'm using a 22n here)

• C9 - 10n capacitor from tone 1 to ground

• Germanium Diodes:  different combinations, types - usual diode mods...

• Reverse log gain pot like the SS-3

CORNISH SS-2 USING DIODE COMPRESSION OP-AMP - VERO LAYOUT

SCHEMATIC

FREQUENCY RESPONSE - LOW TO HIGH GAIN

ON THE BENCH TESTING SOME CAP VALUES

And a buffer to match

ON THE SCOPE

caution - start with low volume levels 

 

First adjustments to gain, then tone.   440hz sine wave input source

 

This is at the diodes, after the first opamp, with adjustments to gain

Gain off the first opamp is pretty high, it's really squashed by the germanium diodes.   Like hard clippers, diodes are fun to play with.  With silicon diodes, it looks like there's some additional clipping happening in the second stage.

VOLTAGES

Strangely at 18v it behaves a little differently compared to 9, 12 & 24.  Here's 18v - note the mix of harmonics compared to other voltages.  

 

 

All other voltages to follow in ascending order - no changes to any settings, just the voltage.

ON THE BREADBOARD

And here’s the mess that was the breadboard 

PETE CORNISH: ST-2, Modded (Simplified)

This is a simplified version of a Pete Cornish ST-2 (based on the Colorsound Overdriver).  I did the full layout, and it it kind of large, and double buffers are not for everyone.

So no buffers, and the power supply filtering is simpler.  I'm sure the proper Pete Cornish version is probably better, but if you prefer something smaller and simpler, this might be for you.

The full layout, including LTspice traces can be found here.   Please note that this is not actually an overdrive, it's really just a bass / treble control for tone shaping.

PETE CORNISH ST-2 - VERO LAYOUT - SIMPLIFIED VERSION 

PETE CORNISH: ST-2 (Colorsound Overdriver)

The Pete Cornish ST-2 is a Colorsound Overdriver with a few mods.  The ST-2 is intended to be a tone-shaper; it's not actually an overdrive.  So if you are looking for dirt, you have come to the wrong place with this one.  Although one can make a few tweaks to bring some dirt to this, but I'm not sure it would sound that great.  Could also make it a little hotter on the output by adjusting the gain of the op-amp, if you really want to push some tubes over the edge.

It has the usual Cornish buffer (two in fact) and an additional buffered/boosted output via an op-amp.   The power supply is a little over the top too.  Several feeds for different sections of the circuit.  

All of the extras make for quite a large vero layout, and after all it is really just a bass and treble control - I'll probably do a simplified layout at some stage with a single buffer, or maybe no buffer at all and a smaller power supply.  It should cut down the size and complexity quite a bit.

The wiring is for buffered bypass, which I don't mind.  It bothers some people... 

Schematic and tracing details can be found here, at Aion FX.  Instead of using this gigantic layout, maybe consider buying a board from Aion.  

PETE CORNISH ST-2 - VERO LAYOUT

ST-2 ON LTSPICE

As expected, there's a fairly standard bass/treble response

There's nothing to see on the output trace - no distortion on this one, purely tone shaping.

CORNISH ST-2 VIDEO DEMO

 

PETE CORNISH: SS-2, Vero Layout, Modded Buffer, SS-3 Values

Like the very lengthy title below suggest, it's a Pete Cornish SS-2 with mods.   After finishing the SS-3, they're almost the same, so I thought I would also do a SS-2 layout.

Changes

• Swapped the Cornish buffer for a standard opamp based buffer

• Ran the reference voltage through the spare opamp

• Used a quad opamp instead of 2 x single op amps
• Left SS-3 values throughout (which are mainly cap values and opamp gain)

PETE CORNISH SS-2 WITH MODDED BUFFER & SS-3 VALUES - VERO LAYOUT

PETE CORNISH: SS-3 Soft Sustain, Vero Layout, Buffer Mod

The Pete Cornish SS-3 is one of my favourite overdrives - so I thought I might make another one with a different layout and buffer.

Changes

• Swapped the Cornish buffer for a standard opamp based buffer

• Ran the reference voltage through the spare opamp

• Used a quad opamp instead of 2 x single op amps

PETE CORNISH SS-3 SOFT SUSTAIN WITH BUFER MOD - VERO LAYOUT

Pete Cornish Buffered Bypass - Offboard wiring

A 3DPT or a 2DPT switch can be used for this.  Pete Cornish uses a 3DPT, perhaps because he solders the LED circuit to the switch pins - who knows...

I added secondary power filtering on the buffer, which of course, can be easily removed if you already have it on the effect circuit.

Stating the obvious:  when using switched jacks, it's very important to ensure you are wiring to the correct side, or this will not work.

PETE CORNISH BUFFERED BYPASS METHOD

PETE CORNISH: Buffer

Just a little Cornish buffer that I use for buffered bypass / Pete Cornish builds.  It's small enough to sneak in at the bottom of an enclosure below the foot switch or standing upright against the side.  

PETE CORNISH BUFFER - VERO LAYOUT 

I sometimes add an extra row for additional power filtering - for the circuit that it's buffering, and there's still just enough room to fit a LED resistor on the board (will need an extra cut, and maybe relocate the diode - I'm sure you will work it out).  

PETE CORNISH: NG-3 Fuzz

This has now been traced by Aion FX - it turns out the NG-3 is very different to the NG-2.  Miles apart...  

While this still makes for a decent fuzz, it's NOT a NG-3.  Layouts have been removed for this reason.  

Here's the link to the trace

The Pete Cornish NG-3 is pretty much the NG-2 with the trimmer to bias the last stage placed externally - which is a great addition, even if the knob count starts to get a little high.

The front end is the first section of the Cornish G-2 (a low-gain Big Muff with germanium diodes), and the last stage is a Fuzz Face variant.  

This should be built with the usual Cornish buffer, running buffered bypass.  Hardly the end of the world if you opt to use a standard unbuffered true bypass.   

As I've never seen a schematic for the NG-3, this is my work-a-like.  I've used a 25k pot as the bias pot in my builds, as I preferred the range.  I have had someone else say that they preferred the 50k, and another used a 20k pot without issues.  Either way, it's best to have a low-value resistor at the end of the range to stop the circuit from completely turning off - I use 4k7 for this, 8.5k has also been reported as a good value.  

PETE CORNISH: P-2

It has now been traced by Aion FX - updated layout can be found here.

The Pete Cornish P-2  is somewhat of a mystery as it's never been traced, so all information is gleamed and guessed from various sources.  It seems that no one, including myself, wants to pay top dollar to de-goop what we all know is some kind of Big Muff. 

So what do we know?

• it uses the same PCB as the G-2 (photos here)
• silicon diodes
• double buffered
• the tone control is a low-pass filter, not a standard BMP tone stack (description here, listen here)
• reportedly first made in the eighties, before Big Muffs from the former Soviet Union appeared on the market in the nineties

So this leaves the P-2 reasonably open to interpretation in many regards, but there are parameters to work within that will get you in the general area regarding sound.  Pete Cornish was working with David Gilmour, who liked Rams Head Big Muffs.  Kit Rae describes the V2 1973 #3 Rams Head Big Muff as the closest sounding to the tones Gilmour produced and very similar to the P-1.

Kit Rae sound comparisons below - to my ears, the P-1 and P-2 sound very similar in gain/clipping; the main difference seems to be the tone control.

P-1, P-2 and G-2 chords

P-1, P-2 and G-2 tone pot sweep

To make things a little more interesting/confusing, here's a gut shot from an early Pete Cornish pedal before he started gooping circuits and including double buffers.  They're calling it a P-2, but I think it might be an old P fuzz - who knows...  The board is laid out the same as the G-2, but you can see 2 x capacitors in the tone section instead of just the one - so this seems to have a traditional BMP tone stack.  There are also a lot of 220n MKT caps visible, following the same pattern as the G-2.  

PROBABLY NOT A P-2, BUT MAYBE IT'S CLOSE ENOUGH VERO LAYOUT

This is how I built my P-2, which is 100% guaranteed to not be an actual P-2...  but it will get you in the same area.  It has plenty of gain on tap; it could perhaps even do with a little less - maybe increase the emitter resistors a little.   

Update:  I did reduce the gain structure a little by increasing the emitter resistors and decreasing the collector resistor on the last clipping stage.  Not a massive difference, really.  Subtle, yes; game-changing, no.

Please remember that the tone control is a low pass filter; setting it to the centre like a typical Big Muff is not the best place to start.  Start with it open, then roll it back to tame the highs.  Don't forget to put the Cornish buffer in front of this too.   

Layout removed, as values have now been confirmed (I was pretty close)

ON THE SCOPE / FFT

Signal:  440hz sine wave, approx 130mv TRMS

 

Boost stage, Sustain 100%

First clipping stage, Sustain 100%

  

 

 Second clipping stage, Sustain 100%

 

 

PETE CORNISH: G-2

The Pete Cornish G-2 is a Big Muff variant:  germanium diodes, double buffered, and sporting a low-pass filter instead of the usual Big Muff tone stack.  

That being said, this is not your standard Big Muff - there's little resemblance in sound, largely due to the lack of scooped mid-range provided by a standard Big Muff tone control, and the germanium diodes change the clipping profile quite a lot.  Do not expect this to sound like a Big Muff.  

There are so many opinions on how this should be built - but keep in mind that the same topology is used for any variation.  The main complaint is that it's too dark-sounding using stock values, so builders try to address this by making various changes.  

Now we have some new traces from Aion, which probably puts all of this to bed.

Some people change the diodes too, but once you get away from germanium diodes, you may as well make a Pete Cornish P-2.  Pete Cornish uses the same PCB for both; one uses silicon diodes and is supposedly based on a Rams Head-era BMP. The other is closer to a BMP from the former Soviet Union but with germanium diodes (or perhaps glass-encased Schottky).

The layout below has the same values as the Dirk Hendrik trace; alternate values are all listed below.  I'll update shortly to the Aion trace, bit for the moment, you can work it out or head on over to Dirt Box layouts.

This needs the standard Cornish buffer in front, and should be wired as buffered bypass if you want to stick to the Cornish program.  If you don't plan on using the buffer, it's probably a good idea to drop that 220n cap on the input back to 100n.  

NOTE:  It does have one buffer on the board, as the G-2 is double-buffered.  

PETE CORNISH G-2 - VERO LAYOUT

The odd coloured lines running across the vero board are power and earth - ignore...  nothing to do, just a little visual helper for me that I used to include on my layouts.

PETE CORNISH G-2 BUILD PICS

Initially, I built this with 2N5088 and BC109C transistors, so if they look the wrong way around compared to the BC549s on layout, that's why.  I ended up swapping the B109Cs out for standard transistors, as they weren't really doing anything special - not even sure why I put them there to start with now.

I dropped the 4u7 coupling caps down to 2u2 and the 1n caps to 510pf caps across collector and base.  I used 1N277 germanium diodes with 220n caps in the clipping section to retain the primary character of the clipping sections.  

It sounds pretty good - I like it more than the stock values for chords.  I find that this pedal appreciates running at a decent level, and it's very dynamic compared to a Big Muff (probably due to the lower gain / less clipping compression).  At wife is at home levels, it sounds constrained, at least to my ears.

It does great lead tones with the stock values, it's rounded and smooth, and is probably not one for the speedy shred masters out there.

Chords are hard to describe as it's so touch responsive - moderate gain levels seem to suit chords better than the higher gain settings.  I found the tone control (low pass filter) is only needed for bridge pickups.  

PETE CORNISH G-2 - SUGGESTED ALTERNATE VALUES (BY OTHERS, NOT ME)

• 10n cap on the input buffer - reduce to 1n (brightens the signal from the buffer)
• 220n caps down to 100n
• Collector and emitter resistors on input boost stage, change to 18k and 100ohms
• Reduce 4u7 caps down to 2u2
• All 1nf caps down to the standard 470pf Big Muff values

You will undoubtedly find more via some googling, along with the heated debates.

PETE CORNISH: CC-1 Crunch

The Pete Cornish CC-1 is an interesting one -  two stages of soft clipping and a three-band active tone stack.

I initially built and tested the CC-1 using the larger of the two layouts below, and I can't say that I immediately loved it at the time.  Regarding others in the Cornish line-up, I preferred the SS-2 or SS-3.  It's not bad at all; in fact, it's very good at what it does.  I found that it took some time to dial in tones that I liked, and perhaps I was put off by the number of tones I didn't like along the way to finding the sweet spots.  

What I didn’t realise at the time with the first build I did, was that two resistor values on the schematic were wrong, which affected the bass response.

So after I saw the updated schematic, I decided to do a new layout and rebuild it (partially because I wasn’t happy with the size of my first layout, and I also couldn’t find the circuit that I previously  built anywhere.)

PETE CORNISH CC-1 CRUNCH - VERO LAYOUT

Note that while the layout above is smaller than the one below, the power supply has been simplified.  Filtering for every IC, transistor and bias voltage seemed a bit much to me.

It all fits on the board pretty well - a couple of resistors still missing, as I’m going to try a few different values for the resistors going to the diodes, and I ran out of 200k resistors and need one for the buffer.

The layout works, and I’ve taken the 22k and 51k resistors that are in series with the clipping diodes off the board - I have a dual B50k pot, with a 50k resistor across one side to reduce it down to closer to the original value of 22k.   It provides more control over the clipping - more clipping happens by reducing the resistance.  It already has five knobs; one more won’t hurt.

One thing I have noticed, and this happened on the LTspice simulations as well - the output op-amp clips with some of the tone controls on full.  While this isn’t necessarily always going to happen, depending on how the circuit is used, it did annoy me a little.  Easy fix - run it at 12v.  Problem solved.

OLDER CC-1 LAYOUT

updated November 2021.  Two resistors had an incorrect value on the original trace.  Thread on FSB can be found here. 

There's a smaller layout that includes the buffer over on Dirt Box Layouts - well worth a look compared to mine.

 

ON THE SCOPE / FFT

Signal:  440hs sine wave, approx 130mv TRMS

 

Gain 100%, signal taken from the 1uf cap after the two clipping stages.

 

 

LTSPICE

Mid-range & Treble response - bass on 50%

Bass and middle response - treble on 50%

Mid-range response - bass and treble on 50%

Frequency response varies with gain

Opamp output traces, gain on 100%, EQ all on 50%

Pedal output, various gain levels

PETE CORNISH CC-1 - DIODE MOD

Being a two-stage soft clipper, there are a few options available - the most obvious and usually everyone's go-to would be changing the diodes.  It might be worth testing some LEDs or different combinations of diodes in series etc - all the usual diode mods.

What does get some pretty immediate results is reducing R17 and R12, which are the two resistors in series with the diodes acting as soft clippers.  Reducing the diodes increases clipping, which looks like this when R17 is set to 1ohm, 10k and 22k (22k is stock).  Of course anything involving changing the value of a resistor could be an external pot, which is what I've gone for, as mentioned above.

Then there's always the option to play with the gain of the opamps, but I'm not sure if this would be a good way to go with a circuit based around two soft clipping stages - introducing opamp clipping may not be nice.