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GAINTONEVOLUME

Enclosure not stated · 3 knobs

Tagboard Effects

Cornish G2Verified

Based on the Cornish G-2· 5 other boards clone it

Category
Fuzz
Controls
Gain · Tone · Volume
Build
Vero· 19×22· 17 cuts, 5 links
Layout
Verified · Tagboard Effects marks it as built and working
Tags
Cornish, Fuzz

From the post

I was surprised I hadn't already posted this one since we've had the schematic for a while. Iconic and much admired builder to the stars, popular on TGP and everywhere that guitarists want the size of their gear budgets to be known by all. It sounds pretty good to me. This includes the famous Cornish Buffer at the input as per the original, but omits the bypass buffer for the usual true bypass switching. If you do want to make it buffered bypass then you could use the standalone buffer layout as a bypass daughterboard.

For those who do want the bypass done in the same way as Cornish, the input socket connects directly to the input of the bypass buffer. The output of the bypass buffer then goes to G2 input and daisy chains to the 3PDT stomp switch, lugs 1 and 4. The output from Volume 2 of the G2 will go to 3PDT lugs 3 and 6, and the output socket connects to 3PDT lugs 2 and 5.

The third pole of the 3PDT is used for LED switching.

You could do this with a DPDT stomp just making single connections, but Pete did this using two separate poles to add some redundancy in should one of the contacts fail.

Info from Pete about his original bomb proof effect:

The PETE CORNISH G-2 has been hailed as the most original sounding distortion unit available to guitarists in the Rock Arena. It features a four stage overdriven discrete transistor Class A circuit with additional Germanium components that generate much warmer sounding harmonics than anything else on the market. Within the huge tone generated by this unit, the original guitar sound and dynamics are present creating a much more musical effect than any other distortion pedal.

The G-2 gives a higher level of overdrive for that classic cranked up Marshall sound found on most British rock records of the 70s (Led Zeppelin, Free, Bad Company etc.). The G-2 with its warm Germanium qualities and higher gain starts at around the rhythmic crunch stage of the SS-3 and continues through in controllable degrees to a rounded but dynamic lead.

The input to this unique device is our universally acclaimed High Impedance, Unity Gain, Class A, Buffer Preamp with it's superior RFI rejecting capability (to eliminate Radio Station interference) and Low Impedance output, allowing the use of extended cable runs from the G-2 in bypass mode. The fixed High Impedance load presented to the Guitar allows the pickups to operate at their optimum, even when several effects units are connected after the G-2. The Unity Gain Buffer also prevents "Ghost Distortion" being audible in Bypass Mode. This effect unit gets the most benefit from being fed into a clean, full frequency response amplifier and I recommend that when you receive your pedal you connect it up without anything else in line, just Guitar/Pedal/Amp, and discover the way the controls interact, both with themselves and the guitar/amp controls. Then adding the rest of your effects, you may find that you need to make slight adjustments to these as they are now being fed

Schematic

This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Tagboard Effects. No KiCad fragment has been drawn for this circuit yet.

Parts list 30 rows

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Check before you build · 2 values the reader of this layout was not sure of
  • D1-D4: legend says only 'Diodes are germanium', no part number
  • 100R beside 18K in the lower middle (two of them flank a 100K): read as 100R at zoom, easily confused with the neighbouring 100K
RefValueNormalizedTypeNotes
Resistors 16
×5100K100kread from the layout by eye
×48K28.2kread from the layout by eye
×3470K470kread from the layout by eye
×3100R100read from the layout by eye
×239K39kread from the layout by eye
×215K15kread from the layout by eye
×21K1kread from the layout by eye
×2680R680read from the layout by eye
×11M1Mread from the layout by eye
×1390K390kread from the layout by eye
×1150K150kread from the layout by eye
×1120K120kread from the layout by eye
×168K68kread from the layout by eye
×118K18kread from the layout by eye
×12K22.2kread from the layout by eye
×1120R120read from the layout by eye
Capacitors 9
×41n1none drawn as a ceramic; read from the layout by eye
×110n10nread from the layout by eye
×347n47nread from the layout by eye
×1100n100nread from the layout by eye
×3220n220nread from the layout by eye
×34u74.7uelectrolytic; read from the layout by eye
×222u22uelectrolytic; read from the layout by eye
×1100u100uelectrolytic; read from the layout by eye
×1220u220uelectrolytic; read from the layout by eye
Diodes 1
×4germaniumGERMANIUMD1 to D4, part number not given; read from the layout by eye
Transistors 1
×5BC549CBC549Cread from the layout by eye
Potentiometers 3
GainA47KA47kPotentiometerread from the layout by eye
ToneB25KB25kPotentiometerread from the layout by eye
VolumeA10KA10kPotentiometerread from the layout by eye

Other boards based on the Cornish G-2