Guyatone - HD2 Harmonic Distortion  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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EmmG
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Post by EmmG »

I see you meant pics of the board, not the schem. Anyway, since it seems the main unique part of this Big Muff is the dual op amp boost and recovery stages, I came up with a layout of just those parts for easier testing.

Image

I'm not sure if I got it totally right concerning the switching, but both stages boost. For the real test, I spliced it into an unboxed Muff build where it worked fine.

We still don't have R9's value, but testing it with 22k gives a deeper mid dip at a lower frequency, which matches up the
"thinner" sounds I've heard in demos.The two 47k's coming off the tone section can be replaced with a linear 100k pot.

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Manfred
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Post by Manfred »

JellyBelly wrote:Hi, i reuploaded the schematic beacause it was no longer online!
I would very much appreciate it if you could reuploaded the shots too.

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Chrisfromiowa
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Post by Chrisfromiowa »

EmmG wrote:I see you meant pics of the board, not the schem. Anyway, since it seems the main unique part of this Big Muff is the dual op amp boost and recovery stages, I came up with a layout of just those parts for easier testing.

[ Image ]

I'm not sure if I got it totally right concerning the switching, but both stages boost. For the real test, I spliced it into an unboxed Muff build where it worked fine.

We still don't have R9's value, but testing it with 22k gives a deeper mid dip at a lower frequency, which matches up the
"thinner" sounds I've heard in demos.The two 47k's coming off the tone section can be replaced with a linear 100k pot.
So, the schematic looks like it has a dozen diodes and two IC chips. Is your board a sound a like? I love the HD2. It seems to smooth out the sound. Old time distortion addict and would like to figure out the HD2. Thanks Chris

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