EHX - Graphic Fuzz  [schematic]

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soggybag
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Post by soggybag »

Has anyone seen a schematic for the EHX Graphic Fuzz? This looks pretty interesting. I'm curious how it works.

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Post by dune2k »

i got the factory schematic, if anyone wants to redraw it pm me & i'll send it to them so they can post it.
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Post by RnFR »

moved to modern section. and yes, it needs to be redrawn before we can post it. :wink:
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Post by Sweetalk »

I JUST got one this week, I love the EQ and wanted to see the schematic. A little bit annoying the 40V supply. It came with the original EHX power supply but 110V (220V AC line in my country).

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Post by Sweetalk »

My two cents!

Image

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Post by borislavgajic »

Thanks....it is more then 2 cents!!!!!

if it is possible to unscrew 3 screws and take photo of component side?

thanks

Boris

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Post by borislavgajic »

Can somebody please post component side of this pedal?

thanks
Boris :thumbsup

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Post by Dirk_Hendrik »

Can anyone give a comment on the sound? I played one some 2 years ago after fixing it and still wonder why anyone would spend money in this thing while there's many, far better sounding and cheaper, Behringers around?
Sorry. Plain out of planes.

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Post by Dirk_Hendrik »

borislavgajic wrote: if it is possible to unscrew 3 screws and take photo of component side?

thanks

Boris
and
borislavgajic wrote:Can somebody please post component side of this pedal?

thanks
Boris :thumbsup

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Post by Sweetalk »

Gimme some time to finish studying and I'll take a picture of the component side. Badly I hasn't got a camera with macro, only a cellphone :oops:

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Post by borislavgajic »

Hey Dirk what do you say??? :? :block: :hug:


Hey Sweetalk...thank you very much...if you find time.....I know you have other important things in your life....so take your time :)


thanks
Boris

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Post by mictester »

Sorry it's a bit late, but here's my slightly modified Graphic Fuzz. I haven't made any changes to the signal path, just to the stupid power supply arrangement. The circuit works on +/-12 Volts at low current, so a simple pair of half wave rectifiers and two regulator ICs with a bit of filtering is perfect for the job. The power supply that was originally in this pedal was just plain stupid - 40 Volts and big power resistors to drop most of those volts and radiate much of the power fed to the board as heat!

Here's the re-draw:
GRAPHICFUZZ.GIF
I've got a lashed together version of this thing, and it's quite good, but more can be done with the distortion section....
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Post by Ben N »

Son of a Gun! I thought it was something more like a Quadrafuzz, with separately distorted bands, but it's really a distortion with an eq tacked on.

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Post by Sweetalk »

Thanks a lot for the schematic, sorry for the pictures. I'll take it soon if anyone still wants them.

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Post by mictester »

Ben N wrote:Son of a Gun! I thought it was something more like a Quadrafuzz, with separately distorted bands, but it's really a distortion with an eq tacked on.
Exactly. It could be interesting to make the bands each feed their own distortion stage (like the quadrafuzz), make the distortion stages switchable (feedback diodes around an op-amp or diodes to ground), and introduce similar filters after each distortion stage.....
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Post by Ben N »

mictester wrote:
Ben N wrote:Son of a Gun! I thought it was something more like a Quadrafuzz, with separately distorted bands, but it's really a distortion with an eq tacked on.
Exactly. It could be interesting to make the bands each feed their own distortion stage (like the quadrafuzz), make the distortion stages switchable (feedback diodes around an op-amp or diodes to ground), and introduce similar filters after each distortion stage.....
I was thinking something like the eq stage of the Graphic Fuzz feeding CMOS--two hex inverters gives you six 2-inverter distortion blocks.

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Post by FuzzFreak »

Hi all.

Just wondering if anybody ever took a photo of the component side of this? :)

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Post by Pyr0 »

Here's some I just took. Just with my phone so quality isn't great.
I can take more if need be.

Image

Image

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Post by FuzzFreak »

Ah thanks very much for those pics! Really appreciate that. :D

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Post by MarkusBass »

Can anyone post the schematic of the original power supply for this effect? I'm trying to fix the effect, which was heavily modified and I need to know how the original power supply looked like. Another problem that I have is with 4kHz filter. It does not work but what is interesting I simulated the schematic posted above and it also does not work (most probably due to some other reason). Is the 4kHz part drawn correctly on the schematic?

Mark

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