Can Anyone Tell Me What Circuit This Is?

[Bluenoser]

I bought this on a guitar forum years ago. It's a nice overdrive but I dont know the name of it or if it's a clone of something else. Thanks

[imJonWain]

Can you take a clearer picture?  What PN is on the opamps?

[Bluenoser]

Sorry I hope this is better. This overdrive has 4 knobs - vol/gain/treble/bass

[antonis]

Actually, it's worse.. 

[willienillie]

https://postimg.cc/vgwc7nDT

Two (fake) JRC4558Ds, a MAX1044 charge pump, and something in TO-92.  It's not a Klon, that's as far as I get.

[Rob Strand]

Showing the front panel would help.   What do the pots do?

At the top I can see 2x224 caps and at least 2x1k, top right 220 ohm.
So I would call that a TS-9 tone control.

The clipper at the bottom left is hard to tell.   I think it's a feedback clipper like a TS-9 more than a clipper to ground since there's no output cap close by.   Resistors don't look familiar, 560R, 62k, 2k2, 1k.

Lastly,  with 2x dual opamp you would expect more than just a TS-9.

Does it have a blend?  Maybe voodoo labs sparkle drive?   Other than that where in DIY territory.
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Sorry I hope this is better. This overdrive has 4 knobs - vol/gain/treble/bass

Sorry missed that.   Maybe the TS-9 tone control is "fixed" and the bass and treble are separate.   That explains the extra opamps.

That points more to an Xotic pedal.   One with a charge pump.
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Can't find such a thing.

Maybe the bass control replaces the 4.7k resistor on the gain opamp, similar to what the Timmy,  Menatone, etc do.

[Mark Hammer]

Not that it is a guarantee of anything, but the orientation of all the components suggests that it is a stripboard/vero layout rather than a simple perfboard.

Correct? 

[EBK]

Some variation of this:

http://tagboardeffects.blogspot.com/2012/05/maxon-od820.html?m=1

Here's the Google query that led to my answer:
jrc4558 max1044 bass treble gain veroboard layout

[Rob Strand]

Some variation of this:

Awesome.

I discarded the OD820 because it didn't have a bass control but that layout is soo soo close.

So maybe it's that layout and the bass is a variable TS-9 "4.7k" resistor on the gain stage like the Timmy etc.

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This page mentions a mod,  but it looks like a blend not bass,
http://tagboardeffects.blogspot.com/2012/05/maxon-od820.html

[Mark Hammer]

I made a clone of a Lovepedal Eternity a while back, and stole the Timmy Bass control to add to it.  Useful.

And does the handle "Bluenoser" imply you hail from the southern shores of "New Scotland"? 

[Rob Strand]

Your last post went to the wrong thread,

https://www.diystompboxes.com/smfforum/index.php?topic=124690.0

Thanks for the responses everyone. The layout is volume/gain on the top row and bass/treble on thec bottom. Doesnt sound like a Timmy to me, and smootjervtjan a TS type pedal. Closest guess so far as sound goes would be the Maxon 820.

Yes I live in Halifax

It's not that it *is* a Timmy,  it *is* a Maxon 820  but someone might have adapted the a bass control *like* a Timmy, or one of the many variations used on other pedals, to the Maxon 820.  The stock Maxon 820 doesn't have a bass control so there must be some form of mod present.

Are you sure it is a bass control?  Maybe it's a clean blend?   Clean blend can sound like more bass.  From what I understand the layout I posted the link to is some sort of modded version of EBK's Maxon 820 layout but with a clean blend added.   (I have not deciphered the layout to see exactly what was done.)    What you could do is compare your wiring with that modded layout.   If it doesn't match then it might not be a clean blend but some sort of bass control mod applied to the layout EBK gave.

Whatever the case your unit is definitely some sort of variation of the Maxon 820 layout BK gave.  The only thing to work out is what the difference is.
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Here's the Menatone Blue, the *Presence* pot at the top left is a different and simpler variant of the Timmy bass control,
http://i206.photobucket.com/albums/bb41/JHSNRW/early_Blue_Collar.gif

You basically replace the 4.7k resistor on the TS-9 with a pot.   Some people also change the cap value and the resistor in series with the pot.

[Rob Strand]

The OD820 schematic is on this page,

http://revolutiondeux.blogspot.com/2012/05/maxon-od-820.html

At the top of the schematic there is R1 = 2.2k and C1 = 100nF =0.1uF.

On the layout EBK posted,
- the 2k2 resistor is to the left of pin 4 of IC1.
- the 100nF capacitor is the big green one below pin 4 of IC1.

So what you would need to do is to see if your Bass pot is wired to any of the tracks going to those parts.

If you can't see anything then the bass mod is elsewhere.   There's actually plenty of places to put some form of bass mod on that circuit and it might be easier to take some pics showing where the bass pot wires onto the PCB.

[Bluenoser]

Thanks for the help everyone! I was playing with the pedal again tonight, and it really seems like its bass and treble knobs. *shrug* All I know is it sounds terrific 

Thanks again

[Rob Strand]

Thanks for the help everyone! I was playing with the pedal again tonight, and it really seems like its bass and treble knobs. *shrug* All I know is it sounds terrific 

Thanks again

It is what it is!   At least you know it is pretty much a Maxon 820.

One idea I thought of:  if your drive/gain control *isn't* a dual-ganged pot ie. a pot with six pins, then maybe you unit is the layout EBK posted *but* with separate (single) pots for each part of the gain control.     What that would do is make one of the pots act like a clean blend control and that may very well be perceived as adding bass.