Budda - Om Overdrive  [schematic]

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

I traced this unit a couple years ago, i took some photos at the time but i can't find them anymore.
T1 is a BC547, the Jfet is a J201 and the Opamp is LF353.
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Budda om overdrive.png

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Frabbio
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Post by Frabbio »

I found the photos, there is a mod i did after tracing the pedal, adding a RC filter by cutting a trace and upping the stock 2.2uF filter capacitor.

In the hand drawn schematic part names are as in the pedal.
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buddaschematic.jpg
budda4.jpg
budda3.jpg
budda2.jpg
budda1.jpg

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roseblood11
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Post by roseblood11 »

Have you built a clone based on that schematic?

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Frabbio
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Post by Frabbio »

No I haven't, but it's a good sounding overdrive, i remember i did some mods also on the eq of the pedal to make it more full sounding.

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dv8r601
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Post by dv8r601 »

Thanks for this.
Ill try and whip it up and see if it works as is.

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Post by JRombold »

Thanks for the great work on this. I had a couple questions about the caps on the board as compared to the schematic. C9, C10 and C11 mainly in comparison from board to schematic. Reason I ask Is I built this and the voice of the drive is killer but over is really bright and noisy. C10 schematic shows a 2.2uf on the board it looks like a standard cap. C11 I can't find on the schematic (could be me....I am blind as a bat). C9 on the schematic shows 2.2uf on the board is 5.6n. C6 on the board I am guessing is 1uf but c6 on the schematic is the 5.6n
Thanks for any help on this.
Sorry if this is a ridiculous question.
Thanks again for all the great work!
Dirty

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Frabbio
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Post by Frabbio »

The hand written schematic in the second post shows the component name as in the pedal!

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Post by Manfred »

I would very much appreciate it if you could measure the voltages at the transistor pins and give us the read values.
Which gain class has the BC547 A, B, or C?

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Frabbio
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Post by Frabbio »

I am sorry but i don't have the pedal anymore. IIRC the transistor was a Bc547C.

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Post by Manfred »

Frabbio wrote:I am sorry but i don't have the pedal anymore. IIRC the transistor was a Bc547C.
Thanks, I found the read values on this website:
http://runoffgroove.com/mayqueen.html
The OM overdrive is derived from the May Queen overdrive.

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dv8r601
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Post by dv8r601 »

Well I KNEW I'd seen this odd arrangement somewhere. Its a Escobedo punch in the face betwixt the two opamp stages. Well Lo and behold its a damn near exact copy of the wonderful Carl Martin Crush Zone Image

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Post by Manfred »

Haha, I am hettin old, I do believe it. :?
I totaly completely forgot, I did trace the Martin Crushzone on my own. :shock:
viewtopic.php?f=7&t=28021&hilit=crush+zone

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Post by Manfred »

Manfred wrote:Haha, I am hettin old, I do believe it. :?
I totaly completely forgot, I did trace the Martin Crushzone on my own. :shock:
viewtopic.php?f=7&t=28021&hilit=crush+zone
The edit buttom did not work once again :evil:
I meant mean of course:
Haha, I am getting old, I do believe it. :?

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Post by Manfred »

I give up ,a further write error. :slap:
I should think about to use the preview function. :scratch:

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Post by Frank_NH »

I thought the Crushzone sounded pretty good, as does this. Too bad Budda didn't add something interesting to the design like 3 band EQ, rather than just producing a straight clone.

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dv8r601
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Post by dv8r601 »

I built a crush zone off Tagboardfx a while back and noticed the input cap at 220pf was WAY smaller than anything I've ever used so I swapped it out for a 8.2nf and it was slamming. Then put a hot 2n5485 in the fet socket and its been on my board ever since. Now knowing what the om is I wonder if their compressor is a clone as its quite weird as well

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