Can I use 12V with my MXR Distortion+?

Frequently asked questions regarding powering your pedal.
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J-fish
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Post by J-fish »

Hello, I'm writing just to ask if you could explain to me if I can power my MXR Distortion+, current version (M-104 model..) with 12V instead of 9V.
The fact is, I read many threads about this pedal and, since I'm mostly trying to avoid clipping from the opamp itself, I was hoping if raising the voltage a little bit might help me some.
Would I damage some electrolytics or some other parts?
Thank you very much in advance, I hope you can help me

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Fender3D
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Post by Fender3D »

Actual op-amp used in pedals can stand safely 30V, some even 36V...
I don't guess MXR mounted capacitor lower than 16V either...
You can safely run it @ 15V.

J-fish
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Post by J-fish »

Thank you!

bool
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Post by bool »

If your pedal has a tantalum cap inside (a yellowy mustardy teardrop-shaped thing, but can also come in different colours), be careful to read out a voltage rating, as these caps really don't like being overvolted. For practical use, these caps should be derated by 50% or better wrt. their rated voltage. (Ie, if rated 16V, run at max 8V). Although I used tantalums rated 16V in 9V circuits with no ill effects since late 80's.

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Post by J-fish »

I wouldn't have even considered 12V if I hadn't read about opamp overdrive..
But, I read also that perhaps switching to 12V wouldn't have much of an effect, because the opamp in this pedal doesn't clip rail to rail....actually it's influenced by starved bias, or something like that...
Can anybody explain this to me? Is there any way I Can understand how much strenght the signal of my pickups should have at maximum to not make the opamp distort?
I hope this was clear enough...thank you very much in advance!

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Post by bool »

Look, the easiest way to prevent the opamp to clip to the rails is to include clipping diodes in the nfb path. As-is (without diodes), the opamp (741) by itself will go to about 1.2V close to the rails; which means you will have about 6.6V peak-to-peak headroom at 9V supply; and 9.6V at 12V (may vary from one chip to another).

If you put a "3V worth" of diode-drops in your nfb; you will prevent the opamp to clip; which will change the character - for the better or worse.

IOW, putting 4 small red LEDs as clippers (similar to timmy pedal does with ordinary diodes) would in the best-case scenario prevent the opamp to clip to the rails.

HTH

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Post by J-fish »

Thank you, I appreciated the idea!

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