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| Fred Briggs – Super OCD Schematic |
The Fulltone OCD has been an overdrive favourite for many years now. It’s got a really nice tone when your amp is set right (I prefer it with Marshalls I must say). Well, I’ve always thought about modifiying the basic circuit (which itself is based around the old Voodoo Labs Overdrive) to give it a little more variety and use over a wider spectrum of tones.
As you can see the “Super OCD” has a few extra controls:
– Firstly the “Bass” control – it’s nicked from Paul C’s Timmy pedal and works very well to add in pregain bass for more low end response.
– Secondly the “Saturation” control, this allows you to increase the clipping headroom of the circuit and have an overall “cleaner” tone while dialling in just the required amount of diode clipping.
– Thirdly the “Boost” control, I’ve configured the second opamp to allow a range of clean boosts to be selected to really allow you to push the front end of your amp into overdrive.
– The final control I’ve added is a switch to go between 9 volt and 18 volt operation. The 18 volt operation adds extra headroom to the circuit to stop the opamp clipping from fogging up the tone. The 9 volt operation retains the original headroom seen in the OCD.
– Other changes include alterations to the Tone control and a swap of opamp from the TL082 in the original OCD to the Burr Brown OPA2134. These changes all add up to create a really nice overdrive/distortion box. It’s got all the original Fulltone OCD tones in there and loads more. If you like the original OCD you’ll love the Super OCD 🙂
Here’s a vero layout by beedotman, it’s unverified at the moment, if you build it report back please 🙂
Here’s the discussion topic on freestompboxes.org: http://freestompboxes.org/viewtopic.php?f=13&p=183753