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I built a Green Pony, which I'm assuming has similar mid hump overdrive to a Tubescreamer. I've read that the Tubescreamer design uses symmetrical clipping whereas the SD-1 uses asymmetrical clipping. Sonically, I'm not sure what this would mean, and I'm wondering if there is a BYOC pedal that would resemble the SD-1 sound. Or is it already embedded in one of the options in the Green Pony? I know that SD-1's are cheap as hell, but I'd prefer to just build the thing if I could. I saw that General Guitar Gadgets provides a PCB and a BOM, which means I'd have to source each resistor, capacitor, diode, pot, etc. Thanks, and for educating me on the differences and a comparable BYOC circuit.

viewtopic.php?f=12&t=45077

Symmetric clipping is accomplished by using an even number of identical clipping diodes to clip the signal. One diode clips the positive half of the signal while the other diode clips the negative half of the signal. Asymmetric clipping is accomplished in a few ways. One is to use thee identical diodes to clip the signal (the SD-1 uses this type of clipping). One diode to clip one half of the signal and the other two in series with each other to clip the other half of the signal. It can also be accomplished by using two different types of diodes. A Silicon diode on one half and a Germanium diode for the other half for example. It can also be accomplished by using two of one type of diode and one of another. In this example a Silicon and Germanium diode are connected in series with each other to clip one half of the signal while a single Silicon (or Germanium) diode is used for the other half of the signal. Another example would be a Silicon diode on one half and an LED on the other.

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"It’s your soldering."

The SD-1 is really nothing more than a slightly modified tubescreamer. And by slightly modified, I mean, there are just a few component value differences. IMHO, the biggest difference between the two is the roll off frequency of the tone knob. The SD-1 operates at a higher frequency and is more of a "treble" control, whereas the TS tone knob can cut or boost everything above what would be considered the upper midrange, but both are flat when the knob is set at noon. Don't overestimate the difference between symmetrical and asymmetrical clipping. You couldn't hear the difference unless you put it on a switch were able hear the change instantly....and event then, you'd have to assure yourself that you're actually hearing something. I would be willing to bet that if you were blindfolded and asked to tell the difference between an SD-1 and a TS9, you'd only get it right 50% of the time.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Wow, thanks to both of you! First, Stephen for explaining how to do it, and secondly, for byoc, for making me wonder whether it's worth doing. I've been exploring Marshall JCM800 amp builds, and I've seen quite often that SD-1's are recommended to push the pre-amp section into the sounds that most people associate with the Marshall hard rock sound. If I want to remove all doubt, I could build the Classic Overdrive with Stephen's changes, or I could try the Green Pony and see if its various controls won't give me a boost that I like, based on byoc's theory that my ears wouldn't be able to reliably identify a preference between the two circuits anyway. It sounds like there might be a bit of a placebo effect or religious aspect to this SD-1 preference...

I got my Green Pony in on Monday with super fast shipping from BYOC. Can't believe it got to Florida that fast. Just curious how the Green Pony compares to the Tubescreamer/SD1? I should be able to start building it tomorrow. This will be my first pedal build.

At its core, the OD-820 is really just a TubeScreamer, but it has a dry blend that is integrated into the "drive" knob, i.e., the more you turn the drive knob counter clockwise, the more the gain is reduced and the more dry signal is mixed in. At full turn CCW, it should be completely dry, and act more as a clean boost with a tone knob. While it accomplishes this in a different way, it functions exactly the same as the Klon Centaur. Keep in mind that the clipping and norm/thin/fat switches affect only the overdrive part of the circuit, so if you have the gain knob full turn CCW, you won't be able to hear anything from these toggles because you are only hearing dry signal.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com