Build Your Own Clone Message Board

The Silver Pony/Sentaur is a wonderful circuit that I've never really got along with very well. Being designed in the early 90's, it's a fairly old-school circuit. Part of that oldschoolnes is a big cut in bass similar to a tube screamer. This is not very apparent when playing the circuit with gain at 50% or less, but increasing the gain >50% and using a guitar equipped single coils, it is very apparent to me. I tend to play a telecaster, and I don't like a big drop in bass in my overdrive pedals.

Stepping back a bit, the circuit splits the signal into two paths - a clean path and a dirty path. The gain control sweeps from 100% clean path at full counterclockwise, to 100% dirt path at 100% CW, and blends the two parallel signal paths at all points between the extremes. So, as the gain control goes over 50%, you are hearing more of the dirty path than the clean path.

Last weekend, I set about tweaking my Silver Pony II to EQ the dirty path bass more to my liking, in hopes that it would make my live board. And I think I found a really easy solution to EQ the bass in the overdrive portion of the circuit. A while back, I'd messaged with Keith about the 1K5/1uf RC network that is present at the input of the dirty path (R9 and C8 in the SP II schematic), and we discussed how much low end that network was likely siphoning off. So I started tweaking there.

What I found was that altering the value of R9 resistor makes a big difference in the bass content of the dirty path. Increasing R9 to 10K seems to eliminate the R9/C8 network, in that a 10K in R9 sounds about the same as removing R9 altogether. This was a bit too much bass for my liking and I settled on 4.7K in R9 in my build. I was shooting to get the SPII to sound like my tweed super with the volume on 8 (a lovely distorted tone but too loud for most venues) but at a lower volume. With R9 at 4.7K, the amp tone sounds nearly identical with the amp volume on 4 (typical gig volume), SPII gain at 60% (LED clipping)/treble at 75%, as the amp at 8 on the volume with no pedal boosting anything. Perfect for me!

If you try this, one thing that you might notice is that the treble content is not as apparent after this mod. You may find that you need to run the treble control quite a bit higher than usual to get those highs to pop.

Also, substituting an A10K pot for R9 makes a great bass control for the dirt portion of the circuit.

Anyway, if you'd like more lows in your SP or SPII, try out different values in R9!

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Nicely done, Sir.

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Everyone likes sausage. Nobody wants to see how it's made.

Cool mod, great explanation. Thanks for sharing!

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Scott

My band, Austin Hollow