sd-1 to bluesbreaker

[rice37]

Hey guys been a while,
          Just scored a free boss sd-1, its not really doing what i want. I clipped the c6, and i jumped the d3 and r31.
What im really looking for is more of a Bluesbreaker. My Peavey Classic 50 heads' clean channel is SUPER clean. Ild like to give just the slightest touch of hair. but the sd-1 is either too thin when the gain is off, or too harsh/effecty sounding. Ive looked at all the mods, but i just dont know really which ones are best for what im looking for. Ideas? Thanks dudes and dudettes!

[Mark Hammer]

You may be trying to turn a sow's ear into a cup and saucer, rather than a silk purse.  That said, the SD-1 seeks the same goals as the TS-9 does: relatively consistent clipping across the entire spectrum.  Only in the SD-1's case , it aims for a little more gain at the top of its range, and a little more output level.  The gain structure is different between each of these and the Bluesbreaker.

Here are some things you can try doing:

1) The stock SD-1 uses a 2+1 diode combo to achieve some asymmetry in clipping, and a somewhat hotter output than the TS-9.  "Cleaner" overdrives, like the Timmy, Dano Transparent Overdrive, various Xotic boosters, and even the Bluesbreaker, use a 2+2 diode combo to raise the clipping threshold on both halves of the waveform.  You lose the asymmetry, but you gain the output level.  Find the diode that tends to the half-cycle on its own, andgive it a partner.  You can simply lift one end of that diode, install the appropriate end of a 2nd one and connect their free ends like the St. Louis arch.  Alternatively, consider replacing the diodes with a simple pair of back-to-back red LEDs.

2) The TS-9 uses a 500k gain pot, while the SD-1 uses 1M, providing more gain.  If you want to have an easier time adjusting the amount of "hair" , a 500k pot would give you finer control.  Don't worry about losing output, since raising the clipping threshold via #1 above will assure plenty of output.

3) Like the TS-9, the SD-1 uses a 4k7/47nf network on the ground leg of the op-amp to trim the bass in order to make the clipping more consistent across the fretboard.  With a higher clipping threshold, you can afford to indulge in a little more ass, so increase that 47nf cap to 100nf or even 220nf.

4) The BB uses a treble-cut tone control, where the SD-1 and TS-9 use a tone control that goes from treble cut to treble boost.  This page - http://www.muzique.com/lab/tstone.htm - provides some useful ideas about how to alter that tone control to achieve different objectives.  Personally, I'd simply stick a 1k resistor between the minus (inverting) pin on the op-amp and that end of the tone pot so that the control provides more cut than boost, but feel free to consider any of the many options provided there

[rousejeremy]

With a higher clipping threshold, you can afford to indulge in a little more ass, so increase that 47nf cap to 100nf or even 220nf.

Great advice

[rice37]

cool thanks so much!!!!! I ll let you guys know how it goes!!!

[Mark Hammer]

As Shakesêare's Touchstone declares in Act II, Scene 4 of "As You Like It": "Nay, I shall ne'er be ware of mine own wit till I break my shins against it."

...and a caution to all that there can be a lot of things your spell-checker will NEVER pick up...but your readers WILL!!  

Thanks for the best chuckle of the day so far.  

[george]

With a higher clipping threshold, you can afford to indulge in a little more ass, so increase that 47nf cap to 100nf or even 220nf.

Great advice

Here I was, so blown away by Mark's grasp of all things stompbox and how they interact with other important things in everyday life (including sow's ears and cups and saucers), until he pointed out that this was a typo.  I liked the Shakespeare homily though.

[Jopn]

With a higher clipping threshold, you can afford to indulge in a little more ass...

I neeeeeed to get me a higher clipping threshold.  asap.