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BSIAB 2 mod

Started by caspercody, July 18, 2009, 08:53:58 AM

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caspercody

I found this quote:

Pinnacle (i think I stated this somewhere else, but can't find the thread)... basically a jfet mu-amp (bsiab-ish) setup, into that big muff style tone control, into a variable twin t type filter for mid control (contour), into a jfet (actually, your version just goes straight out to volume here, but the newer version goes into another jfet stage then to volume).

bright switch is a normal cap to ground off of the twin t, it just lifts it off ground.

The big box ecstasy had the bass control wired like the timmy pedal, just a pot off the feedback loop.

The pinnacle gain switch just changes the resistors on the mu-amp gates. As far as building kits, (and even pedals really...) you never make money by building pedals... you make money by SELLING pedals. And honestly, more time is spent in talking to customers than building pedals. If I had to build everything myself I wouldn't sell anything.

bw

I would like to try this with my BSIAB to try to get the sound of the Pinnacle. But I am not sure what the variable twin t filter is? I think it may be similar to AMZ presence control, but at the end of this article it mentions this presence control would not be suitable for a high impedance output pedal. Is the BSIAB a high impedance output pedal?

Thanks
Rob

slacker

#1
Have a look at this Geofex page for info on twin Ts http://www.geofex.com/Article_Folders/EQs/paramet.htm#variable_fr_twin_t

Also have a look at the scoop control in the Superfuzz or the contour control in the Marshall Shredmaster, they're probably similar to what you're looking for.

caspercody

I have compared the schematics of the BSIAB2, sweet thing, and a mu-amp distortion schematic from Brian Wamplers book and all three are basically the same with different values for some resistors and capacitors. These are the components on the GGG schematic:
C1, C2, C3, C5, C12

R2, R3, R14, R15

I have not included the tone stack, and I was hoping someone could help explain what the different stages of the Jfet's and the above values do? I think they may be filters, but not sure.

Also, is this a high impedance output? I was hoping to add the AMZ presence control at the end, but the article says that this would not be suited for this.

Thanks

caspercody


aron

To get low impedance, put a buffer at the end of the circuit. You can experiment over and over to get the "pinnacle" sound or you could buy one (if it is still available).

Aron