PCBMania Amped-S Bass PreAmp

anevilspar7an

Well-known member
Build Rating
4.00 star(s)
I've had this for a while, close to when I started out actually since this is version 1 of the board with the 1P8T rotary footprint. I decided to revisit it since it'll be a long time before I can afford an actual Ampeg SVT Classic. One of the few boards that actually works for me, though since it is a Bajaman circuit I expect it would take a special kind of someone to ruin it. I don't like the control layout personally, the switches are too close to the gain knob and to each other. I somehow got the toggle switch bezels to fit on them, don't ask me how since I don't remember what I did.

Tomic Gold 1590BBS with Textured Black bottom plate from Stompbox Parts, Wima Film caps, Kemet large value MLCC, TDK small value MLCC, AVX Tantalums, pre-tariff Alpha potentiometers, LMS switches, Lumberg jacks, and knobs, boss style. Left-to-Right, Top-to-Bottom: Treble, Mids, Bass, Level, Gain, Lo, Hi, Bright, Mid Freq.
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I did do the Bajaman mods by changing C3 to 4.7nF, R7 to 560K, and removing D1 and D2 for a cleaner range.
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Some personal mods was to put D1 and D2 on a footswitch to be able to drive the output gain, C17 and C18 are Tantalum since they are in the audio path, and C9 is 5.1nF since I can't find 5nF by itself, I already know I could've used two 10nF in series to get it, I really didn't want to do that. Gain and Level are A100K instead of B100K for better feel. I do plan to change the two 22mH inductors at a later date to 20mH like in the original circuit.
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For the second LED I piggybacked the anode for power and put the ground on the switch that goes to the output jack since it was closest, I'll probably move that to a different ground point it becomes an issue.
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