Xotic BB Preamp

Got a request for the BB Preamp, but not the current version. The earlier version uses a dual-gang pot for the Level control and apparently more bass response. Like many of Xotic's offerings the BB owes a lot to the classic Tube Screamer. Schematic can be found here.

If you'd prefer to build the newer version without the dual-gang Level pot, you can use the same board. Just remove the 1µ capacitor and the 1k and 47k resistors in the bottom right side of the board and replace with a jumper like this:

Death by Audio Soundwave Breakdown 2

Last week for Fuzz Friday I posted the early version of the Soundwave Breakdown from Death by Audio. Here's the newer version of DBA's Soundwave Breakdown with 6 transistors and another external control. On earlier examples of this revision the Sensitivity pot is an internal trimmer, but the newest version seems to have moved it externally. Speaking of trimmers, this one still has the Volume control as a trimmer (50k) and the other trimmer (5k) biases Q6. Originals are in a 1590BB, but I've laid it out to fit in a 1590B with board mounted pots. Drilling template can be found here and the schematic can be found here.

Transistor Tester

Ever hear about "leaky" germanium transistor and wonder how to measure that? Well, here's a little utility board that allows you to test germanium transistors. It's based on this article by R. G. Keen, which you should definitely read. It explains pretty much everything going on in this process. I've included a switch to allow you to reverse the polarity of the power going to the board. This allows you to test both PNP and NPN transistors with the flip of a switch. The pads marked V and Com on the board are for your digital multimeter probes. Use pin headers here for easier use with your DMM probes, and be sure to use a socket for the transistor.

Lovepedal Kalamazoo

Here's another overdrive from Lovepedal, the Kalamazoo. Somewhat similar to the Timmy/OD11 but with different tone controls. D5 on originals is a 1N914/4148 (they're pretty much the same diode), but a 1N5817 or even a 4001 would probably bet better (it's for polarity protection). Also, I've included pads for the capacitor labeled "Cx" on the layout. Some find adding a 820pF capacitor there helps improve the sound, but if that value cuts too much high end, try something in the 47-470pF range.

Death by Audio Soundwave Breakdown 1

Happy Fuzz Friday, everybody. Ranjam over on FSB traced an early DBA Soundwave Breakdown (serial number 4) which it's different than the current model. The unit he traced didn't have the trimmers later units did. Don't know the original value of those trimmers, but 50-100k is a good starting point. Those trimmers control the input signal (the left one) and the output volume (the right one). True to DBA form, this is a bit of a weird circuit with the NPN darlington transistors flipped around from usual (emitter to voltage instead of ground). Schematic can be found here. Should be able to squeeze it into a 1590a.

Run Off Groove UBE Screamer

Apparently it's Tube Screamer week. This is Run Off Groove's adaption of the classic overdrive to work around a CD4049UBE CMOS chip. More info, schematic and sound clip here. As you can see in the schematic, there's a resistor (RX) where different values will work for different guitar pickup types: 100k for single coils, 220k for humbuckers, 330-470k for hot humbuckers. I've included pads for a switch that will allow you to switch between 2 of the options. If you use the switch, remove the 100k resistor (which is RX) right by those pads from the board.

Ibanez TS10 Tube Screamer

The TS10 was apart of Ibanez's mid-80s Power Series of pedals. It's slightly different than a TS9 with an added resistor before signal hits the opamp and a bigger capacitor coming off the volume control. Otherwise not too much is different. I've laid this out for 9mm mini pots that can be board mounted from the solder-side.