freestompboxes.org

Anyone got schematics of the K&K beltclip preamps?
Or someone have one and can shot some nice pics of the circuit?
Im interested by the pure mix, but a single channel version can work too.

Thanks!

K & K pure preamp. Both sides. All box caps on the top of the board, all surface mount resistor on the bottom.

The Pots are:
Volume: measured at 10.2k
Treble: 100k
Mid:10k
Bass: 100k
Trimmer: 100k

IC: TL072

There are two caps under the jacks, not visible in photo. The input jack (closer to the edge) has a box cap. Can't read value. It is soldered to the two round pads. The to square pads under that jack have nothing on them. Surface mount pull down left off? The output jack covers a 1uf electrolytic.

It's so much easier to fix some one else's work than to do it myself...

I changed the gain trimmer; (one leg is not hooked to anything, pin 6 goes to 10k, then 1uf cap to ground. Wiper goes to pin 7 and 470n cap.
I changed the tone stack section. Now all three pots have pin 1 connected (bass and mids through resistors) to pin 1 (output) of the opamp. All three wipers are attached (bass and mids add caps) through resistors to pin 2 (inverting input) of the opamp.

Interesting they decided to make it inverting. I actually use a Baggs para di, and always leave the phase inverter on.

There are only two electro caps on the board. The schematic posted earlier had an additional cap on the voltage divider for Vref, not present on the original but usual good practice.
Thanks for pitching in. Anything I missed?

I have a K&K Pure Mini pickup built into my guitar, so I really want to try and build this, tried filling in the blanks.

-10k input resistor was missing from schematic
-100R (101) output resistor seems to be wired after the pot
-1M biasing resistors
-resistor between pin 1 and mid pot is 1k8 (182)

Great gutshot would almost allow for a fascimile layout, but don't want to mes with them crazy pots (lugs are not in line)