Barcus-Berry 3000A

Stumbled across this schematic on FSB. It's a buffer/EQ/preamp for peizo pickups, specifically all Barcus-Berry electret microphone systems. I figured most would be building this into an instrument and not a pedal, so all the pots are off-board. If you're planning on running it only off a 9v battery, you cab get away without the power filter cap (47uF) or the polarity protection diode (1N4001).

JHS Haunting Mids

The JHS Haunting Mids is an EQ circuit that controls the mid frequencies along with giving a 10dB clean boost. From the JHS site:

The Mids and Sweep controls work very closely together so you can find the perfect frequencies to boost or scoop mid frequencies. When the Mids knob is at 12 o'clock, no frequencies are boosted or scooped.  Turning the Mids knob to the left of 12 o'clock will begin to scoop out midrange frequencies, while turning the Mids knob to the right of 12 o'clock will begin to boost midrange frequencies. The Sweep knob controls the what frequencies will be affected.  Sweep knob to the left will cause low-mids to be affected, while Sweep knob to the right will cause hi-mids to be affected.  The Lo/Hi toggle is like a "Q" function and controls how sharp the frequency peak is that you’re affecting with the Mids knob.  "Lo" is a softer and wider peak for slightly subtler affect as you tweak the Mids/Sweep knobs.  "Hi" is a sharper and steeper peak giving you a very pointed and defined effect as you tweak the Mids/Sweep knobs.

Should fit nicely in a 1590B. Schematic for reference.

HomeBrew Electronics Detox EQ

Here's and interesting 3-band EQ from HomeBrew Electronics. They say it's like adding a second channel to your amp, cleaning up a dirty signal with the level turned down. Think the opposite of an overdrive or distortion pedal. Should fit nicely in a 1590B or 125B. Schematic for reference.

Demeter Fat Control

Looking for a mid-range frequency booster? This one's apparently really good at it. Schematic and discussion on FSB here.

Fender Eric Clapton Active Mid-Boost

Got a request for this one. It's the active midrange boost (of up to 25dB at around 500Hz) found in Fender's Eric Clapton signature Stratocaster. Ended up not board mounting the pots for a smaller board for those building this into a guitar. Here's the schematic for reference.

EWS Bass Mids Control

Here's another one for the bass players. It's a pretty handy EQ pedal from EWS. Originals come in a 1590a, and sadly I wasn't able to duplicate that here, but it will fit fine in a 1590B with board mounted pots. Originals have the Volume control as an internal trimmer, but I've moved that to a full sized pot for more control (and a newer version of this pedal has all 3 control externally as well, so maybe I'm on to something haha). Here's the schematic for reference.

Run of Groove Tonemender

Got a request for this one. It's a nice boost with a 3-band EQ. Pots are board mounted and it will fit in a 1590B sideways (ala Zvex pedals) with the circuit board vertical. From the Run Off Groove article:

The Tonemender is a very flexible, yet simple clean boost with a 3-knob tonestack that allows the user to re-create the classic Fender, Marshall and Vox responses.
We suggest using a TLC2272 for the dual op-amp. The TLC2272 is rated for low-noise and rail-to-rail output, which will offer the highest possible clean boost and dynamic range. The NE5532 is another good choice, but a TL072 can also be used with decent results.
The Mid Shift switch (SW1 on the schematic) selects the center frequency of the midrange dip in the response. The center frequency is moved from around 700Hz (Marshall/Vox) down to 400Hz (Fender) in the HI and LO settings, respectively.
For Fender-style curves, the Mid Shift is placed in the LO setting (closed). To replicate Marshall-style curves, switch the Mid Shift to the HI position (open). Set the Mid control between 12:00 and 5:00 for traditional Marshall settings, with lower settings providing additional flexibility. For a Vox-style response, keep the Mid Shift in the HI setting and set the Mids control fixed at 10:00 and move the Bass between 7:00 and 12:00.
A "flat" equalizer position is set with the Bass and Treble both at minimum, and the Mid control at its midpoint. When Bass and Treble are fully cut, the Mid knob acts as an additional Level control, which is a familiar characteristic of the Fender tonestack.

BearFoot FX Sea Blue EQ

Here's a cool EQ/booster from Bjorn Juhl. If pushed hard, it will break up much like a tube EQ would, and adds warmth and clarity to your tone. It uses 2 JFETs and a James style tone stack.