BRASSM - Maestro™ Brass Master™ Replica

Maestro™, Gibson's effects brand, released the Brass Master™ in the early 1970s as a fuzz for bass players. It generates an octave-up fuzz and lets you blend it with the clean signal, with a switch for two different harmonic voicings, so the bottom end stays intact while the fuzz sits on top: the "brass" in the name is the brassy, horn-like upper harmonics it adds. Originals are rare, and the circuit was documented for the DIY world by R.G. Keen at GEOFEX.

Our Brass Master™ replica comes from that GEOFEX documentation, with thanks to R.G., laid out for a standard stompbox enclosure. It has been one of the quiet steady sellers on the site, mainly to bass players who have run out of fuzzes that don't lose the low end. The kit includes everything you need; the schematic and layout are below.

Building Steps

1. Populate the PCB. Follow the Parts Placement Diagram. You do not need to install the two jumpers (indicated by thick red lines on the Parts Placement Diagram) These jumpers are built into the top layer of the PCB. The transformer can be installed with the primary facing either way, it doesn't matter. Watch the polarity of the aluminum electrolytic capacitors. Note that we did not install D5 protection diode (1N4003) it is not needed for operation and is not included in the kit. When you use the Volume Control, R16 is not needed, so don’t populate R16 if you are building the 4 knob version. If you look closely at the photo below, the R16 is lifted to disable it. 2. Stage 1 Wiring. Hook up the LED indicator as shown in this diagram. There is no spot on the PCB for the “current limiting resistor” for the LED, so it will have to be solder-tacked to the LED and wire. Note that if you build the 4-knob version, the LED will need to go under the PCB. The standoffs provided in the kit are extra tall so that it will easily fit under the PCB. Also wire the PCB input and Pad “M” (ground) to the bypass switch. It is not shown in the diagram for simplicity’s sake, but route these wires (from pads A and M) over the front side of the PCB and back under so that you can have easy access to the bottom of the board (for service purposes) if needed. 3. Stage 2 Wiring. Wire the potentiometers. Use “2A” diagram if you build the 3knob or the “2B” diagram if you build the 4-knob. The volume knob lug 2 wire should route under the PCB, again, for access to the bottom of the PCB. 4. Stage 3 Wiring. Wire the toggle switches and wire the power wires to the DC Jack as shown in this diagram. 5. Stage 4 Wiring. Wire the input and output signal and ground wires to the jacks. Hook up the battery snap to the DC jack and the input sleeve lug.

Here's an inside view of the unit we built to how it looks when assembled in a 1590BB tall enclosure. It is a very tight fit. The potentiometers should to be turned sideways from how we normally install them. Have fun, comments and questions are welcome and can be sent to [email protected]