Project · Boosters & Volume
MXR™ MicroAmp™
This booster has been popular since inception, over 30 years ago and for good reason. It's also a nice simple little booster to build.
The story
About the circuit
MXR™'s Micro Amp came out of Rochester in the late 1970s and has barely changed since. It is a single op-amp clean boost with one knob: a little gain to push a tube amp or the next pedal, or just to make up the volume lost to a long chain. It adds a touch of warmth and low end rather than colour, which is why it has stayed on so many boards for decades.
This project at GGG
Our Micro Amp replica follows the original circuit, and it's a nice, simple booster to build, one of the good options for a first or second project. The kit includes everything to build it, and the page has the schematic, parts list and layout.
Project files
Everything you need to build it
MicroAmp™ Ready-For-Transfer Printed Circuit Board Layout - For use only if you are a complete DIY person who wants to etch and drill your own PCB. Otherwise, we recommend you ignore this PCB mask and buy the Ready to Solder Printed Circuit Board or Complete Kit.
Parts layout
Parts Layout / Wiring Diagram
What you will need
Bill of Materials
Version 2009December10 · Copyright 2009 JD Sleep · Permission refused for posting/serving this file from any site other than www.generalguitargadgets.com · Trademarks are property of their owners
Resistors
| Resistor ID | Value | 3-band Marking | 4-band Marking |
|---|---|---|---|
| R1 | 22M | red-red-blue | |
| R2 | 10M | brown-black-blue | |
| R3 | 1k | brown-black-red | brown-black-black-brown |
| R4 | 56k | green-blue-orange | green-blue-black-red |
| R5 (Volume Control) | 500k Reverse Log | ||
| R6 | 2k7 (2.7k) | red-violet-red | red-violet-black-brown |
| R7 | 100k | brown-black-yellow | brown-black-black-orange |
| R8 | 100k | brown-black-yellow | brown-black-black-orange |
| R9 | 470 ohm | yellow-violet-brown | yellow-violet-black-black |
| R10 | 10k | brown-black-orange | brown-black-black-red |
| R11 | 1k | brown-black-red | brown-black-black-brown |
Capacitors
| Capacitor ID | Value | Type | Possible Marking |
|---|---|---|---|
| C1 | 0.1µF | Film | 104 |
| C2 | 47pF | Ceramic or Film | 47pF |
| C3 | 4.7µF | Tantalum or Aluminum Electrolytic | 4.7µF |
| C4 | 1µF | Tantalum or Aluminum Electrolytic | 1µF |
| C5 | 15µF | Tantalum or Aluminum Electrolytic | 15µF |
Potentiometers
| Part ID | Value | Type |
|---|---|---|
| R5 - Volume Control | 500k | Reverse Log Taper |
Other
| Part ID | Part Name |
|---|---|
| IC1 | TL061 or other single opamp |
| D1 | 1N4001 or 1N914 Diode (Small Blue diode in the Kits) |
| D2 | LED |
| J1 | Stereo quarter-inch jack |
| J2 | Mono quarter-inch jack |
| J3 | DC Jack |
| B1 | 9 volt battery (Not Included in the Kit) |
| Sw1 | Heavy Duty 3PDT foot switch 9v battery snap, 24 gauge stranded hookup wire, Enclosure, Knobs, Solder |
More about this project
Notes, sounds and related links
Ready to build? We have the kit.
Buy a MicroAmp™ Complete Kit. Includes all the parts and materials you need to build one, all for about the price you would pay for a PCB and parts.
Would you like a Ready to Solder Circuit Board for this project? Note: If you buy the kit, the Ready-to-Solder Printed Circuit Board (RTS PCB) is included in the kit. You do not need to purchase this Ready to Solder Circuit Printed Board if you buy the kit.