Project · Boosters & Volume
MXR™ Headphone Amp
A very nice simple headphones amp for your guitar. Similar to the Microamp. Thanks to Alfonso Hermida for the schematic information.
We built on with a configuration such that it can go in a effects chain with the footswitch switching the output sound from the line to your amp to headphones. We also built an effects loop on the input so that a speaker simulator or EQ could be included to effect only the headphone sound. Switchcraft™ enclosed jacks were used for the loop since they are smaller and easier to fit in.
Project files
Everything you need to build it
MXR™ Headphone Amp Ready-For-Transfer Printed Circuit Board Layout
Schematic
Schematic
Parts layout
Parts Layout / Wiring Diagram
What you will need
Bill of Materials
Version 2014January28 · Copyright 2014 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 | 10M | ||
| R2 | 500k Reverse Log Potentiometer | ||
| R3 | 4k7 (4.7k) | yellow-violet-red | yellow-violet-black-brown |
| R4 | 22M | ||
| R5 | 1k | brown-black-red | brown-black-black-brown |
| R6 | 3K9 (3.9K) | orange-white-red | orange-white-black-brown |
| R7 | 56k | green-blue-orange | green-blue-black-red |
| R8 | 3K9 (3.9K) | orange-white-red | orange-white-black-brown |
| R9 | 10k | brown-black-orange | brown-black-black-red |
| R10 | 100 ohm | brown-black-brown | brown-black-black-black |
| R11 | 100 ohm | brown-black-brown | brown-black-black-black |
| R12 | 10k | brown-black-orange | brown-black-black-red |
| R13 | 10k | brown-black-orange | brown-black-black-red |
| R14 | 1k | brown-black-red | brown-black-black-brown |
Capacitors
| Capacitor ID | Value | Type | Possible Marking |
|---|---|---|---|
| C1 | 0.1µF | Film | 104 |
| C2 | 4.7µF | Aluminum Electrolytic | 4.7µF |
| C3 | 47µF | Aluminum Electrolytic | 47µF |
| C4 | 47µF | Aluminum Electrolytic | 47µF |
| C5 | 47µF | Aluminum Electrolytic | 47µF |
| C6 | 150pF | Ceramic or Film | 151 |
Potentiometers
| Part ID | Value | Type |
|---|---|---|
| R2 - Volume Control | 500k | Reverse Log Taper |
Other
| Part ID | Part Name |
|---|---|
| D1 | 1N914 |
| D2 | 1N914 |
| IC1 | TL071 or similar single opamp |
| Q1 | 2N4401 (NPN) |
| Q2 | 2N4403 (PNP) |
| J1 | Stereo quarter-inch jack |
| J2 | Stereo quarter-inch jack |
| J3 | DC Jack |
| J4 (Bypass Version only) | Mono quarter-inch jack |
| J5 (Input Loop Version Only) | Normally Closed jack (12A) |
| J6 (Input Loop Version Only | Mono quarter-inch jack |
| B1 | 9 volt battery (not included in the Kit) |
| Sw1 (Bypass Version only) | Heavy Duty 3PDT foot switch oR DPDT 9v battery snap, Printed Circuit Board, 24 gauge stranded wire, Enclosure, Knob |
More about this project
Notes, sounds and related links
Ready to build? We have the kit.
Would you like a Ready to Solder Circuit Board for this project?