The M³ stereo headphone amplifier


  • M³ circuit boards are available.
  • Effective February 12, 2009, all new M³ boards shipped are version 1.02. If you have a M³ version 1.01 board, please read the special notes before using them. These notes do not apply to versions 1.0 or 1.02.
  • Custom-built, ready-to-use M³ amplifiers are available from some professional builders.
  • Reviews of the M³:
    • "They're building stuff that sounds so good that it makes me have to keep coming up with better sounding products or I'll be left in the dust!" - Tyll Hertsens, HeadRoom.
    • "I've got to tell you that it sounds good enough to have cost me some sleep." - Wes Phillips, Stereophile. [full text]
  • n_maher created a BOM spreadsheet (XLS format) with hyperlinks to vendors. It includes all parts for the M³ board except connectors, and does not include the enclosure, knobs, jacks, etc. Please also refer to the Parts list section of this site for detailed recommendations.


M³ is a high-end DIY stereo amplifier for dynamic headphones. It includes a number of distinctive features, carefully considered to maximize performance while keeping the cost modest. M³ is also usable as an excellent pre-amplifier line stage or low-power speaker amplifier. See the other options section for details.

Pronounced "M cubed", the name reflects the three MOSFET output channels, which is the defining feature of this amplifier. Some people type "MMM", "M3" or "M^3" as its name.

The M³ is the result of a community service project for the audiophile hobbyist. The schematic diagram is open source. The circuit design, as well as the printed circuit board layout are a culmination of the work of Team M³ with participation from the DIY community. It is designed to be easy to build, but it is not recommended as a first-time project for the beginner.

Team M³ is AMB and Morsel.

Inspired by the PPA and SDS Labs headphone amplifiers, the M³ incorporates key features of both, plus additional enhancements. It is intended to be wall-powered, with no compromises made for battery compatibility.

See the History & acknowledgements section for further details.

To obtain the blank printed circuit board and some related parts, visit the AMB audio shop. Other parts are available from online vendors. See the Parts list section.

Please be sure to read every section of this site carefully before attempting to build the M³ amplifier. If you don't thoroughly understand everything, please consider having someone more experienced to build the amplifier for you, or build a simpler project.

The scope of the M³ project

The M³ project is primarily centered around the main headphone amplifier board. To build a working amplifier, you will also need a regulated DC power supply to provide power to this board, as well as select and/or build an enclosure chassis to house the amplifier board (and power supply, if the one you chose does not come with one). For further information see the Power supply section and the Parts list sections. Also, visit the AMB DIY audio forum to see what others are doing to build their M³ amplifiers.

An assembled M³ circuit board (click to enlarge)

What skills and tools are needed

You should know how to read a schematic diagram and correlate it to the circuit board layout, identify electronic parts and their pin-outs, have decent soldering skill, and be proficient with a multimeter. You need at least a basic set of tools for electronics work, such as a good soldering iron and accessories, screw drivers, needle nose plier, diagonal wire cutter, etc. For the chassis case, you will also need to be familiar with using the tools that are necessary, such as an electric drill, bits, center punch and others.

Why not offer a full kit

AMB is not prepared to stock all the needed parts and offer them as a full kit. This amplifier also provides a number of customizable options that makes it unwieldy for such a kit. Lastly, this amplifier is Team M³'s contribution to the DIY community rather than a for-profit product, AMB cannot assume the commercial support role that might be implicit with a full kit.

Why not offer completed amplifiers

This is intended to be a project for DIYers, and AMB is not set up to manufacture completed amplifiers.

Professional builders

Inquire with the following list of professional builders if they would build you a completed M³ amplifier, in case you cannot build one yourself.

Where to get help

Be sure you read all the information at this site. If you cannot find an answer to a question, or encounter a problem you cannot solve, the best place to get support is the AMB DIY audio forum. Search the forums for an answer before asking a question. Your question may have already been asked and answered.

AMB M³ prototype (click image to enlarge)
See more photos in the M³ gallery

Main: M³ Main | Next: Tech Highlights