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Overviewσ22 ("sigma 22") is a high-performance DIY dual-rail, tracking, linear regulated power supply (PSU). Originally designed as a companion PSU for the β22 amplifier, the low-noise, high-current, excellent line/load regulation, wide-bandwidth, and stability characteristics makes it also ideal for other DIY stereo headphone amplifiers, preamplifiers, power amplifiers and other applications requiring a dual-rail regulated PSU.The circuit uses all discrete components (no integrated circuits) in a complementary topology, and features high-current MOSFETs as the output "pass" devices. Please see the Tech highlights section for a description of the circuit design. σ22 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 the work of AMB with participation from the DIY community. It is designed to be relatively easy to build, but it is not recommended as a first-time project for the beginner. 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, which also contains details about configuring the σ22 for various output voltages. You will also find information about the maximum output current capability of the σ22 in the Tech highlights section. Please be sure to read every section of this site carefully before attempting to build the σ22 PSU. 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 σ22 projectThe σ22 project is primarily centered around the PSU board. To build a working power supply, you will also need a power transformer, IEC power entry receptacle, power switch, as well as select and/or build an enclosure chassis to house the board (and optionally the amplifier or device that this PSU will provide power to).An assembled σ22 circuit board (click to enlarge) 
What skills and tools are neededYou 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.WARNING: Building a PSU will require that you work with AC line voltage, which is a lethal shock hazard. If you don't know what you're doing, please ask someone who is experienced to help you. Why not offer a full kitAMB is not prepared to stock all the needed parts and offer them as a full kit. The PSU provides a number of customizable options that makes it unwieldy for such a kit. Lastly, this PSU is AMB'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 assembled boardsThis is intended to be a project for DIYers, and AMB is not set up to manufacture assembled and tested boards.Professional buildersIf you are having an amplifier or other audio device custom-built for you by a professional builder, you can specify that the σ22 be used to provide power to it (if it is an appropriate application for the σ22). The following professional builders are listed for your reference. If you would like to be listed as a professional builder here, please contact AMB.Where to get helpBe 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 on the DIY forum at headwize.com. Search the forum for an answer before asking a question. Your question may have already been asked and answered.Main: σ22 Main | Next: Tech Highlights |
