The γ1 Modular Miniature DAC
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News

  • Mar 31, 2010: AMB announces its own DIY audio forum. Please use the new forum for support.
  • Mar 24, 2010: We have received reports of damage to the γ1 when used with the Starving Student hybrid headphone amplifier. This amplifier has also been known to damage other DACs, so be warned.
  • Nov 06, 2009: TORX147PL Toslink receiver and TOTX147PL Toslink transmitter modules are now available from AMB audio shop.
  • Jan 13, 2009: The value of R20D resistor has been changed from 75Ω to 47KΩ. If you had already built a γ1 with the old value, this is an optional, but recommended update.
  • Jan 03, 2009: Pre-drilled and engraved γ1 full configuration front and rear panels are now available from AMB audio shop.
  • Dec 23, 2008: γ1 circuit boards are available.
  • Custom-built, ready-to-use γ1 DACs are available exclusively from MisterX (Marshall Wyant). Please contact him directly for details.

Overview

γ1 is a high-performance, full-featured DIY stereo digital-to-analog converter (DAC) for portable and home use. Designed to be housed in a very compact enclosure, its footprint is almost exactly the size of a credit card, and about 0.9" (23mm) thick. Despite the size, a full-configuration γ1 has S/PDIF coaxial and optical digital inputs as well as a USB interface. Ideal for computer audio, CD/DVD players and digital media players, γ1 offers an economical DIY alternative to costly commercial DACs. Its 1.5Vrms analog output provides line-level interface to a stereo preamp, headphone amplifier or other device. The low output impedance and high output current capability allows a long interconnect cable to be used without degradation.

γ1 is also designed to be modular, its two circuit boards can be used together or independently in different configurations, allowing it to suit different usage needs. See below for details.

In conjunction with an off-the-shelf enclosure solution and wire-free board mounting of all components, γ1 is easy and inexpensive to build. The only surface-mount parts are the integrated circuits, all other parts are through-hole. See the Tech highlights section for details.

γ1 is designed by AMB and MisterX with community input. See the History section for details.

Basic feature set

  • Designed for the Hammond 1455C80x case (same as Mini³ portable headphone amplifier).
  • The γ1 "full++" configuration uses the Box Enclosures B2-080 series case.
  • Supports USB, S/PDIF coax and optical inputs (switchable).
  • 24-bit 192KHz high-performance Wolfson ΔΣ oversampling DAC chip.
  • 192KHz S/PDIF receiver chip with low-jitter clock recovery.
  • Modular: A separate DAC board and a USB interface board that could each be used standalone, or mated to each other for the full feature set.
  • The S/PDIF inputs (coax and optical) support resolutions and sampling rates up to 24-bits 192KHz, but the DAC configuration is limited to 24-bit 96KHz for best digital filter response (see the circuit descriptions in the schematic diagram section for details).
  • The maximum USB resolution and sampling rate is 16-bit 48KHz.
  • When used standalone, the USB interface board can be configured as a bus-powered USB-to-S/PDIF or USB-to-I²S converter.
  • When used standalone, the DAC board supports only S/PDIF (coax or optical) inputs and must be powered by external power.
  • When mated to each other, the two boards can support all inputs and can be USB-powered or externally-powered.
  • Auto-sensing of external-power.
  • Onboard power supply voltage regulation (separate LDO voltage regulators for the USB board, DAC digital and analog sections).
  • Analog line output (3.5mm stereo mini jack), with high output current and low output impedance.
  • Illuminated mini-toggle input selector switch (USB/coax/optical) with power-on indication and operation status (green = normal, red = error or no audio).
  • 1.3mm miniature barrel-type DC power jack, RCA phono S/PDIF coax jacks, standard Toslink-style S/PDIF optical jacks, 3.5mm stereo mini jack for audio line output, mini-USB connector.
  • Through-hole resistors, capacitors, ferrites and other parts to reduce build difficulty. The only SMD parts are the various ICs and voltage regulators.
  • In default configuration, all parts (including jacks) are PCB-mounted. No internal wiring necessary.
  • USB host interface supports Linux, MacOS and Windows (no additional software driver necessary).

Modularity

Due to γ1's modular nature, there are five main possible configurations:
  • A: Full configuration (USB, S/PDIF coax and optical inputs, selectable with front panel switch).
  • B: Lite configuration (USB input only, no selector switch).
  • C: USB-to-S/PDIF converter (no DAC board).
  • D: USB-to-I²S converter (no DAC board).
  • E: S/PDIF DAC only (coax and optical inputs, selectable with front panel switch, no USB board).
  • F: Full++ configuration (combination of A and C).

Upgrade

See the γ2 project about expanding γ1 to an upsampling DAC with onboard ultra-low jitter clock, switch selectable digital filters and anti-clipping mode. While γ1 is already excellent, the γ2 upgrade elevates it far into the high-end.

Some photos of the full and full++ configuration γ1 (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 (with a fine tip) and accessories, screw drivers, needle nose plier, diagonal cutter, a sharp tweezer (for positioning the SMD integrated circuits), etc. For the front and rear panels, you will also need to be able to accurately drill the holes needed for the input, output and DC power jacks, etc. (unless you opted for the pre-drilled and engraved panel set).

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 γ1 DAC. If you don't thoroughly understand everything, please consider having someone more experienced to build the DAC for you.

The scope of the γ1 project

The γ1 project is primarily centered around the USB and DAC board set. You should also add a Hammond 1455C801 or 1455C802 enclosure. The γ1 circuit boards are designed to slide into these cases without additional mounting hardware. The γ1 "full++" configuration uses the Box Enclosures B2-080 series case.

Why not offer a full kit

AMB is not prepared to stock all the needed parts and offer them as a full kit. This DAC 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. However, to make sourcing parts easier, AMB includes the the ferrite beads and pin headers (for use as USB and DAC board interconnect) with each board set. Several other related parts are also available from AMB.

Why not offer completed DACs

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

Professional builder

Inquire with the follow professional builder if they would build you a completed γ1 DAC, 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 or the DIY forums at head-fi.org and headwize.com. Search the forums for an answer before asking a question. Your question may have already been asked and answered.

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