Parts listThe table below is a complete parts list for all main configurations of the γ1. See the sections below for specific parts recommendations and options. For parts not offered by AMB audio shop, Mouser, Digi-Key, Newark, Farnell, RS Components or another vendor's stock numbers for the recommended parts are listed for your convenience.The A through E columns denote the γ1 configuration. "Y" means the part is required, "N" means that the part should not be populated, and "O" means optional (see corresponding notes below).
NotesSee the parts list table above, which refer to specific notes here.
Parts selection guideDue to the tight spacing within the enclosure, and to ensure proper fit when the DAC and USB boards are plugged into each other, please observe the following recommendations. Do not use oversized parts or mount parts in a manner that was not intended. Since the γ1 is mostly a digital circuit, with the exception of the output coupling capacitors, there is no benefit to using "boutique grade" parts. Also, do not substitute parts values unless you know what you're doing. Many of the parts are carefully selected and tuned for optimum operation.ResistorsAll discrete resistors (except the resistor networks R5D, R6D and R7D) are miniature through-hole axial-lead types with a body length no longer than about 4mm (the recommended Xicon, Panasonic and Multicomp resistors are 3.5mm or 3.2mm), and no wider than 1.9mm. Metal film 1% resistors are recommended for their thermal stability.
CapacitorsThere are four types of capacitors used in the γ1: conductive polymer electrolytic, audio-grade electrolytic, film and multi-layer ceramic.C6D, C10D and C8U are conductive polymer electrolytic type for their ultra low ESR characteristics. They are through-hole with radial leads, 2.5mm lead-pitch, a maximum diameter of 6.3mm and a maximum height of 12.5mm. C22D, C24D and C25D are "audio grade" electrolytic capacitors. They are through-hole with radial leads, 2mm or 2.5mm lead pitch, a maximum diameter of 6.3mm and a maximum height of 12.5mm. C24D and C25D are the DAC's analog output coupling capacitors. See the film capacitor descriptions below for C24D/C25D options. If you plan to drive headphones directly from the γ1, then you should use Nichicon KW or FW 470µF 6.3V or 10V capacitors to avoid low-frequency roll-off. Note that some of these "for audio" electrolytic capacitors are non-polarized.
All remaining capacitors are multi-layer ceramic type, with through-hole, radial-leads and 2.5mm lead-spacing. Some capacitors have 2.5mm pitch leads but come pre-bent to 5mm, you must straighten them to fit the board. The TDK FK24 series 1µF multi-layer ceramic capacitor specified have smaller size and lower profile than most others of comparable specifications, ensuring that they will fit without hitting other parts when the DAC and USB boards are mated. C4U and C5U are C0G/NP0 grade, which provides the best thermal stability and is important for the crystal oscillator circuit. C18D is also C0G/NP0 but all other multi-layer ceramic capacitors are X7R grade because C0G/NP0 is only available in small capacitances. Do not use Z5U, Y5V or other lower grades. Inductors and ferrite beadsL1D and L3U are miniature 47µH through-hole axial-lead inductors with a maximum body length of about 4mm and no wider than 2.3mm. L2D, L3D, L4D, L1U and L2U are through-hole ferrite beads.
Pulse transformersA 1:1 pulse transformer is used for T1D and T1U. The recommended transformers are as follows:SemiconductorsThe integrated circuits in the parts list table above should be used, with alternatives as specified below. Some ICs come in several package styles, be sure to use the correct ones that the board is designed for.The default U3D stereo DAC chip is Wolfson WM8501GED/V which outputs 1.5Vrms at 0dBFS when the supply voltage is 4.5V. The Wolfson WM8759GED/V is pin-compatible and may be substituted, but the output voltage is 1Vrms under the same conditions (but it is otherwise identical. For U1U, the "technically-correct" USB DAC chip is the PCM2707PJT. The PCM2706PJT has the same TQFP-32 package, but several pins have different functions. These pins are unused in the γ1, thus the PCM2706PJT may be substituted and will function correctly. You may use either the LP2985 series or the TPS793xx series LDO voltage regulators for U5D, U6D and U3U, as shown in the parts list table above. For U4D, you may use MCP100 or DS1818 in TO-92 package. Each of these come in several "threshold voltage" variants. It is recommended that you use the 3.15V or 3.00V versions if available (see their datasheets for the meaning of the part number suffix). Similarly for U9D, the options are MCP101 or DS1817. The Q1D and Q2D transistors are specified to be 2N3904, but you may subtitute them with just about any NPN TO-92 transistor with the same pin-out. Some examples are 2N4401, PN2222, 2N5088 or MPS8099 just to name a few. Use a T-1 (3mm) high brightness red LED for LEDU. You may also use green or yellow, but do not use blue or white, because blue or white LEDs typically require around 4V or more and we only have 3.3V here. If you get insufficient brightness, decrease the value of R7U. The default value of 560Ω will run 2.7mA through a red LED, which usually has a forward voltage of around 1.8V. If you change R7U's value, do not exceed 10mA to keep the USB power consumption reasonable. Use this online LED resistor value calculator.
Connectors
Chassis / caseThe γ1 is designed specifically for the Hammond 1455C80x series extruded aluminum cases.The γ1 full++ configuration (F) uses the Box Enclosures B2-080 series extruded aluminum case.
AC adapter or power supplyA 5V DC regulated AC adapter ("wallwart") or external 5V DC regulated power supply may be used to provide power to any γ1 configuration equipped with U1D and the 1.3mm DC power jack.The AC adapter or power supply's output plug should be a barrel-type with 1.3mm ID female, the polarity is center-positive. A compatible plug for the 1.3mm DC power jack is the CUI PP3-002D (Digi-Key CP3-1003-ND). The appropriate input AC mains voltage, frequency and plug style depends on your country. The output voltage should be between 4.85V and 5.4V DC, with a minimum current capacity of 300mA. A linear regulated power supply is preferred over a switching type for lowest noise. You may purchase one that is pre-built, or build your own. The σ25 regulated power supply is a suitable DIY option, and offers clean, linear-regulated power. For the γ1 (and γ2 upgrade), set up the σ25 to output 5V DC, and use a 2.8VA or higher power transformer with 9V secondary. The following is a partial sampling of such transformers:
The σ11 regulated power supply is another DIY alternative, providing the best in low-noise, high-current performance. It is more costly and complex than σ25 but merits consideration if you're also building the γ2 upgrade. See the σ11 website for details. Main: γ1 Main | Prev: Boards & panels | Next: Instructions | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
