What is Chu Moy (cMoy)?

Chu Moy (cMoy) is an individually hand-made portable pocket headphone amplifier, built to power and improve the potential of quality headphones.

cMoy amplifier was first introduced by Chu Moy, and later improved by Tangent. Currently a new lay-out has been introduced to make it even smaller, so it can potentially decrease the chance of picking up external signals and interference from electronics devices such as televisions, radios, mobile phones, or even personal computers.

Each cMoy amp is constructed with high-quality well known parts, and is individually tested to make sure it is completely operational and produces high quality sound output without any distortion.

CMoy headphone amplifier will make a great gift for anyone of any age! Many have mated this amp with Sennheiser, Grado, Etymotic, Sony and Koss headphones and have reported nothing but praise.

Constructed with "high-quality well known parts".

This is an upgraded version of the cMoy amplifier which uses a High Precision, Low Noise Burr-Brown OPA2227PA Operational Amplifier (Op-Amp) from Texas Instruments. The OPA2227PA is dual channel 8-DIP Op-Amp chip, and it's pin-for-pin replacements for the industry standard OP-27 and OP-37 with substantial improvements across the board. According to Texas Instruments, the OPA227 series 'A' op-amp are ideal for professional audio equipment. In addition, low quiescent current and low cost make them ideal for portable applications requiring high precision. Furthermore, Tangent, notes that this family of op-amps sounds very similar to the OPA132 and OPA134. The main difference is that the OPA227 isn't as tubby on the bottom end as the OPA132, and the OPA227 will run to slightly lower supply voltages than the OPA132/OPA134. In conclusion the OPA227 is a good alternative to the OPA132/OPA134, and it is arguably even a significant upgrade.

The volume control is a Panasonic EVJ series 10K audio rated potentiometer combined with a black anodised aluminum knob for aesthetic look and feel. A sub-miniature SPDT power switch for easy power ON/OFF and low-votage LED are selected to keep the battery consumption level as low as possible. The input and output connectors are tin plated 3.5mm stereo mini jacks which are standard size for headphone plugs. Internally wired with a Linear Crystal Oxygen Free Copper (LC-OFC) 24 AWG high quality tinned copper wiring. Also, for safety and quality look, all wire joints are covered with heat-shrink sleeving.

Additionally, in the standard CMoy power supply, the two 4.7KΩ resistors (resitor divider) create a "virtual ground". This circuit works adequately in many situations, but it has weaknesses, for example "Unequal Virtual Ground Splits". In the current cMoy, the resistor divider is being replaced by a simple buffered virtual ground circuit, a TLE2426 "rail splitter" is being used instead of resistor divider (as this article suggests one way to fix "Unequal Virtual Ground Splits" is to replace the virtual ground "resitor divider" with a TLE2426 "rail splitter").

With what devices can cMoy be used?

This is an excellent amplifier to use with MP3 players, MiniDisc players, CD players, DVD players, or even computers where quality sound is a must. Audiophiles often use an external amplifier like this cMoy to bypass the portable player's weak internal amplifier to drive bigger, less sensitive headphones, like Sennheisers, Etymotics, and Grados.

Parts used:

• Red Penguin Tin
• High Precision, Low Noise Op-Amp from Texas Instruments (Burr-Brown) OPA2227P
• Panasonic EVJ-Y10F03A14 10K Audio Potentiometer
• Black anodised aluminum volume knob
• Sub-miniature SPDT toggle switch
• Gold plated 3.5mm stereo jack
• Hard plastic 9V battery strap
• Panasonic 1000μF 16V electrolytic capacitor, radial leads
• BC Components 0.1μF 63-plus volt box type polyester cap
• Yageo 10KΩ 1/4W metal film resistor
• Yageo 4.75KΩ 1/4W metal film resistor Texas Instruments TLE2426 rail splitter
• Yageo 100KΩ 1/4W metal film resistor
• Yageo 1KΩ 1/4W metal film resistor
• 3mm Pink/Water Clear Lens low voltage LED
• High-quality heat-shrink sleevings
• Protoboard Customised PCB
• LC-OFC (Linear Crystal Oxygen-Free Copper) 24 AWG internal wiring

Purchase

Or bid on eBay here

Notes:

Texas Instruments TLE2426 rail spliter or a 2.1mm DC jack can be added on request.
*one brand new 9V battery will be included with your purchase.

All parts used are high-quality, well-known parts. Built into a tin box for easy battery changing, toughness, and cool-factor.
100% tested and parts were matched for quality sound.
iPod and audio cable are not included.

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