The headphone amplifier is designed around single or dual-channel op-amps such as Burr-Brown's OPA2134 or OPA2132PA, however, a wide variety of op-amps have been successfully implemented. The op-amps directly drive headphones, even though they are not designed for such low-impedance loads, leading to poor performance and audible differences between op-amps that would not exist in a good design. The amplifier's design is quite simple. It consists of only a few components, can be assembled on a small section of protoboard, has a lower parts cost than other headphone amplifiers, and can run for many hours on a single 9 volt battery. The CMoy headphone amplifier can be fit into Altoids tins and can often be found for sale on eBay by searching for "CMoy".
Power is supplied to the opamps using a dual power supply, which effectively divides the input voltage source in half to create a virtual ground. Many virtual ground circuit options are presented in the various CMoy tutorials found online.
- How to Build the CMoy Pocket Amplifier
- Original article on Headwize.com
- Amazing Collection of Mint Tin Amp Designs
- Do-it-Yourself CMoy with bass boost
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