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cmoy headphone amp

CMoy Headphone Amp

The CMoy headphone amp is a popular headphone amplifier that is small enough to carry everyday and powerful enough to drive headphones at higher levels than normal. Most headphones and most sources will get along ok, but there are players with weak output, and high end headphones typically give up efficiency for the best sound.

The CMoy amp was originally designed by Chu Moy, and at this point there are hundreds of variations with different components, layout, and features. Sometimes, users simply swap op-amps for a different sound and performance. This circuit uses op-amps to directly drive headphones, something they are not designed to do, also, some of the op-amps used are not even designed for audio applications!

It provides decent audio fidelity from just a few small and inexpensive components. In the last few years, CMoy style headphone amplifiers have been very popular with the DIY audio crowd to increase the audio output to some of the larger and higher impedance headphones available.

cmoy headphone amp

DIY audio enthusiasts typically stuff these components into an Altoids tin, other tins, or other small project boxes. The CMoy style of amplifier is versatile enough to fit into many different form factors. Users also determine the container based on what features they choose to include with their circuit. They might add features like bass boost, DC input, and rechargeable batteries.

7 Comments

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  • dmullins941sbcglobal-net

    I am looking for an Audio amp.to picked up normal conversation with earphone
    output. I have a hearing problem that hearing aides can not help.

  • Just Had TOo

    HaHa, there is feedback in this circuit, r5, r10 no. If there was no feedback, what would happen?

  • r de vreede

    Fun, but not suitable for pro’s like myself, though great for peoples which are learning basic circuit building and be able to understand it, instead of a lot op amp diy circuits with balanced inputs and feedback etc in one schematic , withouttrafo, and an explenation. But buying(orso) a couples of audio books and don’t forget the math. with speakerbuilding nobody gives an explaination , since the computer has done things for them, so they still don’t know electronics, they think they can. But a nice circuit which values ain’t that sharp like they suppose to do. Then for starters i would use a high grade pcb and not a tin box and no bateries. , high grade shielded cable and not and average variable resistor. And i’m building it for fun tonight with a tiny trafo, shielding and the possibilty to load via a ic , which can load every kind of accu these day, i think just li-ion, and a bandpass filter to lower noise . I will post the schematic or probably a schematic made with pen, The gain has to be higher , i don’t use low z headphones.
    A nice smps-audio amp would be nice to see here , totally explaines, since class g is the future.

    gr richard

    • Just Had TOo

      LOL, thanks gr richard. I didn’t know the OPA2132 wasn’t suitable for fools…, pros like you. Does this go for all the Burr Brown Opamps. Looks like I need to to get rid of a lot of pro sudio stuff. Forget my ears. So if BB opamps are not suitable for pros like you. What opamp do you suggest. Batteries isolate by not being connected. Oh should I use wire wound potentiometers for such circuits.

      My q is this. Why take ref from a voltage divider, instead of between batteries? Was this to simplify it for idiots like DICK, so they want get confused with voltage potential, and make it easier to adapt to other v sources. Hope Dick was smart enough to add a ferrite bead and a 1uF + 0.1uF filter caps. My guess is NO, I bet he has no idea, and just thinks he does since he went to fullsail. Maybe he could explain impendence as it relates to audio… Don’t make yourself sound like a Dick, you don’t grasp it like you think… Remain objective… Peace

  • Michael

    For the UA1 and the R6, they are not listed in the Bill of materials. Are they neccessary?

    • Gary

      U1 and U1a are the same part, I don’t want it listed twice in the BOM.

      Same for R1/R6.

  • Jonas

    Very interesting

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