How to Build the CMoy Pocket Headphone Amplifier for $20

Okay, so you were intrigued by my claim that you can build a CMoy pocket amp for US$20, but then disappointed when you saw that the parts can easily crest $40. What’s the deal? It’s pretty simple: in the main part of this article, I’m in a position to recommend parts, which means I have to like the parts and I have to think you’ll like them, too. That leads me to be conservative.

However, if you really wanted to skimp, here’s how you could get the cost down to around $20:

Description Qty ID Price Where to Get It, Comments
220 µF/25 V electrolytic capacitor, radial leads 2 C1 $1.00 Any electronics store will have these
0.1 µF metallized polypropylene caps 2 C2 $0.68 Digi-Key E1104-ND
Metal film resistors 11 R* $1.21 Anywhere. 1/4 W metal film resistors average 11 cents each.
LED 1 LED $0.10 Any electronics store will have these
OPA2134PA 1 IC1 $2.63 Digi-Key
Chunk of protoboard 1 BOARD $1.50 many places
1/8" jacks 2 IN/OUT $2.00 Digi-Key, Mouser, or Newark
Power and level switches 2 SW $5.00 Mouser for cheap but good. The NKK ones at Digi-Key are nice, but expensive.
Basic enclosure (PacTec HML) 1 BOX $6.00 Newark, Mouser
Total: $20.12

In the above part list, I include the same enclosure Chu Moy used for his original amp. It’s not actually a very popular enclosure, however; personally, I find it rather ugly. Mint tins are more popular, partly because they save you several bucks, and many think they look good.

Counterbalancing this are many things that can inflate the cost:

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