Wednesday, August 27, 2008

Meet Mr CMOY

Last winter, I finally joined in the crowd and bought an Ipod. I was disappointed with the earphones, so I upgraded to a set of Shure earphones. This led me to the Headwize forum. Since I have this DIY thing, I began building compact headphone amps. The guy who started this was Chu Moy, who published a simple opamp headphone amp and started many a hobbiest on their merry way. There are many versions and upgrades to this amp in both the elctronics end and also the cases. The standard case is the venerable Altoids box. I've built about a half dozen of these amps from both point to point methods and also commercially made pcbs. I also constructed the patch cord from silver coated cables with TFE insulation, but that is another post.

Cmoy under the hood

I've showcased my 3 favorite Cmoy amps. The first point to point Altoid amp was my first attempt. I spent an entire Sunday afternoon getting this together including troubleshooting. the larger one is also a Cmoy amp with an 18 volt power supply and a crossfeed circuit-hence the two additonal switches. The last Altoids amp was built form a PC board I bought from a guy on Ebay. It also includes a rail splitter power supply and a bass boost circuit. I don't need the boost for my regular headphones, but the Shure earphones could use the help.

I also have completed a SOHA tube headphone amp, but you will have to tune in next time to see this one. Also on deck is a class A Tube headphone amp and a Dynaco 70 upgrade.