Hey guys, I was thinking about building / buying a Cmoy headphone amplifier and was wondering if it would be a bad idea to get one without a volume control.
Also, is it possible to use the audio sockets as power switch, so when two jacks (line-in and line-out) are plugged in, the amplifier is powered on?
Finally, since my left ear is totally deaf and listening to stereo material is quite "annoying" because I cannot hear stuff that plays on the left channel, I wanted to have a stereo/mono switch. Wanting to preserve battery life, I was thinking about doing something like this (very basic sketch only to get the idea):



In stereo mode, the left and right channel is amplified separately as usual. In mono mode, the left and right channel is combined, amplified and then splitted to left and right. The first amplifier is powered off. The volume is not going to be as high as in stereo mode, though, I guess.

Could you do the channel mixing from your source? No problem on a computer, and you can do it on portable hd players with rockbox as well. Probably easy to do in the amp too but I wouldn't know.

I think amplifier boards tend to be at least stereo. You could give your right ear a treat and make a balanced right 1 channel amplifier!

I would put in a volume control since a separate preamp for a cmoy is a bit absurd and without one your sources may lose resolution from having to play very quietly.

I can't help you on the mono bit, but i built mine without volume control and it's fine. All dap's have volume controls anyway, and since it's a pocket amp it is possible for the knob to accidentally turn while it's in your pocket.

It's possible to get stereo jacks with builtin switches, but you need to make sure that the switch is separate and not connected to any of the audio pins or ground. Then just wire them up with the power in series and you're done.

Check out how this guy is making his cmoy amps. I think you will find a few of your questions answered. http://cgi.ebay.com/New-Headphone-Amplifie...1QQcmdZViewItem

I have been considering a tin-cmoy for my pocket [outdoor ear/headphones] and perhaps later something more substantial for home headphones. Hope it gives you some ideas!

Thanks for the link. I might order one from him instead of building myself since getting all parts would probably cost me just as much (due to shipping costs) and I never built something like that before, meaning that it could take me at least two attempts to build a Cmoy.

BTW, what is considered "high impedance headphones"? I doubt 32 and 64 ohm headphones fit into this category, right?

High impedance would be 200 ohm or more.