Switching Power in Audio?

[solis365]

I am working on a small pocket-sized headphone amp. It will be battery powered, but I have not decided on the battery. I was considering doing a lithium ion for its compactness and rechargeability.

Anyway, I don't see what the issue would be if I used a switching DC-DC regulator to step up the battery voltage, as long as it was operating at a frequency out of the range of human hearing. The IC that I have, a MAX642, operates at 40-60kHz or so. Anyone see any problems with doing this?

 

[Nigel Goodwin]

No, should be fine.

 

[solis365]

Thank you. It's tough to get good info from the DIY audio community as it is filled with self-proclaimed audiophiles that tell you the switching frequency introduces unwanted harmonics or nonlinearities that they can somehow hear... despite being unable to tell you exactly what the mechanism IS that introduces the distortion.

anyways, I appreciate it. I am hoping to extend battery life this way instead of using two 9v batteries, which are both bulky and expensive to keep rebuying. hopefully a single lithium battery can make it smaller, lighter, and have a longer battery life.

 

[Ubergeek63]

Thank you. It's tough to get good info from the DIY audio community as it is filled with self-proclaimed audiophiles that tell you the switching frequency introduces unwanted harmonics or nonlinearities that they can somehow hear... despite being unable to tell you exactly what the mechanism IS that introduces the distortion.

anyways, I appreciate it. I am hoping to extend battery life this way instead of using two 9v batteries, which are both bulky and expensive to keep rebuying. hopefully a single lithium battery can make it smaller, lighter, and have a longer battery life.

well the mechanism would be RF rectification. the dithering of the switcher feedback loop being demodulated by the nonlinear effects of the amplifier, of course what they will not admit to is that it would be 100 to 1000x less loud than what you are listening to if it is there at all.

that said you are better off using a class D amp anyhow since there is potentially more losses in your amp than in your regulator. a good class D should run fine right off a lithium cell.

Dan

 

[audioguru]

Why do you need plus and minus 9V (a total of 18V) for a headphones amplifier? MP3 players run off a 1.5V to 3V battery and don't step up the voltage.
Any opamp can use a single polarity supply if it is biased properly. Many opamps work perfectly with a supply as low as 3V.