using below 1hz?

[davesaudio]

can tripath/others work below 1hz?
thinking about non-audio applications-
about driving a small motor etc?

[theAnonymous1]

I've tried 1hz with a Tripath amp. I couldn't get much power output before the amp would shut off; probably due to over-current.

I think you would be better off finding/building an actual motor controller.

There's quite a few of them on ebay.

[Pierre]

The problem with that is that you can get "bus pumping", an increase in the supply rails that is produced when you try to play low frequencies at high power.
Perhaps a couple of modules in bridge mode, or a full-bridge design, can solve this issue.

[davesaudio]

Originally posted by theAnonymous1
I've tried 1hz with a Tripath amp. I couldn't get much power output before the amp would shut off; probably due to over-current.

I think you would be better off finding/building an actual motor controller.

There's quite a few of them on ebay.

Too Bad, a motor controller with that level of efficiency would be nice
existing ones seem to be analog

Buss pumping-- hmm

[Pano]

Guess it depends on what type of motor, too.

Years ago I worked with motor controllers from Citroen that were as about "digital" as class D stuff. The 220V AC in was rectified, filtered then chopped up in to 3 phase 220. The motor speed was controlled by the frequency of the 3 phase sine output. Direction was controlled by phase. The motors were 3 phase 220V

IIRC, switching frequency was about 22 KHz, operating frequency from DC to 200Hz. DC was used as a brake and worked well. Control was from a 0-10V input. Worked like a charm. We had 4 controllers in a console for control of theatre machinery. Each controller was on a signal card.

So I don't see why a switching amp couldn't be adapted.

EDIT: You can get variable DC out of a Tripath chip if you want. That should be OK for driving a motor. You just want to be sure that the motor isn't of a too low impedance. Then you have the problem of filters.