Low voltage amplifiers?

[mrbigstuff]

There are a ton on eBay and Amz. But I don't know the differences. The various models are based on their chips, all class D amps. I'm using a small battery of 8v but may step up to a 9.6v pack. I'm building a cheap bluetooth boombox with parts I've got lying around. But I don't have a decent low voltage amp. The other thought is to scavenge a radio and use that board.

[davemchine]

I have one class D amp that I paid around $100 for. It has an external 12v brick so I assume running one off battery is doable. Mine makes pleasant noise thru the speakers but doesn’t get terribly loud. Doesn’t the AppleHiFi use a class D amplifier? It has a d cell battery compartment.

[Forrest]

Adafruit sells a couple of Class D amps ranging from 2 W to 20 Watts. Adafruit designs and builds their own products, and there’s plenty of info on their products

[mrbigstuff]

Forrest wrote:
Adafruit sells a couple of Class D amps ranging from 2 W to 20 Watts. Adafruit designs and builds their own products, and there’s plenty of info on their products

Excellent! Thanks. Rabbit hole, here I come.

[kj]

davemchine wrote:
I have one class D amp that I paid around $100 for. It has an external 12v brick so I assume running one off battery is doable. Mine makes pleasant noise thru the speakers but doesn’t get terribly loud. Doesn’t the AppleHiFi use a class D amplifier? It has a d cell battery compartment.

I'm sure everything that is portable uses a class D amp due to the efficiency. In fact, just about everything is class D nowadays (even a 1000w bass amp).
I think power ratings are often a bit inflated (which is not a new thing). The adafruit "20w" amp is rated at 20w at 10% distortion, so it's actual usable wattage would be a fair amount less (probably 10w). It may still be a good amp, but it won't be as loud as you would expect a 20w amp to be.

Also, from what I understand it can be tricky giving a class D amp the input characteristics that utilize the amp optimally. In essence you're providing the preamp which may or may not suit what the amp needs. So that can affect performance with these type amps.

I' ve wanted for quite a while to make some of my passive speakers into active speakers with an amp like these, but like you guys, there are so many available, I don't know where to start. Plus, my speakers seem to be a little picky about power.