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Help designing for a low(ish)-power, low-impedance, low-distortion amp? Answered

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Alright, so I blew up my iHome2GO's internal amplifier board, (Don't ask, long story, lots of electrical shenanigans) and I am attempting to design a new board to go inside it, and I'd prefer it to be a through-hole design (although I could use SMD parts if I HAD to...) The speakers that are inside the iHome are rated at 3 ohms, 3 watts, and I'd like to have an amp that outputs 3 watts. I just need help with the actual amplifier's design, I can't find anything like a chip suitable for the job (although I probably missed several), and am an amateur electronics hobbyist. I'd like low-distortion sound as well, I dabble in high-end audio, and I'd like this to sound at least as good as my headphones do, like it used to. Also, it runs at 6V (4xAA). Thanks!

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steveastroukBest Answer (author)2013-02-10

3 ? You sure that isn't an 8 ?
For a low power system, I'd suggest you used an LM4667 or that family anyway

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hxr.keltz (author)steveastrouk2013-02-10

Yeah, they're actually 3 ohms. it seems kinda odd to me but w/e. Looking at the datasheet for that chip, I'm a bit worried about trying it at 3 ohms, because all specs point to it being designed for an 8 ohm speaker. In my experience, that can often cause the chip to overheat and die prematurely.

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steveastrouk (author)hxr.keltz2013-02-10

It REALLY looks like an 8 in the first photograph ! Three is a completely non-standard.

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hxr.keltz (author)steveastrouk2013-02-12

So, are there any other chips you could recommend?

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steveastrouk (author)hxr.keltz2013-02-13

Depends on how efficient you want to be. If you want to use class D amps, then look further at the Boomer family.

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hxr.keltz (author)steveastrouk2013-02-13

Got it. I just found the LM4871, which seems to suit my needs.

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hxr.keltz (author)steveastrouk2013-02-10

Well, that's what I thought at first as well, but the other driver actually says "3" a bit more clearly, you can see it a lot better IRL than on the camera. Also, when I was playing around with them, I had hooked them up to my home receiver, and they sounded great, but the receiver got an alarming amount hotter than normal when driving these tiny things.

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