TDA 2822 practice amp advice

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lykwydchykyn
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Post by lykwydchykyn »

I'm trying to build a practice amp using an 8 Ohm speaker and a TDA 2822 IC that will run on 9v pedal power.

For a first attempt, I built the bridged example from the datasheet, shown here:
tda2822-bridged.png
It works, and it's a bit more volume than the usual LM386 amps I've built (ruby, noisy cricket, etc), but zooks its dirty. Like fuzz dirty. If I crank WAY back on the input volume it cleans up OK, but I'm just wondering if I can do anything to make that sample circuit play nicer while still getting volume. Has anyone used this chip in an amp? Is this just the limitation of a single-supply 9v circuit?

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Frank_NH
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Post by Frank_NH »

I had a peek at the data sheet and found the plot below. Looks like the distortion goes up quickly in the bridge mode! At 9V supply your probably pushing over 2W through the amp (see the datasheet). Try reducing the supply voltage or padding your input.

I think this chip was meant for amplifying portable headphones for radios and cassettes running on batteries.
TDA2822.png
TDA2822.png (27.08 KiB) Viewed 1209 times

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lykwydchykyn
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Post by lykwydchykyn »

Thanks. It seems from some more reading I've been doing that I can lower the gain a bit with a resistance in series with C1. May see if I can wiggle that onto my vero build.

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Post by Frank_NH »

After reading your post I've been surveying all of the obscure power amp chips there are out there (many now obsolete). It's amazing the number of unique chips that were produced for all manner of devices (TVs, cassette players, radios), and many like this chip were designed for low power supplies.

If you're looking at making a headphone practice amp for guitar, this chip may be a good choice. If you want to push a small speaker, there are other chips that may be better besides the usual LM386 types.

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