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Old 9th December 2012, 04:47 AM   #11
JMFahey is offline JMFahey  Argentina
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Dreadful?? 1/3 of 1% ??? -70dB noise???
Get REAL folks, it's a chip designed for 9V battery portable stuff.

Leave cork sniffing to those guys who can justify it.
As in 30Kg PSU Class A with no feedback and such.

Yes, it has exactly 4 (four) extra components, compared to, say, an LM1875 or TDA20xx , those being:
1 and 2 ) a bootstraped resistor and capacitor , which by design swing *beyond* the 9V rail for full drive.
A more "modern" and linear Constant Current source, from a PNP transistor hanging from said rail, will *lose* the CE saturation voltage, and in *no way* will swing above it.
3) an external compensation capacitor, which is *good* because it lets you get stability at widely different closed loop gains, while many chipamps can not go below, say, 15dB because they start oscillating.
4) an (optional) ripple compensation capacitor, for those who want to increase ripple rejection. At least now you have the option.

Precisely that's the point: to use efficiently up to the last tenth of a volt (which is the precious commodity here), they added some external bootstrapping ... big deal.

But of course, it's the end user decision.
If he prefers to lose 25% power to lower distortion from 0.3% to 0.003% , that's his choice.
In any case, what I see is that when my TBA820 starts clipping, "the others" are supplying a nice squarewave struggling to reach same power.
And then, how much distortion we have?
Just sayin'

Of course, anybody can use whatever he wants.
Including paper in oil caps, silver wire wound transformers, cryogenically treated tubes and wool from Woolly mammoths cabinet damping.
Why not?
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