Lm1875. Power Supply Capacitors

[jacco vermeulen]

Originally posted by jackinnj
the other a turbocharged 2.6 litre 6

Naaah,
the whimp 2.3 litre turbocharged straight-4 Mustang Opec edition you mean. Same as in the Arab ed. Thunderbird Coupe, what a joke.
The idea was to have an optional V6 instead of the 302, but that decision was fortunately cancelled.

NBCI, be it GTs or GC's.

[frank1]

Originally posted by jackinnj
there's not too much subjective about picking the power supply capacitors for a chipamp -- as a circuit draws more current from the power supply the voltage sags -- the repeat charging cycles of the filter capacitor reduce the "potential" of the supply -- less potential (voltage) means less music.

I am questioning the (many) posters here that are saying that larger caps somehow degrade the mid/hf performance somehow, why this might be and if it can be measured.

Some might infer from the above that the gain of a chip-amp depends on supply voltage - It doesn't. Supply voltage sag will only limit the maximum output. If the amp is running at much less than max, supply sag will not matter one iota.
True ?

Frank

[jackinnj]

Originally posted by frank1


I am questioning the (many) posters here that are saying that larger caps somehow degrade the mid/hf performance somehow, why this might be and if it can be measured.

Some might infer from the above that the gain of a chip-amp depends on supply voltage - It doesn't. Supply voltage sag will only limit the maximum output. If the amp is running at much less than max, supply sag will not matter one iota.
True ?

Frank

1) as far as I can determine, no one has provided empirical evidence to support the assertion that larger caps degrade the sound. it is very easy to demonstrate, either by simulation or on the test bench that an inadequate power supply capacitor will cause high levels of THD%

FWIW, National Semi has said recently that the input coupling cap can have a dramatic impact on sound quality.

2) -- the ultimate gain (of any amplifier) is limited by the supply's ability to maintain its potential -- there are two control loops in a chipamplifier -- that controlled by Rf/Rg and that determined by the impedance of the power supply.