Audio input, why need gain and attenuation?

Dec 07, 2006 6 Replies

Hi All,



I have a audio sink ( it is chip's audio input ), there are gain and attenuation settings.



My audio source is constant level, so, I think I only need gain or only need attenuation for this sink, am I right ?



What I am confusing is I saw a setting both have gain and attenuation ...



I feel it is strange, is the setting is correct ? could you please advice ?


Thank you very much!



Best regards, Boki.



Ok, if you dont tell us what the chip is, how can we help you?

martin

It might be for the same reason you have two gear levers on your bicycle.

Or the reason that you can move the main sail both inward and outward on a sailboat.

-Le Chaud Lapin-

The output impedance of an attenuator is nearly constant even if the input impedance of the source is not. So, an input is often conditioned by some attenuation before an amplifier. It means an open input (loose wire) doesn't generate as loud a POP when it connects, and can extend the permissible input range as well.

And, some amplifier circuits benefit from limited gain range (like op amps which are only stable with voltage gain > 5), and an attenuator is less inflexible. Amplifiers of some sorts (current-controlled gain transimpedance amplifiers) are most accurate with small signals (like, 10 mV peak), even though they work with larger signals.

So you have more control and can optimize for noise, or for distortion, with the separate gain and attenuation settings available.

Sheesh, with so much lack of information from Boki (as usual), you've come up with all this stuff

How?

martin

snipped-for-privacy@gmail.com =BCg=B9D=A1G

Great information, thanks!

Best regards, Boki.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required