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NEWBIE: Designing a Simple Audio Amp


N. Thornton

Jan 1, 1970
Fwom:Ricky Romaya ([email protected])
[email protected] (Bob Masta) wrote in
On 01 Jan 2005 17:04:46 GMT, Ricky Romaya <[email protected]>
wrote: rails.

Care to elaborate on this? I've noticed that the power amp op-amps have
their gain preset. Do you mean that to drive them to max output, you need
1 VRMS input? Take TBA820M for example, it's gain is preset to 20 (if not
mistaken), then a 1 VRMS input will give 20 VRMS output,

right, but the amp can only give that if its supplied with enough V to
deliver that, which it wont be in practice. What the amp does is take
the power supply V and limit it to whatevers needed for the speaker at
any moment.
and the power on
the 8 ohm speaker is then (20^2)/8 = 50W? But it says that TBA820M is a
2W power amp (on 8 ohm load and 12V rails).

Hence under those circumstances it would have a life maesured in
seconds, maybe less.