Build a Home Theater Amp: Voltage & Current Ranges

[JerryG]

I am interested in attempting to build a home theater amplifier, but I have a few questions. What is the voltage range from the audio outs on something like a DVD player or processor? Also, what is a typical current or voltage range from the speaker connection terminals?

 

[0xDEADBEEF]

http://en.wikipedia.org/wiki/Line_level

I think you can get the output levels from the fact that you might want to have something like 50W into a 6 Ohm speaker.

 

[Mike_In_Plano]

Hey Jerry,

Welcome on.

The line level commonly quoted level for stereos is about .35 - .5 V RMS. Since the volume control operates in dB, it has a HUGE range of control and this doesn't make much difference.

As for the output, that gets tricky. Some brands lie, some scrape by, and some have large power margins. Generally, I left about 25% over my target value at the target speaker impedance.

For 50w, P=V^2 / R => V^2 = PR => V=sqrt(PR)
For 8 ohms, Vrms=20Vrms
For your inside power supply, V+/V- = Vrms * sqrt (2) * 125% + transistor drop
For 8 ohms, V+ = 38V, V- = -38V.

Power supply parts are most easily obtained from busted stereos.

Good Luck,

- Mike