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Home theater amplifier

  1. Feb 20, 2010 #1
    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?
  2. jcsd
  3. Feb 20, 2010 #2
  4. Feb 21, 2010 #3
    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
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