opaqueice;292163 Wrote: > Actually, I -am- confused about Phil's post. > > > > In your examples you treated the amp as a voltage source and the output > impedance as if it were in -parallel- with the load. But (regardless of > the class) I thought output impedance is defined as the part of the > internal resistance that's in -series- with the load (again, treating > the amp is a voltage source, as you did). > > If that's right, an amp with an output impedance of 2 ohms driving an 8 > ohm speaker will only lose (40-32)*(40-32)/2 = 32 watts of power, not > 512, and the efficiency goes to 1 as the output impedance goes to > zero. > > The reason class A amps have low efficiency is because they have an > output transistor which dumps current to ground even when the signal is > zero. > > Right?
erm... surely the speaker is wired in parallel across the amp output? - thats why if you wire 2 identical speakers in parallel to an amp their impedance halves and the power delivery doubles...at least until the amp psu gives up! when the internal impedance of an amp hits zero that's a short circuit and the amp blows up! My example was VERY simplistic. AFAIK the amp is a voltage source in most cases. That's what the transistors do - they they act as a "tap" for the PSU voltage. I'm happy to be wrong... -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...SB3+Stontronics PSU - Altmann JISCO/UPCI - TACT RCS 2.2X with Good Vibrations S/W - MF X-DAC V3/X-PSU/X-10 buffer (Audiocomm full mods)- Linn 5103 - Linn Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Kimber & Chord cables ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=46347 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
