Kevin Killebrew wrote:

Here is my question:

I've got a tubed receiver (Sherwood S8000) that is going to be connected to
two sets of speakers via an external switch. One set is outside on the
patio, the other inside at the bar. Most of the time only one set of
speakers will be playing, but occasionally I forsee both sets being played
simultaneously. Both sets of speakers are 8 ohms so when I occasionally
run both pairs I will have four ohms (assuming they are paralleled) per
channel. Which receiver output should I run to the switch box? Four or
eight ohms?

Is it best to run an occasional four ohms on the eight ohm tap? or run
mostly eight ohms on the four ohm tap having a four ohm load only when both
sets of speakers are playing? I suspect the eight ohm tap is the right
choice because it will be correct most of the time, but I wanted some RAT
opinions of the effect of running mismatched impedances, i.e., four ohm load
on an eight ohm OT tap. I want to avoid an overly complex switch
arrangement.

Kevin Killebrew
Austin, Texas

Whatever you do, don't wire the speakers in series. For a two speaker hookup,
that removes the amplifier damping from both speakers since they would be then
be sourced through each other, an intolerable situation.

Better a lower Z match than higher since PP pentode amps benefit from that. The
3rd harmonic is reduced. Most speaker loads are far too high anyway at their
resonance(s). A parallel hookup tends to smooth that out provided the speakers
are dissimilar.

Good Luck, John Stewart