4-ohm setting with 8 ohm speakers

A linear impedance is not necessarily a constant impedance. For instance, a speaker having an impedance of 2 ohms at 20Hz, and 20 ohms at 20kHz, could still be described as having a linear impedance, if a plot of that variation approximated a straight line.

Without a detailed impedance plot, which doesn't seem to be available as far as I can tell via a Google search, their statement about maintaining a linear impedance tells us essentially nothing.

I agree with the suggestions to just go with what sounds best.

Regards,
-- Al

The manufacturer's claims of the Nightingale speakers and the difference in quality between the 4-ohm/8ohm settings on amps so equipped are separate issues since these taps affect the sound quality driving any speaker. As a user, sound quality is the whole point for me.

I have a problem with manufacturer's using taps for reasons other than sound quality (in SS. Have no experience with tubes). Skip the taps and design it to perform well under varying conditions for about 20 years. That's just me and yet another issue not related to the question.

Arnettpartners,

"I have a problem with manufacturer's using taps for reasons other than sound quality (in SS. Have no experience with tubes). Skip the taps and design it to perform well under varying conditions for about 20 years. That's just me and yet another issue not related to the question."

Can you give an example?

Okay, I see a lot of erroneous info flying around in this thread. A 4-ohm load is a lower impedance and thus a tougher load for an amp to drive (not easier).

Some confusion creeping in here involves the typical solid-state vs tubes. Typically, solid-state amps have more power driving into lower impedance loads, in fact, many of them double power into 4-ohms (this does not mean they sound better driving 4-ohms). Tubes, on the other hand (which is what we're talking about here) are typically optimised to drive 8-ohm loads, with some optimised for closer to 4 ohms.

This means that many tube amps will deliver a bit more power into 8-ohms than they will into 4-ohms. In most cases, the actual power difference is small, unlike solid-state.

That said, if you use a tube amp's 4-ohm taps to drive 8-ohm speakers it does increase damping factor and decrease distortion. In some cases, this can sound "better" to the listener, and in other cases it can sound "dryer" and more like solid-state. Sometimes the little extra distortion and looser bass is preferable to some listeners, because it usually gives a sweeter, though less focused, sound.

In this particular case, the results probably have to do with the tube amp being optimised to drive closer to a 4-ohm impedance coupled with this particular listener's personal bias. And of course interaction with the impedance curve of the particular speaker will come into play. This is why amplifiers can sound different when driving different speakers.

And yet, nobody has said a single word about reactance. This is implied when taking about impedance. Tube amps do not like capactive loads. period. I hope I got that right.
A 'flat' impedance curve? I've never seen one. If their are any crossover components at all, the speaker should 'swing' from capactive to inductive at some point, shouldn't it?
I think damping may be called on for Plato's above comment about 'looser bass' when using 4 ohm taps. With the whole amp OFF, how much resistance would I measure on 4 ohm or 8 ohm taps?

Other than that? Plato makes sense. Use whichever tap you like. I'd add that if the amp runs too hot while using the 4 ohm taps, I'd reconsider either amp or speakers.