Tube amp speaker output 4 ohms VS 8 ohms

My experience is that there is no way to tell without trying. The sound will be much different in most cases. I have had 4 ohm speakers sound better on 8 ohm taps many times. You certainly will not hurt anything by experimenting. If you run searches in the right places you will find that it is very common for people to experiment.

The 4 ohm taps utilize more transformer windings and can deliver more current which typically equates to better control over the drivers. However, many times this will be at the expense of "sparkle" on the top end and almost always ultimate spl output.

Try both and go with what sounds best without looking back.

8 ohm should be fuller sounding but may not have the bass control of the 4 ohm

Thanks everybody

The combination of your personal preferences, amplifier, speaker, and speaker cables make your question impossible to answer.

Try both taps and use the pair that sound best to you.

"Best performance", as you say, is subjective.

FWIW the 4 ohm tap is there so you can load the tubes correctly. The tubes are likely wanting to see about 3000 to 5000 ohms from plate to plate and your speaker is much lower.

The transformer does exactly what it says it does. It transforms impedance, voltage and current.

If you load the 8 ohm tap with a 4 ohm load, the load that the tubes will see will be a lot lower. The result will be higher distortion and a loss of power. You may heat the tubes up a little more too, as the loss of power I just mentioned is actually being dissipated in the power tubes rather than your speaker.

Some output transformers don't do 4 ohms so well, and by using more of the windings (8 ohms) sometimes you can get better response. Usually this tactic is limited; the better transformers will operate correctly on 4 ohms, IOW the better the amp the less using the 8 ohm tap will help.

So most of the above responses have some truth to them but I thought if you were interested, now you have the whole scoop.