Tube amp speaker output 4 ohms VS 8 ohms


A tube integrated amps (ARC VSI55) have 2 ways of speakers connection. (4 and 8 ohms).

Are you likely damaged the amp (or speakers) when you connect 4 ohms speaker to 8 ohms tap of the amp ?

Do you get different sound with connecting a 4 ohms speaker to either 4 or 8 ohms tap of the amp.

What is the best connection to get the best performance.

No, you should not get any damage from connecting either output tap to your speakers, unless, of course, you send a clipped signal to your speakers or overdrive them. Yes, the sound will be different from both taps, especially if your speakers are a difficult load. You may find that bass output, dynamic range, and ultimate loudness may suffer if you connect a 4 ohm speaker to an 8 ohm output tap, but it is difficult to say without knowing the impedance vs frequency curve for your speakers. It is generally best to match the output tap to the speaker load to get the lowest distortion and highest power output.
What are your speakers rated at? That would be the first clue to which taps to use.

My speakers are the 4 ohms Totem Model One signature

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.
Post removed 
8 ohm should be fuller sounding but may not have the bass control of the 4 ohm
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.
It's very interesting, thank Atmasphere
Robr45 is correct. You should experiment with both sets of connectors. For example, ARC tube amps such as the D76A, the Classic series and the VT series (VT100, etc), in many cases, sound better when driving 4 ohm speakers from the 8 ohm amp connectors.