4 ohm vs 8 ohm taps

inpepinnovations@aol.com...You have it backwards. The different taps of the transformer secondary make it possible for the tubes to see the same (high) impedance with different loads.

Here is a way for you to test your theory. Short out the speaker terminals of your amp and drive it hard. If your theory is correct, the tubes won't see the short. After the fire department has left, post results of this experiment :-)

Eldartford, exactly - the tubes do not see the difference of what is connected to the secondary taps or to which taps the speaker is connected. The poster that said that connecting the speakers to the 'wrong' tap would make the tubes 'see' a different load and thus distort their output.
The reason that the amp overheats when shorting the speaker taps is due to the tranformer trying to drive a 0 inpedence load and thus drawing more power from the tubes on the primary side. It has nothing to do with the impedence changing on the primary (which doesn't), which the tubes 'see'.
Salut, Bob p.

inpepinnovations@aol.com...How can you say that a zero ohm load is "seen" through transformer coupling, but yet loudspeaker loads are not?

In another area, when you use a step up transformer for your moving coil phono pickup it can be connected to a standard MM preamp input, 47K input load, and still present the proper loading of a few hundred ohms on the pickup. The loading applied to the secondary is "seen" through the turns ratio of the transformer.
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Been using the 4 Ohm taps from the beginning and will stick to that. Thanks!

Eldartford, I think that we are saying the same thing, but not understanding our explanations. I never said that the tubes 'see' a 0 inpedence. We both agree that the transformer effectively isolates the speaker load from the load imposed on the tubes, i.e. the tubes 'see' a constant (high impedence of the primary windings on the tranformer) regardless of the speaker load and regardless of the tap used for the speaker. If an 8 ohm speaker is attached on the 4 Ohm tap, however, the power transfer is not as good as using the 8 ohm tap, but the level of distortion should be lower and the damping factor higher. The tubes never 'see' this, which was the claim made by the original poster (Atmaspere, I think) that using the lower tap would cause the tubes to 'see' a different impedence and thus distort.
Salut, Bob P.