8 Vs 4 ohms

inpepinnovations@aol.com...If the 4 ohm and 8 ohm taps have the same voltage (per your comment) why do we have two taps?

Actually, the 8 ohm tap has twice the windings of the 4 ohm tap, and puts out twice the voltage as Cford noted. So, for a given setting of the volume control, the amp will play louder. But it will clip at lower power because the output tubes are not optimally loaded. This may also increase distortion.

Eldartford, must be my dyslexia! Of course the voltage is twice as high on the 8 ohms as the 4 ohms taps, I reversed voltages with current to speakers or power or something in my mind! My comments about power transfer to unmatched speakers to taps holds, I believe.
Bob P.

I switched to the 4 ohm taps and wow what a difference. It was like a blanket had been removed from the speakers. Much better nearfield and detail.

Rgds,

dan

Hi Eldartford, actually the 16 ohm tap is twice the number of turns as the 4 ohm tap. The 8 ohm tap is in between. The impedance of the winding goes up by the square of the number of turns. So the 4 ohm tap is the center tap between 0 and 16.

Also, the voltage of the 8 ohm tap is higher but it is not double! The difference is about a factor of 1.414, assuming that you have the same amount of power into your speaker loads of 4 and 8 ohms and the taps are properly loaded.

If you put a 4 ohm load on the 8 ohm tap the tubes will not be able to make the right amount of power and it is possible that your output voltage may go down rather than up. This depends quite a lot on the way the output section is constructed.

Atmasphere...Right about the impedance ratio. (I should have known that).