Do old tube amps wattage ratings change with speaker load??

faster100

I am looking into later this year getting a old tube amp/amps, either a Dynaco 70 or heathkit w-5m Mono amps x2, both rated at 35 wpc and 25 wpc respectivly, I see nothing stating at 8ohms, 4 ohms, I see the heathkit amps have a common speaker lead hookup and 3 others, 4,8,16 ohm... But does the wattage change at said ohms, or what is the rated watts for?? The lowest load 4ohms, or is it the same no matter what on old tubers?? I wanna know, i am hooking them to a set of RTI28's or possibly lsi 7's, neither do i have yet so its open, later this year also will this project for a 2 channel rig take place,

madmax

The wattage stays the same. These different ohm outputs are different windings on the transformer which keep the voltage and current within spec. So you hook up an 8 ohm speaker to the 8 ohm tap. You get a given voltage and current which gives you a certain wattage. (voltage x current = watts). If you hook up a 4 ohm speaker to a 4 ohm tap the voltage and current vary but the voltage x current equals the same wattage.
madmax

RuSsMaN

Did not know that mm, thanks. Makes a little more sense why there are different speaker taps now.