Power Output Selector Switch

Dennis Detweiler · From: Solon, Iowa, US

On the Fender 75 amp, there is a power selector switch. The low side has 15W output. The amp has two 6L6 power tubes. If the amp is putting out 15W, are the 6L6 tubes being used? Or is there a smaller power tube switched inline and the 6L6's bypassed? If the amp is used extensively on 15W can one or both of the 6L6 tubes be pulled out?
Thanks
Dennis

Jon Light (deceased) · From: Saugerties, NY

Dennis--the switch cuts down the voltage to the power tubes. Same 6L6's, not some alternative tube. And no, you can't remove one of a pair of tubes. You can remove two of a quad but bottom line is that the tubes are run as an A/B pair (in a class AB amp such as this), whether 2 tubes or 4, and they need to be in pairs. Ultimately, if you want to reduce output power (volume) in a tube amp but maintain a certain level of tube saturation, your best bet is a speaker attenuator.

[This message was edited by Jon Light on 16 September 2004 at 04:56 PM.]

Dennis Detweiler · From: Solon, Iowa, US

Thanks Jon

John Daugherty · From: Rolla, Missouri, USA

Jon nailed it correctly. One more tidbit.... Power amplifiers multiply the power applied to the input. To reduce the power out, turn that little thingy labeled "vol" or "gain". .........JD

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