Bass amp output / load mismatch

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Bass amp output / load mismatch

Postby etinsley » Sat Aug 01, 2009 5:06 am

I have a question for all of the tube gurus here at diytube...

I recently purchased a Fender Bassman 300 Pro tube bass amp (6 x 6550). This amp has a switchable 8/4/2 ohms output transformer. I have a 6 x 10 cabinet with a 5.3 ohm impedance. My question is which setting should I use to operate the amp safely into the 5.3 ohm load? I've read that tube amp output stages don't like the impedance to be higher than they "expect" to see, so I'm leaning toward using the 8 ohm setting. That said, 5.3 ohms is not much more than 4. I just want to be safe and not damage the amp or its output transformer.

Thanks in advance!
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Postby Geek » Sat Aug 01, 2009 3:08 pm

Pentodes don't like higher loads, nope. I'd use the 4-ohm tap.

-= Gregg =-
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Postby dhuebert » Tue Aug 04, 2009 8:25 pm

There is no safety issue here, you cannot damage the amp by using the wrong impedance. Try the different settings and choose the one you like the sound of and forget about it.

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