Quote:
Originally Posted by Grandturk
So, talking about the taps on the output transformer to out different outs on the back on your amp - 16 ohm, 8 ohm, 4 ohm etc.
On all the Marshall's I've owned, and most common sense online and everywhere, the warning is pretty clear - don't plug into the wrong speaker out - you will blow up your amp. So I've never even tried it.
I picked up an old Boogie combo earlier this year (first non-Marshall tube amp I've ever owned) and its got a 100/60 Watt power select switch, and 1 8 ohm and 2 4 ohm outs. In the manual it basically says "if you're running at 100 watts, use the 8 ohm and if your running 60 watts, use the 4 ohm" but it then goes on to say that you will not damage your amp by running the 8 ohm out to a 4 ohm speaker, or vice versa. And it encourages you to mess around with impedence mismatches.
This seems incongruous to me. What's the deal?
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Well, Randall Smith is in a league of his own when he comes up with some of his hair brained ideas. He's one of the ones that say lower impedances will shorten tube life and in my experience I've found no one else to agree with that. Basically, you need to match impedance no matter what. They say the transformers in the Mesa/Booger stuff are more tolerant of a mismatch, but that only means they'll take a little longer to fry.
By running the amp at 8ohms to a 4ohm speaker you are less susceptible to damage, but the other way around is a definite NO NO. Match the impedance always, no matter what wattage is going on.
UNLESS, when you flip the half power switch, do half of the output tubes cease to work? If that's the case you may have to adjust the impedance accordingly.
I wouldn't trust much written by Smith and his colleagues, they share a completely different view on things than the rest of the amp world. Ol' Randy doesn't even believe in tube amps with adjustable bias, he says it's a crock and it's unnecessary,
BUT, it only works like that if you buy the tubes
from MESA. Sounds like a scam to me. I like some Mesa/Booger stuff too, I even own one, but the president of their company is a loon.