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Neil[_9_] Neil[_9_] is offline
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Default Silly Question: Can an 8 Ohm Speaker on a 16 Ohm Output of a TubeAmp, Blow out the Main Fuse?

On 1/15/2021 1:06 AM, Paul Dorman wrote:
This is on an Ampeg VT-60 amp.Â* Here is the schematic:


https://ampeg.com/support/files/Sche...SCHEMATICS.pdf



It was the main AC fuse F1, a 2.5 Amp Slow-Blow fuse, that was blown open.

Then I noticed the single 12" 8 Ohm speaker, was incorrectly hooked
up to the 16 Ohm output.Â* Was this possibly the cause of the blown
fuse?

That seems unlikely to me. The main power fuse is a protection for the
power supply portion of the amplifier. The output transformer isolates
the speaker from direct connection to the rest of the circuit, so it is
unlikely that an impedance mis-match would have any effect on the amp's
power supply. But, there would be an audible difference in the speaker's
sound.

Some people on the internet, feel that with tube guitar amps, the
impedance of the speaker is not as critical as it is with solid-state
amps, and that the main danger is to have a no-load condition (an open).

This is way to generic to have much value. Whats can happen with
solid-state amps all depends on the design of their output stage. Cheap,
poorly designed amps can have many reasons to blow, just as
well-designed SS amps can have protections built in, including output
transformers.

--
best regards,

Neil