Page 1 of 1

amp impedance question

Posted: Sat Oct 16, 2010 9:51 pm
by leastwise
if you remove a speaker from a 4 x 10 (cuz it is blown), does that have an effect on impedance? is it then dangerous for the cab or speakers to play through 3 instead of 4? or is it all good?

thanks!

Re: amp impedance question

Posted: Sat Oct 16, 2010 10:25 pm
by nbabmf
Absolutely. If you want to continue to play through that cab in the meantime, you'll have to rewire it to match one of the outputs of the amp to match the impedance. You risk blowing a transformer if you run it like it is now.

Re: amp impedance question

Posted: Sat Oct 16, 2010 10:35 pm
by devnulljp
leastwise wrote:if you remove a speaker from a 4 x 10 (cuz it is blown), does that have an effect on impedance? is it then dangerous for the cab or speakers to play through 3 instead of 4? or is it all good?

thanks!
Yes. Maybe. No. In that order.
It really depends on how the speakers were wired in the first place, but in a 4x12 the change will not be as extreme as in a 2x12.
You can damage your amp's output transformer if you present a load with too low impedance. (Genrally, it's safe (well, safer) if you give your amp a higher imedance load than it's designed for.

It might be possible to rewire it as a 2x10 (or a 3x10) that will be safer -- higher impedance than your amp is rated for is OK, lower is a no-no.

What was the original impedance of the cab? Impedance of each speaker? Are they wired in series or in parallel?


Have a look here to calculate the change in load: http://www.bcae1.com/spkrmlti.htm

Re: amp impedance question

Posted: Sun Oct 17, 2010 12:15 am
by leastwise
thanks for the feedback. I don't have details, as I was just asked this question at a party and didn't have an answer, so I turned to ILF for help. yay ILF!