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heads n cabs [message #27229] Wed, 15 February 2006 05:31 Go to next message
Ben is currently offline  Ben
Messages: 6
Registered: May 2009
Esquire
can anyone tell me wat would happen if i was to use a 100w head with a 50w (single speaker) cabinet. I read somewhere that you can half the heads power by takin some of the tubes out is this true?

Re: heads n cabs [message #27230 is a reply to message #27229] Wed, 15 February 2006 09:38 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Don't remove any tubes. Just don't crank it as much or you'll let the smoke out of the speakers.


Re: heads n cabs [message #27231 is a reply to message #27229] Wed, 15 February 2006 15:11 Go to previous messageGo to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
100W amp probably has 4 output tubes (most often EL34 or 6L6GC) in push-pull parallel. Simplified, first and second power tubes are "push" half, wired in parallel. Other two tubes (3rd and 4th) are "pull" half, and also wired in parallel.
You can remove, say first and fourth (or 2nd and 3rd), and have a PP amp with only two output tubes. Power would be halved, and most of "half-power" switches on some amps work that way - to disconnect (cathodes) two of four power tubes.
Then you have the "proper load" part - theoretically, you must now connect your (say 8 Ohms) cabinet to the 4 Ohms tap, to have the "proper" load for the power tubes. Some authors find it unecessary (see "London Power" FAQ), but better be carefull with "Marshalls".
I`d simply buy 100W+ guitar speaker and replaced 50W model in the box...

Re: heads n cabs [message #27232 is a reply to message #27231] Thu, 16 February 2006 05:21 Go to previous message
Ben is currently offline  Ben
Messages: 6
Registered: May 2009
Esquire
thanks for your help!! its startin to make sense now, but i missed the opportunity anyway. there was a 60's laney cabinet on E to the Bay (; it went for 26 pound in the end.......... couldnt believe it. but i probably dont really need that much power yet anyway so i can live with it! cheers for the info

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