Tube amps & speaker impedance

Keith Murrow · Post by **Keith Murrow** » 14 Mar 2002 1:47 pm

..[This message was edited by Keith Murrow on 26 October 2004 at 04:34 PM.]

Michael Holland · Post by **Michael Holland** » 14 Mar 2002 1:52 pm

Tube amps are the same. If the amp is rated for a minimum of 4 ohms, you shouldn't run a load LOWER than 4 ohms. You can connect the 8 ohm speaker with no problem, it just won't be as efficient as a 4 ohm. You can also connect two 8 ohm speakers. Just don't connect two 4 ohm speakers.

Keith Murrow · Post by **Keith Murrow** » 14 Mar 2002 1:54 pm

..[This message was edited by Keith Murrow on 26 October 2004 at 04:34 PM.]

Bruce Derr · Post by **Bruce Derr** » 15 Mar 2002 10:53 am

Actually, a tube amplifier will usually accomodate a load mismatch of 2:1 in either direction, up or down. Even when the mismatch is greater than 2:1, you are more likely to cause damage with too high an impedance than too low. A typical tube amplifier will actually tolerate a short circuit more easily than an open circuit. In fact, the speaker output jack on a typical Fender tube amp is a shorting type, which will short the output to ground if the plug is removed, to protect the amp. (Solid state amps, on the other hand, can usually run all day with no load but don't like shorts at all!)

Here's an interesting link that talks about this: http://www.geofex.com/tubeampfaq/taffram.htm
Under "Transformer Questions", scroll down to "Match Speaker to Output Impedance?"