Jim wrote in message
...
N Cook wrote:

Could a Crate BV120H valve amp really blow 4x 12 inch 16 ohm speaker box
?

Yes, if speakers can't handle 30W.


Amp as received was set for 16 ohm output, I measured the speaker box
impedance at 13 ohm,

You mean you measured DCR, DC resistance. 13 is typical for 16 ohm
speakers.

or so, before connecting up just to be sure.
Very feeble and distorted sound. No signs of the reported burning smell,
output matching transformer primaries at about 50 ohm seemed ok and
secondaries not open circuit in the amp so turned to the speakers. The
amp
o/p switch setting was set for 4 ohms instead of 16 ohms but as I
measured
16 ohms I assumed a switch problem.

You can get flyback voltages sufficient to punch through windings in the
OPT, or sufficient to arc tube sockets. If it was good before the
mistake, and bad after, the answer is obvious.


Taking apart 2 pairs of paralleled 16 ohm speakers so settable as series
pair of 8 ohm for 16, or 4 paralleled for 4 ohm.
3 of these speakers are open circuit leaving one giving the 16 ohm
reading ,
and the fourth one driving from another source is distorting.

Wait a minute. Conventionally wired 16 ohm cab with 16 ohms speakers
will have NO SOUND if three speakers are blown.


Can a valve amp really progressively burn out, in turn, 16 ohm speakers
?
Driving just one initially, I could understand, like the final remnant
one
here.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





it would progressively have failed from collective 4 ohm to 5.3 to 8 to the
current overdriven and useless single 16 ohm one