well noire rather than grise
I'm not geting a consistent story from the recording studio where these
2 Marshall MG250DFX came from, with Eminence 2x12 in each. One amp , one
of the headers was partially disconnected for the power and signal to
one TDA7293 PA. Would this be a possible scenario. TDA o/p driven to DC
with loss of one rail and burns out one of the speakers but as music
still coming from the other, not much thought about it at the time,
perhaps reporting smoke/loss of power to someone at the studio. Then
someone with the studio jumpers back-to-back that amp to the speakers of
an exactly similar amp, and blows the mirror-handedness speaker of that
combo.?
First one seriously burnt up including part of the spider, but the
second one barely had time to get warm before the wiring of the VC fused
o/c so not even any scorching on the VC former , but a neat split. The
first blown speaker due to intermittant DC and then the second full on
DC drive?

I deconed the second speaker and the magnetic/DC current force was so
great it axially split the former of the VC, beyond the inertia of the
cone, tearing the VC tails and so fast that not the slightest trace of
any heating anywhere

N_Cook wrote:
I'm not geting a consistent story from the recording studio where
these 2 Marshall MG250DFX came from, with Eminence 2x12 in each.

It's an eminence front, it's a put-on.

I'll get my coat.

Matt Roberds

I wonder if there was no real bang if the cone had no chance to move any
air, and there was little more than a ripping noise

On 07/10/2013 08:43 AM, N_Cook wrote:
well noire rather than grise
I'm not geting a consistent story from the recording studio where these
2 Marshall MG250DFX came from, with Eminence 2x12 in each. One amp , one
of the headers was partially disconnected for the power and signal to
one TDA7293 PA. Would this be a possible scenario. TDA o/p driven to DC
with loss of one rail and burns out one of the speakers but as music
still coming from the other, not much thought about it at the time,
perhaps reporting smoke/loss of power to someone at the studio. Then
someone with the studio jumpers back-to-back that amp to the speakers of
an exactly similar amp, and blows the mirror-handedness speaker of that
combo.?
First one seriously burnt up including part of the spider, but the
second one barely had time to get warm before the wiring of the VC fused
o/c so not even any scorching on the VC former , but a neat split. The
first blown speaker due to intermittant DC and then the second full on
DC drive?

Maybe you could take donations and buy the studio a DMM? The speakers
have a 1/4" plug on them. What do you mean "jumpers back to back"?
Whenever a Solid State amp starts freaking, disconnect the load first!.

The 7293s are 7 bucks at Digikey.

"Nutcase Kook"

I deconed the second speaker and the magnetic/DC current force was so
great it axially split the former of the VC, beyond the inertia of the
cone, tearing the VC tails and so fast that not the slightest trace of any
heating anywhere


** If I have de-coded Kook's tortured English correctly - what happened
was the voice coil separated from the cone and this instantly broke the tiny
copper feed wires that carry current to the coil from the tinsel leads, so
precluding the chance of a fire.

Strongly suspect the VC to cone attachment was already weak or damaged for
this to happen.



.... Phil