Re: Am I going to blow a speaker cab?

On 12/24/2011 4:25 PM, Les Cargill wrote:
BW wrote:
Colleagues,

Quick question. It seems to me that I can plug a high output head
(like a Markbass Tube 800) into a cabinet rated for substantially
lower power (like an SWR 2x10 rated at 350 watts) and won't do any
damage to the cab as long as I am gentle with the volume output on the
head. Am I right?

Happy holidays and a grand new year to all.


if. That's a big if.

Okay - speakers fail from:

1) getting stuck at Xmax ( full extension ) and burning up the voice
coil. If the cone cannot move, all 800 watts go into heat. The voice
coil will fry, and you get to replace or recone the speaker.

2) From clipping from an underpowered amp throwing too much
high frequencies in square waves that are expressed as heat.
This is cause by an *under*powered amp.

Both true, but speakers also fail from too much power through the VC WITHOUT maxing out throw. The VC can overheat and start rubbing, or it can plain old burn the VERY fine wire on the winding.



We are Goldilocks, and want Just Right! We also want
limiters to help catch us when we mess up.

With too much power, you are concerned with 1). But 800
vs 350 isn't a moral outrage of a mismatch, and *so long as
you are careful*, shouldn't fry anything.

I wouldn't.

A bass can have a lot of dynamic range. You may be fine, then hit a string a bit harder, and POOF!

Then we have another BIG issue.

Depending on how your speakers are wired, if you end up with an open circuit on your cab? Good chance you will arc over power tube sockets, and possible punch holes right through the insulation in the output transformer winding. Google flyback and tube amp if you have questions about that. Bottom line is you will build up very high voltages if your speaker load goes open. And it's instantaneous.

My opinion: Risky business with a SS amp. WAY too risky with a tube amp!


I had a type 1) failure
when I got lazy and used only one cabinet of my rig. The people
I was with were also *FAR* too loud*. It should have been fine -
into 8 ohms, it was only 300 watts, but I stuck the voice coil
sure as shootin'.

*knuckledragging Suthrun Rawkers - meh :)

the problem is that you are busy, and you are probably too close
to the rig to really tell if there is a problem.

--
Les Cargill

.

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