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Disconnecting speaker while power amp on - any dan


Something like this happened yesterday - managing to disconnect the left speaker (B&W 803S), I just missed to turn off the Rotel RB-1090. Nothing dramatic happened - there was not any “pop” sound from speaker, not the amp protection circuit was activated nor fuse burned... Probably because the preamp was turned off (or maybe on? - being upset at a moment I am not able to recall 100%..., but FOR SURE without any signal from the CD) Only my nerves suffered...

What is actually going on in such a situation, electronically speaking?

I can guess that the disconnected half (channel) of the amp “is seeing” a change in the level of resistance, unlike the other channel, still connected to the speaker. What a change is it? Is the disconnected channel “seeing” an ENDLESS resistance, or ZERO resistance?

IS THIS SITUATION HARMFULL FOR THE AMP CIRCUITS, even if no visible reaction of the amp (protection, fuses etc...)?

Electronic engeneers - any thoughts???

Thanx!!!
zormi
15 responses Add your response
timrhu
2,779 posts
 
As long as you don't short (touch) the loose hanging speaker cable to the other cable nothing bad will happen. The amp sees the same thing as having no speaker connected at all. The important thing is make sure the speaker wires DON'T touch. Smoke may be the result or a blown fuse if you are lucky.
Owners manuals are very explicit about not doing this for good reason.
shadorne's avatar
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shadorne
7,477 posts
 
If you short the amp output while disconnecting the speaker wires then there is of course potential for damage to the amplifier.
unclejeff
1,313 posts
 
Better to not have done it; however considering how many times my maid knocks the speaker cables of the speakers, if there were damage it would have happened to me long ago.
johnjbarlow's avatar
johnjbarlow
175 posts
 
I connected my speaker cables to my maid and she sounds great.
unclejeff
1,313 posts
 
John,, you might be on to sometning as I am never home when the maid 'hits'the speaker wires.......
andrewdoan
223 posts
 
What's the AWG you guys use ? Mine is 10 AWG and the maid seems not having any interest " kocking it on the floor"
mitch4t's avatar
mitch4t
1,611 posts
 
If the maid weighs more than 150 lbs and is clumsy...use locking bananas and 8 AWG wire. If she's more than 200 lbs and clumsy, use barbed wire.
zormi OP
105 posts
 
Can anyone explain the mode of resistance change in the disconnected channel? Does the resistance goes to ENDLESS or to ZERO?

Thanx,

Zoran, Macedonia
atmasphere's avatar
atmasphere
11,841 posts
 
Zormi, The load becomes infinite when the speakers are not hooked up. Its OK as long as there is no input signal to the amp. If there *is* an input signal, some amplifiers can be damaged, both tube and solid state.

So if you disconnect the speaker, just make sure that the input signal is turned all the way down.
mmakshak
589 posts
 
I believe that I blew a Classe amp when a speaker cable became disconnected from it.
atmasphere's avatar
atmasphere
11,841 posts
 
Yes, if you have signal applied all bets are off!
zormi OP
105 posts
 

Thanx guys,

Things pretty calm now... Amp OK, nerves as well.
unclejeff
1,313 posts
 
Yes, truly bananas are better than spades.
zaikesman
3,017 posts
 
Another reason to avoid this is that you may accidentally bridge the binding posts (with your wrench, or by rotation of a spade lug) while the power is on and the speaker is still hooked up, which can sometimes zap a driver or crossover element.
limomangus's avatar
limomangus
1,428 posts
 
Blowing up your speakers or amp fuse....
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