Sub Impedance

Quick question,

I have a 250W 2 Channel amp that is said to work at 4ohms. If i connect a 4ohm sub in bridge mode across the 2 channels, am i overloading the amp, or will it work fine?

Will work fine.

If the amp STATES SPECIFIECALLY it is only 4 ohm stable, no it will NOT work fine. A 4 ohm load, bridged, is equivalent to a 2 ohm load per channel. This is twice the load the amp is designed to work at, and it will either protect itself by shutting off, or if a cheap amp, fry itself, because of lack of protective circuitry.

What kind of amp IS it?

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Do they have amps in Botswana that are only stable at 4 ohms/channel or higher?

And it makes me wonder.........have I seen any amps at all that are only stable at 4 ohms per channel?  I don't think so....but then, I'm an nOOb.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

@stevdart    this is a very cheapie sansui SCS-652PZ amp.

Its says on the stats "speaker impedance 4 ~ 8 Ohm allowable"

So this gives me the impression that it is only stable at 4 Ohm per channel. And since it is a real cheap amp, im sure it doesnt have protection circuitry so it will fry itself like haemphyst says.

Anyway, i just wanted this info coz the amp is lying around and im looking for something to do with it.

Ok, here's the test:  if the amplifier is bridgeable, in that it has markings on the terminals showing which ones to use and says "bridged"....and...

.....knowing that 4 to 8 ohm speakers are allowable.....

....it would mean that it is 2 ohm stable per channel.  However, if bridging is not an option with this amp, that would mean that it is only stable to 4 ohms/channel.  (Almost all two channel amps tell you that 4 ~ 8 ohm speakers are to be used.)

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Actually a lot of older MOSFET stereo or 4-channel amps are minimum 4-ohm stable and will blow if connected to a 2-ohm load.  Many cannot be bridged at all.  I don't know anything about the Sansui model you have, but I'll bet it is min 4-ohm stable per channel and if it's bridgeable, it must be into 8-ohms or higher.

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