Is is possible to bridge every amp

[priscared]

Gday,
Is it possible to bridge any stereo amp simply by connecting your speakers to the positive termanils and haveing a mono opposite input?
Thankyou
Or does it have to be built for this operation.
Daniel Priscared@hotmail.com

[richie00boy]

It works with probably all conventional amps, just be aware that you must use double the rated minimum load impedance per channel.

I know for a fact that you can't do it with the Technics New Class-A and Class-AA amps as they use funny o/p circuitry/rail arrangements.

[Cybergent]

Basically you can bridge any amps having an output signal referred to ground.

Amps, that already have a bridged design cannot be further bridged.

[Aud_Mot]

Most amps could be bridged, but many cannot. The main factor is if the grounds or black binding posts of each channel are common to each other and to the ground power supply.

Some amps have the equivelent of a balanced output and both positive and negeative posts swing agianst the other to create a potential that the speaker "floats" between. Classic case of Single Ended Output Vs Balanced Output.

My advice: If you are not sure, do not try. It could be an expensive and smokey mistake. Conventional wisdom says bridging will give you 2 times the power but that translates into only 3dB louder. is it worth it?

Aud_Mot

[maylar]

The amp outputs have to be referenced to a common point (typically ground), and one channel has to be inverted. The output voltage doubles but the current limit stays the same, so you need to double the rated load impedance to be safe.

[azira]

Originally posted by Cybergent
Basically you can bridge any amps having an output signal referred to ground.

Amps, that already have a bridged design cannot be further bridged.

Talking very theoretically and certainly not practically.... shouldn't you be able to parallel two bridged amps?

[sreten]

Originally posted by Aud_Mot
Conventional wisdom says bridging will give you 2 times the power but that translates into only 3dB louder. is it worth it?

Aud_Mot

Erm..... not quite true.

If your standard amplifier is capable of doubling current
into half your loudspeakers impedance load its not.
(e.g. 60W into 8 ohm > 100W into 4 ohm)

P = Vsquared/R or IsquaredxR, either way its times 4 = 6dB.

(with the above example assuming current limiting = > +4.5dB)

But what is true is an amplifier that cannot drive low impedance
loads is not suitable for bridging, and that low impedance speakers
are not suitable as a load for bridged amplifiers.

I completely agree with the sentiment "is it worth it ?" nearly
allways its not as the speakers are not a good load for bridging.
(Unless we are talking about car audio etc)

sreten.

[manxam]

Assuming that all of the above were true about an amp (common ground and what-not), could someone please post a schematic describing this 'bridging' circuit.

I'd like to use a 4 ohm stereo stable 20 year old solid state Toshiba receiver for a sub amp.

Any help would be appreciated.

Thanks!

[sam9]

Using a bridged amp to drive a 4 ohm speaker is dodgey. The reson is that from the amp's point of view (pardon the anthromorphology) is will see not 4 ohms but 2. That's real low for many amps and smoke the output transistors or at least activate short circuit protection.

That's no to say you can't do it but a large number of amps (Most, perhaps) won't do well. That said I did this once with a Carver M-400 with no appearent harm, although thinking about it kept me kind of puckered up.

[millwood]

Originally posted by priscared
Is it possible to bridge any stereo amp simply by connecting your speakers to the positive termanils and haveing a mono opposite input?

the answer is clearly no. as it is entirely possible to design an amp that is NOT bridgeable.