Bridging channels on amplifiers--Good or Bad? (1 Viewer)

[Steve*MH]

In many cases in which bridging is allowed with certain amplifiers, great increases in power output are possible. But what are the downsides of bridging together amplifier channels?? I have heard the following possibilities: degredation of sound quality compared to the non-bridged version (despite the greater power output) and the inability of the bridged channels to perform adequately into the lower impedences, such as below 4 ohms. Are these two statements generally true and what are the major downfalls of bridging channels together in terms of sound quality and a control of a speaker?
Thanks.

 

[Brad Wood]

Steve,
I've never encountered a degradation in sound quality by bridging a power amplifier. When you bridge an amp output however, you do need to be careful of the load that you are driving. Confirm what load your amp will drive in bridge mode before you hook it up. Most amps will only drive an 8 ohm bridged load. Some higher end and pro amps will drive loads down to 2 ohms bridged. Just be completely sure, as driving a 2 ohm load on an amp that will only bridge at 8 is a sure way to blow out your amp and possibly your speakers as well.

Brad Woodhouse
Edina, MN

 

[Kevin C Brown]

Yes, yes, bridging can be bad, because it halves the impedance load the amplifier's output stage sees, so more current is drawn. Most "quality" amps (however you want to define that) will have no problem, but some might. Remember, that even nominally 8 ohm speakers can drop into the 4 ohm range across certain ranges of freq response. So that halves to 2 ohms if the amp is bridged.

I know there are better explanations out there, maybe some one has a link. You could also check some amplifier's makers sites in that I know I've seen this talked about elsewhere before.

If you have a choice: don't do it. But if you have an amp around and want to try it, just be careful. I really don't think there is any expectation of *better* sound quality by bridging an amp, just a way to get more power.

 

[Chuck Bogie]

I've heard that one can't reliably bridge the old Phase Linear 400s or 700s - you let the magic smoke out.