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Post by leonski on Mar 7, 2019 16:25:26 GMT -5
One other thing about bridging is that you Seldom Hear that it sounds even as good as the Unbridged Amp. Usually the sound goes downhill in some audible fashion.
If you don't believe me, check out hi-fi sites for bridging reports. Few report any improvement. Most are not favorable.
The other thing? A good rule of thumb is that while the amp SHOULD quadruple the power, they NEVER do. I've seen 'em be rated at 2x the 4 ohm power.
My old RB1070 from Rotel is a good example. Something like 130x2@8ohms. And 330 MONO @4ohms.......'bridged'.
To me? That imples 165x2 @4ohms.
My panels ate the amp alive and I sold it 3 months later. My BIGGEST single hi-fi mistake. It just NEVER delivered the goods.
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KeithL
Administrator 
Posts: 10,273
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Post by KeithL on Mar 7, 2019 18:23:51 GMT -5
When you bridge an amplifier, each channel sees HALF of the load.
Let's say you start with an amp that delivers 100 watts/channel into 8 Ohms and 200 watts/channel into 4 Ohms.
If you bridge it, and connect an 8 Ohm speaker, each channel sees a 4 Ohm load.... so you should get 400 watts into 8 Ohms. (You're only getting the overall rated 4 Ohm power since both of the original channels have been combined into a single bridged channel.)
HOWEVER, if you were to try to connect a 4 Ohm speaker to it, each channel would see a 2 Ohm load, which would probably be... bad. Even though most of our amps are stable into 2 Ohms, asking one to deliver a lot of power into a 2 Ohm load long term would make it get UNCOMFORTABLY HOT... (A fully differential amp, like the XPA-DR amps, is designed with lower supply rails, which optimizes it for operation with the low-impedance loads encountered by a bridged amp.)
The only issue is that it's really difficult to design an amp to run optimally in both bridged and non-bridged modes.
It's also worth noting that, in order for an amp to work well in bridged mode, the two channels have to be very well matched.
One other thing about bridging is that you Seldom Hear that it sounds even as good as the Unbridged Amp. Usually the sound goes downhill in some audible fashion. If you don't believe me, check out hi-fi sites for bridging reports. Few report any improvement. Most are not favorable. The other thing? A good rule of thumb is that while the amp SHOULD quadruple the power, they NEVER do. I've seen 'em be rated at 2x the 4 ohm power. My old RB1070 from Rotel is a good example. Something like 130x2@8ohms. And 330 MONO @4ohms.......'bridged'. To me? That imples 165x2 @4ohms. My panels ate the amp alive and I sold it 3 months later. My BIGGEST single hi-fi mistake. It just NEVER delivered the goods. |
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