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Can someone provide some quantification to Emo's claim (which I'm sure is true) that a UPA-5 driven into 2 channels can make "more" power because the other amps aren't being used?


How much more does it produce into 2 channels vs 5?


Also, is there any problem with running a UPA-5 in 2 channel mode 50% (roughly) of the time? Does it cause the amp any undue stress to drive 2 channels and have 3 other channels sitting unused?


Thx!
 

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It IS true. Up to a point.


To understand it, you have to understand amplifiers.


There are three factors which limit power -

* Supply voltage (aka rail voltage)

* Power supply

* Limiter circuitry


As the power supply is designed to handle five amps, two amps should mean that the amp power won't be power supply limited.


Limiter may not kick in with two channels driven.


Rail voltage would be expected to be either at it's nominal value, or lower under load.


According to Emotiva (and if I understood a post by Lonnie) driving only two channels of an XPA-5 could result in over voltage. Meaning the underloaded power supply could supply more than rated voltage. So Emotiva does not recommend extended two channel operation. It's almost certainly ok unless you push the amp really hard. They claim there have been failures for this reason.


So maybe you should not worry about whether it can produce a lot more power into two channels, especially if you are considering using it mainly as a two channel amp.


Same general idea may hold true for the UPA-5.


Don't panic about all of this. Just saying, that according to Emotiva, the amp may not be properly protecting itself against all overloads (yes, I am reading into this a bit.) You should probably avoid pushing their multi-channel amps really, really hard for a extended periods of time as a two channel amp. Normal usage should be totally ok.
 
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