thd of the upa-1

[maggieuser]

Does anyone know why the thd for the upa-1 is so much more into a 4 ohm load than a 8 ohm load? Is that difference something that can be heard?

[jackfish]

Some research has shown that there is only a very weak correlation between IMD/THD and listener perception. Generally, the literature reveals that THD levels below 1% are considered inaudible. Even clipping which is visible on a scope at 10% THD is often inaudible. I am using the UPA-1s with Magnepan MMGs and believe the increased THD measurements of the UPA-1s into 4 Ohms is a non-issue. Emotiva lists the power output of the UPA-1 as 350 watts RMS into 4 Ohms with 0.1% THD. The Audio Precision test lists the THD+N ratio as 0.279648% at 4 Ohms. However, if you want a better (or different) indication of how this amp's THD level might affect the sound look at the frequency response graphs, the THD vs. power output part of the report including the THD+N Ratio vs Measured Level graph, and the Amplifier response across the audio bandwidth part of the report including the last graph, THD+N Ratio. I see nothing there that would indicate anything but neutral and clean output from the UPA-1 into a 4 Ohm load.

[maggieuser]

Thank you for your input. I use mg12s and would love to take advantage of the sale going on right now and hoped the upa-1's would be an excellent pairing with them.