- Written by Chris Heinonen
- Published on 30 January 2012
The Pioneer SC-57 Receiver On the Bench
We will start with the video test results for the receiver bench. For all HDMI data, the Pioneer SC-57 performed perfectly. Resolution and detail were kept correctly, and even the scaling wound up looking nice. With component video there was a bit of chroma and luma detail roll-off so it didn't pass those tests, but there were no issues that would render component video unwatchable.
When using the SC-57 as a preamp by using the pre-out jacks, it performed really well. The 1 kHz THD+N numbers were very, very low, and the rest of the tests came through with very good numbers as well. This helps us to isolate the performance of the amplifier section from that of the receiver as a whole, since it gives us an idea what the overall noise floor is in the machine.
Now tested using the Class D amplifier section as well, the SC-57 still did well. With a 1 kHz sine wave, THD+N was right around 0.008% with both 4 ohm and 8 ohm loads, and with 2V or 4V of output. Lesser receivers will start to show signs of strain on this test, so it is a good start for the Pioneer.
With the 10 kHz THD+N tests, the results are not quite as good, but still very good overall. There is a spike at 30 kHz that leaves as little at 55 dB of headroom for the fundamental. 30 kHz is well beyond the human hearing limit, but that can still lead to distortion if a tweeter is straining to try to reproduce it in addition to the 10 kHz primary note. Looking only at the first harmonic, which itself is not audible to most people, we see around 85 dB of headroom available to us. Unlike the 1 kHz tests there is a very noticeable increase in noise once we double the power output.
The 19 kHz + 20 kHz IMD test shows that we have very noticeable peaks on the sides of both tones, with around 60 dB of headroom overall.
The 60 Hz + 7 kHz IMD tests showed better results than the prior ones. There were no A+B or A-B peaks visible, and headroom was right around 85-90 dB in all versions of the testing.
Frequency response showed difference values, based on the load the amplifier encountered. With an 8 ohm load, we had a ride of 0.7 dB from 20 Hz to 20 kHz, but with 4 ohm loads we had a fall of just over 1.0 dB across the same range. A bit peculiar, but those were the bench results.
Finally on the THD+N tests, most of the values stay below 0.02% but past 1 kHz we see a ramp up to a peak of almost 0.2% in 8 ohm and 0.4% into 4 ohm right after 10 kHz, and then a quick fall off again. This corresponds to the differences we saw with the 1 kHz and 10 kHz THD+N tests at the start of this section.