- Written by Chris Heinonen
- Published on 16 January 2013
The Pioneer SC68 Receiver On The Bench
The Pioneer SC-68 is not rated for 4 ohm loads, so all of my testing was done with an 8 ohm load.
Leaving out the spike from power line noise that you can see at 60 Hz, there is around 75-80 dB of range between the fundamental and the secondary harmonic on the SC-68 with a 1 kHz test tone. THD+N drops as power output increases from 2V to 5V, but most listening will likely be done at the lower levels.
When we test with a 10 kHz tone we see the opposite on our testing, as THD+N rises with the higher output level. Here we only have 55-65 dB of headroom, depending on the level, which is much worse than we saw with the 1 kHz THD+N result. The 3rd order harmonic at 30 kHz is the main culprit here and might not be audible, but the one at 20 kHz is also relatively high.
With the IMD test using 19 kHz and 20 kHz tones, there is a clear rise in IMD as the power level increases. We have around 65 dB of headroom, though you can clearly see the distortion rise around our fundamental tones.
Surprisingly the IMD testing using 60 Hz and 7000 Hz tones is much better than with 19 kHz and 20 kHz tones. Here we see very little in the way of A-B or B-A peaks, and we have around 80-85 dB of dynamic range.
The bench results for the Pioneer SC-68 indicate that distortion rises as the frequency of the test tone increases, as the tests using lower frequency tones scored far better than those using higher frequency ones. I'm not certain if this is a Class D issue that I had not run into before, or something specific to the tests, but this could account for why myself and others often praise Class D with bass and midrange sounds and then find it to be not quite as excellent at the high frequencies.
On the video side, the SC-68 did very well, passing all colorspaces correctly without a loss of chroma or luma resolution when the video processing was disabled. With the video processing enabled and with interlaced video content, it successfully did 2: 2 and 3: 2 pull-down, though it was a bit slower to lock onto the cadence than most Blu-ray players are now. Once it did lock on it did not drop it or have other issues. Jaggies were done well for a receiver, and mixed content also performed well. On the video side, I have nothing to complain about with the SC-68.