Introduction to the Pioneer SC68 Receiver
Pioneer has been revising and refining their Class D amplifier technology inside of their Elite receivers for a few years now. The performance has kept improving, as it is one of the few receivers out there that actually delivers its rated power output into all channels at once. They’ve continued to add more features to their receivers as well, and the SC-68 has added two more advanced features to the SC-57 from last year: A Zone 4 HDMI output, and an asynchronous USB input.
The USB input is an important one, as the transition from SACD and DVD-A to high resolution downloads is moving quickly. The asynchronous USB input simplifies the task of getting those downloads from your PC into your audio system, without a loss in quality. Combined with their D3 Class D technology, the SC-68 has the specifications of a winner, now to see if it performs up to those expectations.
PIONEER SC68 RECEIVER SPECIFICATIONS
- Design: 9.1 A/V Receiver
- Codecs: All that are Currently Available
- Power Output: 140 WPC x 9, 1 kHz, THD 1% @ 8 ohms
- Video Connections: HDMI 1.4a (7 rear in, 1 front in, 3 out), Component (3 in, 2 out), Composite (4 in, 4 out), No S-Video
- Audio Connections: USB 2.0, RCA Stereo (5 in, 3 out), Optical (2 in, 1 out), Coaxial Digital (2 in, 0 out), 7.1 Multichannel (1 in, 11.2 preout), iPod, Sirius Radio, Bluetooth (optional), Phono (MM compatible)
- Other Connections: Ethernet (Internet Radio, Networked Audio, Firmware), 12V triggers (2), USB, RS-232, IR (2 in, 1 out), Headphone Jack (6.3mm)
- Dimensions: 7.3″ H 17.1″ W x 17.4″ D
- Weight: 39 Pounds
- MSRP: $2,500 USD
- SECRETS TAGS: Pioneer, Receiver, Audio
Design and Setup of the Pioneer SC68 Receiver
At first glance the SC-68 appears to resemble the SC-57 from last year, but there are a few key additions. First is the USB 2.0 input that I touched on earlier. Sample rates up to 24 bits, 192 kHz are supported, though 176.4 kHz is not and is a common sample rate for some downloads that are converted to PCM from DSD. Because the USB input is of the asynchronous variety, the SC-68 is able to control the flow of data from the computer, leading to lower jitter and other timing errors than for models with synchronous USB connections. For Windows PCs you will need to install a driver to take advantage of the higher sample rates, but with a Mac they will work as soon as it is connected.
Another important update is to the multiple zones of output. The audio output for Zone 2 has had a subwoofer output added to it, but they have also added a Zone 4 output that sends a signal over HDMI. As most sources are now becoming HDMI only, the move away from Component video to HDMI makes for a more useful multi-zone controller. Additionally if you don’t need all 11 channels of amplification for your main listening room, you can assign those to zone 2 or 3 and drive a set of speakers in those areas.
Unlike prior models there are no longer exposed heatsinks on the bottom of the SC-68 and only a small fan on the side of the unit that I never heard. The exposed heat sinks on prior units would get very hot to the touch, so I’m glad to see they are no longer an issue. Setup of the SC-68 was quick, as I used HDMI for most sources and then connected it to my Definitive Technology Mythos five-channel setup, and to a projector and plasma using the dual HDMI outputs. I ran MCACC to set speaker distances and levels which worked fine, though it still only supports a single crossover frequency. For testing the USB input I used both a PC desktop running Windows 7 and a MacBook Air running OS X 10.8.2.
The Pioneer SC68 Receiver In Use
Going straight to my favorite music release in the past year, I put on Pink Floyd’s Wish You Were Here SACD. Through the SC-68 the sound was completely enveloping, with effects that went from speaker to speaker and completely surrounded me in the music. The bass and midrange from guitars and drums were rendered with great depth and detail, as the SC-68 has the power to take control of the woofers and not run out of steam. Pushing the SC-68 to reference level with the aggressive surround mix was easy, with no strain or effort from the speakers or receiver.
Utilizing the DAC, I went through a variety of albums from HDTracks played directly to the SC-68. Comparing the CD version of Not Too Late by Norah Jones to the HDTracks version showed a larger soundstage on the high-resolution download, as well as more clarity and separation between instruments. Paper Airplane from Alison Kraus and Union Station showed increased detail in the treble with notes floating effortlessly in the air of a larger soundstage.
Playback of all the albums through the PC was simple, as I just had to select the USB input on the SC-68. The only issue that came up was the lack of 176.4 sample rate support, which is used on HDTracks albums from The Rolling Stones and many others that are converted from DSD sources. Given the support for 88.2 and 44.1 sample rates, it would seem that this support shouldn’t be impossible. The one issue I ran into was an inability to have the Pioneer displaying what sample rate and frequency the incoming file was playing at. This might lead to users playing back everything at 16/44.1 instead of higher bit rates if they forget to install the driver, but have no idea this is the case.
Watching Cars 2, the race sequences sounded great through the SC-68. The effects of driving through tunnels or passing other cars sounded realistic and natural, despite the film being CGI. Panning effects were very transparent as they moved from speaker to speaker. Here I setup a pair of Epos bookshelf speakers to use as rear surrounds for 7.1 and the race sequences were even more involving than before without taking away amplifier power from the main channels. I had concerns that I might hear some issues due to the limited crossover options, but watching a film I didn’t notice any.
Listening to Sea Change from Beck, I experimented with turning MCACC on and off to see the change. I found that leaving it on led to a bit more clarity and definition in the music, likely due to the delay adjustments in MCACC that ensured all sounds arrived at the correct time to my listening position. While these aspects were improved, bass response remained the same with room issues remaining unaddressed unless you have a separate EQ for your subwoofers.
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.
Conclusions about the Pioneer SC68 Receiver
Years ago I switched from a receiver to separates as it was the only way to get enough power to drive any speaker system that I might review to its limits. With the exception of truly demanding speakers like planars from Magnepan, the Pioneer SC-68 is free of that limitation. Any conventional speaker system you throw at it is going to find plenty of power in reserve, even when driving 7 or 9 channels at once. The sonic highlight of the SC-68 for me is the tight, clear bass and midrange that it produced, really bringing out guitars and drums from the music.
The largest change is the addition of the asynchronous USB input, allowing people to easily get high resolution downloads from their PC to their audio system without worrying about DLNA or file formats. With HDTracks and other services offering more downloads every week, and often new releases the same day they hit stores, the future of high resolution music looks to be PC-based on the Pioneer SC-68 is well positioned to take advantage of it.
Pioneer continues to do a wonderful job with the SC line of receivers. They have all the modern features we want, including USB inputs now, and plenty of power for your home theater. I still want to see them improve upon their bass management capabilities inside of MCACC, but that is the only real fault I have with the SC-68. Overall it proved to be a fantastic update to the SC line and remains at the top of the list of receivers that I recommend.