Surround Processor Reviews

Analog frequency response in Bypass mode:
–0.19 dB at 10 Hz
–0.05 dB at 20 Hz
–0.15 dB at 20 kHz
–0.94 dB at 50 kHz

Analog frequency response with signal processing:
–0.45 dB at 10 Hz
–0.14 dB at 20 Hz
–0.15 dB at 20 kHz
–40.84 dB at 50 kHz

The graph shows the frequency response of the left (aqua), center (green), LFE (purple), and left surround (red) channels at the preamp outputs of the Dolby Digital decoder. The left channel measures –0.04 decibels at 20 hertz and –0.11 dB at 20 kilohertz. The center channel measures –0.03 dB at 20 Hz and –0.15 dB at 20 kHz, and the left surround channel measures –0.04 dB at 20 Hz and –0.14 dB at 20 kHz. The LFE channel, normalized to the level at 40 Hz, is –0.02 dB at 20 Hz, reaches the upper –3-dB point at 108 Hz, and reaches the upper –6-dB point at 115 Hz.

Response from the multichannel input to the main output measures –0.17 dB at 10 Hz, –0.05 dB at 20 Hz, –0.09 dB at 20 kHz, and –0.54 dB at 50 kHz. The analog THD+N was less than 0.032 percent at 1 kHz with a 100-millivolt input and the volume control set to 84. Crosstalk with a 100-mV input was –80.56 dB left to right and –78.94 dB right to left. The signal-to-noise ratio with “A” weighting was –118.88 dBrA.—MJP

Video Test Bench
The PT-7030’s Genesis Torino video processor provides a passthrough for HDMI signals that leaves the signal intact with no visible issues I could find. I tried a variety of different color spaces with HDMI, and all of them looked untouched by the video processor. This is great news for anyone looking at this product as an HDMI switcher. These are the results reflected in our usual Video Test Bench grid.

While the Torino processor did a good job deinterlacing both SD and HD film-based sources, it couldn’t pass our 2:2 cadence tests for either resolution. More critically, while the processor was not clipping any below-black information, it was clipping well into the signal’s white information at an undetermined level that was well below digital 235 (reference white). This made even some menu text unreadable as it blended right into the white background. There is also noticeable Y/C delay, which is a timing error between the luminance (black and white) and chroma (color) parts of the image. This causes noticeable outlining that almost looks like a convergence issue. Luma resolution is rolled off in the upper end for both SD and HD signals. This robs the image of some high-frequency detail, and scaling artifacts were noticed quite often. Ringing is easily identified in sharpness patterns or any dark-to-light transitions. Sherbourn’s engineers identified the problem as an improperly set input level for the Torino’s video DAC and is working on a firmware fix that will be applied to existing inventory and made available to current end-users via an update. But until that fix has been verified, I’d recommend bypassing the PT-7030 with any analog video source and going straight into your display. Again, for HDMI switching, the PT-7030 performed flawlessly.—KD

Sherbourn PA 7-350 Amplifier

Two channels driven continuously into 8-ohm loads:
0.1% distortion at 424.0 watts
1% distortion at 488.3 watts

Five channels driven continuously into 8-ohm loads (see notes below):
0.1% distortion at 280.7 watts
1% distortion at 356.3 watts

Seven channels driven continuously into 8-ohm loads (see notes below):
0.1% distortion at 249.5 watts
1% distortion at 286.3 watts

Frequency response RCA input:
–0.27 dB at 10 Hz
–0.07 dB at 20 Hz
+0.08 dB at 20 kHz
–3.14 dB at 50 kHz

Frequency response XLR input:
–0.29 dB at 10 Hz
–0.08 dB at 20 Hz
–0.13 dB at 20 kHz
–2.23 dB at 50 kHz

This graph shows that the PA 7-350’s left amplifier channel, with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 424.0 watts and 1 percent distortion at 488.3 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 609.4 watts and 1 percent distortion at 746.9 watts. Unfortunately, the dedicated 20-Ampere branch circuit that supplies power to our test bench was not up to the task of measuring the full power capabilities of the 7-350 with all channels driven continuously. Be aware that the 7-350 appears to be capable of producing even more output with five to seven channels driven continuously if more mains power is available. Thankfully, program content is not likely to ever put these brutal demands on an amplifier or the branch circuit supplying it in your home theater.

An input level of 52.2 millivolts was required to produce an output of 2.83 volts into an 8-ohm load, indicating an overall gain of +34.70 decibels using the RCA input. When using the XLR input, a level of 52.5 mV was required to produce an output of 2.83 volts into an 8-ohm load, indicating an overall gain of +34.67 dB.

THD+N from the amplifier was less than 0.011 percent at 1 kilohertz when driving 2.83 volts into an 8-ohm load using the RCA input. When using the XLR input under the same conditions, THD+N was less than 0.011 percent. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was –94.80 dB left to right and –94.73 dB right to left using the RCA inputs and –91.36 dB left to right and –95.25 dB right to left using the XLR inputs. The signal-to-noise ratio with an 8-ohm load from 10 hertz to 24 kHz with “A” weighting was –100.60 dBrA using the RCA input and –100.71 using the XLR input.—MJP