I have a Rotel RSX-1055 receiver with the latest firmware. I wanted to find out for certain how the crossover worked on the digital connections and on the multi-channel inputs. So I got the Stereophile Test CD 2 which has a bass sweep.
The test was done in 2-ch stereo using just my floorstanding mains. The subwoofer was set to Yes in Speaker Setup. However, my subwoofer's on/off switch was turned off. The volume value was set the same for each test. I did not try to match up dB's at a given frequency (e.g., 200 Hz) between tests. I used C weighting and Fast response on my SPL meter. The multi-channel inputs are supposed to pass the L & R signals "as-is" to the mains. The Large/Small front-speaker settings and Sub X-Over setting are not supposed to have any effect on multi-channel inputs. The bass < 100 Hz is also supposed to be copied to the subwoofer, which yields bass doubling on that frequency range with the L & R mains. As I'm sure everyone expected, my tests verified this. I got the same frequency response from the mains regardless of the Large/Small and X-Over settings when using the multi-channel input. Here are the full results:
Freq (Hz) Multi-Ch_In (dB) Dig_In_80_X-Over (dB) Dig_In_120_X-Over (dB)
---------------------------------------------------------------------
200_______68_____________67_________________67
160_______71_____________70_________________70
125_______74_____________73_________________72
100_______75_____________74_________________71
80________74_____________71_________________67
63________71_____________66_________________61
50________65_____________60_________________55
40________57_____________52_________________51
31.5_______60_____________52_________________50
Once again, although the subwoofer was set to Yes in Speaker Setup, it's switch was off. So, it is not contributing to the output. The output is due solely to the two mains.
The multi-channel inputs are the full-range response. I guess the roll-off there is due to my speakers and room acoustics.
But, what I was surprise at is how much of the signal the mains are playing below the crossover on the digital input. Comparing the 80 Hz crossover to full-range, there is just about a 5 dB difference at each frequency from 80 Hz to 40 Hz. I know that it takes something like double the power to get a 3 dB gain. So, maybe 5 dB is significant. But, it's still just 5 dB and just a very small turn on the volume knob.
I know this is a long and complex post (especially since you will not be getting any college credit for it), but here is what I would like to know:
1. Has anyone done a test like this on their Rotel? If so, did you get results like this?
2. Is this type of slow roll-off from the crossover the "norm" with A/V receivers and pre/pros?
3. Has anyone done a test like this using another brand of A/V receiver or pre/pro? If so, did you get a quicker roll-off or about the same as I got with the Rotel?
Thanks in advance for your responses.
- maddog
The test was done in 2-ch stereo using just my floorstanding mains. The subwoofer was set to Yes in Speaker Setup. However, my subwoofer's on/off switch was turned off. The volume value was set the same for each test. I did not try to match up dB's at a given frequency (e.g., 200 Hz) between tests. I used C weighting and Fast response on my SPL meter. The multi-channel inputs are supposed to pass the L & R signals "as-is" to the mains. The Large/Small front-speaker settings and Sub X-Over setting are not supposed to have any effect on multi-channel inputs. The bass < 100 Hz is also supposed to be copied to the subwoofer, which yields bass doubling on that frequency range with the L & R mains. As I'm sure everyone expected, my tests verified this. I got the same frequency response from the mains regardless of the Large/Small and X-Over settings when using the multi-channel input. Here are the full results:
Freq (Hz) Multi-Ch_In (dB) Dig_In_80_X-Over (dB) Dig_In_120_X-Over (dB)
---------------------------------------------------------------------
200_______68_____________67_________________67
160_______71_____________70_________________70
125_______74_____________73_________________72
100_______75_____________74_________________71
80________74_____________71_________________67
63________71_____________66_________________61
50________65_____________60_________________55
40________57_____________52_________________51
31.5_______60_____________52_________________50
Once again, although the subwoofer was set to Yes in Speaker Setup, it's switch was off. So, it is not contributing to the output. The output is due solely to the two mains.
The multi-channel inputs are the full-range response. I guess the roll-off there is due to my speakers and room acoustics.
But, what I was surprise at is how much of the signal the mains are playing below the crossover on the digital input. Comparing the 80 Hz crossover to full-range, there is just about a 5 dB difference at each frequency from 80 Hz to 40 Hz. I know that it takes something like double the power to get a 3 dB gain. So, maybe 5 dB is significant. But, it's still just 5 dB and just a very small turn on the volume knob.
I know this is a long and complex post (especially since you will not be getting any college credit for it), but here is what I would like to know:
1. Has anyone done a test like this on their Rotel? If so, did you get results like this?
2. Is this type of slow roll-off from the crossover the "norm" with A/V receivers and pre/pros?
3. Has anyone done a test like this using another brand of A/V receiver or pre/pro? If so, did you get a quicker roll-off or about the same as I got with the Rotel?
Thanks in advance for your responses.
- maddog
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