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Stereo crosstalk at high frequency on my mixer
Hi,
I tried the RMAA audio analyzer program on my soundcard (ST Audio DSP24 Value) using line-in to line-out through the Behringer UB1002 mixer (connecting to tape-in and tape-out). The result was quite good, with very low noise level. But looking at the Stereo Crosstalk plot, I saw something quite strange. Crosstalk was fairly low all the way from 30Hz-1KHz (below -90dB), but then it rised linearly (in logarithmic scale) from -94dB at 1KHz to -72dB at 20KHz. It didn't happen when I did a direct loop-back test, which kept stereo crosstalk below -90dB all through the spectrum, so it must be the mixer that added this peculiarity. Is this normal in any mixing board? Would that level of crosstalk be audible and affect the sound coming through the speakers? I guess it would lessen the soundstage/stereo image, or worse, make the sound field positioning imprecise (or unreliable, e.g., instruments moving left and right when played at different octaves) due to different levels of crosstalk at different frequencies. The last question is: Should I concern myself with the issue? Maybe it's not much of the problem, or you may have a suggestion as to how I could correct it. Thank you very much in advance. Poonna |
#2
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Stereo crosstalk at high frequency on my mixer
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#3
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Stereo crosstalk at high frequency on my mixer
Dreamist wrote:
I tried the RMAA audio analyzer program on my soundcard (ST Audio DSP24 Value) using line-in to line-out through the Behringer UB1002 mixer (connecting to tape-in and tape-out). The result was quite good, with very low noise level. But looking at the Stereo Crosstalk plot, I saw something quite strange. Crosstalk was fairly low all the way from 30Hz-1KHz (below -90dB), but then it rised linearly (in logarithmic scale) from -94dB at 1KHz to -72dB at 20KHz. It didn't happen when I did a direct loop-back test, which kept stereo crosstalk below -90dB all through the spectrum, so it must be the mixer that added this peculiarity. Not peculiar. You jam all thet stuff in a small case and you don't use individual shielding on each section or channel strip and you don't use shielded wires for the buss, and you get capacitive coupling between channels. This problem is more apt to happen at high frequencies. You skimp on supply decoupling, and you get signal from one channel coupling into another through the power supply. This problem is more apt to happen at low frequencies. Is this normal in any mixing board? Would that level of crosstalk be audible and affect the sound coming through the speakers? I guess it would lessen the soundstage/stereo image, or worse, make the sound field positioning imprecise (or unreliable, e.g., instruments moving left and right when played at different octaves) due to different levels of crosstalk at different frequencies. This is typical of cheapie single-board consoles. This is one of the reasons why professional mixing consoles are modular; in part it is so that the individual modules can be shielded and not interact with oen another. The last question is: Should I concern myself with the issue? Maybe it's not much of the problem, or you may have a suggestion as to how I could correct it. You can't correct it without spending a lot more money on a real console. So don't worry about it since you can't do anything about it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#4
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Stereo crosstalk at high frequency on my mixer
Based on my experience with my amps and RMAA, it is not the mixer but
the cable raised the crosstalk above 1KHz. See my RMAA tests he http://www.fixup.net/products/benchmarks And you can easily see at the last graph of below link, what the cable does to the crosstalk at high frequency (exactly what you found): http://www.fixup.net/products/benchm...MU1212M3ft.htm The cable is a 3-feet long RadioShack gold series. If I use very short cable (shorter than 6 inches), then there is no such a problem. The problem is, I have to use long cable; otherwise the amp must be very close to the computer and get lots more noise. |
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