In Reply to: I'm with Roland posted by NYCProAudioNut on March 29, 2002 at 09:50:57:
By all means feel free to jump in, but please don't ignore the reality of what StarQuad Cable is and what it is intended for. StarQuad is an excellent cable for rejecting EMI and RFI interference, which is very valuable in a broadcast studio setting. Unfortunately, the design of the StarQuad cable results in a much higher capacitance per foot than other cable designs.From the Canare website, StarQuad cable capacitance is listed at 145 to 170 pF per meter. Lets assume an average of 158 pF/m for the sake of argument.
From the Belden website, 1800F cable capacitance is listed at 43 pF/m.
Assume a typical mic output impedance = 600 Ohm. Assuming the load impedance is much greater than the source impedance, then the -3dB roll off frequency of a cable can be calculated as follows:
Fc = 1 / (2 * Pi * C * Z_Source)
For a 100 meter cable of Canare StarQuad the -3dB frequency would be:
Fc = 1/(6.28 * 158 pF * 100m * 600 Ohm) = 16800 Hz.For a 100 meter cable of Belden 1800F the -3dB frequency would be:
Fc = 1/(6.28 * 43 pF * 100m * 600 Ohm) = 61720 Hz.Based on these figures I would be very comfortable using a 100 meter Belden 1800F cable, but would be somewhat concerned about the audible sonic effects of using a 100 meter Canare StarQuad cable. The -3dB frequency for a 300 meter StarQuad cable is a totally unusable 5600 Hz, while the Belden 1800F cable -3dB frequency is still a perfectly respectable 20573 Hz.
Belden 1800F has the same or better EMI/RFI interference rejection properties (due to it's double braided, French shield) as StarQuad cable without the high capacitance penalty. I can understand StarQuad being used in a studio where a 50 meter mic cable is considered a long run. Live audio is different from studio use though, cable runs of 100 meters or more are not at all uncommon and even longer runs are encountered in concert settings. StarQuad doesn't do anything better than Belden 1800F, and 1800F will do it for further distances at a lower cost.
Phil
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Follow Ups
- Re: I'm Not - Haldor 15:22:45 04/01/02 (6)
- Re: I'm Not - Roland 07:04:57 04/02/02 (5)
- Re: I'm Not - Haldor 15:02:05 04/02/02 (2)
- Re: I'm Not - SSL Tech 09:02:27 04/03/02 (1)
- Re: I'm Not - Roland 14:40:20 04/03/02 (0)
- Results of a very quick test... - SSL Tech 13:08:50 04/02/02 (1)
- Re: Results of a very quick test... - SSL tech 13:35:28 04/02/02 (0)