Analog Interconnects- How Long Is OK?

James Edward · 09-15-2003, 06:01 PM

I have a great separate 2 channel system apart from my 5 channel HT. I would like to run the analog outs on my satellite receiver to my stereo pre-amp, to utilize the music channels available.

When I'm done snaking them around, the length will probably run to 50 feet or so. Can a low-level signal be sent this far, and if so, do I need to use any special sort of cable?

If this is feasible, where do I get lengths like this at reasonable cost? Thanks.

Chu Gai · 09-15-2003, 07:19 PM

I'll offer this reply which was written by AES fellow, Fred Davis.

Quote:

(Since we don't have a lot of data to work from, this is going to involve a few 'if's so bear with me.) If your preamp has 200 ohms output impedance (or less, which is typical, but let's look at the worst case), and if your power amp looks like 100kohms in parallel with 150 pF (again, this is worst case. Most amps are about 50k and less capacitance), and if you set a loss of -3 dB at 20kHz (enough so you can hear it), and if you used something like RG58 (or any other coax with about 30pF per foot), THEN you could run over 1300 feet of cable. This works out to about 0.039uF cable capacitance (39,000 pF). Given that your preamp has lower output Z, and your power amp has lower input Z and less capacitance, I doubt that running the cable across the room will make an audible difference *unless* you have a *really* big room!

This would suggest to me that the 50 feet is no big thing and you should search out the type of coax cables Mr. Davis suggested (or of lower capacitance) and have them terminated in RCA's. This might be a situation James where you can buy a spool of the stuff, possibly locally, and some crimp on RCA's and go to town.



Skin Chooser:	Contact Us - Advertising Information - Home Theater Forum - Archive - Top