Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

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RE: You have proven that which is already known

Posted by tomservo on June 21, 2010 at 15:26:01:
“Who knows - perhaps the cables tested were no better than zip cord in the test system. BTW, what was the test system? Could others duplicate your test for verification? I use low DC cables because electrostats are more sensitive to both C and L. Others are not.”

First, I understand your skepticism. Second, in particular electrostatic speakers require a low inductance as a capacitive load will form a second order low pass filter. Understand, I am not saying cables do nothing, they do something to be sure and what they do is in part related to the length.
I have a tower I use to measure speakers up in the air so that there are no significant reflections into the bass range. I need to do this in order to design the crossovers I use which do not result in phase shift, the result being something like a full range ESS, not spreading a signal out in time.
A hundred feet of good mic cable is no real problem but a hundred feet of speaker cable is a real problem. I need to have the measurement error it adds to be very small even at 100 feet. I evaluated all the likely choices but none had low enough series L, normal extension cord would produce an error/ roll off of 2 dB at 20KHz with accordant phase shift, TOO large.

I ended up making a cable from a pair of low loss coax cables (a variant of RG-9913) cross coupled.
That 100 foot cable pair ended up having the L and C in the range of the 10 foot kimber cable sample I had while having about 1/8 the Rdc. If you want to try a theoretically blameless cable, the stuff (the modern low loss RG-8’s extended family) is dirt cheap compared to audio hose, the electrical parameters are very good, the design scientific.
If you have a ham fest locally, you can pick up usable lengths of this stuff for a few bucks, look for the stranded center conductor which is more flexible.