What will be a simple test with q403 to compare good turntable cable vs cheap one.
regards
tks
Dan
Hi @dlap56,
Cables are very difficult to test even with a $30k analyzer because the noise and distortion introduced by a wire is much less than even the best opamp. And a modern opamp cannot be tested with a modern $30k analyzer–the opamp is too good. To solve this problem, the opamp makers put the opamps into special modes of operation that degrades their performance in a known way. And then you can test the opamp and learn the THDN of the opamp. Then you numerically subtract the error you injected, and that’s how you can measure an opamp with -130 dB THDN.
Unfortunately, because a cable is a passive device, this trick doesn’t work.
The link below is to the TI OPA1612 opamp. See section 8.3 on how TI degrades the opamp performance to measure it.
My guess is that a paperclip has better THDN than a top opamp such as the OPA1612.
Place it near a mains cable and measure the mains harmonics that are induced on the cable - an indication of how effective the screening is?
Hi Mark,
I did some tests as you suggested.
- R channel with 6 feet turntable cable with a separate ground tie with the ground at the other end.
- L channel with a cheap 5 feet rca cable.
no connection with any device just unplug the cable.
a cable hook to 60 watts bulbs crossing both cables on about 6 inches.
perform a test with an on and off lamp.
see the photos
We can clearly see that the cable on the left channel is really noisy!!!
i didn’t notice a very large difference with a lamp on and off.
Thanks you
Dan
