In article ,
Fred McKenzie wrote:

I have a desk microphone without the cable. I need to put on a cable
that is just a center conductor and shield. It will be about 3 to 4
feet long.

This is a crystal mic going into a tube amplifier. As this is high
impedance, is there a special mic cable ,or can I just use some rg58 or
rg 8x cable without degrading the audio. It is only for communications
quality speech.

I know all about RF type cable, but have not ventured into the audio.

Ralph-

I think RG cable is more than adequate for audio use, maybe "too good"!
It may not be as flexible as you would like.

For that short a distance, and for speech-quality audio, I agree on
both points. The flexibility of the cable may be an issue, although
since it's a desk microphone that may be less of a problem.

If you do want to optimize... professional microphone cables are often
designed with low capacitance per foot (to minimize the degree to
which the cable's shunt capacitance loads down the mic element and
affects the frequency response) and low amounts of triboelectric
effect (so that bending the cable doesn't generated voltages inside
the insulation which are then transferred to the conductors - this can
cause crackling or other noises in the audio).

Most of the big cable manufacturers (Belden, Mogami, etc.) make cable
of this sort. Markertek sells it, but only in bulk quantities :-(

Ralph, if you want to experiment... I have a whole bunch of fancy
mil-spec cable sitting in my garage from a previous project / sideline
business... it's stuff like Belden 83318E. I've got some fairly thin
one- and two-conductor (plus braided shield) that might work for
you... it's not as flexible as rubber- or PFC-insulated of the same
diameter but is definitely more flexible than RG-58 or RG-8x. I've
used it for line-level audio wiring in my stereo setup, among other
things. Email me directly, send me a mailing address, and I'll post
you a long enough piece to try with your microphone.