long interconnects

[howardnair]

My daughter who has a Stereomour that I built for her has asked me to build her a pair of 20 foot rca interconnects from her dvd player to the Stereomour-Building the interconnects is simple enough but I am unsure about any problems that may arise from 20 feet---I will be using shielded microphone cable--Any input is appreciated--thanks howie

[Grainger49]

Howard,

What is the capacitance per foot of the microphone cable?  I use some Belden that is 7pF/Ft.  That is low capacitance.

[Paul Birkeland]

Is the model number of the DVD player available?

If it's just being used for stereo, an inexpensive 20' optical cable, a short pair of analog interconnects, and a $50 DAC might be a better combo.

[howardnair]

Paul I don,t  have that info at the moment -I will get it -regardless I see where you are heading-I am glad I asked -it will be used for the tv/dvd /cd but not looking for a movie sound just the nice sound of the stereomour
Grainger  it is canare LE6S-it is 57pf per foot-7pf is really quite low-that may also be a option--

[Grainger49]

I just looked it up.  It is 17pF/Ft, (56.7pF/Meter).  But it is sold by Handmade Electronics by the foot.

http://www.hndme.com/productcart/pc/viewPrd.asp?idproduct=2953&idcategory=210

[Paul Joppa]

Most solid state sources will have a low output impedance and will be able to drive the capacitance of a long cable with ease.

Just a caution though - if the source and the amp are far enough apart to be on different power circuits, there could be some ground-loop or other ground-induced hum. A reasonable precaution would be to use a cable with a heavy shield (woven copper, typically) and RCA plugs which a good grip on the jack outer connection.

[Grainger49]

The linked Belden is a heavy woven copper shield.

[mcandmar]

I just looked it up.  It is 17pF/Ft, (56.7pF/Meter).  But it is sold by Handmade Electronics by the foot.

http://www.hndme.com/productcart/pc/viewPrd.asp?idproduct=2953&idcategory=210

Nice call Grainger, i got some of this cable in the post today and made up a few .75m interconnects.  They sound very good to me (but doesn't everybody say that when they make up a cable) so to try and add some objectivity i measured a few cable lengths i had to hand and got the following,

Belden 89259 .75m = 47pf
Cambridge Audio Silver Reference .75m = 52pf
Cambridge Audio Qunex 99% OFC .75m = 104pf

Multicore cables (i.e. non coax)
NavShips 2x24g dual core shielded silver plated 1m = 54pf
Canare L-2T2S dual core shielded 1m = 78pf
Van Damme XKE quad core shielded silver plated 1m = 88pf
Canare L-4E6S quad core shielded 1m = 160pf

Very interesting results, and that Belden cable clearly performs very well.  I have always wired my amps internally with Navships cable, and used the Cambridge Audio cable on my S.E.X. amp so i was pleased to find both cable types had the lowest capacitance.   I learnt two things today, my preferred cables all have low capacitance, and that you can easily measure a cables capacitance to gauge its quality.  Now i need to order up a bunch of RCA plugs to make more interconnects