interconnect capacitance

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martyo

interconnect capacitance
« on: 29 Nov 2006, 02:12 pm »
Hi Frank,
Don't want to open this can of worms again  :deadhorse: but I would appreciate your feed back. Before I joined the AVA club (used Super Pas-3i) I bought some "quality interconnects".(expensive to me, $40 for .5 meter). Over time, from info here on the circle and probably in Audio Basics, to keep it simple, I believe what I should be concerned with is the capacitance, and we're looking for low. There was no useful technical info on the website or package (only terms such as oxygen free, continuous cast....)and recently I noticed there were directional arrows on the cables! :oops: Now I figured I wasted my money and I emailed them and asked for the capacitance of the cables I bought. Here is they're reply:
Dear Marty,

Here is the information you requested:

CCC/II Capacitance:
(A): Conductor to Conductor: 80.27 PF/M at 1KHz
(B): Conductor to Braid: 163.88 , 164.12 PF/M at 1KHz

Best regards,

Jessica Westgate
Manager
sci@vampirewire.com

Would these be considered low capacitance?
Thanks in advance Frank,

martyo

elcaptain88

Re: interconnect capacitance
« Reply #1 on: 29 Nov 2006, 02:56 pm »
On a short audio cable capacitance is a non-issue. Even on longer ones, I doubt it would make any measurable difference. I did some math awhile ago and figured that for the average interconnects I use the -3db cutoff might conservatively be in the neighborhood of 10Mhz - well beyond 20khz.

Video apps are a different story - NTSC signals for example are 6Mhz.

Psychicanimal

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Re: interconnect capacitance
« Reply #2 on: 29 Nov 2006, 10:28 pm »
My 1/2 meter Ridge Street Audio Midnight Silver Edition II's were more than six times that--and I get the amigo deal!  All my interconnects are Midnight Silver Edition I & II's.  I really like them and although rather unconventional, my system revolves around the interconnects.

The speaker wire I use is 65 cents/foot, military surplus, signal transfer wire ( 12 ga silver plated copper, Teflon insulated).  This has defeated a LOT of expensive boutique cables and gotten uncomfortably close to cables up to the $50/ft price!!! Some of my power cords are made from the military surplus cable--which has equaled $800 Jena Labs power cords--and others are $50 Absolute Power Cords.

I know I can get away with cheap solutions for speaker wire and power cords, but not so with interconnects.  Believe me, If I could I would.  However, my interconnects are made with naturally insulated, medical grade, solid core silver and is the best material I've ever heard.  I suggest you keep an open mind...you can buy used cables from Audiogon and sell them at or near the price you buy them for, experimenting with different kinds.  That's how I came to my own conclusions. If you do this the learning experience will be priceless. 8)


WEEZ

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  • Posts: 1341
Re: interconnect capacitance
« Reply #3 on: 29 Nov 2006, 10:58 pm »
Those pf values don't seem too high. If your high frequency response is satisfactory, I wouldn't worry about them.

avahifi

Re: interconnect capacitance
« Reply #4 on: 30 Nov 2006, 02:14 am »
Lets see 160 pF per meter, about 50 pf per foot then.  A good low capacitance Belden woven braid shield cable is in the range of about 12 pF per foot.  How long a cable are you using? 

Does the load make any difference?  Easy way to tell is with a square wave generator set at 10K Hz, and the preamp terminated into a 24,000 ohm load or thereabouts thru a very short interconnect (or with the load resistor directly across an RCA plug.  Then solder a capacitor across the load resistor of about the same value as the total capacitive load of your cables.  Solder one end, keep the other end of the cap free so you can make or break contact with it.  Watch what the square wave output does when you attach the load.  With a high quality preamp with adequate output current drive and speed, the square wave should round off the shoulders a bit (your cable is a built in treble cut control - how nice.  With a lesser circuit design, you may see a leading edge spike and ringing fall-away, damped oscillations (known by the golden ears as "detail" :)  yah sure.  With a really load sensitive preamp, you may just see "fuzz" full bore oscillations.  Don't do that for very long!

Regards,

Frank Van Alstine