From: dplatt@snulbug.mtview.ca.us (Dave Platt)
Newsgroups: rec.audio.high-end
Subject: Re: Homemade Interconnect -- experience and question
Date: Sun, 10 Jan 93 12:58:18 -0800
Organization: Snulbug Software
Reply-To: dplatt@snulbug.mtview.ca.us
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

kuo@asc.slb.com writes:

>The consensus in the archive (and further verified by my Audioquest
>and Moster Interlink cables) seems to be, for shielded twisted pair,
>connect the center conductors to the signal, and tie (only at the
>source, CD for my case) the shield to the RCA shell.

Perhaps I'm misreading you?  The configuration I use and recommend is:
tie one of the two center conductors to the "hot" pin on the RCA plugs;
tie the other center conductor to the shell (at both ends);  tie the
shield to the shell at one end only and isolate the other end of the
shield.

If you tied _both_ wires in the twisted-pair to the center pin on the
RCA jacks, and did not tie either to the shell, and have connected the
shield to the shell at only one end - then your cables are incomplete.
They're carrying the "hot" signal but are not completing the ground.  As
a result, one of two things will happen - either the system won't work
at all, or it will work (but perhaps poorly) because a ground connection
is being established through another [inferior] channel, such as the
ground wires in the AC power cords connecting the two units to the
powerline.

>After 1 hr of "hard labor", I have a pair of shining (the Canare and
>Belden cables look real nice) interconnect. For safety purpose, I
>first connected them to NAD 5000/NAD 7100 driving a pair of Snell/E.
>Comparing to the Monster Interlink (CD), the sound is more refined,
>especially on the mid range, though I didn't listen long enough to do
>a detail comparison.
>
>So I then switch to the NAD 5000/the recently acquired Acurus DIA.
>The result is very disappointing!!!
>There's a constant low level hiss/hum. I have to turned up twice the
>volume knob to get the same speaker volume, and all the dynamics are
>lost.

That sure sounds like you may have an inadequate ground in the cable.
Try running a jumper cord between the ground shells at the two ends of
the cable - if the sound improves all of a sudden, then it's a sure
indication that your cable ground is inadequate.  The fix wouldn't be
difficult - open up the RCA-jack shell, lift one of the two wires from
the center pin (make sure it's the same wire at both ends!!) and
re-solder this wire to the ground-shell connector.  This will establish
a solid ground connection between the two components.

>My suspicion is in the Acurus DIA passive preamp section, since it has
>high sensitivity.

The place where you usually see incompatibilities between an
interconnect and a passive preamp is if you use a high-capacitance cable
for the _output_ of the passive - the cable capacitance interacts with
the passive preamp's high output Z to form a low-pass filter.  [I
understand that some high-end interconnects (e.g. some MIT cables) have
as much as 1000 pF per meter.].  This can cause a "softening" of the
sound of the system - sometimes subtle or even euphonic.

I don't think that's what you're seeing - the symptoms you're reporting
are far more severe than cable-capacitance problems can reasonably
account for.  I think you have an inadequate ground path.

>Shall I try different grounding methods, get a different cable (I
>can't seem to find a local dealer willing to sell the Belden #89182
>for < 50 fts)?

I sell Belden 83318 (24-gauge shielded twisted pair, silver-coated
stranded copper conductors, silver-plated braided copper shield, Teflon
jacketing and insulation) in small or large quantities for roughly a
dollar a foot - my minimum order is $10.  This is mil-spec "type E"
interconnect cable... I have a bunch of different types.  Let me know if
you're interested in some samples.
---
Dave Platt
    dplatt@snulbug.mtview.ca.us       (domain/MX)
or  apple!snulbug!dplatt              (uucp path)
or  dplatt%snulbug.uucp@apple.com     (non-MX Internet)