quieter cabling

S

saxman72

New member
Okay this is more of a question than anything (and it has nothing to do with monster cable!).

Is there any benfit to using twisted 2 conductor wire for unbalanced connections?

...If star quad cable rejects more interference for balanced lines, does it follow that 2 conductors (twisted) rejects more interference in unbalanced lines. And yes, my star quad cables are EXTREMELY quiet. :>

I started rewiring my studio with good cable and it is WAY quieter now. I'm planning on making cables for my keyboards next and I'm trying to figure out if I should go with 1 conductor to 2.

Thanks for your input everybody!
 
Well, yes, no, and maybe.

Shielded pair does offer noise advantages over shielded single-conductor cable for line level use. You can connect tip-tip and ring-ring with the pair, and then connect the shield only at the input end ("telescoping" the shield). This prevents currents induced in the shield by noise from common-impedance coupling into your signal return, and can indeed help make things quieter.

But be forewarned: by itself, this does nothing for the common-impedance noise coupling that lets *ground loop* noise into your rig, though. In a single-ended system, ground-loop currents travel up your signal return, whether it is the shield or not. If your noise floor is dominated by ground-loop-induced noise, using paired cables won't help as much: you have to kill ground loops at the source, by breaking the loop- and that's a topic that has been discussed elsewhere on this site, and in the references at the bottom of this post.

The only place that you typically would want to avoid using paired cable is for high-impedance instrument use (guitar and bass): the capacitance is quite high, when compared to a high-quality single conductor guitar cable), and this will result in rolling off the high-frequency components of your guitar's sound if you use longer cables.

Using good quality shielded pair cable to replace indifferent-quality single-conductor cable (like the molded-connector bubble-packed patch cable junk) *can* result in significantly lower noise. If you solder well and use good assembly techniques, you can also achieve improved overall reliability in your rig.

The other benefit is that you can inventory only one flavor of cable... (;-). The real benefit of using starquad is in mic lines, where ultimate noise rejection is crucial. For your basic balanced or unbalanced line-level interconnect, just keeping a good big roll of good shielded pair around to use for everything else makes a lot of sense.

A couple of web sites to look at for further info:

http://www.jensentransformers.com/apps_wp.html (AN003 and AN004, in particular)
http://www.rane.com/note110.html
http://www.hut.fi/Misc/Electronics/docs/groundloop/index.html
 
Thanks Skippy,

I was hoping you'd find your way to this post. I seem to have most of the grounding issues under control (except for another loop i found sneaking it's way through a midi cable).

Two questions though:

You said to connect tip to tip and ring to ring and then the shield at the input end. Should I use TRS plugs even though the source and the input are TS? Or do I combine the 2nd conductor and the shield at the input end on the sleeve of a TS plug?

Also, is capacitance not an issue when dealing with line level signals (of say cable runs of under 20 feet)?

Thanks again,
Saxman72
 
Akkkk! You're exactly right, of course: I meant "sleeve", not "ring". Mea culpa. I screwed up: I oughta proofread my freakin' posts better. Use a TS plug and jack, _not_ a TRS plug and jack, for single-ended runs.

Capacitance is not an issue when dealing with line level runs of less than maybe 100 feet (unless the designer of the driving equipment is a freakin' _putz_). It is primarily an issue when driving instrument level signals _from an instrument_, which is by definition a high-impedance source. It is also a problem for crystal mics (like anybody'd ever use such a thing except for a special effect...).

Anyway, it is one minute to Christmas here. Merry Christmas, all!
 
Noise elimination

I'm still working on removing some noise from my rig. I think some of it is due to a poor power source. I read something about power conditioners and their RFI/EMI shielding. Something else was mentioned...a balanced isolation transformer...used to cancel extraneous noise in the power line buy means of cancellation.

What is a balanced isolation transformer? Who makes them for studio applications? Where can I get one? Could it potentially help? Thanks in advance!
 
I haven't ever used balanced power: haven't ever needed it, even in my most EMI-polluted environments. And it wasn't really commonly discussed back when I was still current in the audio arts, except as a side note to the use of an isolation transformer in a last-ditch effort to salvage badly designed gear. However, it seems to be all the rage these days, and the basic concept certainly *does* make some sense.

But only "some" sense. I personally remain to be convinced that it is the use-for-everything panacea that some folks in the current publications think that it is. I think that most noise problems are from the same simple, basic ground loops as ever, and in many cases are caused by loop currents or common-impedance coupling issues *on signal connections only* that the use of balanced power would not correct. But whadda I know?

A quick Google search reveals the following white papers on the use of balanced power:

http://www.hut.fi/Misc/Electronics/docs/groundloop/balanced_power.html
http://www.equitech.com/articles/articles.htm
http://www.furmansound.com/BalPwr.html

and about 1700 other hits. Note the last 2 of those 3 are written by the marketing departments of companies that want to sell you balanced power gear, so caveat emptor. Needless to say, I like the first one the best: that's an excellent starting place. If I ever meet the gent who put together those hut.fi audio web pages, I'll buy him several beers...

Take a look, and make your own call. For my own purposes, I still rely on the tried-and-true grounding techniques used by many folks since the advent of sound recording... and only use those expensive isolation tranformers (signal or power!) when the equipment is too badly designed to allow any alternative. Read: nearly never. I'll rip apart gear that does silly things in the power supply, and fix them there, before buying big hot lumpy transformers. Your mileage may vary, though- so get educated and try some experiments for yourself!
 
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