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Re: XLR Cable Connection

Subject: Re: XLR Cable Connection
From: "Scott Fraser" scottbfraser
Date: Fri Apr 22, 2011 8:03 am ((PDT))
<<The wire arrangement in star quad cables is superior for rejecting magnetic 
field interference (when wired properly mono), but I don't think it has much 
effect on radio pickup. Mics wired stereo through star quad are still balanced 
lines. I'm not denying your experience, but I'm skeptical about your 
attributing it to the "off label" use of star quad cable.>>

That's the problem with something like this, correlating cause to effect. There 
are certainly many variables available & unfortunately one can't use a client's 
time to experiment. 

<<I suspect your interference problem might rather have been what engineers are 
calling "the pin 1 problem," where the cable shield at the preamp input is 
wired to the circuit board ground, rather than directly to the chassis as is 
current practice. The pin 1 problem causes radio interference to be re-radiated 
inside the equipment. Another possibility is that you were close to a 
transmitter, a situation that often no manner of wiring can remedy.>>

It's been too long to recall all the circumstances, but that combination of mic 
& preamp was good when using other cables, though I've moved on to much better 
preamps since. It perhaps is a leap to a conclusion, but the cable appears to 
be the one variable leading to the bad results. I currently use the 5 pin XLR 
fanouts I made for that cable with my Mogami 2 pair cables, so I know they're 
OK.

<<Of course RF problems are notorious for being sensitive to location, 
geometry, and even weather, and thus are hard to reproduce or pin down.>>

For all I know there was an impurity in one bit of solder which resulted in 
demodulating the radio. Or perhaps a campus radio station on top of the 
building, modulating the mains. It could be that a transformer based preamp 
would have fixed the issue. (I have had radio breakthrough with a different set 
of Neumann TLM mics & a very high end preamp at the late Plant facility in 
Sausalito, so I try to mix & match source & destination carefully.) Perhaps 
swapping which white lead pairs with a given blue lead may have worked better, 
I don't know, & didn't really care to test differing hypotheses at that point. 
But the fact is, on at least two paying jobs I had a problem which appeared to 
arrive & then depart with the use of that Star Quad 100' cable wired for 
stereo. Twice bitten, thrice shy. I subsequently cut it into 25' lengths, wired 
mono, & have used them on hundreds of album releases since then. 

Scott Fraser











"While a picture is worth a thousand words, a 
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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