Question about long unbalanced line-level runs

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Matt C.
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Question about long unbalanced line-level runs

Post by Matt C. » Mon Dec 07, 2009 6:36 pm

I'm wondering about the possibility for noise/interference/signal loss when running a line level signal (mixer inserts, direct outs to computer, etc) down a long stretch of unbalanced cable. I know the rule about guitar cables being kept under about 25ft, but does the same rule apply to line level signals?

my problem is i have a Tascam M520 mixer, which is almost entirely unbalanced. the biggest issue is the channel send/receives for effects - right now i have them all sending the signal out through 6 or 10 feet of RCA cable, into a normalled patch bay, and back through another 6-10 feet of cable. so even if i have no effects patched into the signal path, there is close to 20ft of unbalanced cable built into the path at all time.

basically my questions are:

1. if i DO patch an effect into the channel insert point, does that piece of outboard gear act as a "buffer" and give me a clean slate as far as cable length goes? or should i be counting the total length of the cable run from mixer send all the way back to mixer receive?

2. am i just being too paranoid about signal loss? with my current setup, i have never noticed what i would consider problematic noise or loss, but it concerns me that everything i run through the board is experiencing just a bit of degradation and it might add up. is it worth rearranging things to put my patch bays closer to the mixer, thereby minimizing the length of the effects loops?

any help would be greatly appreciated. this question has been driving me crazy!

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rhythm ranch
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Re: Question about long unbalanced line-level runs

Post by rhythm ranch » Mon Dec 07, 2009 6:49 pm

mattcastore wrote:i have never noticed what i would consider problematic noise or loss...
You answered your own question.

If you're really concerned, unplug all the insert cables and see if it sounds any better. Since your board is unbalanced, you don't have much choice unless you want to add transformers. Most lower and mid level boards have unbalanced inserts.

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Post by ashcat_lt » Mon Dec 07, 2009 11:29 pm

For noise purpoises, it's total length that matters. For tone or signal loss, I think you can sort of reset things to a point, but I honestly think noise is going to be a bigger factor anyway.

If it's not a problem, it's not a problem. There is a reason I don't run the inserts of my board to the rear side of my patchbays, though. I just plug in the insert cable when I need it, and patch it to the proper points on the front of the bay. Then, when I'm not actually inserting anything it never even leaves the board.

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Post by dsw » Tue Dec 08, 2009 11:42 am

Most lower and mid level boards have unbalanced inserts.
not most, ALL.

Because by design an insert jack IS unbalanced.

If an insert jack were to be balanced it would have to have 5 contact points on the 1/4 plug. You can do it with two jacks (used to always call this a patch point), but not one.
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LazarusLong
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Re: Question about long unbalanced line-level runs

Post by LazarusLong » Fri Dec 11, 2009 3:21 pm

rhythm ranch wrote:
mattcastore wrote:i have never noticed what i would consider problematic noise or loss...
You answered your own question.
+1. Though, that cable is a giant antenna. It's good that you're having no problems now, but you're playing with fire.

Well, actually, RF. Still, of course something nasty will happen in the middle of the best take ever.

Is your input balanced?
The truth of a proposition has nothing to do with its credibility. And vice versa.

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