#1039469 - 10/01/05 10:12 AM
The truth about Balanced Cables
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Brilliant
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Registered: 05/06/02
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Loc: Port Arthur, TX, UNITED STATES
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What is their purpose, their benefit?? Are they useful in long runs?? short runs?? through electrically noisy areas?? or is it best to use balanced cables whenever possible. Is their ever a time when a balanced cables aren't the best option??
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#1039470 - 10/03/05 12:28 PM
Re: The truth about Balanced Cables
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Bill@Welcome Home Studios
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The purpose is that cmrr occurs when using a balanced circuit... but the cables do you no good if either end of the connection is not balanced.
Bill
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"...it's easier than hitting the kids, and almost as much fun..."
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#1039471 - 10/19/05 01:55 AM
Re: The truth about Balanced Cables
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shmolous
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Registered: 10/16/05
Posts: 26
Loc: Southern Calif.
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[QUOTE]but the cables do you no good if either end of the connection is not balanced.
QUOTE]
I don't concur. The issue is shielding. If a piece of balanced gear is connected to a piece of unbalanced gear the end result is that the circuit is unbalanced..this is true...however, using an unbalanced cable (single signal carrying conductor and a ground) in this scenario often results in the dreaded 60hz. hum. I always use a balanced cable and tie the low side and the shield together at the unbalanced end...The result? no hun!
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#1039472 - 10/19/05 12:05 PM
Re: The truth about Balanced Cables
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paully
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Loc: Northern New Jersey
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Originally posted by GovernmentCheck:
Is their ever a time when a balanced cables aren't the best option??
Only in the obvious scenario.. when you're working in an unbalanced(semi-pro) environment, at cable lengths shorter than app. 18'. Why waste the money on balanced wire/connectors? Guitar players and keyboardists use them all the time with no problem. As to the last post, I'm not sure where the 60hz hum was coming from, but I doubt that the cause was a cable shielding problem. Sounds more like an equipment grounding problem, which is often circumvented by completing ground only on one end of the wire, or fixed by improving the system ground bussing. As long as the shield is solid and well soldered, you should get no hum from balanced or unbalanced wire.
Paul
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WUDAYAKNOW.. For the first time in my life, I'm wrong again!!
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#1039473 - 10/19/05 03:12 PM
Re: The truth about Balanced Cables
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Bill@Welcome Home Studios
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Originally posted by shmolous:
[QUOTE]but the cables do you no good if either end of the connection is not balanced.
QUOTE]
I don't concur...... I always use a balanced cable and tie the low side and the shield together at the unbalanced end...The result? no hun!  )
In a professional rig, it is not uncommon to float the shield at one end to prevent ground loops. Ground loops have nothing to do with shielding other than the shield cable was carrying the chassis ground between devices.
Bill
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"...it's easier than hitting the kids, and almost as much fun..."
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#1039474 - 10/20/05 12:58 AM
Re: The truth about Balanced Cables
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shmolous
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I suppose I didn't express myself clearly enough. The comment regarding shielding had to do with why unbalanced cabling (single conductor and a ground) lends itself to noise issues. Ever heard the squish squish sound a long guitar cord makes?
The purpose of lifting a shield is to prevent the loop caused by tieing 2 chassis' grounds together. The purpose of the shield itself however is to act as a "noise supressor" (RF or whatever) I don't like using the terms balanced or unbalanced when referring to cables. We actually need to be more precise. As stated in the previous post balanced/unbalanced is a function of the actual circuit-I prefer in the context of the first question to speak of single conductor vs. 2 conductor cables. The equipment combinations determine the actual wiring of the cable. As for the 60cycle issue, When using single conductor cable it is impossible to lift a shield. There is no shield. That is the point! The shield in an "unbalanced i:e-single conductor cable is actually a ground, and earth and the shield are two different things. Using 2 conductor cable with a shield (called a pair or paired cable) is ALWAYS the best choice when a multitude of connection possibilities are present, such as in a studio with patchbays. Have you ever had a hum using a paired cable to connect an insert send AND return? If it didn't hum you were lucky for reasons I don't want to get into due to the limited space of this forum. I already feel like I've blabbed too much already (grin) If you have a chance look at my website-www.boblewisaudio.com- There is an article I wrote there regarding 60hz. hum that may muddy the issue further..(bigger grin)
Bob
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#1039475 - 11/02/05 08:57 AM
Re: The truth about Balanced Cables
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mudsmith@earthlink.net
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Registered: 10/30/00
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Loc: Martinsburg,WV,UNITED STATES
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In short, balanced is better always when connecting to a balanced circuit; and care must be given to how a balanced circuit/cable is connected to an unbalanced circuit.
It is frequently the technical recommendation to "float the shield" at the unbalanced end, as indicated above. In the real world, however, I have found that it is generally more successful to tie the shield to the low side of the unbalanced signal, as shmolus suggests above.....When I built my remote truck in 1990, I followed this pattern when dealing with a fairly large installation (especially in the patch bays for the unbalanced insert points), and I never had a single hum or noise problem directly associated with this wiring technique. That is some fairly strong evidence.
There will be occasions when the shield lift is the only acceptable solution for a variety of reasons, but I have found that the shield tie is a better place to start.
There are other issues that can come up when you unbalance circuits (level changes, for instance) depending on the nature of the circuit, but each case should be dealt with on its own merits.
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#1039476 - 11/02/05 09:57 AM
Re: The truth about Balanced Cables
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paully
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Loc: Northern New Jersey
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Good discussion about this going on here:
http://gearslutz.com/board/showthread.php3?t=47084
Paul
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WUDAYAKNOW.. For the first time in my life, I'm wrong again!!
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#1039477 - 11/03/05 10:20 PM
Re: The truth about Balanced Cables
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blas
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Registered: 03/06/01
Posts: 517
Loc: St. Louis, MO. USA
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Hey Mud, Got any pictures of the truck? I'm always amazed at the great work that goes into a mobile gig on wheels! We do location work, but strickly out of road cases (what a pain in the ass)...that's why we attempted to have road gear and studio gear as sharing isn't fun!
Show somw shots.
blas
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#1039478 - 11/07/05 11:18 AM
Re: The truth about Balanced Cables
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mudsmith@earthlink.net
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Registered: 10/30/00
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Loc: Martinsburg,WV,UNITED STATES
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....I'm working out of road cases now myself. Truck has been parked in my yard since late '97, though I still do a fair amount of mixing and production in it while I finish constructing my new mix and mastering room in the barn.
I only have some very old promo pictures that don't tell you much about how it looked in its last road-worthy state or now. I made some serious mistakes in building it, but not in wiring or the basic acoustic treatment to make me able to hear while mixing (in a fairly small sweet spot)....I built the truck in the winter of '89-'90 and learned a lot in the process. The first big shcoker was realizing that I was now basically working outside, almost in the weather all the time.
That is the one part of the carry-in rig that is massively better than the truck deal. They are both trade-offs, however. The truck gives you better monitoring and some quicker setup. The carry-in gives you better cable runs, a lot more flexibilty and scalability, and keeps you out of the weather....
There are also a lot of gigs where the truck simply does not work, or where the schedule and budget don't allow you the time and place to park. One of my most constant clients changed venues to a place where the truck just could not happen. That spelled the end of it for me, and the beginning of the unpleasant game of lugging equipment in and out of the studio that you allude to.
Whenever I am pissed off about lugging all the cases in, I like to remember dragging power and snake cables though the garbage-slimed alley in the rain at Blues Alley at 3 or 4 in the morning....Or chopping the cables out of the ice after being snowed in at a gig in February. What a glamorous business, eh? That's entertainment.
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#1039479 - 11/22/05 02:09 PM
Re: The truth about Balanced Cables
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Greg A
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Registered: 04/29/02
Posts: 85
Loc: Edmonton, Canada
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To answer your original question, G.C., in short: Balanced cables allow you to do long cable runs with little or no signal degradation. With unbalanced cables, you start to lose signal after 15' or so.
All wires and electronics are susceptible to picking up noise. Essentially, as I understand it, the noise in the hot and neutral wires of a balanced cable arrive at the input of a device out of phase and the noise cancels out.
I hope this gives you the basic idea behind balanced cables. Good discussion; just thought I'd go back to basics and put it in a nutshell.
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