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Is this a balanced signal path?

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Posted on December 6, 2014 at 07:23:57
Nglazer
Audiophile

Posts: 365
Location: New york
Joined: June 22, 2003
 My new pre has a balanced out option, which mfr. recommends; my amp is only balanced in. If I use RCA IC's, but plugged into XLR/RCA adaptors on balanced pre and amp ends, will I still have a balanced signal path? Or must I use XL IC's? (Put aside effects of adaptors, please; this is a temporary arrangement.)

Thank you.

 

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RE: Is this a balanced signal path?, posted on December 6, 2014 at 08:47:56
mingus
Audiophile

Posts: 355
Location: mid-atlantic
Joined: July 19, 2001
 Depending on the design of the cable, your return ground may end up being the other half of the signal... your main signal wire in the RCA would carry one half of the balanced signal, the negative/return/ground may carry the other - and you might not have a "ground" which is usually the 3rd wire in a balanced cable... Whether that sounds good (the ground carrying half of the circuit)? but it will work electrically, again depending on the design of the cable... Some cables do not connect the return/ground between 2 ends (say amp or preamp) for sonic reasons.

 

RE: Is this a balanced signal path?, posted on December 6, 2014 at 09:03:15
Nglazer
Audiophile

Posts: 365
Location: New york
Joined: June 22, 2003
 Thanks, Mingus. The IC in question a JPS Aluminata, which cannot be reterminated to XLR, and I have no idea whether it will do what it needs to do. Sounds like I will keep using the RCA output option on the pre until I can get equivalent quality XLR IC's. Sounds darn good now, but you know how it is . . . .

Cheers,

Neal

 

RE: Is this a balanced signal path?, posted on December 6, 2014 at 09:13:02
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
 With an RCA plug it is always unbalanced with a ground return path. What is usually done is there is a shield that is connected at only one end. There is still a separate ground wire. What you don't get with this arrangement is the shield carrying the signal.
Using adapters as the OP is using will ground half the signal though.
Dan Santoni

 

RE: Is this a balanced signal path?, posted on December 7, 2014 at 12:48:08
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002



A balanced signal path involves differential signalling which requires both ends to feature balanced circuitry in order to form a "relationship" between both source and load. An unbalanced line-level rca interconnect interface, also known as a single-ended cable, involves no balanced circuitry to form a balanced relationship between the two ends of the cable. As such, it's not possible to have a true balanced signal path without corresponding balanced circuitry at each end and a correctly wired XLR cable involved at each end in order to provide the noise reduction benefits of a balanced XLR cable interface.

The following text is taken from from Wikipedia - Balanced audio

-snip-

Interference reduction

Balanced audio connections use a number of techniques to reduce noise.

A typical balanced cable contains two identical wires, which are twisted together and then wrapped with a third conductor (foil or braid) that acts as a shield. The two wires form a circuit carrying the audio signal; one wire is in phase with respect to the source signal, the other wire is reversed in polarity. The in-phase wire is called non-inverting, positive or "hot" while the out-of-phase wire is called inverting, phase-inverted, anti-phase, negative or "cold". The hot and cold connections are often shown as In+ and In− ("in plus" and "in minus") on circuit diagrams.[1]
Kabel-Symetrisch.png

The term "balanced" comes from the method of connecting each wire to identical impedances at source and load. This means that much of the electromagnetic interference will induce an equal noise voltage in each wire. Since the amplifier at the far end measures the difference in voltage between the two signal lines, noise that is identical on both wires is rejected. The noise received in the second, inverted line is applied against the first, upright signal, and cancels it out when the two signals are subtracted.

This differential signal recombination can be implemented with a differential amplifier. A balun may also be used instead of an active differential amplifier device.

The wires are also twisted together, to reduce interference from electromagnetic induction. A twisted pair makes the loop area between the conductors as small as possible, and ensures that a magnetic field that passes equally through adjacent loops will induce equal levels of noise on both lines, which is canceled out by the differential amplifier. If the noise source is extremely close to the cable, then it is possible it will be induced on one of the lines more than the other, and it won't be canceled as well, but canceling will still occur to the extent of the amount of noise that is equal on both lines.

The separate shield of a balanced audio connection also yields a noise rejection advantage over an unbalanced two-conductor arrangement (such as used in typical home stereos) where the shield must also act as the signal return wire. Any noise currents induced into a balanced audio shield will not therefore be directly modulated onto the signal, whereas in a two-conductor system they will be. This also prevents ground loop problems, by separating the shield/chassis from signal ground.

-snip-

See link:

 

RE: Is this a balanced signal path?, posted on December 7, 2014 at 16:21:31
Nglazer
Audiophile

Posts: 365
Location: New york
Joined: June 22, 2003
 Thanks, friends. I am illuminated. I ordered a pair of HiDiamond 3 XLR IC's, so we'll see if I hear any difference.

Neal

 

Sorry, no. n/t, posted on December 7, 2014 at 17:51:41
madisonears
Audiophile

Posts: 1587
Location: midwest
Joined: September 6, 2006
 nt
berate is 8 and benign is 9

 

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