balanced/unbalanced

pmckeealaska

OK...call me ignorant, but what is the difference between balanced (XLR) and unbalanced input jacks? My Rotel RB1080 amp has both. Is one better than the other??

unc2701

Balanced has a positive, negative and ground signal. If there is EMI/RFI it'll impact the positive and negative signals in equal but opposite directions. when they're put back together, the interference is canceled out (in theory).

You see them on just about all pro gear and more expensive consumer gear. Now what the amp does beyond the input varies as does what happens before the output on the preamp/ source. Some components are balanced design meaning the the signal is split positive and negative the whole way through and some designs convert it back to single ended.

Basically you will get better sound [using xlr's] if:
A)You have truly balanced signals start to finish
or B)You have very long cable runs or a noisy environment

dorokusai

A balanced design isn't indicative of better sound, that's an idea and theory. It's certainly marketable....hell, what isn't these days?

unc2701

dorokusai wrote:

A balanced design isn't indicative of better sound, that's an idea and theory. It's certainly marketable....hell, what isn't these days?

Very true- i didn't mean to imply that a balanced amp was in any way better. However, if you've got a balanced design + balanced sources, you're gonna benefit from the XLR's

Emlyn

pmckeealaska wrote:

OK...call me ignorant, but what is the difference between balanced (XLR) and unbalanced input jacks? My Rotel RB1080 amp has both. Is one better than the other??

With Rotel gear, I didn't notice any difference between their amps using XLR or RCA cables. Rotel gear is not fully balanced, so I have assumed there's no real difference with their connections. Rotel no longer makes a preamp for the U.S. market with XLR inputs or outputs, but it was my understanding that Rotel put XLR connectors on their amps for marketing purposes because it gives the impression of being higher end gear.

In my experience, benefits of using XLR cables have been in synergy between gear, not anything inherent in the cable design. My preamps have higher gain levels from their XLR outputs than the RCA outputs, and the amps have higher gain from the XLR inputs. This means the preamp volume has to be turned up less using the XLR connections than the RCA connections. This may or may not lower the noise floor of a system. It depends on the design of the gear (theoretical mostly). The only difference I can tell myself is that I have to turn the volume control up more with RCA connections than XLR connections.

There are a couple of design factors that can influence whether XLR connections are better in practical use. The Parasound Halo C2 processor has a separate board inside for its two channel direct XLR connectors. The only way to avoid running audio signals through the digital processing board in the C2 is by using the two channel XLR connectors. Audio quality is greatly improved by using its direct mode, and again this mode is only available using XLR cables. I also have a CD player with balanced outputs, which the manufacturer claims a somewhat lower noise floor when using XLR cables from its balanced outputs than through the RCA outputs. I can't tell any difference with it though. I'm also aware of, but don't own, Krell gear that the manufacturer recommends be run with XLR cables for optimum performance.

XLR cables used to be more secure physically than RCA cables, until good locking RCA connectors became available (Kimber, PS Audio, MIT and others use them now). XLR cables tend to be more expensive if purchased new than RCA cables of equivalent design level because of the extra materials required. However, the prices of XLR cables seem to fall more quickly than RCA cables in the used market because of lower demand. If I have the option of using XLR cables, I always end up using them. If it's not an option, it's not worth worrying about.

heiney9

My best advice (opinion) is if you are considering using balanced inputs make sure ALL your components are balanced otherwise it not really worth it unless you have RFI/EMI interference or you have very long runs of cable.

H9

BlueMDPicker

Another advantage of a balanced line might lie in its resistance to ground loop hum. If the ground potential between separates is different (which is often the case), mild to moderate hum can occur. Lifting the ground from the power cord of all but one component usually solves for this issue. But, since the balanced signal is always floating with respect to ground, any difference in potential should have no effect on output. (Thanks to Raife and Chuck for helping me get my Jr. EE merit badge )

I'm just starting the learning curve with my first balanced components. Like the Halo C2 Emlyn referenced, the Lightstar Direct provides a passive, silicon free signal path in balanced operation. It will be interesting to compare the nuances once my XLR cables arrive.

Question: my CDP does not have balanced outputs. What would a properly constructed RCA>XLR IC consist of with respect to conductors and shielding? Would it have two conductors and a shield - with the shield not terminated on the RCA end?

unc2701

Tie the negative and the ground to the shield and the positive to the core if you're using coaxial cable. If you use the twisted pair XLR cable, then it's the same thing- neg and shield go to the neg on the RCA and positive goes to the tip.

However, you're probably going to find that you have to turn up the volume twice as loud and your only benefit is the direct processing in your Lightstar.

rskarvan

Every truly balanced (XLR) connection that you add to a system adds an additional 6 db of gain to the overall volume level. This is (usually) one of the three advantages of operating in balanced: 1- its a better sounding circuit in general overall over that of a single-ended design, 2 - you get a lower noise floor - meaning you hear more of the music and less noise, and 3 - you get an additional 6 db of gain.