Balanced vs. Unbalanced output

[Bossbandbob]

Would a powered mixer or speaker with XLR outputs deliver significantly more high fidelity to FOH than a mixer or speaker that only has an unbalanced 1/4" output going into a DI box then XLR out to FOH?

This is what a Sound guy told me at a gig on Sunday. I know a balanced line cuts down on noise interference on long runs but I don't understand how the sound fidelity could be that much different. If that were the case wouldn't high end home stereo systems employ XLR cables as well?

[b3plyr]

All things equal, an XLR output will not deliver higher fidelity than an unbalanced output. The primary advantage of the balanced XLR outputs is, as you noted, lower noise over a long run. However, if you have an unbalanced output that you connect to a direct box by a fairly short cable, and then the direct box XLR to FOH, you will still get the advantage of a low noise long run.

 

Some keyboards, but not many, have balanced outputs. Roland has used XLR, and Kurzweil balanced phone jack outputs. So you don't have to have an XLR connection to have a balanced output. You just have to have a balanced output stage and the appropriate output connector.

 

Having said this, and having owned keyboards with balanced outputs, my current keyboards do not have balanced outputs and I use the short cable to direct box to XLR to FOH and have no noise issues.

[WesG]

High-end home stereo systems DO have balanced connectors. But for noise reasons.

[Bossbandbob]

Come to think of it my Roland VK7 has Balanced 1/4" outputs.

[Sven Golly]

Unless you're connecting a balanced output to a balanced input, you don't have a balanced system, so there's no benefit to having balanced outputs.

 

Balanced Audio on Wikipedia.

[ArKay]

Unless you're connecting a balanced output to a balanced input, you don't have a balanced system, so there's no benefit to having balanced outputs.

 

This

PS> Good to see you back SG

[timwat]

Unless you're connecting a balanced output to a balanced input, you don't have a balanced system, so there's no benefit to having balanced outputs.

 

Balanced Audio on Wikipedia.

 

Yup. Often overlooked if the user only knows "this shape plug" and "this shape socket" equals "this shape Radio Shack converter thing".

[ITGITC]

In my youth, about a hundred years ago, my band played at a venue that was very (very) close to WEED's AM radio transmitter.

 

Yes. In my little town, (besides being the birthplace of the infamous RMI Electra-Piano), we had a radio station with the call letters WEED.

 

However, back then it was the Golden Weed that we were concerned with, as Eastern North Carolina was a big tobacco producer. (We've even got a city named Winston-Salem.)

 

 

Perhaps it was because I was using a crystal microphone (anybody remember these?) It was a Tandberg brand that was a companion to a reel-to-reel tape recorder my father bought along with some prerecorded Broadway musicals like The Music Man and The Sound of Music.

 

Of course, the mic cable was unbalanced & the mic was high impedance... and there was NO WAY we could keep the Golden WEED out of our system that night. (I am STILL talking about tobacco.)

 

To make matters worse, the venue had huge dimmer controls for their house lights. These added a substantial buzz. (Yep! Still tobacco.)

 

Fun times.

 

So this topic has forever been a big deal to me.

 

I don't know if anything could have keept the Golden WEED out of the mic signal... or the guitar amps. However, maybe balanced cables could have helped stop the 60Hz noise.

 

OTOH, I've never seen a balanced jack mounted on a guitar... and I'm pretty sure that's where the noise was infiltrating our signal that night.

 

And back then, guitarists used extra long COILED cables - like you would find on your kitchen wall phone... If you followed the cable back to the amp, you would see that it often was the tuck-and-roll variety.

 

http://www.vintageguitaramplifiers.net/wp-content/uploads/2010/07/-94242506652394960.jpg

 

Aha.

 

Funny thing about the crapababble sound men say - it seems to me if they could back it up with, "I have HEARD better fidelity when using balanced cables (system)." their rhetoric would become a little more believable.

 

I've got ears. Although they're not as sensitive as when I was younger, I still trust them before I'll beieve some sound guy I don't know who's blowin' secondhand smoke in my face.

 

Besides... somebody right here on this forum (a long, long time ago) kept saying "Google is your friend".

 

Over and over and over again.

 

I think that finally stuck with some of us.

 

AND, most everybody's got a smartphone on their person these days. We know when sound guys are lying. (When their mouth is moving.) (Ummm, Izzat The Internet in your pocket or are you just glad to see me?)

 

 

Ummmm... that's enough for today.

 

Unless you want my opinion about whether or not Rock & Roll should ever be humble.

 

Tom

 

 

 

[Ken Beaumont]

Guitars use humbucking pickups to reduce noise. The two coils are wound in opposite directions so when a noise or hum is induced the two coils created cancels the noise. Which is why a person playing a single coil guitar like a Telecaster can have a ton of noise while a Les Paul won't have the issue. In extreme situations a noise gate pedal is a handy device to have.

 

Though rarely I have picked up AM radio stations before, its annoying to say the least. Edit: I remember once the band ended a song and the religious station came out of the PA "Thank the Lord!"

[JeffLearman]

First, ignore the connector type, because either can be used for either. You have to read and understand the product specs to know for sure.

 

XLR is *usually* balanced but not always. It's a more robust connection than a 1/4".

 

1/4" can be either unbalanced (TS) or balanced (TRS). It's a less robust connection, but seems fine for most live uses.

 

Balanced is unquestionably better than unbalanced for a number of reasons, but probably not in any significant way for typical live applications. The main reason is "common noise rejection", which means it's less likely to pick up hum from the environment. There are others, though (less transmission-line attenuation of high frequencies) but none likely to matter.

 

Furthermore, having a balanced connection doesn't mean you don't need a DI box, because you may need the ground lift that a DI box will do. Also, you don't want to plug line outputs into low-Z mic inputs, which is another (impedance matching) function that a DI provides.

 

Line outputs are designed to be plugged into mid-to-high impedance inputs (e.g., 5KOhms). They used to have specs to indicate the minimum impedance for the load, but don't any more. Does that mean that they can be plugged into a low-Z input without any loss of fidelity? I sure don't know. It might be that manufacturers just gave up posting specs that few people bothered to read.

 

Bottom line: Balanced is better (when used correctly, as Sven points out). If I were comparing two pieces of gear that are otherwise identical but one has balanced, I'd prefer balanced. But I've always chosen gear based on far more important issues.

 

Cheap brand-X balanced gear is unlikely to sound better than top quality unbalanced gear.

[JeffLearman]

Here's a good example of needing to read and understand the specs. In a recent thread, someone asked about the daisy-chain output XLR connector for a powered speaker.

 

As it turns out, that connector is balanced if and only if the input signal was balanced (which could have been from an XLR or TRS 1/4" jack).

 

[J. Dan]

Jeff nailed it. I'll add just one thing. If a balanced and unbalanced output from a device are equal sound quality, running the unbalanced through a DI can degrade the signal compared to the balanced and depending on the quality of the DI. Passive DIs use transformers, which have some signal loss, frequency response limits, and potentially distortion. Active DIs can add noise and distortion. Most of this is negligible with a high quality DI, but there are a lot of low quality DIs floating around out there.

[OB Dave]

And if you find yourself in a situation where you need to mix balanced and unbalanced signals, this will tell you how to do it correctly.

[Bossbandbob]

Yes, Google is your friend..sometimes. I could find nothing about balanced vs. Unbalanced regarding fidelity, however. That is why we have forums like this. Thanks for all the informative responses. Yes, sound guys are not always right, but who is? In my experience though, I often wonder how many sound guys have hearing deficits due to dealing with years of excessive volume! Some are great but a few seem to have a particularly hard time hearing keyboards...

[Jazzmammal]

Here's a real world example of balanced vs unbalanced.

 

I have a PC3 which has balanced outs. I also use the EV ELX112P powered speaker which has balanced ins. I had two gigs last month at the same bar with the same band. The first gig I used an expression pedal for volume and used my balanced cable to go to the EV. This is a loud bar and I have that EV maxed out and control the volume from the keyboard and exp pedal. I have enough power for that gig. I noticed that pedal was giving me problems so for the next gig I brought my old analog volume pedal and I have to use my regular unbalanced cables for it by taking the audio output to the pedal and then the pedal to the EV. The power output loss from the EV was dramatic. I had the volume pedal on full and the volume slider on the PC3 up full and for some screaming B3 solos I was barely being heard.

 

I've read that there can be some power loss going from balanced to unbalanced and in my case it's correct. Hard to quantify exactly but it was certainly there. I bought another exp pedal that works fine and the system seems to have a bit more power again using the balanced cable.

 

Before somebody says it could have been my old analog volume pedal and not the unbalanced cables all I can say is I noticed the same thing at a big band rehearsal a week after I bought the EV over a year ago. An 18 piece big band can get LOUD and I was barely being heard so I switched to a balanced cable one of the guys had and again, more power. I didn't use any pedals, it was just a rehearsal so I controled it using the volume slider on the Kurz. A few days later I bought a couple of 10' TRS cables.

 

Using that EV at least, there's a definite power difference, not huge but it's there.

 

Bob

[J. Dan]

Depending on how it's handled by the EV, the balanced signal can be twice the voltage of the unbalanced. Think of it this way: you have Positive Voltage, Ground (zero), and Negative Voltage. Pick 1 volt. A balanced input takes + minus -. So +1 - (-1) = 2V peak to peak. IF it handles unbalanced the same way, then the '-' is now 0V. +1 - 0 = 1 volt.

 

So that's a 3dB reduction in volume using unbalanced vs balanced.

[miden]

FWIW I notice no difference in dB levels using UB or B - I would be looking at other things before arriving at that conclusion. And even if the was, I would be looking at the cable itself and impedance levels of the materials (ie swg rating, shielding specs, oxygen free etc etc) as the culprit, not that it is UB or B per se.

 

The example above (afaik) may be a little incorrect in that the + and - signals are phase reversed which is how an unbalanced cable rejects RF/other noises via induction over long cable runs with a separate non-connected ground/shield. I don't beleive it can be said that this means the dB level is increased (or decreased for that matter)

[Ken Beaumont]

My carvin power amp's manual says that if you use the unbalanced 1/4 inputs vs the balanced XLR gain is reduced by 6 db. LINK

[Stephen S]

There are a whole bunch of different topics/effects here. Some are interrelated, some are not.

 

Balanced vs. balanced - all other things being equal, fidelity is not necessarily better from balanced, but noise immunity is better.

 

Plugging a balanced vs. unbalanced cable end into a balanced input may or may not give you a hotter signal. It depends on the design of the input circuitry.

 

Side note - a hotter signal does not increase the maximum output capability of the speaker, but it may allow you to reach that maximum output level with a lower gain setting.

 

Related (sort of) is OUTPUT impedance of the source - in this case, the keyboard, driving the line. A balanced output is a professional type of output, which is almost guaranteed to have low source impedance. This means that it can drive long cables more effectively without degradation from the cable capacitance, etc. An active unbalanced output will probably have low source impedance, but exactly how low is dependent on the design. A passive keyboard (like a vintage Rhodes without preamp, for example) will have very high source impedance; the signal will be subject to a lot of degradation over long cables.

 

Adding an intermediate device (such as pedal, volume control, etc) may introduce any number of variables including signal attenuation, high output impedance, etc.

[ITGITC]

 

 

http://www.mediacollege.com/audio/balanced/cable-balanced.html

 

 

Balanced Audio Cables

 

Balanced audio cables use an extra line, and consist of a hot line (positive), cold line (negative) and earth. The audio signal is transmitted on both the hot and cold lines, but the voltage in the cold line is inverted (i.e. the polarity is changed) so it is negative when the hot signal is positive. These two signals are often referred to as being 180 degrees out of phase with each other but this is technically incorrect the signals are not actually out of phase, they are opposite polarities, i.e. one signal is effectively flipped upside down rather than being delayed 180°. This confusion could be due to the fact that in a graphical representation of a sine wave (pictured below) the effect of changing polarity and changing the phase 180° looks the same.

 

When the cable is plugged into an input (on a mixer or other equipment) the hot and cold signals are combined. Normally you would expect these two signals to cancel each other out, but at the input stage the inversion is reversed before being merged together, so they actually combine to form a stronger signal.

 

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Removing Noise

 

Along the length of the cable, noise can be introduced from external sources such as power cables, RF interference, etc. This noise will be identical on both hot and cold lines. This is known as a common mode signal - a signal which appears equally on both conductors of a two wire line.

 

So the hot and cold lines carry two signals: A desirable audio signal which has an opposite voltage on each line, and unwanted noise which is the same on both lines.

 

This is where the trick of balanced audio kicks in. At the input stage when the inverted audio signal is re-inverted to make both desirable audio signals the same, the unwanted noise is inverted. Voila - all the unwanted noise is cancelled out, leaving only the combined original signal.

 

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Note: For more information about sound phasing read Sound Wave Interactions, but note that sound wave phase interference is different from audio signal inverting.

 

Next Page: Combining Balanced Connections

 

 

[J. Dan]

My carvin power amp's manual says that if you use the unbalanced 1/4 inputs vs the balanced XLR gain is reduced by 6 db. LINK

 

Correct - my bad, I was thinking power gain, not voltage gain, in terms of dB.

[JeffLearman]

Even a 3dB difference is notable. My rig has a switch to reduce the power, and when I cut the power in half (for a 3dB SPL reduction), my rig is just not quite loud enough for those loud stages (e.g., blues jams). Normally it's fine. Shows you I don't have as much headroom as I might want!

 

A 6dB reduction is pretty significant. To many people, it sounds about half as loud.