Balanced v. Unbalanced

[AIA]

Hi All-

It's time for me to move into separates. One big decision point is to go with a balanced or unbalanced system. One obvious difference is cost; balanced systems are (relatively) more expensive than unbalanced. That said, it is not clear to me how much better a balanced system is compared to unbalanced - and I have not seen any metrics to make an argument one way or the other.

In the High End 7.x Channel Recommended Systems here at Audioholics, Steve Munz notes
"On the amplifier side, the Model 7200 isn’t a balanced design like the 7700, which does appear to have a marginal effect on distortion and noise."
That 'marginal effect' (as well as a few other features) translates into a nearly 40% bump in cost. Is the balanced system 40% better than the unbalanced? Is that even a fair question?

A long time ago (1994) , Martin Colloms concluded after a four page article on Steroeophile.com that
"Balanced mode may turn out to be a fashionable whim—a device to promote sales—and may not add any musical value to home-audio systems, even at the highest quality level." Part of the concern then was lengthening (and duplicating) the signal path in what where already satisfactory unbalanced systems.

So....I put it to the value-oriented Audioholics community: Balanced or Unbalanced?

 

[markw]

When I did pro work, sound for churches, we used balanced connections when long runs for very low level signals (like microphones) were needed because balanced runs would provide the most noise free signal.

for home use with normal home type lengths in the typical home environment, it's not needed.

It may look and sound impressive, and the unknowing might be impressed, but it's like putting "Y" rated tires on your car when you don't go over the speed limit.

 

[AcuDefTechGuy]

2 words that always associate with speakers, subs, and electronics: Diminishing Returns.

Paying twice as much won't always get you twice the actual AUDIBLE performance.

Also, not all "fully balanced" electronics are created equal.

 

[elwaylite]

I have short runs and did it over a blue jeans cable LC1 RCA setup for a couple of reasons:

1) Their XLR cable is more flexible
2) They lock in place
3) XLR does reject noise better, BUT, there is no guarantee it would be worth it

I just spent $3400 on a preamp and amp, wasn't really worried about the cost of the XLR's and it's done and they are there without concern.

1 ft of LC1 is $13, 1 ft of XLR is $23.

 

[Irvrobinson]

There's a difference between balanced electronics and balanced connections. I agree with Mark about balanced cables. For short runs they're likely not necessary; for longer runs (like my 35' preamp to amp connections) they're preferred.

Balanced electronics are a more controversial topic. In theory balanced electronics can be superior, due to common mode noise and distortion cancellation, which can be considerable, but some folks question if the benefits are worth the 2x or more circuitry cost. Gene has been a big advocate of balanced electronics, and he measures them for a living. In my case, I have balanced and unbalanced amps from the same manufacturer, and I can't hear any differences between the amps, including the idling noise floor. Still, my audio system is balanced end-to-end, well, just because I wanted to take advantage of every opportunity for improvement, and I spent 99th percentile money on it (which is another questionable decision). For people with more sense than money I think unbalanced electronics generally work more than well enough.

 

[Swerd]

Mark has it right, Martin Colloms guessed right back in 1994, and your instincts are right. Save some money, and pass on paying more for balanced connections.

Balanced connections are commonly used for live audio and in recording studios, especially for microphones with long cables. Long cables (30 feet or more) carrying weak microphone signals, (~1-3 mV) can pick up noise induced by electromagnetic interference (EMI) or radio frequency interference (RFI). Balanced connections along with the differential circuits required on the electronic gear can cancel out this noise. Pro audio chose to standardize on one type of signal cable, mainly to avoid confusion.

Balanced connections do seem to be fashionable in home audio for preamp-to-amp connections, and many higher priced examples feature these as a sought-after and expensive feature. The voltage levels between preamps and amps (in the range of 0.1 to 5.0 volts) are much higher than at the microphone level. So it is likely that interconnects at this level are much less prone to EMI induced noise, especially if they are less than 30 feet long. Unless you have an unusually noisy environment with high levels of EMI, there are no benefits from using balanced connections over standard RCA interconnects.

To be fair, if the entire electronic signal chain has full differential circuits and is connected with balanced cables on all devices in the chain, it could provide an additional 3 dB in dynamic range. This would include all devices from a sound source like a CD player (or DAC) through preamp and amp. For stereo sound, it would require a 4-channel DAC, a 4-channel preamp and a 4-channel amp to maintain balanced operation from input to output, summing the signal at the speakers. In theory, this would cancel all common mode distortion in the electrical path, and achieve as much as 3 dB extra headroom depending on how much distortion there originally was to cancel. While not insignificant, this would cost a premium.

Providing balanced connections only between a preamp and amp will not accomplish this.

 

[slipperybidness]

Personally, in my home(s), I have not yet had any need for balanced connections.

That's the deal, don't correct a problem that doesn't exist in your system. If your system has a particular problem, then balanced might make sense.

1 thing that I do like about XLR Connectors is that they tend to "click" into place and hold very well. That click is re-assuring that you have indeed made a good connection.

 

[TheWarrior]

For a long run to a subwoofer, I use XLR on the off chance a long RCA is able to pick up some interference. That, and its a solid locking connection. Otherwise you would never notice.

 

[herbu]

It's time for me to move into separates.

This sounds like your audiophile journey is not yet at its peak.
Have you spent > $10k on your speakers?
Do your subs, (plural), go for $1.5k or more... each?
Is your theater room especially designed for audio?
If one or more of these answers is "no", there are probably bigger bang for your buck ways to spend $ than on balanced equipment, IMO.