Unbalanced vs Balanced Interconnects. Was I taught Wrong?

[Want.to.Learn]

Considering Interconnects

What is the trade off. Transformers or Electronic Balancing Circuits (usually op amp) in line and the sound degradation inherent with balanced systems from those components, vs. long unbalanced RCA terminated cables.

Lets assume the components are powered from the same source and the interconnect cables are similar length to the ac cables to minimize ground loop hum

For example mounting small power amps on the back of 2 way speakers to eliminate external speaker wires and the whole debate.

Shall we choose 14ft long interconnects to start with? and 25-30ft?

Anyone have any thoughts?

 

[Blumlein 88]

Are you in Australia by any chance?

 

[Speedskater]

a] There are no real world frequency response differences between well designed XLR balanced interconnects and RCA unbalanced interconnects.
b] Long RCA interconnects can have more background noise & hum, especially when the units are powered from different AC circuits.

 

[Plcamp]

The thing balanced is good at is rejection of common mode noise.

Your chances of hearing common mode noise are higher with unbalanced and higher with the length of the unbalanced. If you do experience noise, you might be able to at least partially suppress it with clamp on ferrite beads.

I have used 50’ unbalanced rca in my basement with no noise…I am just lucky.

 

[AnalogSteph]

b] Long RCA interconnects can have more background noise & hum, especially when the units are powered from different AC circuits.

Although contrary to popular belief, length actually isn't necessarily the deciding factor... plenty of people have run into nasty ground loop issues just hooking up some active monitors on their desk to the PC right besides.

I have used 50’ unbalanced rca in my basement with no noise…I am just lucky.

Just a matter of the right equipment. If there are no direct ground loops involved and power supply mains leakage is low, unbalanced with decent-quality cabling and low output impedance works just fine. I see no problem with hooking up a typical CD player or a little headphone amp (the kind with a modest-size transformer plug pack, think e.g. Atom Amp+ / Magni Heresy / L30 / L50) using a fairly lengthy RCA cable. A high-wattage power amp may prove more tricky, they commonly are IEC Class I devices for one reason or another.

As a rule of thumb, interconnects in general lend themselves to greater lengths than speaker or headphone cable. The cable cross-section required for the same damping factor in passive speakers goes up with length and may become fairly impractical past a few meters (not to mention that some amplifier designs do not appreciate capacitive loading too much), and it is virtually impossible to extend a traditional unbalanced TRS headphone cable without compromising crosstalk. Admittedly, a floating transducer cannot be part of a ground loop.

It should come as little surprise that I tend to suggest keeping headphone amps in arm's reach, which is the most convenient option for operating them by far.

 

[Katji]

Are you in Australia by any chance?

Quite clearly in America.

 

[Speedskater]

Although contrary to popular belief, length actually isn't necessarily the deciding factor... plenty of people have run into nasty ground loop issues just hooking up some active monitors on their desk to the PC right besides.

Very true.
The deciding factors are:
a] difference in potential of the two connection chassis.
b] end-to-end resistance of the RCA cable's shield.

 

[DVDdoug]

What is the trade off.

There are no trade-offs. Balanced is (potentially) better!

Transformers[/quote]Transformers pretty much went out-of-style with vacuum tubes! But they are still used in guitar direct-boxes and it's often a good solution if your equipment doesn't have a balanced connection and you need one. (And transformers can be very good.)

or Electronic Balancing Circuits (usually op amp) in line

There will be an op-amp (or discrete circuitry) anyway. It doesn't take much more to make a balanced circuit. With an op-amp input it just means a couple more resistors. For a balanced output you'd need another op-amp, or a dual op-amp, etc. The biggest additional expense might be the XLR connectors.

For example mounting small power amps on the back of 2 way speakers to eliminate external speaker wires and the whole debate.

That's a different issue. The amp built-into an active speaker can be balanced or unbalanced. Most active studio monitors have balanced connections, sometimes with an optional unbalanced RCA connection. Most active subwoofers are unbalanced RCA connectors.

 

[radix]

I believe many (most? all?) high-end DAC chips put out a balanced signal to begin with, so it's not something that has to be fabricated with an extra op-amp. As @DVDdoug mentioned, there will always be a line driver op-amp.

Another possible advantage of balanced is they usually run at 4V (or more), so you could have higher SNR. So, hot outputs and common mode noise rejection are the two big pluses for balanced.

 

[DonH56]

The basics:
https://www.audiosciencereview.com/...d-balanced-unbalanced-and-all-that-jazz.1352/
https://www.audiosciencereview.com/forum/index.php?threads/ground-loops-101.7162/

 

[dfuller]

Transformers pretty much went out-of-style with vacuum tubes!

Not really. Transformers are used in a lot of pro audio stuff, both for the belief that they can impart color onto a signal (they can certainly induce audible distortion) and that they can provide impedance matching and step up/step down capabilities, as well as blocking DC.

What is the trade off.

Balanced is marginally more expensive, I guess?

For example mounting small power amps on the back of 2 way speakers to eliminate external speaker wires and the whole debate.

Speaker level signals are more or less immune to interference unless you live next to a radio tower or something, and even then, more likely it couples in elsewhere. No, the benefit there is to go active and place the crossover before the amplifiers.

 

[solderdude]

Considering Interconnects

What is the trade off. Transformers or Electronic Balancing Circuits (usually op amp) in line and the sound degradation inherent with balanced systems from those components, vs. long unbalanced RCA terminated cables.

Lets assume the components are powered from the same source and the interconnect cables are similar length to the ac cables to minimize ground loop hum

For example mounting small power amps on the back of 2 way speakers to eliminate external speaker wires and the whole debate.

Shall we choose 14ft long interconnects to start with? and 25-30ft?

Anyone have any thoughts?

When you are not plagued by hum/ground loops there is no benefit in going balanced in that specific circumstance when one already has SE system running.

Circumstances may change over time (different speakers/gear/position of the gear or changed components) or when one doesn't have gear yet and money and component size is less of a constraint then going balanced may prevent some possible issues with ground loops/hum.

Sound quality (assuming no external interference) is not going to be better between balanced and SE.

 

[kongwee]

XLR is technical superior especially in solving noise. There are many device doesn't take this advantage but give more attention to single end. $150k tube amp no balance, but it people's dream amps. Of course, there are solid state amps no give a damp about XLR. You have read the designer philosophy. For XLR, just need to know you have to keep the differential signal active at both end and nothing else.