Balanced inputs and outputs

[mrohde]

I have noticed these connections on the high end amps Krell and others. Could someone explain these connection, advantages where they go etc.

Thanks, for dealing with my basic questions,
Mike

[dyazdani]

This is a highly debated topic - balanced vs. RCA connections. They are line level connections just like the inputs/outputs with RCA connections. They are wired differently - balanced connections utilize a dedicated ground and a +/- signal. Single ended (RCAs) combine the ground and - signal on the same conductor. Balanced connections are typically said to have less noise infiltration, especially with long cable runs.

As far as actual benefits, you'll get stories all over the board on the merits of one way vs. the other.

[mrohde]

So, to use the balanced connections it looks like I have to give up my MIT Terminator 2 spealer hoses is that correct?

[dyazdani]

Not for speaker wires, it would be an interconnect change...

[whoaru99]

The biggest thing to consider is that most gear with balanced inputs and outputs is just that - balanced ONLY at the input and output stages with all circuits in between just the plain old single-ended variety.

Certain models of high-end gear do contain fully balanced circuits all the way though, but those are a fairly small percentage overall.

IMO, the biggest pro and con arguments I've seen are...

PRO - Can reduce/eliminate certain kinds of noise from getting into the system through the cables due to common mode rejection.

CON - Typically more complex circuity therefore more parts in the signal path and more potential sources of signal degradation.

I use one pair of balanced connections in my music/HT system. That pair is between a 2-ch pre-amp and power amp that are integrated into my HT via a surround sound pass-though. It's used not for the CMR, nor for any particular sonic characteristic. The use is purely because I need the 6dB gain to have more optimal symmetry between the HT and HT bypass loop gain/levels.

[mrohde]

Thanks to everyone for the info!

[Lex]

The original reason for balanced or XLR connections was noise reduction over long runs. Like 50 feet or more. Whoareu99 is mostly correct I think in his explanation. It is typical that "true balanced" topology tends to be found only on higher end gear only. Mark Levinson etc... The fact is, true balanced only requires 2 pins be used, I have such infrequent requests for such, I rarely get into this area. But generally that's true. Those same interconnects may not work when connected to gear that is not true balanced if built strictly for true balanced.

[aud19]

Yup, for starters a good percentage of equipment with balanced connections isn't truly balanced topology, hence no real bennefit.

Second, as also pointed out balanced connections are really only benneficial on long and/or noisy runs with truly balanced equipment. In the case of noise, your likely better off finding and correcting the cause of the issue if possible.

So basically most of the time your better off spending the extra money on higher quality RCA's or other improvements/equipment in your system IMO.

[ThomasW]

The only downside to fully balanced gear with dual differential circuitry is cost.

The sonic benefit of balanced audio circuitry is increased headroom at all frequencies, lower noise floor, and greater dynamics.

[Shawn Parr]

Whether equipment is 'fully' balanced or not, you will get better performance for long runs. Typically long runs are considered anything over 20'. Whether a transformer is used or a differential amplifier you will get an increased CMR from balanced connections.

The whole point of having 'fully' balanced inside of equipment has less to do with noise rejection and more to do with the fact that both transformers and differential amplifiers can have an audible effect, which many find to be negative. If the equipment doesn't require input transformers/differential amps you get the benefit of running long runs without the coloration of converting back and forth to balanced.

EDIT: I wanted to add that since in a balanced circuit you can get a full electrical circuit between the hot and cold legs, you can remove the ground (referred to as a ground lift) to combat noise/hum from ground loops. Ground loops can be caused by many things, including having equipment interconnected while on different circuits, badly designed equipment, and improperly grounded cable TV runs (very, very common).

[whoaru99]

Whether equipment is 'fully' balanced or not, you will get better performance for long runs. Typically long runs are considered anything over 20'.

Maybe, maybe not.

Is the potential benefit of balanced connection really a benefit if the (noise) problem it addresses is not an issue?

Kinda sorta, IMO, like putting premium gas in a car that runs just fine on regular...

[Shawn Parr]

Is the potential benefit of balanced connection really a benefit if the (noise) problem it addresses is not an issue?

The benefit of a balanced connection in and of itself does very little if you do not need the improved CMR, or if you do not need to deal with special grounding systems.

However some people like the sound that the transformers/differential amplifiers give to the equipment on non-fully balanced equipment. In that case those people would like balanced whether they have the technical issues requiring it or not. Some people dislike the color from those components and thus try to avoid it when possible. That becomes a matter of taste/preference.

Case in point, in my home studio I have the capability to be balanced in all of my connections except the input to my amplifier (a Crown DC-300A Series II). I purposely chose to unbalance the signals at the volume control for my monitors as I installed a DACT CT-2 stepped attenuator.

The cable runs from my equipment into the volume control module I have are extremely short, definitely less than 10', so noise was not an issue, and the DACT is an amazingly pure & precise volume control (it had better be for over $200 for a friggen' pot), so the sonic benefit from the CT-2 greatly outweighs the possible lessened CMR in the system at that point.

I also happen to work in the Theatre as a Sound Designer. When I set up a system in a theatre I almost always have runs in excess of 10', often over 30' -50'. In that case I will definitely always use balanced as with dimming systems, motorized equipment, and other fun goblins, noise is a significant issue. Any unbalanced equipment goes into a DI box within 10' of cable to balance it before running to anything else in the system.

In that situation, even if there is less that preferred coloration due to the balancing circuits, that greatly outweighs the potential noise issues if you do not use balanced. Also you never know when you will be forced to utilize multiple circuits/legs of power and have to ground lift to remove ground loop issues.

But everyone has their own situations and preferences. Personally I wouldn't go with fully balanced HiFi gear unless upon listening to it there that specific piece of gear sounded good enough to justify dealing with it. Of course that can lead to issue as then you need other equipment to interface it with and the potential for them to be unpleasantly colored.

In the end, you should probably find a way to listen to it first if you can, then make your choice on what makes your ears happy.