Balanced or unbalanced - that is the question

[GCT]

Just a theory question here.

If pro amps need 1.3V to deliver max power and the input is 1.3V unbalanced, the power amp gets 1.3V. If the mixer output is balanced that is + - 1.3V so the preamp will subtract in the input stage and give 2.6V to the power amp.

Or is balanced analogue output not + - 1.3V at 0VU

Cheers
GCT

[Allanvh5150]

I think you will find the voltage is measured peak to peak and not +-. 1.4v balanced or unbalanced.

Allan.

[GCT]

I'm guessing that balanced out will take into consideration the increased voltage that would appear at the amps differential input and compensate. Will have to measure it to be sure but I'm guessing balanced output is + - 0.7V

OK Allan I think you just said that. Mystery solved.

Thanks
Graham

Oh yes you did say it and also that unbalanced is also 1.4V which is where the question started, as I knew my unbalanced output was 1.4V at 0VU. I understand stuff little by little. Cheers.

[Eaulive]

I guess when it's mentioned "1.3V for max output" it is assumed that this voltage is applied between pins 2 and 3.
When you apply this voltage to pin 2 only and use pin 1 and 3 shorted as ground, the amplifier sees half the voltage and its voltage output is halved (75% less power output)

That's my take on it.... if that was the question

[Rolf]

Don't know about this V question, but to get the same quality in sound using balanced as unbalanced, my experience is that balanced cables is much more expensive to get the same sound quality.

Just a theory question here.

If pro amps need 1.3V to deliver max power and the input is 1.3V unbalanced, the power amp gets 1.3V. If the mixer output is balanced that is + - 1.3V so the preamp will subtract in the input stage and give 2.6V to the power amp.

Or is balanced analogue output not + - 1.3V at 0VU

Cheers
GCT

[GCT]

Thanks.
Yes, my mistake was thinking balanced was + - 1.3V and it's not - As Allan pointed out it's + - 0.7 ish so that the amp will always get the correct voltage from balanced or unbalanced desk - unless you use a balanced desk and only use half the signal - in which case the amp gets half voltage + noise.

Cheers
GCT

[Eaulive]

I'm not quite sure I follow but if you found your answer, that's what counts

[1audiohack]

http://www.rane.com/note124.html

See if this helps.

All the best.

[Ducatista47]

Don't know about this V question, but to get the same quality in sound using balanced as unbalanced, my experience is that balanced cables is much more expensive to get the same sound quality.

Your question is off topic but worthy of answers. In all my years of looking into this, I find the answer seems to be:

Balanced is to eliminate outside (non source signal) noise in a line. The current interest in wiring things balanced to increase sound quality - as in the high fidelity sense - is indeed worthless.

Balanced is traditionally the domain of sound reinforcement for concert and PA (public address - amplification of voice so a crowd can hear) systems. That is because one might have low level lines (= interconnects), speaker cables and power (AC) cables strung all over each other, and for long runs. Most home audio setups have none of these conditions present.

The one hifi situation where balanced might be necessary would be powering a dynamic - non electrostatic - headphone from two monoblock amplifiers.. Then you need to split the common ground used in almost all headphone cables. But it does not make sense there either, as it will need to be two wire into the monoblock.

Over at Head-Fi kids are crazy about balanced wiring. These are the same guys who think you need a $2000 DAC and believe they can hear jitter.

Even if balanced did have some sonic advantage besides elimination of outside noise sources, to work that would need to be balanced from the source - CD player, phono cartridge, server and DAC, whatever, all the way to the power amp. In sound reinforcement, transformers are sometimes used to create a balanced line for cable runs; a DJ turntable to a mixing board or amp is one possibility. Nothing to do with sound quality of the original music signal. Sound reinforcement usually does need a balanced source - look at the wires lying all over a concert stage at a club - so professional microphones have balanced outputs. The same for recording studios, where cables run or route all over the place, often in close proximity.

To those guys at Head-Fi: Good luck finding a moving coil phono cartridge with balanced output.

Edit: this is pretty esoteric, but I am told balanced can double the slew rate of an amplifier in certain setups.

[10 Watt Street]

"To those guys at Head-Fi: Good luck finding a moving coil phono cartridge with balanced output."

A moving coil phono cartridge is a balanced source, all that is needed is the correct cabling for connection to a balanced input phono stage. Easily done.

[Eaulive]

A moving coil phono cartridge is a balanced source

Indeed, just as a moving magnet cartridge or dynamic microphone element, as long as they have no lead connected to the chassis.

[Ducatista47]

I stand corrected! Still, I think it would be sonically useless for home use.

Sorry to go OT.

[10 Watt Street]

I prefer balanced operation whenever possible, home or pro applications. Indeed it is more costly and problematic with tube electronics. In general, it is more dynamic and quieter.

[Eaulive]

I also don't think there's a difference for home use, if all the devices are in close proximity and the power cabling and grounding is good, no problem.

The problem when mixing pro and consumer gear is that they have different levels of signal, not so much because of the balanced / unbalanced issue.

The output of a PRO audio equipment can reach in excess of 20VRMS, which is way higher than the consumer level of a couple of volts.

[jcrobso]

With unbalanced you the common mode rejection of interference signals along the cable.
This makes the balanced cable less prone to outside interference.
The Amp needs 1.3V for full power, it will not matter if the source in balanced or unbalanced.