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Difference between impedance and electronic balancing?

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Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 8:39 am
by Arpangel
I’ve been looking at the manual for my MixWiz mixer, it says that all the outputs are impedance balanced, what is this? Here is an extract from the manual.......

"MATRIX OUT A, B Each matrix output is available on an impedance balanced TRS jack operating at -2dBu line level. An internal option is available to fit a balanced line driver IC to provide an electronically balanced output operating at +4dBu. Note that it is not usual to require this option as the im- pedance balanced standard drive provides significant interference rejection when feeding balanced equipment inputs.
The matrix outputs are typically used for stereo or mono recording or broad- cast feeds, delay and fill speakers, zone feeds, hearing assist loops and so on"

In what circumstances would electronic balancing be used, or be beneficial? just a bit confused here.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 8:52 am
by CS70

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 8:58 am
by Arpangel
CS70 wrote:https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing#:~:text=Impedance%2Dbalanced%20Send%3A%20Increasingly%2C,ensure%20proper%20common%2Dmode%20rejection.

Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 9:54 am
by ef37a
Arpangel wrote:
CS70 wrote:https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing#:~:text=Impedance%2Dbalanced%20Send%3A%20Increasingly%2C,ensure%20proper%20common%2Dmode%20rejection.

Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

Perhaps the main advantage of a twin amplifier differential output is the 6dB lift when going into a proper balanced input? There are a couple of disadvantages however, especially for the 'knockabout, home recordist' who might not have much technical knowledge.

The first is possible distortion or at least 'breakthrough'. If a TS plug is inserted into a TRS jack the ring is of course shorted to ground. If that ring is driven, the op amp will clip and although modern chips will likely stand that indefinitely, the clipping could break through into the hot output because the balance output IC is almost sure to be a dual op amp.

The second pitfall is polarity preservation. Even in a modestly complex setup (i.e. NOT yours Tony!) it is possible to have a miss wired TRS plug or XLR and with a dual amp output you might never know until it is too late. Impedance balanced outs give you Jack **** if you wire them wrongly.

Dave.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 10:59 am
by Arpangel
ef37a wrote:
Arpangel wrote:
CS70 wrote:https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing#:~:text=Impedance%2Dbalanced%20Send%3A%20Increasingly%2C,ensure%20proper%20common%2Dmode%20rejection.

Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

Perhaps the main advantage of a twin amplifier differential output is the 6dB lift when going into a proper balanced input? There are a couple of disadvantages however, especially for the 'knockabout, home recordist' who might not have much technical knowledge.

The first is possible distortion or at least 'breakthrough'. If a TS plug is inserted into a TRS jack the ring is of course shorted to ground. If that ring is driven, the op amp will clip and although modern chips will likely stand that indefinitely, the clipping could break through into the hot output because the balance output IC is almost sure to be a dual op amp.

The second pitfall is polarity preservation. Even in a modestly complex setup (i.e. NOT yours Tony!) it is possible to have a miss wired TRS plug or XLR and with a dual amp output you might never know until it is too late. Impedance balanced outs give you Jack **** if you wire them wrongly.

Dave.

Thanks, should I be surprised that Allen & Heath have opted for this? or is electronic balancing only for really high end mixers?

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:27 am
by ef37a
Arpangel wrote:
ef37a wrote:
Arpangel wrote:
CS70 wrote:https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing#:~:text=Impedance%2Dbalanced%20Send%3A%20Increasingly%2C,ensure%20proper%20common%2Dmode%20rejection.

Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

Perhaps the main advantage of a twin amplifier differential output is the 6dB lift when going into a proper balanced input? There are a couple of disadvantages however, especially for the 'knockabout, home recordist' who might not have much technical knowledge.

The first is possible distortion or at least 'breakthrough'. If a TS plug is inserted into a TRS jack the ring is of course shorted to ground. If that ring is driven, the op amp will clip and although modern chips will likely stand that indefinitely, the clipping could break through into the hot output because the balance output IC is almost sure to be a dual op amp.

The second pitfall is polarity preservation. Even in a modestly complex setup (i.e. NOT yours Tony!) it is possible to have a miss wired TRS plug or XLR and with a dual amp output you might never know until it is too late. Impedance balanced outs give you Jack **** if you wire them wrongly.

Dave.

Thanks, should I be surprised that Allen & Heath have opted for this? or is electronic balancing only for really high end mixers?

No, I think it is a perfectly reasonable design decision? There is surely little need for signal capability* of +28dBu these days? There might be certain 'professional' situations where you need to drive very long, >50mtrs say balanced lines and a symmetrical very low source resistance drive is needed to combat noise in areas of high field strengths but for the vast majority of small scale indoor setups bit of an overkill?

For the home recording bod, balanced operation is not even needed in many circumstances and in any case, how many synths, drum machines and guitar amps have balanced line outputs? "Balanced" is undoubtedly desirable but not always required. What IS important is that sources have as low an impedance (resistance really) as possible. It is a Law of Physics that if a cable is at zero Ohms you cannot 'interfere' with it!

* For a long time my setup was a ZED 10 feeding 5 mtrs of cable to a pair of OEP 10k-10k bridging transformers then to the RCA inputs of an M-A 2496 card. The noise floor, Main Out pot at min was -93dBfs.

Dave.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:35 am
by Hugh Robjohns
Arpangel wrote:Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

It is cheaper, but not inferior if done properly (and A&H know how to do it properly), and a lot more practical for a mixer like yours. The situations where a fully symmetrical active output are genuinely required are few and far between, and actually in most of those a floating transformer output is often a better idea anyway!

In the case of the A&H desk the reasons for installing the balanced line-driver chip would probably centre on a need for a +4dBu nominal output level (instead of the -2dBu in its i-Z form).

I'm astonished this is a new concept to you...

And Cristian, thanks for saving me a lot of typing! :D :thumbup:

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:41 am
by CS70
Arpangel wrote:
CS70 wrote:https://www.soundonsound.com/sound-advice/q-how-impedance-balancing-audio-different-normal-balancing#:~:text=Impedance%2Dbalanced%20Send%3A%20Increasingly%2C,ensure%20proper%20common%2Dmode%20rejection.

Thanks, seems like impedance balancing is the cheap option, although not inferior to electronic balancing?

Yeah, insofar I read Hugh, it's less components so cheaper (and less that can go wrong), sonically identical when connected to balanced inputs (it does the same job), but perhaps "better" when connected to unbalanced inputs, because you won't get the usual -6dB reduction due to reading only from one wire.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:42 am
by CS70
Hugh Robjohns wrote:And Cristian, thanks for saving me a lot of typing! :D :thumbup:

I read that very article when I was wondering myself what it meant, so thank you :)

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:43 am
by Arpangel
ef37a wrote:
No, I think it is a perfectly reasonable design decision? There is surely little need for signal capability* of +28dBu these days? There might be certain 'professional' situations where you need to drive very long, >50mtrs say balanced lines and a symmetrical very low source resistance drive is needed to combat noise in areas of high field strengths but for the vast majority of small scale indoor setups bit of an overkill?

For the home recording bod, balanced operation is not even needed in many circumstances and in any case, how many synths, drum machines and guitar amps have balanced line outputs? "Balanced" is undoubtedly desirable but not always required. What IS important is that sources have as low an impedance (resistance really) as possible. It is a Law of Physics that if a cable is at zero Ohms you cannot 'interfere' with it!

* For a long time my setup was a ZED 10 feeding 5 mtrs of cable to a pair of OEP 10k-10k bridging transformers then to the RCA inputs of an M-A 2496 card. The noise floor, Main Out pot at min was -93dBfs.

Dave.

Thanks, yes, I used to work completely unbalanced, never thought it necessary with my short cable lengths, but I do have a lot of balanced stuff now, so, why not?

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 11:54 am
by Hugh Robjohns
Everyone gets hung up on the benefit of 'balanced' being the rejection of interference, but in most modest installations there is negligible interference, especially for line-level signals.

Instead, the more useful benefit is the fact that a differential input doesn't require a ground reference. That provides a very powerful means of avoiding ground-loop problems when working with unbalanced sources... if you know how to make use of it correctly.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 1:32 pm
by The Elf
ef37a wrote:how many synths, drum machines and guitar amps have balanced line outputs?
Quite a few (don't know about guitar 'amps', but my Helix does). At a rough guess I'd say at least half of my gear (and the more I think about it, well over half) has balanced outputs, both old and new. A few examples... Jupiter-80, MKS-80, System-8, Hydrasynth, Elektron Analog Keys, ARP Odyssey, Pro Soloist, every Kurzweil I've owned... even the humble Behringer Neutron and Poly D.

It's not as rare as you might think, and it's always worth using a balanced cable, even if the effect is tiny - the difference in price is worth it IMHO.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 1:51 pm
by ef37a
The Elf wrote:
ef37a wrote:how many synths, drum machines and guitar amps have balanced line outputs?
Quite a few (don't know about guitar 'amps', but my Helix does). At a rough guess I'd say at least half of my gear (and the more I think about it, well over half) has balanced outputs, both old and new. A few examples... Jupiter-80, MKS-80, System-8, Hydrasynth, Electron Analog Keys, ARP Odyssey, Pro Soloist, every Kurzweil I've owned... even the humble Behringer Neutron and Poly D.

It's not as rare as you might think, and it's always worth using a balanced cable, even if the effect is tiny - the difference in price is worth it IMHO.
(Mmmmmmh...Alway one!)

Dave.

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 2:09 pm
by The Elf
:lol:

I've re-wired a few synth studios in my time, and using balanced cables *throughout* has made a huge difference (presumably a cumulative effect)! And I have witnesses! ;) :D

Re: Difference between impedance and electronic balancing?

PostPosted: Tue Mar 09, 2021 3:46 pm
by ef37a
The Elf wrote::lol:

I've re-wired a few synth studios in my time, and using balanced cables *throughout* has made a huge difference (presumably a cumulative effect)! And I have witnesses! ;) :D
Tongue firmly in cheek Ee!

I was going by the (interminable!) synth and synth related reviews in the magazine? Most seem to have unbalanced TS jacks, often a pair that deliver left and right or a mono sum if you just used the left jack.
I have not worked it out (can't be arsed at my age!) but if they were TRS balanced I think that would defeat that configuration. I had also assumed, probably in ignorance, that most 'performance' synths would go into an unbalanced 'instrument' amplifier?

It has come to me that there is one other advantage to a 'proper' balanced output? Portable gear. Getting twice the output means the internal supply rails can be a bit lower and thus less battery drain.

Dave.