Mixing unbalanced and balanced, isn't that asking for trouble?

[antcollinet]

What many here don't seam to understand is, You can Perfectly fine connect a unbalanced source to a balanced input.
With the Proper Cabel:

you even get a lot of the benefits like common mode noise rejection from the balanced connection

Balanced Line Technology

The Douglas Self Site. audio amplifiers, genealogy.

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of cause there is many ways to even improve this,
for example impedance matching or ground lift:

but even without extra resistors the unbalanced to balanced concretion with impedance mismatch is better then unbalanced to unbalanced.

As you can with a balanced output to unbalanced input - though you do need to know what the output circuit topology is.

I believe most modern kit (or at least home kit) has hot and cold separately driven and ground referenced - in this case you connect hot to the center RCA pin, and ground to the ring, leaving Cold unconnected.

 

[DanielT]

That is an unbalanced (single ended) RCA cable with an additional grounding fork, used for connecting turntables to mixers or other devices.

I actually knew that this was the case, for turntables to mixers or other devices , but at the same time I wasn't entirely sure about this if it could somehow be seen as semi-balanced. Yes, I know it sounds crazy to say and that there is an old trick that is not so stupid to use in case of confusion: Read up on things, ask the more knowledgeable.....which I have now done.


Soandso,Lambda,tonycollinet. Thank you for the answers. This is interesting I must say.

 

[Lambda]

As you can with a balanced output to unbalanced input - though you do need to know what the output circuit topology is.

Only in some cases and you loose all CMRR

There is no rejection of ground noise (CMRR=unity) or electrostatic crosstalk; in the latter case the 1mA notional crosstalk signal yields a -20 dBv​

 

[antcollinet]

Only in some cases and you loose all CMRR

Well yes - obviously you no longer have a balanced signal so are subject to all the earth noise problems you get with standard unbalanced.

But what are the cases in which an balanced outptut cannot drive an unbalanced input. I acknowledge the one where a 4V transformer output might saturate an input that can't take 4V (though that could be solved with an attenuation network).

 

[Lambda]

But what are the cases in which an balanced outptut cannot drive an unbalanced input.

if the output is floating or emulating a floating output
or if its "fully differential"
or if it's only impedance balanced and your adapter is not using the driven line.

Balanced Line Driver with Floating Output

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Balanced I/O

Balanced drivers and receivers - the stuff no-one tells you

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[antcollinet]

if the output is floating or emulating a floating output
or if its "fully differential"
or if it's only impedance balanced and your adapter is not using the driven line.

Balanced Line Driver with Floating Output

Balanced Line Driver with Floating Output - High performance active balanced line driver rivals transformer.

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Balanced I/O

Balanced drivers and receivers - the stuff no-one tells you

sound-au.com

Surely with a floating output you just connect cold to ground, and the hot will provide the full voltage output - albeit unbalanced.

Fully differential - I'm not sure what difference you are describing compared with floating.

Only impedance balanced. Well make sure the adapter is using the driven line.

Fundamentally - a balanced output is providing a voltage across two contacts (hot/cold). Either these are both ground referenced - in which case just one (the hot) can be connected into the input of an unbalanced input (and the other should be left open or risk damage if grounded) - or they are floating - in which case the cold can be grounded and the hot used as input to unbalanced, with possibly the need for an attenuator network if the resulting voltage is too high.

I guess the opamp based (rather than transformer based) floating output may have an issue if the cold is grounded, and then the hot voltage goes outside the power supply range - but I'd call that a design error on the output.

Forgive me if I am misunderstanding one of these.

 

[Lambda]

- but I'd call that a design error on the output

Call it how ever you like
The balanced output expects to provide current only between the outputs hot and cold not between hot and gnd.
Sometimes you can load it unbalanced but you risk significantly degrading its performance if you have impedance imbalance on it's output.
Or even damage the output if it's shorted.

 

[Sokel]

Here's a question I always had (even if I have tested them)

How and where would you connect an unbalanced dac/preamp/etc for measurement in the following inputs?
(notice there's a ground lift too if needed)

Edit:forgot the impedances
1.5Kohm for the XRL/TRS (L channel)
1Mohm for the TRS (R Channel)

 

[DanielT]

Tip:

Ultra-High Performance Stereo RCA to True Balanced XLR Converter

All, I have designed a stereo RCA (single-ended) to XLR (balanced) converter. I will have both fully assembled and bare boards available. Fully Assembled boards: 150 to 180 USD + shipping depending on interest Bare boards: 12 to 18 USD + shipping depending on interest, see BOM in attachments...

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[djtetei]

You might find this converter very useful:
ART Cleanbox Pro
The CLEANBoxPro provides two channels of unbalanced to balanced level conversion and two channels of balanced to unbalanced level conversion.

 

[SoundGuy]

You might find this converter very useful:
ART Cleanbox Pro
The CLEANBoxPro provides two channels of unbalanced to balanced level conversion and two channels of balanced to unbalanced level conversion.

I use DI boxes all the time on stage but I don’t think they are high enough quality for audiophile applications. They allow high impedance instruments to plug direct into a microphone balanced XLR cable and to the mixer or stagebox. This preserves the characteristics of the instrument by not loading it. It also means longer runs are possible without picking up noise. I believe Jensen make some high quality transformers for the application you are looking for.

 

[djtetei]

I use DI boxes all the time on stage

Cleanbox Pro is not a DI box. It is a an active level converter, which helps to convert an unbalanced connection to a balanced one and vice versa and also has built-in preamplification for level matching. You can think of it like a little mixer, with two channels in two channels out, without equalisation or effects.

 

[DanielT]

You might find this converter very useful:
ART Cleanbox Pro
The CLEANBoxPro provides two channels of unbalanced to balanced level conversion and two channels of balanced to unbalanced level conversion.

But with it this is added in the audio chain:

Total Harmonic Distortion <0.1% @ 1kHz
Signal to Noise Ratio > 90 dB

CLEANBox Pro – Dual Channel Level Converter – ART Pro Audio

artproaudio.com

 

[djtetei]

Yes, it is, but do you hear that <0.1%THD?
Those 0.1%THD are 60 dB lower than the music.
Keep in mind that it is a tool meant to help with a problem.
If I want to avoid using this tool, I simply use a very high quality mixer with very high signal to ratio and low THD.
Personally, I own this level converter as a backup tool for situation where a proper mixer is not at hand or until a proper one arrives.
It is a handy tool to have around and you will not be able to tell the difference in a blind test.
It is designed to do a job and do it well.
If you need something more competent you can use the Sonifex Redbox RB-UL2.

 

[DanielT]

Yes, it is, but do you hear that <0.1%THD?
Those 0.1%THD are 60 dB lower than the music.
Keep in mind that it is a tool meant to help a problem.
If I want to avoid using this tool, I simply use a very high quality mixer with very high signal to ratio and low THD.
Personally, I own this level converter as a backup tool for situation where a proper mixer is not at hand or until a proper one arrives.
It is a handy tool to have around and you will not be able to tell the difference in a blind test.
It is designed to do a job and do it well.
If you need something more competent you can use the Sonifex Redbox RB-UL2.

0.1% nop not when I test this anyway:

1% maybe if I concentrate and work up my ability to detect distortion.

Besides, it's still the speakers that are the big thief in the HiFi drama.

Also, different types of distortion, from #134 in this thread:

As for distortion, as the fundamental gets louder, low order distortion products become less and less audible. Compression drivers have second order dominated HD profile. According to Geddes Lee's research, participants of the research couldn't hear even %20 distortion of compression drivers while they are playing loud.

Genelec S360 Review (Studio Monitor)

The review compares to the 8361a, but isn’t the 8351b the better comparison at the same price point? Which is the better speaker then?

audiosciencereview.com

Going from, for example, inaudible distortion to extremely inaudible distortion is not something that interests me. I'm not chasing the best SINAD regarding DAC for example. Then I'm much more interested if noise is introduced into the audio chain. Then the usual, durability, functionality and so on. Applies of course to all types of hifi stuff.

 

[SoundGuy]

Cleanbox Pro is not a DI box. It is a an active level converter, which helps to convert an unbalanced connection to a balanced one and also has built-in preamplification for level matching. You can think of it like a little mixer, with two channels in two channels out, without equalisation or effects.

Sorry my bad. It looked exactly like the ones we use on stage for keys and guitars…

 

[Midnight Audiophile]

I've got a specific question on this. I have an ifi Zen Signature DAC with a 4.4mm balanced output. I want to connect a Rolls SX95 sub filter via this output. I'm using the DAC's unbalanced output for an A07 amp, both outputs will work at the same time with no problem seems to be. I've been using them this way for over a year. I am currently using one of these adapter cables:

Here are the specs on the DAC and SX95:

It's working fine connected this way (I use the pot on the DAC as variable) and I have no ground-loop noise issue. Is this an ok way to connect these two devices? Any long-term harm? What if I switched the connections on the A07 and SX95, any benefit there?

 

[Lambda]

Any long-term harm

impossible to tell definitive without knowing output topology of the DAC.
Other DACs with Differential balanced output might get damaged from this cable shorting out the low side.
This is why i would avoid this in general if you don't know exactly what you are doing.

but if it work fine till now it will probably continue working fine