How do I wire unbalanced outputs to balanced inputs?

[ripwire]

Like the title says, I'm looking for information on how exactly to wire up a cable that will take a single ended output and connect to a balanced input.

Or should I not do this at all? Browsing the net I've seen references to this being done, but have yet to dig up concrete wiring information. But if this is a bad idea then I won't try it.

 

[sergeauckland]

No problem at all doing that. Take the unbalanced signal wire to XLR pin2, and the unbalanced screen to XLR pin 3. Strap together XLR pins 1&3.

If you get a hum loop, which depends on how the unbalanced unit is grounded, then remove the strap and leave XLR pin 1 floating.

S

 

[voodooless]

No problem at all doing that. Take the unbalanced signal wire to XLR pin2, and the unbalanced screen to XLR pin 3. Strap together XLR pins 1&3.

Like so is a bit better Did this with CAT7, worlds like charm.

 

[JaccoW]

There are ready-made cables available that do this. One affordable one is the Cordial CFU FC.
Can be had for about €15 + shipping.

Very nicely made and supple cables as well.

 

[ripwire]

Thanks! That's really helpful.

Are the pinouts of balanced XLR cables an industry standard? (ie, there aren't some manufacturers doing things differently from everyone else.)

 

[sergeauckland]

Thanks! That's really helpful.

Are the pinouts of balanced XLR cables an industry standard? (ie, there aren't some manufacturers doing things differently from everyone else.)

Pin 1 is always ground/shield, Pin 2 is usually +ve, pin3 -ve, but a few older items have them the other way round. It doesn't actually matter whether you ground pin 2 or 3 except that the 'wrong' way round reverses polarity. Only an issue if you're phasing-up with surround 'speakers and/or your belief system requires the 'correct' polarity.

S.

 

[ripwire]

Got it, thanks!

 

[Wright Sound]

View attachment 241767
Like so is a bit better Did this with CAT7, worlds like charm.

No! no! No! Never do that. Why ? Because if some genius (moron) turns on the phantom power, {some small mixers have phantom power all the time} you will shoot 48 volts into the headphone output or line out of your playback device, and most likely ruin it. I have seen it happen a hundred times. Always Always use a direct box. Passive are the best. They are not expensive. The direct box has a transformer that isolates the two circuits, so even if the phantom power is on, it will not pass into your phone or iPad, or laptop, or little MP3 player, or whatever you are using to play music.

 

[Wright Sound]

View attachment 241767
Like so is a bit better Did this with CAT7, worlds like charm.

There are ready-made cables available that do this. One affordable one is the Cordial CFU FC.
Can be had for about €15 + shipping.

Very nicely made and supple cables as well.

Hilariously the Cordial cable is female XLR and won’t work anyway. But still, never connect a music player to a professional mixer without using a direct box.

 

[voodooless]

No! no! No! Never do that. Why ? Because if some genius (moron) turns on the phantom power, {some small mixers have phantom power all the time} you will shoot 48 volts into the headphone output or line out of your playback device, and most likely ruin it. I have seen it happen a hundred times.

Most of these use cases are for devices that do not even have phantom power, so "never" seems very much like "sometimes". Especially when going from RCA to XLR, the chance that the RCA out has phantom power is very, very limited.

Nevermind that most DI boxes are very low quality, especially if they are cheap:

Measurements and comparison of isolation transformers and DI boxes

Almost a year ago I posted this short IMD comparison of various transformers in a iso box review by @amirm, and promised that I'll try to follow up with a more detailed post. This will be it. :) A few different types of devices will be measured and compared, here's a list of units under test...

www.audiosciencereview.com

 

[Moonbase]

RCA is a lot lower power than XLR, so converter cables are a good way of introducing noise. The small cost of the direct box all these issues.

 

[Speedskater]

While typical RCA outputs are at a lower voltage (not power) level than typical XLR outputs, most input stages have enough gain adjustment range to deal with this without adding noise.
* * * * * * * * * * *
Phantom power is only available on some (microphone) inputs, it's never available on an output.

 

[Moonbase]

Phantom power is only available on some (microphone) inputs, it's never available on an output.
*****
The phantom power is provided to the Mic from the input stage of the pre-amp being used with the Mic? I suspect what the poster is suggesting is that an RCA sends a signal to an input XLR there could be an issue.

 

[Speedskater]

I suspect what the poster is suggesting is that an RCA sends a signal to an input XLR there could be an issue.

Yep, reading some of those off-the-wall audiophile forums could confuse a person.

 

[Sam Ash]

I have a preamp with unbalanced outs which I need to connect to a stereo power amp that has balanced ins. Using RCA male to XLR male cables will obviously be unbalanced meaning that the amp all be fed a lower voltage which results in attenuation. Is it better to use an RCA to XLR converter that corrects the voltage? Some converters have gain adjustments for the L and R. I will be using 3 feet cables between my preamp and amp, is a converter worth it?

 

[Speedskater]

Actually it's less voltage gain rather than voltage attenuation.
But many RCA pre-amps have way more than enough voltage output for an XLR input.
And many power amps have to attenuate their XLR inputs.

 

[somebodyelse]

I have a preamp with unbalanced outs which I need to connect to a stereo power amp that has balanced ins. Using RCA male to XLR male cables will obviously be unbalanced meaning that the amp all be fed a lower voltage which results in attenuation. Is it better to use an RCA to XLR converter that corrects the voltage? Some converters have gain adjustments for the L and R. I will be using 3 feet cables between my preamp and amp, is a converter worth it?

What preamp and what power amp? Check the sensitivity of the power amp, and the output level of the preamp to see if the preamp can drive the power amp to full output.

 

[Sam Ash]

What preamp and what power amp? Check the sensitivity of the power amp, and the output level of the preamp to see if the preamp can drive the power amp to full output.

My preamp is the Wiim Ultra which has a Line Output of 2.1V rms. The sensitivity of the power amp is 5.0V rms at 4 ohms. Just read another post by a fellow member that says the sensitivity of the power amp is 4.15Vp. I presume that is at 8 ohms.

 

[Sokel]

My preamp is the Wiim Ultra which has a Line Output of 2.1V rms. The sensitivity of the power amp is 5.0V rms at 4 ohms.

That won't drive 1200as to full output obviously but it's maybe a good thing as with a digital volume control as Wiim's you can never be sure 100% if it will go full blow.
If by all means you need all the 2x600 Watt you'll have to find another source,obviously balanced with an output to match it.

 

[Sokel]

My preamp is the Wiim Ultra which has a Line Output of 2.1V rms. The sensitivity of the power amp is 5.0V rms at 4 ohms. Just read another post by a fellow member that says the sensitivity of the power amp is 4.15Vp. I presume that is at 8 ohms.

That's from the datasheet:

So,about 3.5V rms