What if I connect a headphone to the RCA output of a (pre)amp ?

[PenguinMusic]

Hi guys,

Having a DAC/HP Amp device, I was wondering if something would happen if I would connect the Headphone to the RCA (or Balanced) output of the DAC ?
I assume this is then a pre-amp... Will that produce any sound if hooked up to headphones directly ? Can it do any harm ?
Regards.

FRED

 

[sergeauckland]

Some preamps, have identical outputs for headphones and main outputs, so there is no reason why a headphone shouldn't be able to be connected to a preamp output. However, whether in your case it can or can't, depends on the circuit used and the headphone's impedance. Good circuit design should be fully protected so you can't damage anything by putting headphones on the output, but again, that depends on the manufacturer following good practice.

My advice would be to ask the manufacturer if you can do it. They'll need to know the impedance of your headphones. If they won't help, then you'll need to get hold of a circuit diagram to see how the outputs are configured.


S

 

[Veri]

In my experience there are pre-amps that will simply work via RCA to headphone adapter. It all depends on the output impedance; depends on the circuit inside.

Worst case you have boomy bass due to impedance mismatch. Which should be immediately audible. If it sounds "fine", it's fine.

 

[Vincent Kars]

You can do it but it probably sounds bad.
Just an example: Output impedance: 200 Ohm balanced, 100 Ohm unbalanced
This is the RME ADI-2-DAC
Lot of headphones are 32 today.
One prefers to have the output impedance much lower than the impedance of the headphone.
If not the damping is insufficient .
Maybe this article gets you started ( skip the marketing part) : https://benchmarkmedia.com/blogs/application_notes/37983617-the-hpa2-headphone-power-amplifier

 

[PenguinMusic]

Hi,

Tried to read, but understood nothing :-(

It seems someone has measured my DAC/Amp and said the he measured 11.1 ohms from the headphone output.
Can this value be the cause for which the headphone output is "super loud" and is totally unusable on 90% of it's "scale"

 

[PenguinMusic]

Hi,

As a follow-up I'd like to say that I just got an XLR to 3.5 jack cable.
I plugged the XLRs into the amp and the mini-jack into the headphones.

I am listening to the result as I write this.
It seems there is nothing wrong with the sound and I can fine tune the thing...

Regards.

[EDIT : mind you, I am even under the impression that the sound is even better ! Purely subjective of course, but that is as I feel it... So this is a keeper it seems ]

 

[Veri]

As a follow-up I'd like to say that I just got an XLR to 3.5 jack cable.
I plugged the XLRs into the amp and the mini-jack into the headphones.

Can you link the cable? XLR to 3.5jack should never be used.

 

[Jimbob54]

Can you link the cable? XLR to 3.5jack should never be used.

Might be a TRRS 3.5 jack and 'phones wired up for balanced?

 

[PenguinMusic]

Can you link the cable? XLR to 3.5jack should never be used.

Sure,

Here it is...

https://www.amazon.fr/Adam-Hall-Cab...=XLR+mini+jack+femelle&qid=1582812228&sr=8-11

You're scaring me :-(

I'll avoid using them until you tell me I can.
But so far, they're workiing and the result is simply SUPERB !!!!

Regards.

 

[Jimbob54]

Sure,

Here it is...

https://www.amazon.fr/Adam-Hall-Cables-K4YWFF0180-Femelle/dp/B009Z94QBG/ref=sr_1_11?__mk_fr_FR=ÅMÅŽÕÑ&keywords=XLR+mini+jack+femelle&qid=1582812228&sr=8-11

You're scaring me :-(

I'll avoid using them until you tell me I can.
But so far, they're workiing and the result is simply SUPERB !!!!

Regards.

What headphones?

 

[PenguinMusic]

B&O H9 Gen 3...

I know... But honestly I think they sound really good. Much better than the "Best" according to reviews.

Regards.

 

[Veri]

Sure,

Here it is...

https://www.amazon.fr/Adam-Hall-Cables-K4YWFF0180-Femelle/dp/B009Z94QBG/ref=sr_1_11?__mk_fr_FR=ÅMÅŽÕÑ&keywords=XLR+mini+jack+femelle&qid=1582812228&sr=8-11

XLR is a balanced signal. You are using a cable to connect to an unbalanced end point. This can cause issues, worst case it can even damage equipment. Since that didn't happen I guess there's no dramatic effect here, but it's still something that is highly discouraged.

Balanced to unbalanced over cable is always a bad, bad idea.

 

[PenguinMusic]

XLR is a balanced signal. You are using a cable to connect to an unbalanced end point. This can cause issues, worst case it can even damage equipment. Since that didn't happen I guess there's no dramatic effect here, but it's still something that is highly discouraged.

Balanced to unbalanced over cable is always a bad, bad idea.

Uh-oh... Wasn't absolutely aware of that.
Was just super happy to listen to the sound that came out of that solution.
I now have to decide if I take the chance or not...

I already pushed the sound to a volume I don't think I will listen... (before you told me this).

 

[sergeauckland]

XLR is a balanced signal. You are using a cable to connect to an unbalanced end point. This can cause issues, worst case it can even damage equipment. Since that didn't happen I guess there's no dramatic effect here, but it's still something that is highly discouraged.

Balanced to unbalanced over cable is always a bad, bad idea.

Depends on the type of balanced output. There are three ways of balancing an output, differential centre tapped (or earth referenced), differential fully floating and single ended impedance balanced. There are two ways of unbalancing a cable, connecting pin 1 to pin 3 or leaving pin 3 floating.

Which you do depends on which type of output you have, so provided it's done correctly, there's NO problem, and it's a perfectly good idea if you have to connect a balanced output to an unbalanced input.

If you don't know what sort of output you have, then a transformer is the safest way, but I've unbalanced any number of outputs perfectly successfully.

S

 

[solderdude]

Some pre-amps have a high output resistance. Usually around 50 to 100 Ohm.
So using that with some low impedance headphones may not be the best idea.

The biggest problem, however, is what Veri mentioned.
You could connect headphones to balanced outputs but ONLY when they have balanced connections and not have an output transformer.
2.5mm TRRS jacks (for portable balanced equipment), a 4-pin XLR, or a Pentaconn connection.

The H9 is single ended TRS jack so cannot be connected to a balanced output because you would be shorting the L- and R- channel outputs.
No big issue for the pre-amp most likely but when the output resistance of the XLR out is very low impedance < 10 Ohm you could damage the pre-amp

 

[PenguinMusic]

Hi,

Thanks a lot for your answers...

That is complicated !

It seems the wisest is to use the unbalanced output of the DAC/Amp...

If that can be of any help, it is the ASUS XONAR Essence One (https://www.asus.com/supportonly/Xonar Essence One/HelpDesk_Download/)

Regards.

 

[PenguinMusic]

Depends on the type of balanced output. There are three ways of balancing an output, differential centre tapped (or earth referenced), differential fully floating and single ended impedance balanced. There are two ways of unbalancing a cable, connecting pin 1 to pin 3 or leaving pin 3 floating.

Which you do depends on which type of output you have, so provided it's done correctly, there's NO problem, and it's a perfectly good idea if you have to connect a balanced output to an unbalanced input.

If you don't know what sort of output you have, then a transformer is the safest way, but I've unbalanced any number of outputs perfectly successfully.

S

Hi,

This is the complete web page from the cable I bought.

I have no idea what most of this means... But if can tell me by seeing this what connection is used, it would be nice
https://www.adamhall.com/shop/fr-fr...tionnes/cables-audio-divers/3381/k4-ywff-0300 (french)
https://www.adamhall.com/shop/gb-en...d-cables/other-audio-cables/3381/k4-ywff-0300 (english)

Regards.

 

[solderdude]

These cables should only be used to connect a 3.5mm TRS device (like a phone) to XLR inputs.
Only 'half' of the XLR input is used this way.

 

[sergeauckland]

Hi,

This is the complete web page from the cable I bought.

I have no idea what most of this means... But if can tell me by seeing this what connection is used, it would be nice
https://www.adamhall.com/shop/fr-fr...tionnes/cables-audio-divers/3381/k4-ywff-0300 (french)
https://www.adamhall.com/shop/gb-en...d-cables/other-audio-cables/3381/k4-ywff-0300 (english)

Regards.

The specification doesn't say anything about how the cable is wired. You can easily unscrew the XLR connector and see how the pins are wired. Pin 1 will be earth, pin 2 will be signal and pin 3 will either have no connection or be connected to pin 1. If you don't want to open up the XLR, you can check if pin 1 and three are connected using a multimeter.

If pins 1 and 3 are not connected, then this will be completely safe, but the sound could be thin and lack low frequencies depending on what sort of balanced output you have. If pins 1 and 3 are connected, then it's possible this could put a short circuit one one side of the balanced output. Whether that matters or not depends on whether the outputs are properly protected or not.

The best approach if you don't know what sort of balanced output you have is not to connect pins 1 and 3. Then, if the sound is fine, that's the right way. If the sound isn't fine, then you can connect pins 1 and 3, but only if the XLR output allows that.

S

 

[PenguinMusic]

These cables can only be used to connect a 3.5mm TRS device (like a phone) to XLR inputs.
Only 'half' of the XLR input is used this way.

Hi SolderDude,

Thanks a lot for your answer.

Can I assume that if I can connect a TRS 3.5mm device like a phone, I can also use this cable to listen to my music with the H9 Gen 3 using the balanced output of the Asus Xonar Essence One ?

That would be super nice... (I am listening with the unbalanced output and I am under the CLEAR impression that it sound MUCH better than the dedicated headphone output ! Am I really deaf or stupid ? )