Signal degradation over a cable

[Rich-D]

I'm hunting for a headphone amp, w/ unbalanced TRS output, to be
connected to a standard unbalanced headphone, 3.5 mm jack.

I need to place my listening chair 20 feet from the unit. If I use
an audio extension cable of that length, will it degrade the signal,
due to ground noise pickup or other reason? Is it important to use the
shortest possible cable, amp to headphone?

Presumably, a balanced setup would mitigate this problem.
Thx

PS Is there another forum on board where this question would be
more appropriate, or duplicated? This is a big place!

 

[voodooless]

Have a look at this post:

Post in thread 'Custom headphone cable of 15m in length.'

Aug 27, 2024

It will depend on the impedance of your headphones. IMHO the cable round trip resistance should be below 1/20 of the headphone impedance.

For example, if your headphones are 24 ohms, you want the cable resistance to be less than 1.2 ohm. A 15 m distance is about 100 ft round trip. From the table below, you'd want 20 or lower AWG.

• NTK

• 

Noise pickup isn’t really a concern, and a balanced connection in the case of a headphone won’t help with that either.

 

[Speedskater]

What model headphones?
* * * * * * * * * *
Headphones have a wide range of impedance.
Some multi-drive headphones have crossover networks.
TRS cables are often made with heaver wires than 3.5mm cables.

 

[Vincent Kars]

Presumably, a balanced setup would mitigate this problem.

No, what they call a balanced output in the headphone world is simply a 4 wired connection so 2x single ended.
Under normal circumstances 20 ft won't be a problem.

 

[Rich-D]

No, what they call a balanced output in the headphone world is simply a 4 wired connection so 2x single ended.
Under normal circumstances 20 ft won't be a problem.

Thanks.
However, a balanced output carries a differential signal, not
ground referenced, hence inherently better noise rejection.

 

[JeremyFife]

The cable length won't really be a problem, as others have said. It will be inconvenient though, cable gets in the way.
Wireless is an option: Bluetooth with a decent codex. In many ways, much easier

 

[Alexander Gödde]

Thanks.
However, a balanced output carries a differential signal, not
ground referenced, hence inherently better noise rejection.

"balanced" headphone outputs != balanced interconnects

The latter has differential signal, the former just eliminates the shared return

 

[DVDdoug]

However, a balanced output carries a differential signal, not
ground referenced, hence inherently better noise rejection.

You can't pick-up enough radiated noise energy to make sound out of a headphone or speaker.

If you've got a noise problem it's coming from somewhere else in the analog chain.

Frequently you'll get twice the voltage from the balanced output (+6dB louder) if it has both balance and unbalanced outputs but there are easier ways to double the voltage (or more than double the voltage) if you need it. IMO balanced headphone connections are a gimmick. A not-so-standard gimmick that's not compatible with most headphones.

And... 6dB louder means any noise is also 6dB louder!

Headphone cables are about the least critical of all audio cables but with very-low impedance headphones (or in-ears) you may need heavy gauge wire for longer runs as you do with 4 or 8-Ohm speakers.

Of course the input to an amplifier is more critical because the impedance is higher making it more sensitive to noise and any noise gets amplified.

Even then, most home connections are unbalanced and noise pickup (or ground loop noise) is not a common problem.

 

[MaxwellsEq]

Thanks.
However, a balanced output carries a differential signal, not
ground referenced, hence inherently better noise rejection.

Hi, welcome to ASR!

Unfortunately, what you have stated above is simply incorrect for higher-voltage signals feeding "floating" devices such as headphones or loudspeaker.