Use balanced or unbalanced interconnects to an unbalanced amplifier with single-ended headphone output?

[Purpl3n3ss]

Should I use balanced or unbalanced interconnects to an unbalanced integrated amplifier with 6.35mm single-ended headphone output? Both RCA and XLR inputs are provided, though the amplifier is not a balanced design.

The manufacturer says:

"Typically we prefer to use the balanced XLR inputs if using a balanced source. This maintains the benefits of the noise and distortion reduction up until the output of the integrated preamplifier stage."

Is this a technically sound take?

The preamplifier section they mention, uses tubes to convert the balanced signal into unbalanced, in the following way (their words):

"Yes, the two 12AU7s are used in the balanced to single ended conversion. Both triode halves in both tubes are used for a balanced source. Only one half of each for single-ended."

My reason for asking this question is that, switching between balanced XLR and unbalanced RCA interconnects, I'm noticing the RCA interconnects to maybe sound a bit crisper and clearer, contrary to their recommendation. Could it be that this balanced into unbalanced conversion when done inside the amp is doing some damage to the signal, and I'm better off with an unbalanced signal from the DAC itself (via RCA)?

Also, the length of interconnects is very short: 0.5m.

 

[majingotan]

If it has an XLR input, you can certainly use a balanced source.

No harm being done in the amp regardless of balanced or unbalanced interconnects since the integrated amp either has an input transformer to convert balanced to unbalanced or just take + phase of the balanced signal + ground and throwaway the - phase.

 

[MaxwellsEq]

If the input stage is properly differential / balanced, then they are correct - the input will be better at reducing common-mode noise as well as minimising potential ground loops.

 

[Sokel]

You must make sure that the output circuit does not gets shorted (some do) going from balanced to unbalanced.

I would ask the company about it cause without the schematic we cannot know.

 

[Vincent Kars]

the amplifier is not a balanced design

That is common. Balanced is about the connection, not about the internals.
The source creates a balanced out by using a balun. This creates a hot (the signal) , the cold (the inverse of the signal) and a signal ground. At the receiver, the hot and the cold are compared and all difference between the two removed. This is called common noise rejection.

 

[unpluggged]

all difference between the two removed

Actually, it's the opposite: everything that is common to the hot and cold signals is removed (i.e. interference). Thus it is called common mode rejection It is achieved by subtracting the cold signal from the hot, cancelling out the common mode (in-phase) and boosting out-of-phase components so they add up in amplitude, hence the 6 dB gain from the differential input.

 

[Speedskater]

A balanced interconnect system is a very good system.
A component with a totally balanced internal circuit is a very different thing entirely. It's a challenging engineering design & cost circuit. But if done correctly it can be a good design.

 

[Miguelón]

Actually, it's the opposite: everything that is common to the hot and cold signals is removed (i.e. interference). Thus it is called common mode rejection It is achieved by subtracting the cold signal from the hot, cancelling out the common mode (in-phase) and boosting out-of-phase components so they add up in amplitude, hence the 6 dB gain from the differential input.

I think you’re talking about two different implementations: “balanced” is referred to equal impedance in two wires that transmits the signal.

In the common mode rejection system a differential amplifier is only sensitive to the differential voltage between the wires, so all interference that affects equally both wires will be neglected.

The signal can be carried either by one of the wires and the other is grounded (thus the interferences ignored because add to both equally),or be parallel in the two wires but one of them inverted 180 degrees (symmetric implementation).

At input side, either a differential amplifier take the difference between the signal and its inversion, which preserves voltage and neglect interferences, or what is more advantageous inverting again one of the signals and giving to a conventional amplifier doubling the amplitude of signal and neglecting interferences.

I suppose most common the third system because has twice signal to noise ratio, but I don’t know if differential amps has any other advantage over conventional that justifies using them today.

POST EDITED: I just seen that you mentioned “the most common” at the beginning, sorry I missed that part.

 

[Julf]

I think you’re talking about two different implementations: “balanced” is referred to equal impedance in two wires that transmits the signal.

In the common mode rejection system a differential amplifier is only sensitive to the differential voltage between the wires, so all interference that affects equally both wires will be neglected.

Recommended reading: Bruno Putzeys: The G word: How to get your audio off the ground

 

[ZolaIII]

Get a normal headphone amplifier! Power amplifier almost certainly doesn't have one and use main power amplifier stages with resistors for hedaphone out and that's ain't very good. If you want lamps get a hybrid solid state ones where such are used as passive oscillator's adding only couple mV of gain. Or you can emulate one of the best such design's for free with PTEq-X VST plugin (ECC81, ECC82, ECC83 & ECC88 included).