Differential Balanced Sound Quality

Have had both and I must say that while the balanced front end was not of the quality that my present unbalanced front end now exhibits, there existed a depth in the music that was at times uncanny. Reducing the noise floor in my opinion is a critical aspect of a system when attempting to hear into the music. 
I still use balanced power with both an EQUI=TECH wall unit and Balanced Power Technologies  AC treatment. Still I have found that "spooky" sound quality a bit less prevalent in the current system. 
Using a BAT VK P 10SE phono stage fed my system a very deep and quiet signal. Alas the unit at 20 years old began to have problems. 
Running high efficiency speakers brings out the charm of a balanced system. I say it's worth it.

@dentdog Do note that the technology that makes power "balanced" is different from the technology that makes amplification equipment (i.e., sources, preamps, and amplifiers) balanced. 

If you care for an explanation, read on. 

Apologies for length, but I'm just now starting to understand all this and wanted an excuse to type it out so that I could consolidate the learning.  Please do offer corrections anyone...

--Balanced Power--

Traditionally, AC power is delivered with 120v on the "hot" line and 0v on the neutral return.  In balanced power equipment, the hot line is run at +60v and the neutral is run at -60v.  

--Balanced/Differential Equipment--

Alternatively, the balanced equipment discussed above separately amplifies the positive and negative parts of the electrical signal.  This requires double the circuitry because you have to amplify two signals (0-to-positive and 0-to-negative) instead of one (negative-to-positive) as in single-ended equipment.   If you imagine music as a sign wave, then balanced equipment is separately amplifying the upper and lower halves of the wave.  The benefit of this added complexity is that any noise introduced into the signal by your equipment will be cancelled out when these two "half" signals are re-combined to make the full-wave signal that drives your speakers. This is because any injected noise will appear positive going in one amplification circuit and negative going in the other... add them together and you get automatic noise-rejection because they'll be in exact opposition. 

--Distortion & Preferences for Balanced vs Single Ended Equipment--

Interestingly, in addition to external noise sources, every amplification circuit also creates its own "ringing distortion." If, for example, you play a sign wave at 1000Hz, the circuit will also produce a signal of reduced amplitude at different harmonics. Thus, you'll see small spikes at 2000Hz, 3000Hz, 4000Hz, 9000Hz, etc. These are called even (2000, 4000, etc.) and odd harmonics (3000, 9000, etc.). The balanced circuitry also eliminates all even harmonics when the signal is combined to re-create the music. This is because their peaks line up directly with the peaks of the original signal and they get cancelled just like any other noise/distortion that affects both the positive and negative amplification circuits at the same time.  

While this is a good thing in principle because your music has less distortion, about 1/3rd of human ears actually find the second harmonic distortion pleasing.  It seems that this harmonic ringing creates the perception of increased warmth and 3-dimensionality in stereo listening.  Alternatively, signals with a dominance of 3rd harmonic ringing is often perceived to have increased clarity and detail... and again is preferred by about 1/3 of listeners.  For more discussion from Nelson Pass, read this link:  https://positive-feedback.com/audio-discourse/the-pass-h2-harmonic-generator/

I believe that variances in preference for these different distortion profiles is likely one reason why you see such different (and strongly held) recommendations about the importance of balanced vs. single-ended gear from different posters. 

While my training as a scientist initially biased me towards a "balanced is better" perspective (why wouldn't you want less distortion???), I have subsequently found that I have a consistent preference for gear with a 2nd harmonic dominant profile.  At this point I'm confident enough in that preference that I'll only buy single-ended gear.  

Sorry for all the typing folks.  I'm bored.  Thanks.

The bit that a lot of people are unaware of is that balanced inputs are actually noisier than single ended (RCAs etc.) in that they utilise relatively high value resistors that introduce their own (johnson) noise into the signal.

This statement is problematic. There’s no reason why any such ’high value resistors’ be used in a balanced circuit that aren’t also in a single-ended circuit.

Because it is so obviously the wrong way to go. The number one factor in quality sound is quality parts. Going balanced requires twice as many parts. A whole duplicate circuit.

@millercarbon This statement is false and is a common myth: it ignores the bit about ’differential’. If the circuit employs differential amplifiers, then the parts count is about 50% higher rather than double. There is a distinct advantage to differential amplifiers (which are often used in amps with single-ended inputs, as they are often used as phase splitters); they have much more power supply noise rejection and if the circuit is fully differential, then even ordered harmonic distortion is cancelled at each stage throughout the circuit, rather than compounded (which can increase higher and odd-ordered content).


There is an advantage to this- when the circuit is fully differential, the primary distortion harmonic is the 3rd, which is treated by the ear the same as the 2nd in that it contributes to ’bloom’ and ’warmth’. But in such a circuit, the 3rd will often be at a 10th of the value that is seen in a circuit that has a 2nd harmonic as the primary distortion component. In mathematical terms, the former has a cubic non-linearity whereas the latter has a quadratic non-linearity. When there is a cubic non-linearity, succeeding harmonics drop off at a much higher rate than they do if the non-linearity is quadratic. In a nutshell, fully differential circuits are much lower distortion and so sound more neutral. This is not subtle either- its easy to hear. So there is a distinct advantage to all those extra parts if the designer took advantage of all the aspects of differential operation!

Balanced is totally designed for professional use. Runs of hundreds of meters. Not tens of feet.

This statement is also false. The benefits of balanced line connections are there even if the connection is only 6 inches. I can go into it further if you like; FWIW this idea of ’only for long distances’ is also a common myth. Think about this- you don’t have to know the technical side; the simple fact that you can run such long distances without coloration is a tip off that those colorations won’t be in a 6 foot run either! If you’ve heard differences between single-ended cables, then you know what I’m talking about when I use the word ’colorations’.

I’m not a fan of preamp to amp balanced connections. I’ve always preferred single ended overall. YMMV

@geof3 The reason balanced operation might not seem to bring home the bacon in high end audio is that there is a standard for balanced line operation, which most high end audio manufacturers do not support (and don’t seem to realize how this degrades the sound). When the standard isn’t supported, the cable construction becomes audible like it does when running single-ended. Balanced operation isn’t two single-ended signals running together in a cable! Its a single signal traveling in a twisted pair with both sides ignoring ground. Please Note that I am not arguing with you here- I’m sure that what you’ve experienced is very real. But what you experienced was not how balanced operation is supposed to work. BTW, the balanced line standard is known as AES48. You can always ask the manufacturer if their equipment supports AES48; if they don’t know or don’t know what it is, then its a very safe bet their gear doesn’t support the standard and so will not demonstrate all the advantages of balanced operation.


Those advantages are:
1) lower noise (blacker backgrounds)
2) neutral, transparent interconnect operation regardless of length (more detailed, less colorations resulting in no need for expensive interconnections)
3) no ground loop noise or intermodulations (not as harsh)

But if the standard isn’t supported these things go away and as you’ve heard, might even be worse.

@atmasphere Ralph, apparently we posted at the exact same time.  Any facts of operation I got wrong in mine?  As always, thanks for your contributions...