Are headphone balanced cables snakeoil?

[Graph Feppar]

Hey everybody,check out this thread on Head Fi.
https://www.head-fi.org/threads/the-crappiness-of-the-3-5-mm-jack-and-plug.458595/

 

[sergeauckland]

I hate the 3.5mm jack, and even more the 2.5mm jack. Not for reasons of crosstalk, that's irrelevant, it's the fragility that gets me. Just about every week I have to replace a failed 3.5mm jack on one of our radio station's headphones. 6mm jacks, perhaps once a year, and even then, only the factory moulded ones, never a proper wired jack. Unfortunately, many of our Presenters want to use their headphones for portable players, so I have to replace the failed 3.5mm jack with another, albeit a wired one which does seem to be that bit more reliable. 6mm to 3.5mm adapters are just too chunky for the portable players.

It's not helped by people pulling the plugs out by the cable!

S.

 

[tomchr]

I believe I read it from your post in the other balanced cable thread,I am too lazy to search for it lol

I've only participated in this cable thread. I generally don't participate in cable threads, but you asked a good question, so I figured I'd jump in.

I really like Tom's earlier explanation, and he mentioned something important. If you're of the mindset that subjective claims are valid, then read the manufacturer's drivel and spend your money and enjoy the cognitive dissonance!

To add precision: The cognitive dissonance is the discomfort you feel when holding two contrary opinions in your mind simultaneously. "I just spent $2k on this cable so it must be good" and "I can't hear any difference", for example. You resolve the dissonance by concluding that you do hear a difference. That the micro-fluidic detail (or whatever) is clearly better. If there was no difference, you'd feel pretty stupid just having spent $2k on the cable. Ego protection kicks in, and even if there is no difference in the stimuli, your brain tells you there is a difference.
These effects tend to get larger with ambiguous stimuli. I would argue that looking for differences among identical stimuli is a case of such ambiguous stimulus. Those interested in these cognitive effects should read Daniel Kahneman's "Thinking fast and slow" or for a lighter read, Ariely's "Predictably Irrational".

That makes me wonder, given the rationalist\objectivist bent of this forum, how many of us are atheist? It would be interesting to do an anonymous poll and see if the numbers skew as I believe they probably do. No, I'm not starting a religious discussion, and will not engage further on the topic, just interested in the data and the correlation between various types of what I believe are examples of cognitive dissonance.

Stronger correlates would probably be openness to new experience and need for cognition.

I do appreciate the science focus here. (Although, psychology is a science too... )

Tom

 

[Jorj]

To add precision: The cognitive dissonance is the discomfort you feel when holding two contrary opinions in your mind simultaneously.

A bit of further precision: In my experience, most of the people who are possessed of said dissonances not only do not find it a discomfort, but quite the opposite; it leaves them feeling better about the situation. This is precisely why it is so difficult to combat, because OF COURSE the $2,000 power cable I just bought sounds better. Just as you said, I'd feel foolish if I could not plainly hear the improvement, despite knowing that it really cannot physically do anything to 'smooth' those electrons. Magic!

 

[tomchr]

A bit of further precision: In my experience, most of the people who are possessed of said dissonances

We all experience cognitive dissonance sometimes. It's a human thing.

not only do not find it a discomfort, but quite the opposite; it leaves them feeling better about the situation.

That's because they've resolved the dissonance. There are many ways to do that and it usually ends well. If we didn't resolve the dissonance, we'd live in a constant state of discomfort from all the conflicting views that have passed through our brains over the years. In many cases, the resolution is a non-event. "I know I said yesterday that I liked vanilla better, but today I prefer chocolate. I've changed my mind." In other cases, it results in irrational behaviour.

This is precisely why it is so difficult to combat, because OF COURSE the $2,000 power cable I just bought sounds better. Just as you said, I'd feel foolish if I could not plainly hear the improvement, despite knowing that it really cannot physically do anything to 'smooth' those electrons. Magic!

Well... Scientists don't know everything... (Sorry. Couldn't resist). Yeah. It's funny how audio is the only field within precision electronic circuit design where the laws of physics don't seem to apply. Ohm's Law? Pfft! Who needs it?!

There is one case where I can potentially see a power cord making a difference and that's in the 'negotiation' of the ground potential between different pieces of equipment. A beefier conductor (and better connectors) will have lower impedance, so the error voltage developed between pieces of equipment is lower. This would improve the signal integrity in a single-ended system. That has very little to do with the cost of the cord and everything to do with the cross-sectional area of the ground conductor. Another - and in my view better - way to solve the issue of ground bounce is to use differential links. There! Back on topic.

Tom

 

[restorer-john]

For example, I measure 115 dB channel separation in my HP-1 when using the XLR output and about 95 dB when using the 1/4" output. The difference is due to the shared ground in the 1/4" plug.

Is it less of the shared ground and more of the capacitive coupling from adjacent terminals or TRS construction of the attached plug itself? Or a combination of both? After all, the tip and ring goes through the sleeve in the plug and the two channels are spaced extremely close in a ~30mm tube.

It would be interesting to have two 1/4" jacks, one for left and one for right and feed them separately and compare test results.

Rotary wafer style selectors in vintage gear had the same issues on high level inputs and inter source breakthrough.

And yes, at 95dB it's academic.

 

[solderdude]

Let me give a real world example of the famed AQ Nighthawk (measurements of the cable here).
It comes with 2 cables which sound different yet measure exactly the same in FR (of course)
The 'trick' they applied (that's the way I see it) to promote their expensive cables is to have 2 of them that differ enough to make people 'believe' the difference in materials matters.

AQ NH = 25 Ohm.
return wire (silver) = 0.5 Ohm
return wire (gold) = 1.6 Ohm

the signal wires are also the same resistance. This results in a level difference of 0.8dB between the cables.

BUT now we are going to take crosstalk into account.
For the silver cable its -34dB
For the (inferior acc. to AQ) gold cable = -24dB !

When one could use a 4 wire cable connected in the 6.3mm plug) that crosstalk could be way down -50dB
With a 'balanced' cable well below say -100dB.

Just an example.

 

[tomchr]

Is it less of the shared ground and more of the capacitive coupling from adjacent terminals or TRS construction of the attached plug itself? Or a combination of both? After all, the tip and ring goes through the sleeve in the plug and the two channels are spaced extremely close in a ~30mm tube.

It's the resistance of the ground connection that dominates. The output of the amp has very low impedance (0.5 Ω). You won't get that to move by capacitive coupling. Even the 300 Ω of a high-impedance headphone would be hard to move with the additional few 10s of pF you get from the connector.

Tom

 

[JJB70]

One of the things that disappoints me is the way the formerly sensible headphone segment has followed the rest of hi-fi down the route of silly expensive cables, an it must be good because it has a four figure price and is made by the fashionable brand of the moment. It is not that long ago that the Sennheiser HD580 was pretty much as good as it got despite being cheap compared to today's high end headphones. I wouldn't call balanced headphone cables snake oil but I would call some of the expensive after market ones snake oil.

 

[solderdude]

Indeed... balanced or not cables don't need to be expensive.

Less microphony, more supple, less weight, pretty colours. It does not have to cost a LOT and are things I may pay a little more for.

Expensive cables are snake-oil, 'Balanced' or otherwise.

Balanced in itself is a feature and not snakeoil for headphone cables.

 

[Roen]

I hate the 3.5mm jack, and even more the 2.5mm jack. Not for reasons of crosstalk, that's irrelevant, it's the fragility that gets me. Just about every week I have to replace a failed 3.5mm jack on one of our radio station's headphones. 6mm jacks, perhaps once a year, and even then, only the factory moulded ones, never a proper wired jack. Unfortunately, many of our Presenters want to use their headphones for portable players, so I have to replace the failed 3.5mm jack with another, albeit a wired one which does seem to be that bit more reliable. 6mm to 3.5mm adapters are just too chunky for the portable players.

It's not helped by people pulling the plugs out by the cable!

S.

What animal pulls it out by the cable and not the plug??????

 

[pkane]

Indeed... balanced or not cables don't need to be expensive.

Less microphony, more supple, less weight, pretty colours. It does not have to cost a LOT and are things I may pay a little more for.
Expensive cables are snake-oil.
Balanced or otherwise.

I made multiple runs of 5-6m balanced cables with various terminations (3- and 4-pin XLRs), each for around $30 and about 10-15 minutes of soldering and assembly.

 

[restorer-john]

You won't get that to move by capacitive coupling. Even the 300 Ω of a high-impedance headphone would be hard to move with the additional few 10s of pF you get from the connector.

True but how do you measure crosstalk? You drive a signal in one channel and measure what you get out of the other undriven channel. I'm not talking about 'moving' the ground, I'm talking about inducing a signal from one close proximity conductor to another where the measuring equipment has a high impedance front end.

If you measure crosstalk with the headphones actually connected as well as your test gear, then the results may be different.

 

[tomchr]

True but how do you measure crosstalk? You drive a signal in one channel and measure what you get out of the other undriven channel. I'm not talking about 'moving' the ground, I'm talking about inducing a signal from one close proximity conductor to another where the measuring equipment has a high impedance front end.

Right. And there are two coupling mechanisms: inductive and capacitive. Any coupling will have to induce enough current or charge to move the output of the amplifier, i.e. establishing a voltage on the amplifier output. The amplifier output impedance is very low and is in parallel with the headphone impedance. Thus, the amplifier output with or without the headphones connected is a low impedance node. You will have a very hard time getting that to move by inductive or capacitive coupling. A simple SPICE simulation (or a few button pushes on a calculator) will tell you that.

If you measure crosstalk with the headphones actually connected as well as your test gear, then the results may be different.

Sure. Zout||Zheadphone||Ztest_equipment will be ever so slightly lower than Zout||Zheadphone. The input impedance of the test equipment is 100 kΩ. The output impedance of my HP-1 is 0.5 Ω. If we assume 300 Ω phones, the math shakes out as follows:

Amp + headphones: 0.499168 Ω
Amp + headphones + test equipment: 0.499165 Ω
That's a difference of 0.000043 dB.

I always measure with a load connected to the amp. For headphones, my standard loads are 32, 50, and 300 Ω. In case of crosstalk, both channels are loaded with 300 Ω (and the test equipment's Zin = 100 kΩ, which is in parallel with the 300 Ω). Only one channel is driven.

Also note that the crosstalk gets worse with 32 Ω load. If the crosstalk was caused by inductive or capacitive coupling, it would get better with a low-impedance load as less voltage would be induced in the output node. The fact that the crosstalk measures worse with a lower impedance load further supports my analysis that the crosstalk is degraded by the shared ground impedance in the 1/4" jack. Physics. Highly annoying.

Tom

 

[restorer-john]

I always measure with a load connected to the amp. For headphones, my standard loads are 32, 50, and 300 Ω. In case of crosstalk, both channels are loaded with 300 Ω (and the test equipment's Zin = 100 kΩ, which is in parallel with the 300 Ω). Only one channel is driven.

Thanks for clarifying. The presence or absence of the load during the crostalk test was what I was driving (pun intended) at.

 

[trl]

I remember once, I was listening to my single-ended cans, and between the tracks there was an audible mains hum. I paused the player and started to investigate this somehow, but after I moved my head few inches the hum decreased in intensity a lot. When I moved a bit further, he hum noise was gone. Switching to balanced cans I got no more mains hum, no matter distance from the DAC/headamp. Seems that the mains hum noise was caused by the not-shielded transformer inside the nearby linear PSU, that somehow interfered with headphones cables. Movign the LPSU few inches away dod resolved the issue for single-ended cans as well.

It was probably related to this http://www.meier-audio.homepage.t-online.de/ or just my cheapo headphones cable, don't know, but noise was there for sure.

 

[AnalogSteph]

That's an odd problem that I've never encountered before. I can only guess that there may have been a ground loop involving the headphone amp output circuitry and the transformer was coupling into that. Electrostatic coupling to the headphone cable or magnetic coupling into the drivers is generally eliminated with low output impedance. (So far nobody has found it necessary to include humbucking coils in headphones. That's what they're doing to eliminate inductive hum pickup in microphones and guitar pickups, where suppressing the signal from the voice coil is not an option for obvious reasons.)

In any case I don't think it's a fundamental problem, just an issue with the particular equipment involved. People were using headphones for many years before balanced wiring caught on, and audible hum would not have been deemed acceptable then any more than it is now.

 

[wadec22]

To elaborate the above post a bit more (as well as other posts)

Advantages could be a higher available output voltage (= power) in high impedance headphones.
This is interesting for battery fed devices as one can (almost) quadruple the output power.
You get double the output voltage (as you basically have 2 amplifiers in counter-phase) and since P= U2/R.

For lower impedance headphones there might be no 'power' benefits when the current limits of each amplifier stage is reached.
Say each amp 'section' is limited to say 50mA and these 2 amp sections are in series this simply is the maximum current.
There cannot flow more current and since R is constant the power does not increase for low impedance headphones.

Then of course there are conditions where the current limit is higher in that case there is some increase in output power.

For desktop equipment creating enough output voltage and having enough current is no problem.
The most common problem is voltage rails which could be limited by the usual op-amps used.
There are plenty tricks for that + discrete designs.

Still we can find enough DT equipment sporting 'balanced' (as in a 4-wire headphone cable + 4 wire connector)
The reason for that is 'demand' and 'prestige' one could argue. Partly true perhaps.

Balanced is used in studio equipment to lower noise floors and above all influences from 'garbage inducing' surroundings.
Mains cables running alongside cables, lighting cables etc. over long distances could be in close proximity over certain lenghts.
What does this have to do with headphone cables... nothing really as these usually don't pick up something unless you have your phone against your cable and an EMC sensitive amplifier section in there.

So ... what could be the reason for a balanced cable for headphones other than have more power for high impedance headphones when a low power supply voltage rail is present.

The answer is simple.... Crosstalk.
No... not crossfeed. In fact it is closer to the opposite of crossfeed.
And then ONLY for 3-pin (and being cheap also 3-wire) headphone cables.
It is a bigger 'issue' for lower impedance headphones.

The reason is the ratio between the headphone impedance and cable+headphone plug+ internal wiring (in some cases) of the RETURN wire only.
The resistance of the signal wires does not matter here.
I can make a long post here with pictures but wrote it down in this article already.

The other advantage of balanced cables for headphones, aside from more power (depends on situation) is improved stereo separation due to the lack of a common return path due to usage of cheap 3-wire cables.
The 4 wire 'balanced' signal thus has no common return path.
Those headphones that already have 4 wires (usually the dual entry headphones) only to combine the return wires in the 3.5mm or 6.3mm plug won't really benefit from 'balanced'. Well aside from the available output voltage increase when played VERY loud.

In short: common return wire gone in 3-wire cables and higher maximum output voltage (depends on circumstances) for 'balanced' operation.

Super educational! Thank you for taking the time to share!

 

[trl]

My measurements with this (a while back - not with my forthcoming HPA1 amp) indicated this crosstalk was less of a problem than many indicate. It depends on the headphone cable configuration and ground impedance in the amp.

If the headphones have separate ground to the drivers commoned at the plug end, and the the ground of the circuit is low impedance I dont consider it a "real world" problem. Measurable yes, significant probably no.

The measurements I performed were not particularly optimised but I saw 115dB fall to 105 dB with a 32 ohm resistive load. I dont think many would hear that level of difference, although I am sure there will be some that claim night and day difference.
[...]

3dB difference with no load and 10dB when loaded with 32 Ohm...that is something indeed, even if we won't fell any changes with our ears for sure.
But let's not forget that Amir is counting every 0.1dB in his tests, so for "Hall of Fame" this should count a lot.
Many thanks for doing these measurements!

 

[trl]

Balanced XLR inputs are so easy to demonstrate that are better when using longer cables, but balanced outputs it's kinda difficult to check. For power amps, I've seen Yamaha A-S701 having a crosstalk of about 50dB @ 20KHz and about 70dB @ 10KHz vs. A-S2100 that has a crosstalk between 70-80dB at same frequencies (A-S2100 being fully balanced, with floating ground). So probably balanced designs might measure a bit better after all, but at what costs? And who can actually hear the differences?

I don't think first ever-made headamp was made fully balanced because someone said the headphones will sound better on balanced cables, I think they did it because the inside amplifiers might measure better (2 amplifiers per channel, each one taking care of it's own polarity). My only balanced headamp is Matrix HPA-3B and it measures a "tiny little bit" better in balanced mode (dynamic, THD, SNR, mains hum) than in single-ended mode, and I had also tested the background noise with sensitive cans and background was a bit darker in balanced operation (inputs shorted, same output levels tested by scope prior to shorten the inputs). However, other amplifiers are made differently, and things might be different too, here's a bit different opinion: https://benchmarkmedia.com/blogs/application_notes/audio-myth-balanced-headphone-outputs-are-better.

What I'm trying to say is that headphones are using balanced cables because balanced amplifiers exist, and not vice-versa. A decent 3-wire headphones cable should sound the same as a balanced 4-wire cable to all of us, I'm sure of that. If balanced cables are snake oil or not, I don't care much if there's a proof that balanced amplifiers measure better (in my case maybe it does, a bit), so balanced headphones could take advantage of that.

So, not sure it's worth going balanced, especially that now with $300 you can buy an Atom and a D50 that measure virtually perfect. What would be the gain if moving balanced, besides about $1000 more? Perhaps 1dB better SINAD...or maybe 2dB if using dual-mono DACs?

P.S.: I think there's a thread about balanced amps here: https://www.audiosciencereview.com/...us-unbalanced-headphone-amplifier-drive.2327/.