• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Absolute Polarity - Myth or "Important"?

  • Thread starter Deleted member 23982
  • Start date

Holmz

Major Contributor
Joined
Oct 3, 2021
Messages
2,016
Likes
1,241
Location
Australia

Without trying to hijack this thread on something model specific, Solderdude (total respect!) and I have been having spirited discussion about the venerable old AKG K240. It is the only set of cans I know of that are PURPOSELY wired "Inverse In Absolute Phase".

WHY would they do this on purpose and not follow convention like all the rest of the cans I know of?


As per the avatar photo…

The Audible Illusions Preamp (line stage) is inverting.
If the the AKG were designed to be used with an inverting amp, then they would need to be inverting to get back to being upwright.
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Not so sure about speakers - I have only witnessed it with this very specific set of cans wired this way.

Note my own use of weasel-words like "maybe" and "YMMV". :)

Still, perhaps narrow the focus to metallic instruments, where it involves two sounds 1) Where the drumstick initially makes contact with a cymbal and then 2) the ring itself.

Watching a well-timed video of drum solos just freaks me out. Almost nauseus if I watch too long.

My brain "sees" and expects the #1 strike, but never gets it. Just the #2 ring. The end result is almost as if the drummer is losing control and the sticks are about to fly into the audience, but never do. That critical detail of the strike(s) removes the natural impact of the sound we are used to - regardless of the FR. So it's just too weird.

So not sure if you'd notice the same with speakers. Or if you are sensitive to it all.

That's why at home if I'm just bored and playing around and FR isn't important, the K240's go on just to trip out. :)
 

MakeMineVinyl

Major Contributor
Joined
Jun 5, 2020
Messages
3,558
Likes
5,870
Location
Santa Fe, NM
Its certainly easy enough to change an out-of-polarity system to in-polarity by the speaker wires (or reversing wires on an XLR), so whether it 'can be heard' or not, there's really no reason to not make it right. ;)
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Don't give me justification to pull off this test with new gear! :) I so want to...

But point well taken - it's an easy fix. I use real hifi cans 99% of the time.

I think though that if one is going to chase this, narrow the focus. In most cases, you don't actually want any psycho-acoustic tricks - the 240 was only being used as an extreme case of being wired specifically for a very small user group not to improve sound, but to actually degrade the impact on purpose - in concert with other issues of FR..

In other words, if you DO hear a difference in absolute phase, from an audiophile standpoint, you probably don't want it, unless there is a GROSS error or mismatch that makes watching drum-solo's sicken you. :)
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,839
Likes
35,808
Location
The Neitherlands
old AKG K240. It is the only set of cans I know of that are PURPOSELY wired "Inverse In Absolute Phase".

Definitely not the only headphone nor is it said that this was done on purpose.

I actually built a remote controlled phase switch for DimitryZ because he wanted to know for sure.

It is known that with some recordings and test signals there can be an audible difference.

You can do a very simple test using freeware software such as Audacity. Use a track where you think you can hear a difference.
Run that track through the program and let it do a phase inversion only.
Now use ABX comparator (Foobar2000 for instance) and compare the original and phase inverted file and see how you score with at least 20 attempts.
Then you will know and do not have to guess.

Will cost you nothing (but time) as all software is free.

Success. Don't forget to post the ABX log.
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Hi bro! Not trying to be a petulant nat, but really want to learn - what are the other cans wired this way?

What you propose is a great test for sure. For me it is *any* track with metallic instruments. Thought I was going insane and didn't want to tell anyone. Douglas Self pinpointed it for me. Some might need test tracks, yes, but I don't. There's no guessing.

I had an even older dog-eared reference by Moncrieff that talked about the inverse-absolute phase psycho-acoustic effect, bit I really couldn't relate as he was talking about ensemble locations, suck-out and the like. Maybe if I focused on percussion like Douglas hinted at I would have noticed earlier.

Heh, I'll say it was done on purpose for the true narrow market these were really designed for. Like all-day on-air radio dj's, where fidelity is not a concern, but missing your mark and blowing a commercial spot intro because your ears are desensitized is. And no, you can't turn it down to compensate. Different market need.

Can you imagine if marketing advertised this as a feature when they 240's came out after the DF's: "Now with even LESS impact!" Yeah, don't see that on the box. :)

Anyway, not trying to make this a big deal again. Switching to a decent setup with no tricks solves the problem quicker. :)
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Here's a slightly finer point about this psycho-acoustic trick and ear-desensitization reduction by reducing the impact using this technique.

And it is the antipode of hifi. Take a track you know by heart for like 50 years. Every microsecond of it.

When your ears are not desensitized from metallic clanking high-energy instruments, it can become easier to hear detail you may have been missing. TINY stuff though. Maybe an extra note. Or an off-axis spoken word you couldn't make out becomes clear enough to hear. FR reduction alone won't reveal this.

You won't get this from click tracks. And of course the big YMMV weasel-word applies.

This is what I call the "trip out" effect I use for entertainment every so often.

Sounds like marketing for fake-detail right? It's more like critical listening to dixie-cups if you get my meaning. :)
 
Last edited:

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,839
Likes
35,808
Location
The Neitherlands
what are the other cans wired this way?

From the top of my head Beyerdynamic DT1770 (DT1990 is properly connected) and the HE400SE (the 400i is properly connected) and have seen this on some other ones too.
Too lazy to comb through all of my reviews. Some Wireless headphones, when used wired, also do this (for technical reasons)

Can you imagine if marketing advertised this as a feature when they 240's came out after the DF's: "Now with even LESS impact!" Yeah, don't see that on the box.

Yes, the frequency response in the upper mids is quite different between the older 600ohm and 50ohm versions. I have no idea if the original one is phase inverted or not opposite the 'convention'. Not many reviewers measure this.
 
Last edited:

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Cool! I'll have to look into them as possible stablemates!

Again - thanks for all the work you put into this. Really adds a nice dimension to stuff I don't own, but can trust!
 

krabapple

Major Contributor
Forum Donor
Joined
Apr 15, 2016
Messages
3,154
Likes
3,698
It is known that with some recordings and test signals there can be an audible difference.

Thank you. No one should be debating whether it is ever audible. That was confirmed long ago.

They should be confirming with blind tests that it is audible under the conditions they claim to hear it.
 

DimitryZ

Addicted to Fun and Learning
Forum Donor
Joined
May 30, 2021
Messages
667
Likes
342
Location
Waltham, MA, USA
Definitely not the only headphone nor is it said that this was done on purpose.

I actually built a remote controlled phase switch for DimitryZ because he wanted to know for sure.

It is known that with some recordings and test signals there can be an audible difference.

You can do a very simple test using freeware software such as Audacity. Use a track where you think you can hear a difference.
Run that track through the program and let it do a phase inversion only.
Now use ABX comparator (Foobar2000 for instance) and compare the original and phase inverted file and see how you score with at least 20 attempts.
Then you will know and do not have to guess.

Will cost you nothing (but time) as all software is free.

Success. Don't forget to post the ABX log.
I am still experimenting, my attention being mostly devoted to the war in Ukraine.

The box is working excellently!

However, early impressions are:

1. Some recordings do sound different in different phases. In audiophile terms I would describe it as a modest difference.

2. With those recordings that do exhibit a difference, it's not immediately obvious which phase is "better." One some tracks, some instruments appear to benefit from "normal phase" while other parts of the recording seem better in "reverse."
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
Thank you. No one should be debating whether it is ever audible. That was confirmed long ago.

They should be confirming with blind tests that it is audible under the conditions they claim to hear it.
Yep, one is chasing ghosts for the most part if they are looking for some special hidden pizzazz.

If you read that Wikipedia page and what Douglas Self points out that is that "in practice, the absolute phase of an audio system is can be assumed to be inaudible". HOWEVER, just prior to that statement he pointed out there is prima-facie evidence that if you narrow the focus to just percussion, you may perceive it more or less.

It is a very limited trick to actually DEgrade audio, such as the strike upon metallic instruments that can desensitize your hearing a little. That's all it is. AKG only purposely put this to use to DEgrade the impact of long-term listening.

Here is a real-world test track. One of my favorites since I like Robin Trower. Procul-Harum's "Whiskey Train".

Can you make it to the end with ceaseless cowbells and even what might appear to be striking empty wine bottles? It's tiring, all those initial strikes before the "ring". Not to mention distracting from Trower's work. Remove those initial strikes with this trick, and you might be able to listen to it twice in a row - being loud enough to get your groove on of course.

I've A/B'ed this with different gear at home and at work. No question.


Maybe this will suffice until you get Solderdudes test setup going. No cheating - crank it beyond the jazz level. Get your 1970 cowbells on. Enjoy.
 

MakeMineVinyl

Major Contributor
Joined
Jun 5, 2020
Messages
3,558
Likes
5,870
Location
Santa Fe, NM
One huge variable is if the recording itself has maintained absolute polarity through all the microphones and through the mixing console. For example, Ampex professional tape recorder manuals from the 50s and 60s didn't even point out which pins of the XLR inputs and outputs on their tape machines was 'hot' and which was 'cold'. I've even heard conflicting accounts on whether their tape recorders even maintained correct polarity. And Ampex machines were the main machines used to record all American record releases during this period. So there's that. ;)
 

Holmz

Major Contributor
Joined
Oct 3, 2021
Messages
2,016
Likes
1,241
Location
Australia
Here's a slightly finer point about this psycho-acoustic trick and ear-desensitization reduction by reducing the impact using this technique.

And it is the antipode of hifi. Take a track you know by heart for like 50 years. Every microsecond of it.

When your ears are not desensitized from metallic clanking high-energy instruments, it can become easier to hear detail you may have been missing. TINY stuff though. Maybe an extra note. Or an off-axis spoken word you couldn't make out becomes clear enough to hear. FR reduction alone won't reveal this.

You won't get this from click tracks. And of course the big YMMV weasel-word applies.

This is what I call the "trip out" effect I use for entertainment every so often.

Sounds like marketing for fake-detail right? It's more like critical listening to dixie-cups if you get my meaning. :)

Some people would replace flowery words with an impulse response.
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
By all means. Go for it!

I can only tell you what my ears hear. If you've got the gear, let's see what you got.

I'm trying to keep this on the hobbiest level. You know there's that derogatory term they use to describe us right? It ends with ...bator.

It's good to be scientific, but if we descend to that derogatory level, there's no point in being here.
 

Holmz

Major Contributor
Joined
Oct 3, 2021
Messages
2,016
Likes
1,241
Location
Australia
By all means. Go for it!

I can only tell you what my ears hear. If you've got the gear, let's see what you got.

People have.




I'm trying to keep this on the hobbiest level. You know there's that derogatory term they use to describe us right? It ends with ...bator.

Anti-science-bator?

There is actually the word “science” in the URL.
Ideally we take a step function response and can correlate it with what is heard. (Or not.)
 

600_OHM

Active Member
Joined
May 19, 2022
Messages
162
Likes
119
We're cool - just trying to keep it on a friendly level.

That's what I keep pointing out about Douglas Self's remarks about what we're talking about:


And again for a very short description of it where percussion is pointed out as being an exception. Second paragraph of this section.


I'm simply stating that I'm experiencing what Douglas Self has narrowed the focus on this laborious topic. I kinda trust that he knows what he's talking about.
 

Thomas_A

Major Contributor
Forum Donor
Joined
Jun 20, 2019
Messages
3,410
Likes
2,392
Location
Sweden
As noted in another thread bass guitarr was also very easy to hear when flipped. Even using speakers.
 

Holmz

Major Contributor
Joined
Oct 3, 2021
Messages
2,016
Likes
1,241
Location
Australia
All good @600_OHM - it would be impossible with tones, but an impulse (por percussion) is exactly where one should notice it.
 
Top Bottom