Imaging: coaxial vs. traditional layout

[Sancus]

for me the question is, do you here the difference with on and off and what is like ... more like just different, or really better in any regard when on?

Switching between the two is not fast enough to really be testable very well. I thought there was a very small difference when I tried but it could be in my head. It does produce slightly different FR measurements in GLM though so it's probably audible in the right conditions. But I don't think it's going to make a large clearly noticeable difference for most people.

If it had any sort of real downside I would leave it off for sure.

 

[kimmosto]

The Ones are phase linear from 100hz up if you turn extended phase linearity on....

The first two Ones; 8260A and 8351A didn't have phase linearization. Coaxial couldn't guarantee proper imaging at least with 8260A, but I don't actually know was it scattered due to really terrible timing or some diffraction hard to see by looking the design and construction.

 

[Guy.G]

Ken Rockwell measured the audio output of them HERE.
Where do you think they’re defective?
My first thought was it’s an airplay issue, but the RME is also fed a digital signal from an AE over airplay. They are all also on firmware 7.6.9

I would recommend downgrading to the earliest firmware available for your devices (they don't allow downgrades beyond the version they shipped with).
Thankfully you are not on the AirPlay 2 firmware (7.8.x) because that absolutely destroyed the analog output performance.
I can only speculate that they were asking too much from a limited SOC.

I have three of them here as well, and as soon as I installed that update, something sounded wrong.
I only did limited testing, but it was enough to stream a 1kHz tone from an iPhone and see this:

This video shows the output from an AE2 connected to a Behringer UMC22 interface, which was then connected to an iPad running an "Audio Analyzer" app for the FFT.
Though 7.6.9 performed better than 7.8.x, the earlier I went, the better the performance seemed to be (though perhaps only slightly).
I tested the three devices that I own, and they all behaved exactly the same. I suspect that their performance got progressively worse over time, compared to the state they were released/reviewed in.


The AirPort Express devices were great for their time.
Back in 2004 there was nothing widely available and affordable that was streaming lossless CD-quality audio around the home - especially with a digital output.
The 2012 update was a modest improvement to the analog output, but they aren't the greatest DACs - especially when running updated firmware, or when compared to what you can get today.

I don't know about you, but when I set them up with active speakers, I'd end up adjusting the amp volume to the maximum level I'd ever want to listen at, and used the source device (phone) for volume control because it was more convenient - since control is on the back of both speakers.
So I got extra amp noise from the gain being turned up, and reduced SNR from the digital volume control - which was really kneecapping the performance of the system. It ended up well below 16-bits.

And the other issue is that even after the AirPlay 2 update, the digital output is still limited to 16-bit on these devices (other AP2 devices can support 24-bit).
So even if you accept that the analog performance is limited, and wanted to repurpose them as a digital transport for an external DAC, it's probably going to limit the performance of whatever you connect to it - and nearly everything is moving to USB now.

I suppose that is still enough for lossless CD-quality playback, if you don't touch the volume - and that might still cover most of a person's audio library.
But these days, I'm used to having volume leveling enabled in the player, and using DSP like EQ or room correction.
It's also just nice being able to control the volume via the phone than getting up or looking for a remote. And 16-bit doesn't really allow for that.

Running into some networking issues with them recently pushed me to look into replacing them.
And I've found that even a $15 Raspberry Pi Zero 2W is enough to do that (if you can get one right now).
Not by itself, but it can connect to any modern USB DAC and act as a Roon endpoint (or AirPlay/Spotify/DLNA) via RoPieee (XL), streaming up to 32-bit 192 kHz rather than 16/44.

With that, there's little concern about using features like volume leveling, room correction, or digital volume control from the source.
Pairing it with something like a Topping D10 (S/B) should be a considerable improvement for about $100-150 depending on whether you want the balanced output (I would).

 

[don'ttrustauthority]

I went to MTM precisely to stop the image from moving as the sound transfers from the midrange drivers to the horn. I think a non-moving image is "right". Real music doesn't wiggle around because the frequency of a note rises and falls.

It does if goes from one instrument to another!

 

[fpitas]

It does if goes from one instrument to another!

Generally, they are not stacked one on top of the other (?)

 

[Pearljam5000]

So....
Coaxial have a smaller soundstage or not?

 

[RobL]

So....
Coaxial have a smaller soundstage or not?

Nope, they’re the same. My RME was outputting mono…yeah, I’m a dumbass

 

[test1223]

So....
Coaxial have a smaller soundstage or not?

Yes. Coax smaller vertical soundstage and more precise and multi way bigger and more blurry vertical soundstage. Low diffraction enclosure are also important for a precise sound stage therefore not every coax is better than a multi way speaker.

If you can't place the speaker about 1m (3.3ft) away from all obstacles the image won't be the best anyways.

The horizontal soundstage is about the same with a good coax and a good multi way speaker. A more cylindrical or planar wavefront can improve the stability of the horizontal soundstage and provide a bigger size of the vertical soundstage. Therefore as a rule of thumb bigger speakers provide a bigger soundstage.

Edit: resonances are also very bad for the soundstage.

Closing your eyes improves the soundstage of a good speaker.

 

[fineMen]

Yes. Coax smaller vertical soundstage and more precise and multi way bigger and more blurry vertical soundstage. ... important for a precise sound stage ... the image won't be the best ... horizontal soundstage ... A more cylindrical or planar wavefront can improve the stability of the horizontal soundstage and provide a bigger size of the vertical soundstage. Therefore as a rule of thumb ...

Edit: resonances are also very bad for the soundstage.

May be I'm the dump/ here, but could anyone explain to me what the expert's terms of vert./hor. soundstage, imaging etc are all about?! What exactly is a wavefront?

Closing your eyes improves the soundstage of a good speaker.

Shall I paint my listening room with BLK3.0? Or, alternatively the speakers (in/ or outside)?

Seriously, what is the sense of imaging / soundstage at all with stereo, and how might it depend on the listeners expectations?

(https://www.culturehustleusa.com/products/black-3-0-the-worlds-blackest-black-acrylic-paint-150ml)?

 

[test1223]

May be I'm the dump/ here, but could anyone explain to me what the expert's terms of vert./hor. soundstage, imaging etc are all about?! What exactly is a wavefront?


Shall I paint my listening room with BLK3.0? Or, alternatively the speakers (in/ or outside)?

Seriously, what is the sense of imaging / soundstage at all with stereo, and how might it depend on the listeners expectations?

(https://www.culturehustleusa.com/products/black-3-0-the-worlds-blackest-black-acrylic-paint-150ml)?

I am more familiar with the German terms of phycoacoustics regarding localisation since I read the very good books from Jens Blauert where I got 80% of my knowledge of sound localisation from. So I might not be 100% correct with all the terms in english.

With stereo you have placed all sound events on a bended line from the left to the right speaker this is typically called soundstage. If you have an event which you can localize very well exactness is the term which is used and the terms blurry is used if you can't do that.

The size of the events are determined in the horizontal and vertical dimensions.

There is sometimes a very weak sense of depth with stereo.

Stability is most of the time used if you can move your head and the image doesn't gets much worse.

Typically image includes the ability of providing a good soundstage and the sense of being surrounded by the sound which is often called envelopement.

The curvature of the wavefront determines the beaming of the speaker and changes the head related transfer functions. E.g. a point source provides a spherical wavefront. Therefore it is an important part for localisation.

Visual cues will change the perception of the image. Closing your eyes helps a lot for getting a better soundstage. No joke try it.

 

[tuga]

I don’t see how 2-channel stereo or multi-channel can produce an effect of height.
You probably need a vertical channel for that purpose.

 

[fineMen]

... regarding localisation since I read the very good books from Jens Blauert where I got 80% of my knowledge of sound localisation from.

I argue that the work of Blauert was related to stereo in any way. He acted as a scientist, not as an entitled audiophile in person, nor was his work targeted at that demographic. His interest was foremost hearing aids and the like, in short things of real value.

The stereo is a very bad exploitation of basic trivialities circling around the mere fact that most people have two ears.

No, Blauert does not explain stereo.

Stability is most of the time used if you can move your head and the image doesn't gets much worse.

What image?! And not the least, stereo by design has to (!) fall apart with moving the head.

The curvature of the wavefront determines the beaming of the speaker and changes the head related transfer functions. E.g. a point source provides a spherical wavefront. Therefore it is an important part for localisation.

Any proof for that? I have it proven the other way round. HRT and 'phase' are not connected.

 

[test1223]

I don’t see how 2-channel stereo or multi-channel can produce an effect of height.
You probably need a vertical channel for that purpose.

Stereo can provide a sense of a vertically big soundstage but not of placing a sounds event up or down.

 

[fineMen]

Using the track “Hey Brother” by Avicii as an example…The song begins with alternating guitar notes for several seconds before the singer comes in. On the 705P’s the notes are almost amorphous, seeming to (almost?) alternate from left to right at the outside of the soundstage. ... Has anyone else noticed similar effects?

I just rebuild my huge horn loaded speakers. I used a showbox-sized pair before as to explore its versatility with on-shelf mounting.

In short, the musical example you give is accessible for me via my Tidal account. It sounds overprocessed to begin with. The sharp guitar(s?) nearly resembles a contemporary synthesizer, the weeps are unmotivated add-ons, clearly, the voice is doubled-up, the bassdrum later is a watery mess, the reverberation changes from fresh spacey to warm intimate, unmotivated etc pp. Second to the overt processing effort, I personally think that the musical content as such leaves a lot to be desired. I couldn't get around the latter, sorry.

It may have been o/k-ish with the wide dispersion home-fidelity small boxes, but with the razor-sharp horns it reveals all its mess.

Or to put it the other way round, it only reveals that 'soundstage' or 'imaging' are terms not to be used with stereo. Stereo is a purely synthetic layer on top of recorded sound, that shall not be emphasized too much. The stereo is by its basic principles so weak, you will for shure be left unsatisfied whatever you do. With wide disperion speakers its ill effects are a bit tamed. Coaxes most often sport a more narrow dispersion.

 

[test1223]

No, Blauert does not explain stereo.

I didn't claim that Blauert focus was stereo. He never the less did also provide a lot of research regarding two channel and multi channel localisation. Most importantly he provides almost all foundations.

What image?! And not the least, stereo by design has to (!) fall apart with moving the head.

There are ways do get a more sable soundstage and also to get a better envelopment even if you move your head.

Any proof for that? I have it proven the other way round. HRT and 'phase' are not connected.

The reflections of the ear and head are obviously different depending on the curvature of the wavefront and this phase differences cause the dips and peaks of the HRTFs. The phase of the recorded HRTFs aren't important that is correct.

 

[tuga]

Stereo can provide a sense of a vertically big soundstage but not of placing a sounds event up or down.

What is the mechanism responsible for that effect?

 

[RobL]

Stereo can provide a sense of a vertically big soundstage but not of placing a sounds event up or down.

The song “Two Weeks” by FKA twigs has a staccato effect towards the end of the song that appears to run left to right across the ceiling playing it on my 8361’s. I assume it is some sort of phase trickery used.

 

[fineMen]

The song “Two Weeks” by FKA twigs has a staccato effect towards the end of the song that appears to run left to right across the ceiling playing it on my 8361’s. I assume it is some sort of phase trickery used.

Not for me, sorry. Do you like it?

The reflections of the ear and head are obviously different depending on the curvature of the wavefront and this phase differences cause the dips and peaks of the HRTFs. The phase of the recorded HRTFs aren't important that is correct.

If so, that raises another question: plane wave versus circular wave. Which of these possibilities is the The True HiFi? Could You please quote a scientific source for your suggestion? Or is it a derivative that you concluded from your studies in stereo?

 

[test1223]

What is the mechanism responsible for that effect?

There is more than one effect. The curvature of the wavefront, the uniform tactile perception of the lower frequencies can provide a perception of a bigger soundstage. Reflections are also important but I am not an expert regarding floor and ceiling reflections and its influence on the perception of size.

The song “Two Weeks” by FKA twigs has a staccato effect towards the end of the song that appears to run left to right across the ceiling playing it on my 8361’s. I assume it is some sort of phase trickery used.

Interesting some tricks can be made to pan a sound event in the median plane. But it can only be done with some sounds and I haven't heard of an effect like putting a event this high will listen to it tomorrow.

There is a stereo recording which has a sound event which circles around the listener in the horizontal plane and is very convincing, Gwely Mernans by Aphex Twin.

 

[mmi]

Listening to the start of that Aviici track, on my AirPods Pro and Sonos One stereo pair the higher guitar notes are definitely panned slightly right and the bass plucks pan left to right before the vocals kick in. Weirdly enough on my desktop Genelec 8010 running direct from MacMini 2018 headphone jack via split xlr the high notes sound panned left. I checked polarity and the Genelecs are set up correctly. Weird.