A Broad Discussion of Speakers with Major Audio Luminaries

[j_j]

Trying to understand your gripe. "Diffuse" is not at all how I prefer to hear stereo, or what makes stereo emotionally or perceptually "immersive" for me. Obviously two different definitions that may apply to the same theme.

Diffuse means that the wavefronts from many different directions are, across a small range of frequencies (an ERB to start) are not correlated. It is not easy to describe this. In general, without amazing, deep diffusors, you can't achieve that with 2 channels. Physics is like that.

Yes, and the further you go the poorer the imaging becomes, until it sounds like mono (if the room is long enough) - since both ears can hear both sides equally and crosstalk is 100%. So an equilateral triangle in near or midfield is optimal, as I hear it.

Which just means that your room provides insufficient delay to the start of the diffuse field (if in fact it's diffuse). It is generally simple to get a good image in a good room way, way, outside a critical distance, due to the way that the ear emphasizes the leading edges in an ERB.

 

[Holmz]

Remember that as you move back, you become closer to the same distance between drivers. The summation of all the driver outputs changes as a result.


This bears repeating. Often.

What?

 

[Arindal]

All of these things people speak of, transients, ‘fast’ bass, ‘tight’ bass, all of this is measurable in the frequency domain. If you have a woofer that measures flat, the perception of ‘fast transients’ is likely the absence of sub-bass.

I dispute that, despite not supporting the use of the term ´fast bass´ as it is misleading.

There are examples of speakers being capable of producing very controlled, tight bass with perfect transient reproduction, being described as ´dry´ and ´fast´ while reaching to the lowest audible frequency, like 20Hz. Has nothing to do with the mass of the woofer diaphragm or inertia, though.

The explanation for different examples of bass reproduction being described either as ´boomy, bloated, slow´ or as ´tight, controlled, dry, transient, fast´ is group delay distortion or massive decay, or rather absence thereof. We should note that this has no correlation with the frequency response, as we are not talking about true minimum phase systems, and naturally the room has an influence on both.

 

[mglobe]

@j_j not sure if you have enough info to answer this question, but Trinnov has a decorrelation option that is supposed simulate a diffuse field. It definitely has an impact that makes the sound field seem broader. On some recordings I like the affect, on some, not so much. Just wondering if you have any thoughts on how this might work, and/or your opinion on using this type of processing.

 

[DVinylfan]

Apologies if this topic has been covered here already, I haven't read all 56 pages.
My question for the experts is simply this: which is better to couple/decouple speakers to a concrete floor: spikes, or compliant (rubber/ silicon/ sprung etc.) feet?
Thanks.

 

[j_j]

What?

Hardly surprising, but having measured a 5' talll WMTMW at 3' 6' and 10', yeah, back up, baby! The advantage of that, though, is much less energy off the floor and ceiling. This wasn't an accident.

 

[j_j]

@j_j not sure if you have enough info to answer this question, but Trinnov has a decorrelation option that is supposed simulate a diffuse field. It definitely has an impact that makes the sound field seem broader. On some recordings I like the affect, on some, not so much. Just wondering if you have any thoughts on how this might work, and/or your opinion on using this type of processing.

I don't know exactly what they do, but I have done similar things, both in 2, 5, and 7 channel systems.

The problem is that when a diffused signal is delivered from one speaker, of course it's entirely coherent at two ears, and no longer diffuse. This is why 5 or 7 channels can do a much better job, yes, the interference between them helps. A lot.

 

[mglobe]

I don't know exactly what they do, but I have done similar things, both in 2, 5, and 7 channel systems.

The problem is that when a diffused signal is delivered from one speaker, of course it's entirely coherent at two ears, and no longer diffuse. This is why 5 or 7 channels can do a much better job, yes, the interference between them helps. A lot.

Thanks for the info. Trinnov intends it to be a mch tool, I think mostly for the surrounds, but it can be applied to the mains also. This is what I’ve been playing with on my 2.2 system.

 

[dagfinn]

Diffuse means that the wavefronts from many different directions are, across a small range of frequencies (an ERB to start) are not correlated. It is not easy to describe this. In general, without amazing, deep diffusors, you can't achieve that with 2 channels. Physics is like that.


Which just means that your room provides insufficient delay to the start of the diffuse field (if in fact it's diffuse). It is generally simple to get a good image in a good room way, way, outside a critical distance, due to the way that the ear emphasizes the leading edges in an ERB.

Thanks, I will study your reply and see if I can reach understanding that makes sense . I generally don't want the room to contribute much, and experience from big rooms is not good due to poor design and poor acoustical performance. My goal is the build a Auro 3D setup in a room around 6x7m, or a litte bigger, establlishing an "Immersive audio" system as in the definition "Immersive audio is a three-dimensional sound experience that surrounds the listener with sound from all directions, including above, creating a lifelike auditory environment. "

 

[Suono]

When I go to listen to a symphony in an auditorium, the music comes from the front. The soundstage is very distinct and focused in front of me; no sound comes from behind or above.

 

[olieb]

The soundstage is very distinct and focused in front of me; no sound comes from behind or above.

If that were true, you could cut off most of the walls of the building (concert hall) and the sound would be the same.
Well, you would be in for a surprise.

 

[Suono]

If that were true, you could cut off most of the walls of the building (concert hall) and the sound would be the same.
Well, you would be in for a surprise.

Thanks for pointing that out. I hadn't thought about it in 40 years of listening, but it's just a thought. I meant that for me, immersion in the event doesn't mean having sound sources other than two channels.
I know very well the importance of the sound of the walls of an auditorium like those of our listening room.

 

[dagfinn]

As a matter of fact, the ancient Greek had two different type stages for different purposes. The theatre for speach, and the odeon for music and song. The difference was that the odeon had a ceiling, making it a resonant space. The theatre relied on the floor in front to reflect the spoken word, which worked almost perfectly. There's loads of science done on it, the sites have been measured extensively, showing how these venues worked acoustically.

Here's the Greek theatre of Taormina, the only such venue I have experienced.

In the far background on a clear day or night, the volcano Etna can be seen.

Here's a little on the Herodes Atticus Odeion, and a suggestion on how it it may have looked.

https://www.researchgate.net/publication/233658596_The_Acoustics_of_Roofed_Ancient_Odeia_The_Case_of_Herodes_Atticus_Odeion

Whispers Through Marble: The Enigmatic Acoustics of Herodes Atticus Odeon

Built for acoustic delight, The Odeon of Herodes Atticus still offers moments of unforgettable experiences for the audiences that flood its premises to enjoy various spectacles in Athens.

romanempiretimes.com

 

[Arindal]

When I go to listen to a symphony in an auditorium, the music comes from the front. The soundstage is very distinct and focused in front of me; no sound comes from behind or above.

The direct sound might come from the front, so your brain calculates instruments being localized as coming in from the front as well. ´No sound from behind or above´ is not true, though, as particularly concert halls, opera houses and churches have a pretty significant RT60, so actually a lot of sound is coming in from non-frontal angles. Particularly when you are sitting somewhere further from the musicians. It is just your brain being capable of recognizing the significant amounts of indirect sound patterns as reflections, so they are not directly affecting localization.

the ancient Greek had two different type stages for different purposes. The theatre for speach, and the odeon for music and song. The difference was that the odeon had a ceiling, making it a resonant space.

I have recently been attending an opera performance in a ´modern´ (constructed in 1874), some people say the most advanced worldwide, iteration of such a theatre, which offers both excellent singing intelligibility and orchestral ambience, at the same time:

Encourage everyone to witness one or two evenings there. It is a life-changing experience in terms of how you perceive music and sound in a closed venue. Avoid the rows 20+, though!

 

[Suono]

The direct sound might come from the front, so your brain calculates instruments being localized as coming in from the front as well. ´No sound from behind or above´ is not true, though, as particularly concert halls, opera houses and churches have a pretty significant RT60, so actually a lot of sound is coming in from non-frontal angles. Particularly when you are sitting somewhere further from the musicians. It is just your brain being capable of recognizing the significant amounts of indirect sound patterns as reflections, so they are not directly affecting localization.

Of course,
exactly what we should recreate in our listening room. With two cleverly placed speakers, I can have all this.
Nothing else is needed for music.

 

[Mart68]

Here's the Greek theatre of Taormina, the only such venue I have experienced.
View attachment 479228

You'd have thought they'd have waited until they'd finished building it before they started putting on performances.

 

[Arindal]

exactly what we should recreate in our listening room.

Sorry to cause disappointment, but you cannot recreate that, if it has not been recorded. To get a more or less accurate representation of the indirect soundfield, you need at least something like 9 or 11 channels capturing the angles from which indirect parts of the soundfield are coming in. Dolby Atmos and Auro3D are the most basic technology to do so, certainly not two channel stereo.

With two cleverly placed speakers, I can have all this.

It is acoustically impossible, as with two speakers, you can create only a phantom image of the direct sound (´front staging´), plus a very limited representation of the indirect sound. Additional reflections in the listening room will not help, as their reverb pattern contradict the original soundfield. There is nothing to place properly, at best you can manage to bring the additional reverb to a sufficiently diffuse level.

 

[olieb]

I meant that for me, immersion in the event doesn't mean having sound sources other than two channels.

Ok, that is a different thought.
But to reproduce the sound from the walls of the auditorium (from all directions) the two channels are not very well suited. You will only get the reflected sound that your (small) listening room creates and this is a long shot from what the (large) auditorium walls do [ even if part of that is reproduced via the two frontal channels].
I can understand if that this is all the immersion you need, but most listeners prefer a multichannel setup in this regard.

 

[Suono]

Sorry to cause disappointment, but you cannot recreate that, if it has not been recorded. To get a more or less accurate representation of the indirect soundfield, you need at least something like 9 or 11 channels capturing the angles from which indirect parts of the soundfield are coming in. Dolby Atmos and Auro3D are the most basic technology to do so, certainly not two channel stereo.

Don't worry about being disappointed, I listen to a lot of poorly crafted '60s recordings...they knew how to record! You're right, recording is very important!!!

 

[levimax]

If that were true, you could cut off most of the walls of the building (concert hall) and the sound would be the same.

Like being at an outdoor concert venue.