What works for omnidirectional speakers?

[Rhapsody]

The most problematic are the frequencies below your rooms schroeder frequency. Depending on the size and decay time goal, it would lie between 100hz to 150hz in most rooms. These frequencies are not very much dependent on the type of speaker.

I would recommend starting to treat your room corners with deep enough absorbers that could actually work on these frequencies. Front and back wall can be both diffused or one could be absorbing and the other could be diffusing. It depends on your expectations and your distance to these walls.

Other than that, I agree with mostly diffusion for your room but first things first and that is bass nodes and better controlled bass decay.

Congrats on your new system.

The problem with deep enough absorbers, understanding that they would work, is that in this case this is what the Emperyan has said below. Not sure about his wife, but MOST wives that I work with and it's a LARGE number, would be less than receptive to corner absorbers in their living room.

From Emperyan's post above-

"But on the other hand it´s somewhat bad news for me as I am pretty inflexible in placement in my room. I don´t have a dedicated listening room, but it´s the living room which also has to be approved by my wife. And she won´t approve any prominent diffusors (except for maybe some plants). My left side wall is all windows, anyway."

 

[kodomo]

The problem with deep enough absorbers, understanding that they would work, is that in this case this is what the Emperyan has said below. Not sure about his wife, but MOST wives that I work with and it's a LARGE number, would be less than receptive to corner absorbers in their living room.

From Emperyan's post above-

"But on the other hand it´s somewhat bad news for me as I am pretty inflexible in placement in my room. I don´t have a dedicated listening room, but it´s the living room which also has to be approved by my wife. And she won´t approve any prominent diffusors (except for maybe some plants). My left side wall is all windows, anyway."

The age old problem However, room corners are very rarely utilized and if the corner traps are built to be invisible, blended with the wall, not many wives would have problems. There are creative solutions for nearly every room.

 

[Rhapsody]

The age old problem However, room corners are very rarely utilized and if the corner traps are built to be invisible, blended with the wall, not many wives would have problems. There are creative solutions for nearly every room.

Totally depends on the specific wife

If it's in the family living room my experience is that 1 out of 5 wives would be ok with it. That's with having installed hundreds of systems and probably 75% of those systems, if not more, in living spaces vs dedicated rooms.

 

[Emperyan]

Bob is right. I already tried to negotiate for bass traps - no chance. ;-)
But in my current system I have very little problems with low frequency room modes. The room swallowing a lot of low frequency energy is actually more of a problem. Therefore I have smoothened out the low frequency response via Acourate filters and lifted the whole low frequency band slightly. This worked perfectly for me with super tight base down to 15Hz (subwoofer included). I plan to do the same with the Bayz.

 

[Rhapsody]

Bob is right. I already tried to negotiate for bass traps - no chance. ;-)
But in my current system I have very little problems with low frequency room modes. The room swallowing a lot of low frequency energy is actually more of a problem. Therefore I have smoothened out the low frequency response via Acourate filters and lifted the whole low frequency band slightly. This worked perfectly for me with super tight base down to 15Hz (subwoofer included). I plan to do the same with the Bayz.

Dominik, your wife is normal The wives that allow it are abnormal

I'm just kidding for all those guys with wonderful wives that allow bass traps in the corners of their living rooms!

Btw, I have NOT had any issues with the bass on the Courante and Counterpoints. Nothing like bass humps or lack of bass.

 

[Duke LeJeune]

But especially with acoustic instruments and voices, they will sound different in every room. Put the same orchestra in different concert halls or the same Jazz trio in different clubs and they will sound vastly different. So I guess, to capture the atmosphere of the live performance recorded, we also have to recreate the room signature of where it happened. And that´s the most tricky part as you will only have one and the same room at home for each recording - and in 99% of the cases it will be much smaller than the original venue.

Imo rather than trying to make our playback rooms acoustically resemble a concert venue (which is highly unlikely to happen), better to focus on getting our playback rooms "out of the way", so that we can clearly hear the venue cues which are already on the recording.

Assuming a good recording, imo the "atmosphere of the live performance" is ALREADY on it. Those cues ARE being delivered to us, it's just that our playback rooms' inherent "small room signature" typically DOMINATES our perception.

At the risk of oversimplifying, it is the EARLIEST reflections which MOST STRONGLY convey that undesirable "small room signature". This is why MBL prefers to show their speakers in large rooms - the distances to the walls are great enough to effectively preclude undesirable early horizontal-plane reflections. This is also why dipole speaker owners like to pull their speakers well forward of the front wall.

When the early reflections are minimized AND the late reflections are preserved, the acoustic signature on the recording is much more likely to dominate our perception.

Compared to the real thing, at best our stereo systems present us with a poverty of recording venue cues, but ime it is still possible for that poverty of cues to dominate and convey an enveloping "you are there" atmosphere, which inherently (and enjoyably) changes significantly from one recording to the next.

 

[stehno]

Imo rather than trying to make our playback rooms acoustically resemble a concert venue (which is highly unlikely to happen), better to focus on getting our playback rooms "out of the way", so that we can clearly hear the venue cues which are already on the recording.

Assuming a good recording, imo the "atmosphere of the live performance" is ALREADY on it. Those cues ARE being delivered to us, it's just that our playback rooms' inherent "small room signature" typically DOMINATES our perception.

At the risk of oversimplifying, it is the EARLIEST reflections which MOST STRONGLY convey that undesirable "small room signature". This is why MBL prefers to show their speakers in large rooms - the distances to the walls are great enough to effectively preclude undesirable early horizontal-plane reflections. This is also why dipole speaker owners like to pull their speakers well forward of the front wall.

When the early reflections are minimized AND the late reflections are preserved, the acoustic signature on the recording is much more likely to dominate our perception.

Compared to the real thing, at best our stereo systems present us with a poverty of recording venue cues, but ime it is still possible for that poverty of cues to dominate and convey an enveloping "you are there" atmosphere, which inherently (and enjoyably) changes significantly from one recording to the next.

Good points, Duke. For the most part anyway. I agree it makes no sense to try to make a room resemble some concert hall. And as you allude it's most likely an impossible task anyway. I realize this pursuit is longstanding folklore. You're also correct that we can clearly hear the venue - musiic info already embedded in a given recording.

However, I must disagree regarding your take on getting our listening rooms "out of the way". I'm all for compiling a reasonable room that might include minimum reflective surfaces, carpet and pad, reasonable dimesions, etc. but that hopefully is just commonsensical stuff and not worth mentioning. From my limited experience, the only significant focus required on the room is that of locating a or the superior speaker position within a given room but really not much of anything else.

If indeed the majority of a venue's ambient info is embedded in the recording (and it is) then provided it remains audible at the speaker (remains above a raised noise floor) after being read and processed, then during playback the recording's ambient info should completely minimize if not entirely overshadow most any room acoustic anomalies as hopefully these two samples should illustrate.

IME, with certain technologies it is entirely possible to extract (keep audible at the speakers via a much lowered noise floor) the volumes of ambient info embedded in a given recording. Again, hopefully I'm able to illustrate with these same two in-room sample recordings.

IOW, I do nothing to make the room "get out of the way" including first reflections, etc except for superior speaker placement and I'm speculating you should seemingly hear no room influences whatsoever from these two sample recordings.

 

[Duke LeJeune]

However, I must disagree regarding your take on getting our listening rooms "out of the way". I'm all for compiling a reasonable room that might include minimum reflective surfaces, carpet and pad, reasonable dimesions, etc. but that hopefully is just commonsensical stuff and not worth mentioning. From my limited experience, the only significant focus required on the room is that of locating a or the superior speaker position within a given room but really not much of anything else.

We may be in complete agreement; I didn't go into detail about what I mean by "getting our playback rooms 'out of the way'".

My focus is ACTUALLY on the loudspeaker's radiation pattern and set-up, and NOT on "room treatment" as a "fix" for the speaker's off-axis response. But because this thread is about omnidirectional speakers, I left that part out.

Here are some basic concepts I try to pay attention to, articulated by acoustician David Griesinger. He is writing mainly about concert halls so he uses the term "envelopment", which would correspond to a "you are there" presentation in home audio:

"Envelopment is the holy grail of concert hall design. When reproducing sound in small spaces [home listening rooms], envelopment is often absent."

"Envelopment ["you are there"] is perceived when the ear and brain can detect TWO separate streams: A foreground stream of direct sound, and a background stream of reverberation. Both streams must be present if sound is perceived as enveloping." [This implies that a time gap in between the direct sound and the reverberant sound is desirable.]

"The earlier a reflection arrives the more it contributes to masking the direct sound."

If an omni is set up correctly in a large enough room, we will detect the two separate streams which enable the perception of envelopment, or "you are there".

IF a dipole speaker is positioned far enough out from the "front" wall, again we will detect the two streams and "you are there" becomes possible.

I'd rather not go further down this road because this thread is about omnidirectional speakers, not about how to do "you are there". But if "you are there" is a goal, imo it makes sense to consider room interaction and therefore loudspeaker radiation pattern and of course loudspeaker set-up to work with its radiation pattern.

 

[stehno]

We may be in complete agreement; I didn't go into detail about what I mean by "getting our playback rooms 'out of the way'".

To some degree I think we are in agreement.

My focus is ACTUALLY on the loudspeaker's radiation pattern and set-up, and NOT on "room treatment" as a "fix" for the speaker's off-axis response. But because this thread is about omnidirectional speakers, I left that part out.

Here are some basic concepts I try to pay attention to, articulated by acoustician David Griesinger. He is writing mainly about concert halls so he uses the term "envelopment", which would correspond to a "you are there" presentation in home audio:

"Envelopment is the holy grail of concert hall design. When reproducing sound in small spaces [home listening rooms], envelopment is often absent."

"Envelopment ["you are there"] is perceived when the ear and brain can detect TWO separate streams: A foreground stream of direct sound, and a background stream of reverberation. Both streams must be present if sound is perceived as enveloping." [This implies that a time gap in between the direct sound and the reverberant sound is desirable.]

Envelopment per se is or should be the holy grail of high-end audio as well. But in the case of high-end audio, IMO it has little / nothing directly to do with the room.

"The earlier a reflection arrives the more it contributes to masking the direct sound."

If an omni is set up correctly in a large enough room, we will detect the two separate streams which enable the perception of envelopment, or "you are there".

IF a dipole speaker is positioned far enough out from the "front" wall, again we will detect the two streams and "you are there" becomes possible.

I'd rather not go further down this road because this thread is about omnidirectional speakers, not about how to do "you are there". But if "you are there" is a goal, imo it makes sense to consider room interaction and therefore loudspeaker radiation pattern and of course loudspeaker set-up to work with its radiation pattern.

Understood that the topic is omni-directional speakers but more specifically I think the topic is how a room should be treated "differently" for omni-direction speakers. That said, I'm unsure how direct-radiating speakers differ from your omni-directional and dipole speaker comments here. And if the room really makes little / no never mind, aside from speaker placement, not sure why the OP or anybody else might emphasize the potential need for differences of room setup / treatment, etc.

But if the topic is omnidirectional speakers (and di-pole speakers) and room differences, why not toss in multi-channel configs and room differences as well? After all, are they not all attempting to create that "envelopment" sound each in their own way as well as succeeding or more likely failing in much the same way?

I mention "more likely failing because IMO that is clearly more accurate. Going back to your earlier claiims of a performance's ambient info already embedded in the recording and if that same info read and processed remains audible at a direct-radiating speaker, then the room has already disappeared inclduing most any room acoustic anomalies become so overshadowed the room is gone. Hence, the only potential we hear is the "envelopment" of the recording hall. And if that is possible with direct-radiating speakers, then is there still a need for room corrections, omni-directional / dipole speakers, or multi-channel configs?

I suspect for those lacking the ability to keep volumes of ambient info embedded in a recording audible at the speaker fail to consider the cause which is always a much raised noise floor. Every playback system has a much raised noise floor to one good degree or another and in such cases, the first music info to become inaudible at the speaker is the lowest of the low level detail which is the volumes of ambient info. IMO, the real problem lies with those seeking to address the effects of little / no ambient info in the playback presentation, rather than seek to address the cause of little / no ambient info which is always a much raised noise induced by all distortions (inaudible and audible) accumulated.

Hence, I really view omni-directional, dipole, and multi-channel solutions as more of a band-aid dealing with the effects rather than the cause and in so doing introduce a phenomena of a sound attempting to assimulate the inuadible ambient info suppressed by a much raised noise floor. Perhaps this phenomena of sound is more titillating than a playback presentation with little / no real ambient info but why bother with a phenomena of sound when we can invoke much greater pleasure listening to volumes of actual ambient info embedded in a given recording? IOW, if we're only going to deal with effects rather than causes, doesn't it all just boil down to a pick your poison scenario? I guess that's my point.

 

[Lagonda]

Totally depends on the specific wife

If it's in the family living room my experience is that 1 out of 5 wives would be ok with it. That's with having installed hundreds of systems and probably 75% of those systems, if not more, in living spaces vs dedicated rooms.

It is clearly a installation problem, you have to install a wife AFTER the sound system Maybe it is time for a upgrade anyway ?

 

[Duke LeJeune]

Envelopment per se is or should be the holy grail of high-end audio as well. But in the case of high-end audio, IMO it has little / nothing directly to do with the room.

I think it has a lot to do with room interaction, because it has to do with the arrival times of reflections.

Understood that the topic is omni-directional speakers but more specifically I think the topic is how a room should be treated "differently" for omni-direction speakers. That said, I'm unsure how direct-radiating speakers differ from your omni-directional and dipole speaker comments here. And if the room really makes little / no never mind, aside from speaker placement, not sure why the OP or anybody else might emphasize the potential need for differences of room setup / treatment, etc.

In the context of "envelopment", imo room size and speaker positioning are primary considerations with omni and dipole speakers.

But if the topic is omnidirectional speakers (and di-pole speakers) and room differences, why not toss in multi-channel configs and room differences as well? After all, are they not all attempting to create that "envelopment" sound each in their own way as well as succeeding or more likely failing in much the same way?

Yes, but I was trying not to take the thread way off topic.

I mention "more likely failing because IMO that is clearly more accurate. Going back to your earlier claiims of a performance's ambient info already embedded in the recording and if that same info read and processed remains audible at a direct-radiating speaker, then the room has already disappeared inclduing most any room acoustic anomalies become so overshadowed the room is gone. Hence, the only potential we hear is the "envelopment" of the recording hall. And if that is possible with direct-radiating speakers, then is there still a need for room corrections, omni-directional / dipole speakers, or multi-channel configs?

If the ear/brain system is simultaneously presented with two approximately equal-strength sets of acoustic signatures, one for a small room (the playback room) and one for a large room (the recording venue, whether real or not), it defaults towards accepting the signature of the smaller room. So imo it makes sense to minimize the playback room's cues while effectively presenting the recording venue's cues.

I can't begin to see your system in those clips you posted so I have no idea what your speakers or room look like, but I bet your setup inherently has relatively weak early reflections while preserving the later-arrival reflections, even if that was not deliberate on your part.

I suspect for those lacking the ability to keep volumes of ambient info embedded in a recording audible at the speaker fail to consider the cause which is always a much raised noise floor. Every playback system has a much raised noise floor to one good degree or another and in such cases, the first music info to become inaudible at the speaker is the lowest of the low level detail which is the volumes of ambient info. IMO, the real problem lies with those seeking to address the effects of little / no ambient info in the playback presentation, rather than seek to address the cause of little / no ambient info which is always a much raised noise induced by all distortions (inaudible and audible) accumulated.

Agreed, signal-to-noise ratio definitely matters... and in the context of in-room reflections, the playback room's cues are the noise, and the recording venue cues (which are delivered largely by those in-room reflections) are the signal. It probably seems counter-intuitive that we can enhance the one and not the other, but we can, by taking advantage of psychoacoustic windows of opportunity.

Hence, I really view omni-directional, dipole, and multi-channel solutions as more of a band-aid dealing with the effects rather than the cause and in so doing introduce a phenomena of a sound attempting to assimulate the inuadible ambient info suppressed by a much raised noise floor. Perhaps this phenomena of sound is more titillating than a playback presentation with little / no real ambient info but why bother with a phenomena of sound when we can invoke much greater pleasure listening to volumes of actual ambient info embedded in a given recording? IOW, if we're only going to deal with effects rather than causes, doesn't it all just boil down to a pick your poison scenario? I guess that's my point.

What an omni or dipole or other polydirectional or multichannel system theoretically does well is, effectively present the venue ambience cues which are on the recording. These cues should be spectrally correct, should come from all around, should be strong but not too strong, should not arrive too early, and should decay slowly but not too slowly.

The reason we need the in-room reflections is that the WORST POSSIBLE direction for ambience cues to arrive from is the EXACT SAME direction as the direct sound. So we need something besides the direct sound delivering those ambience cues to us.

In my opinion these approaches (omnis, dipoles, bipoles, etc.) are not "band-aids"; rather, they are viable alternatives which may do a very good job of conveying envelopment if set up correctly.

I design speakers with an unorthodox feature intended to improve their ability to convey envelopment, so my familiarity with the topic has a practical rather than strictly theoretical background.

 

[stehno]

I think it has a lot to do with room interaction, because it has to do with the arrival times of reflections.



In the context of "envelopment", imo room size and speaker positioning are primary considerations with omni and dipole speakers.



Yes, but I was trying not to take the thread way off topic.



If the ear/brain system is simultaneously presented with two approximately equal-strength sets of acoustic signatures, one for a small room (the playback room) and one for a large room (the recording venue, whether real or not), it defaults towards accepting the signature of the smaller room. So imo it makes sense to minimize the playback room's cues while effectively presenting the recording venue's cues.

I can't begin to see your system in those clips you posted so I have no idea what your speakers or room look like, but I bet your setup inherently has relatively weak early reflections while preserving the later-arrival reflections, even if that was not deliberate on your part.



Agreed, signal-to-noise ratio definitely matters... and in the context of in-room reflections, the playback room's cues are the noise, and the recording venue cues (which are delivered largely by those in-room reflections) are the signal. It probably seems counter-intuitive that we can enhance the one and not the other, but we can, by taking advantage of psychoacoustic windows of opportunity.



What an omni or dipole or other polydirectional or multichannel system theoretically does well is, effectively present the venue ambience cues which are on the recording. These cues should be spectrally correct, should come from all around, should be strong but not too strong, should not arrive too early, and should decay slowly but not too slowly.

The reason we need the in-room reflections is that the WORST POSSIBLE direction for ambience cues to arrive from is the EXACT SAME direction as the direct sound. So we need something besides the direct sound delivering those ambience cues to us.

In my opinion these approaches (omnis, dipoles, bipoles, etc.) are not "band-aids"; rather, they are viable alternatives which may do a very good job of conveying envelopment if set up correctly.

I design speakers with an unorthodox feature intended to improve their ability to convey envelopment, so my familiarity with the topic has a practical rather than strictly theoretical background.

I think I understand your perspective, Duke, and it is appreciated. Given your comments above, your focus, and experience, would you venture I was successful or unsuccessful at capturing the "envelopment" of the recording hall in these and perhaps other in-room recordings?

 

[Duke LeJeune]

I think I understand your perspective, Duke, and it is appreciated. Given your comments above, your focus, and experience, would you venture I was successful or unsuccessful at capturing the "envelopment" of the recording hall in these and perhaps other in-room recordings?

With the caveat that I'm using inexpensive earbuds, I don't hear ANYTHING in either recording that sounds like I'm listening to "the playback room". It just sounds like I'm listening to a good recording.

Very well done!!

 

[christoph]

It is clearly a installation problem, you have to install a wife AFTER the sound system Maybe it is time for a upgrade anyway ?

This is exactly how it worked and still works for me
No upgrades on the horizon on both ends, though
I'm extremely happy the way it is

 

[Emperyan]

Very interesting discussion!

Based on my personal experience, I find Duke´s arguments very compelling.

There is bunch of advocates for near-field listening or very directional speaker designs who argument that you should get as much of the listening room out of the way in order to hear nothing but the room information on the recording. While this way of listening might sound spectacular in it´s own way, I have never found it to be natural or organic at all. Actually, I have never heared a convincing sounding loudspeaker which was only front firing. All the designs which gave me a sense of "being there" were either omnis or at least some form of dipoles or as well back firing.

It might be just me, but it seems like there is something to the in-room reflections we need for a convincing sound, even if the listening room is much smaller than the recording venue. I guess it´s because what stereo playback is doing is basically a psychoacoustic trick. All sonic events are not really placed in the room, but we are listening to a phantom placement, an illusion in which two speakers playing synchronously trick you into recognizing a specific placement in the room. And I guess this trick will never be 100% convincing in terms of feeling like the real thing. It works in terms of placement, but it has a certain kind of artificial feel to it (or at least to me).

An omni speaker seems to be able to mitigate this artificial feel to a certain extent. And I think Duke is really up to something here, stating that it´s the late reflections which are adding to the realism. I´d say, the first reflections of an omni also add to the realism of sound, but as Duke wrote, they will give you a spatial clue on the (small) size of the playback room - and this might be in contrast to the room information on the recording.

 

[Duke LeJeune]

Actually, I have never heared a convincing sounding loudspeaker which was only front firing. All the designs which gave me a sense of "being there" were either omnis or at least some form of dipoles or as well back firing.

As I think back, that has been my experience as well. I can think of two exceptions, which were both big horn systems in big rooms, and I think the big rooms and fairly long distance from the speakers contributed to a higher-than-normal reverberant-to-direct sound ratio.

It might be just me, but it seems like there is something to the in-room reflections we need for a convincing sound, even if the listening room is much smaller than the recording venue.

Agreed! Reflections done right are our friends! Since I also like some of the things a good horn does well, my own designs tend to be polydirectional horn systems.

 

[Robh3606]

If an omni is set up correctly in a large enough room, we will detect the two separate streams which enable the perception of envelopment, or "you are there".

Hello Duke

Do you know of any speakers that use dedicated drivers and DSP to generate a second stream?? If you think about it you can delay, change amplitude and frequency shade as required to simulate HF loss due to distance. Seems like it might be workable.

Rob

 

[Duke LeJeune]

Hello Duke

Do you know of any speakers that use dedicated drivers and DSP to generate a second stream?? If you think about it you can delay, change amplitude and frequency shade as required to simulate HF loss due to distance. Seems like it might be workable.

Rob

My polydirectional speakers are already doing most of what you describe passively, and the user-adjustable DSP delay you mentioned could be added.

My rear-firing second-stream drivers have their own separate inputs, so they could easily be fed by a separate channel of amplification which has been delayed. The inputs feed into passive filtering which includes user adjustments for level and top-end tilt (as well as some fixed response shaping), so additional processing probably would not be needed. But if someone wanted to bypass my filtering, it would not be difficult.

My directional rear-firing drivers are aimed up-and-back, typically at a 45-degree angle, such that their output bounces off the wall and then off the ceiling before reaching the listening area. This usually results in a path-length-induced delay of at least 10 milliseconds, even with the speakers fairly close to the front wall. Combined with the directional front-firing drivers (normally toed-in to minimize early lateral reflections), ten milliseconds is sufficient to significantly shift the "center of gravity" of the reflections back in time enough to suppress "small room signature" and unmask the ambience cues of the recording venue. A large room is not required, nor is acoustic treatment of the room normally required.

My thinking in doing this passively is to make my products drop-in replacements for most conventional speakers, as all that's needed are the normal two channels of amplification.

Regarding shading to simulate high frequency loss due to distance: Ime it's something which ought not be overdone. To my ears minimizing the spectral discrepancy between the direct and reverberant sound pays greater dividends in most rooms, and to that end, the top-end tilt of the front-firing drivers is also user-adjustable (I can explain why this is desirable if you'd like).

 

[Robh3606]

To my ears minimizing the spectral discrepancy between the direct and reverberant sound pays greater dividends in most rooms, and to that end, the top-end tilt of the front-firing drivers is also user-adjustable (I can explain why this is desirable if you'd like).

Hello Duke

Thanks! I would if you don't mind

Rob

 

[thedudeabides]

Look at my avatar. My previous house in Jackson, WY. Glass behind the MBL 116 speakers with panels below the glass and numerous plants for diffusion. Sounded good to me. I miss that room.