What does a "great room" mean?

[jkeny]

There is the concept of 'fundamental' (think primary) frequency ranges as well harmonic frequencies both above and below the fundamental frequencies of many instruments.

In terms of fundamental frequencies, pipe organ and synthesizer outputs are obvious "pits of hell bass" candidates in terms of potential to produce many tones well below
30, 20 and lower. For synth, Jordan Rudess and others prove this out in various recordings more than adequately. Contrabassoon fundamentals get down into the mid 20s,
artillery shot and largest orchestral bass drums (remember, frequencies are proportional to size and tuning of the drum) and the largest "Taiko" Drums also get close....if I make
any mistakes from memory on this stuff, you have my apologies in advance!

Thanks!

 

[fas42]

You keep on using the Noise Floor term. It certainly has a lot to do but in most cases , in most components we would deem High End , heck! even in many mid-fi, it is not much of a factor.

Frantz, unfortunately you just rolled straight across the big issue as if it wasn't there - but in real systems, no matter how expensive they are, it typically is there ... I listen to a demo of these high end rigs, and I just shake my head at the amount of musical information that goes missing - the system is effectively sandpapering all the detail into nothing, ending up sounding like high gloss midfi - which is great for "audiophile" recordings, but damages more complex recordings so they become nothing, or unpleasant to listen to ..

 

[jkeny]

What's more relevant is how often are those lowest notes actually part of the music making - let's see, in an hour of a performance real musical notes with a fundamental less than 50Hz occur, say 5 times ... but if if I can't hear that "information" then the whole hour's worth is down the gurgler - gimme a break!

What I'm after is the sensation of intense bass, and I haven't heard a system yet with walloping drivers that gives that impression - I hear music, and as an adjunct walloping drivers carrying on with a merry dance - it just an irritant, a distraction from what counts, the music.

A good example of what I want happening is in classic Bony M tracks - there's a sensation of a deep, deep rhythmic punch that goes right through every part of you; if your system can't get this right then something's lacking ...

Gotta agree with you - it's the percentage of time that these instruments vibrate at these low frequencies.
Neither I nor my audio buddies really find this is a missing element - I have heard some great church organ music live but I guess I considered it beyond the capabilities of any real reproduction feeling that it required the acoustic volume of the church for believability

 

[SCAudiophile]

What's more relevant is how often are those lowest notes actually part of the music making - let's see, in an hour of a performance real musical notes with a fundamental less than 50Hz occur, say 5 times ... but if if I can't hear that "information" then the whole hour's worth is down the gurgler - gimme a break!

What I'm after is the sensation of intense bass, and I haven't heard a system yet with walloping drivers that gives that impression - I hear music, and as an adjunct walloping drivers carrying on with a merry dance - it just an irritant, a distraction from what counts, the music.

A good example of what I want happening is in classic Bony M tracks - there's a sensation of a deep, deep rhythmic punch that goes right through every part of you; if your system can't get this right then something's lacking ...

Agree 100% on all points, particularly the last one. Just for the record, there are recordings out there many more than 5 occurrences of deep bass; not arguing!

 

[jkeny]

You keep on using the Noise Floor term. It certainly has a lot to do but in most cases , in most components we would deem High End , heck! even in many mid-fi, it is not much of a factor.

But this is exactly the point stehno was making - that most systems actually don't have this low dynamic noise floor where the finer details of the performance are not masked. When this is achieved correctly, the details within the music become the dominating factor in creating a believable version of the original acoustic. This is in a room of a reasonable quality - what I would deem a normal room. What noise floor means in this context is the dynamic noise floor when playing music, not the usual noise floor seen on measurements using test tones

 

[ddk]

John,

In my entire audiophile years I've only come across two great rooms, the rest as Jack put it you're managing the space, listen for what is or isn't there and finagle it. Neither room was designed for audio and they were as different as they come from one another. One was the living room in typical Long Island colonial wooden house from the 40's, totally barren, no furniture or carpeting. The system was a mish mash of 50's & 60's parts and 70's prototype ss amp and diy speakers. The other one was a finished basement in modern concrete and brick mansion fully furnished with large thick furniture and wall to wall carpeting, all Lamm electronics and high end vintage horns, yes one of mine ! Of course the first system lacked the resolution of the other one but you could hear the magic from the first few notes in both spaces. The sound was expansive and natural, the music just flowed and you forgot you were listening to a system. The images were life sized and scale was correct for even a full orchestra, balance was spot on and you couldn't hear any character or intrusion from the space. With the modern mansion I was there to install the system, I never imagined it would be that great. Speaker setup took all of 10 minutes and everything was in place and again the room boundaries were of no consequence, I've never heard this type of scale or reality in any other rooms exempt this two. Even ground up acoustically designed audio rooms have things that aren't quite right but not these two rooms.

When it comes to managing a space we all have our preferences, like micorstrip I'm not a fan of acoustic tampons splashed across the room either, I prefer to use natural or construction materials so not to introduce new variables into the space. I can't comment on the NXT speakers, never heard them but reading the specs I don't see it negating the effects of the listening space. For the most part its possible to deal with the space in a way that make's it inconsequential to the sound, that's my approach anyway. Others might prefer or have the room as part of their sound, Steve's is this kind of room where its signature is always present and part and parcel of his sound.

On another note, I don't understand why Frank's 40hz has become a point of contention, IME with the right speaker even 50hz is more than enough. Of course if you measure the room you'll it will be lower but that's not the FR of the speakers. In fact my speakers cut off at 50hz and only a couple of years added subs to add a little foundation for when the music requires it but its mostly inaudible and like a layer of air. Subs can become very intrusive when audible.

david

In the "what's most important for 'believability'" thread, there's a kind of gentle & mannerly impasse where a number of members that state the room is the just as important an element in believability (depending on the speaker) as the source & electronics.

I've not had much experience with different room treatments as mostly the rooms I've listened to reproduction in were what I considered of a reasonable quality, acoustically.

Recently I've discovered DML speakers - distributed mode loudspeakers popularised by NXT speakers. I must admit that I never paid much attention to these as they were marketed more as PC speakers & "lifestyle" speakers rather than hiFi. Maybe it's because this speaker technology has evolved somewhat to address the shortcomings of DML & BMR (Balanced Mode Radiators) have developed from them?

But anyway, the point of this technology is that instead of the optimal goal of traditional speaker technology which was a point source radiator for all audible frequencies, DML has a different dispersive way of radiating sound. Traditional speakers use a pistonic driver attached to a cone to generate longitudinal sound waves (correlated between speakers) wheres DML use a panel on which resonances are created at the various frequencies - transverse sound waves.

Unfortunately, I don't have AES membership & this site (Tectonic) have many AES papers on DML & room interaction but this public paper is a good summary of the main ideas - summarised here:



This makes sense to me & would seem to suggest that room treatment for this technology is both far less & essentially different to that used for traditional, directive speakers.

What do people make of this in the light of the idea that one can treat a room to achieve a "great" sounding room?

I have two questions (at the moment):
- how is this room treatment designed to achieve the "great" room as it appears that there isn't a consensus about this?
- Is this lack of consensus because it's not a "great room" that's being designed - it's actually dependent on the speakers being used in that room

 

[jkeny]

John,

In my entire audiophile years I've only come across two great rooms, the rest as Jack put it you're managing the space, listen for what is or isn't there and finagle it. Neither room was designed for audio and they were as different as they come from one another. One was the living room in typical Long Island colonial wooden house from the 40's, totally barren, no furniture or carpeting. The system was a mish mash of 50's & 60's parts and 70's prototype ss amp and diy speakers. The other one was a finished basement in modern concrete and brick mansion fully furnished with large thick furniture and wall to wall carpeting, all Lamm electronics and high end vintage horns, yes one of mine ! Of course the first system lacked the resolution of the other one but you could hear the magic from the first few notes in both spaces. The sound was expansive and natural, the music just flowed and you forgot you were listening to a system. The images were life sized and scale was correct for even a full orchestra, balance was spot on and you couldn't hear any character or intrusion from the space. With the modern mansion I was there to install the system, I never imagined it would be that great. Speaker setup took all of 10 minutes and everything was in place and again the room boundaries were of no consequence, I've never heard this type of scale or reality in any other rooms exempt this two. Even ground up acoustically designed audio rooms have things that aren't quite right but not these two rooms.

Thanks for your thoughts, David. As I said, I'm basing what I say on my experience so far - who knows, I might stumble into one of your two rooms or their equivalents & be completely smitten?

When it comes to managing a space we all have our preferences, like micorstrip I'm not a fan of acoustic tampons splashed across the room either, I prefer to use natural or construction materials so not to introduce new variables into the space. I can't comment on the NXT speakers, never heard them but reading the specs I don't see it negating the effects of the listening space. For the most part its possible to deal with the space in a way that make's it inconsequential to the sound, that's my approach anyway. Others might prefer or have the room as part of their sound, Steve's is this kind of room where its signature is always present and part and parcel of his sound.

The reason I introduced the concept of DML speakers was because AFAI could tell room issues were the result of reflections causing muddying of the sound & causing comb filter effects - both of which are largely dealt with by the uncorrelated soundwave nature of DML operation. I don't know how room modes & DMLs interact? Still looking into them.

 

[ddk]

The reason I introduced the concept of DML speakers was because AFAI could tell room issues were the result of reflections causing muddying of the sound & causing comb filter effects - both of which are largely dealt with by the uncorrelated soundwave nature of DML operation. I don't know how room modes & DMLs interact? Still looking into them.

Not that straightforward John, depending on the room there's all kinds of interactions going on. The DML design seems to be a dipole of sorts so I don't see how it won't interact with the room, also since they don't go below 80hz you'll need some kind of sub which will interact like any other speaker. Their strength seems to be in their relative sensitivity and lack of crossover not room interaction.

david

 

[FrantzM]

But this is exactly the point stehno was making - that most systems actually don't have this low dynamic noise floor where the finer details of the performance are not masked. When this is achieved correctly, the details within the music become the dominating factor in creating a believable version of the original acoustic. This is in a room of a reasonable quality - what I would deem a normal room. What noise floor means in this context is the dynamic noise floor when playing music, not the usual noise floor seen on measurements using test tones

Can you please explain what you mean by "Low dynamic noise floor"? And how does one achieve such low dynamic noise floor?
Once we start inventing such concepts , especially those we deemed not measurable we are delving in metaphysics, IMO but... do entertain me nonetheless. I will in passing note that the room is likely the first to provide a low noise floor... Well isolated room with measured Low noise Floor

I agree some with microstrip , not a first but not the norm either I would have prefered not to tack things all over the room . Would have prefered a room build in a way to provide the requisite acoustic environment for my chosen speakers. I am now of the opinion that room treatments are speaker dependent to a certain extent. MBL omnis and CD horns speakers would likely require different room treatments IMHO.

 

[JackD201]

I agree some with microstrip , not a first but not the norm either I would have prefered not to tack things al over the room . Would have prefered a room build ina way to provide the requisite acoustic environment for my chosen speakers. i am now of the opinion that room treatments are speaker dependent to a certain extent. MBL omnis and CD horns speakers would likely require different room treatments IMHO.

I think what you are stating here is fact and not opinion Frantz.

 

[jkeny]

Not that straightforward John, depending on the room there's all kinds of interactions going on. The DML design seems to be a dipole of sorts so I don't see how it won't interact with the room, also since they don't go below 80hz you'll need some kind of sub which will interact like any other speaker. Their strength seems to be in their relative sensitivity and lack of crossover not room interaction.

david

David,
I found the full NXT document which explains how DMLs work - they are not conventional & don't produce conventional waveforms
They use the idea of bending waves where a sound travels through a solid producing resonances at distinct places. When you have a panel that is resonating (from a pistonic actuator attached to it) it is producing these resonances in distinct areas depending on the frequency of the sound. You will see that in the Youtube videos I linked to. This happens because the speed of the bending wave through the solid is frequency dependent & produces modal resonances. So what you see on the panel of DML speakers are these many areas of resonances, & these areas move around the panel & changing with frequency - all of which produces sound - but it's like there is a matrix of small speakers moving around this panel & outputting sound which is uncorrelated with each other. This collection of uncorrelated vibrating areas has the interesting property that when the sound combines in air we perceive it as a wavefront.

But the uncorrelated nature of these miniwaves actually has a great influence in how reflections are perceived because there is no correlated wave being reflected.

SO traditional ways of thinking about speakers & room interactions don't fully apply

I'll dig up that NXT document & post the link

Here it is - well worth a read - some great info in it http://www.simeoncanada.com/wp-content/uploads/Research-Articles-NXT-Tech-Review.pdf

" in a randomly vibrating panel, diaphragm velocity is
randomly distributed with respect to magnitude and phase. The disparity in
path length between different areas of the diaphragm and the receiving point
is still present, but because there is now no correlation between the source
points’ outputs, there can be no global interference figure B1. Hence the
radiated sound is dispersed evenly in all directions. Diffuse radiation of high
order figure B2 becomes omnidirectional in the far field."

"Anyone familiar with the sound of conventional omnidirectional or near-omnidirectional
loudspeakers might expect NXT panels to produce a relatively imprecise, smeared
stereo image. But in typical domestic surroundings the imaging is at least as well
defined and stable as with conventional directional loudspeakers listened to from the
stereo ‘sweet spot’, despite the panels’ broad radiation pattern. This is because their
diffusivity reduces the detrimental effect of interactions with room boundaries figures 10
and 11. Outside the typically small area of optimum stereo, we have found that NXT
panels actually deliver superior imaging because of their better off-axis performance
and reduced room interaction. Another important contributing factor is the way NXT
panels, quite counter-intuitively, behave like a point source in the far field figure 12.
Research work quantifying stereo localisation errors has shown that listeners can more
reliably localise virtual sound sources with DMLs than they can with conventional
loudspeakers figure 13."

"With conventional wide-dispersion loudspeakers you also tend to hear much more
contribution from the listening room. Standing-wave resonances are more pronounced,
so the tonal balance varies significantly as you change listening position, and
interaction with room boundaries is worsened too, making speaker placement more
critical. NXT panels behave quite differently as a result of the diffuse nature of their
radiation. Because their sound does not emanate from a fixed, well-defined point in
space the distribution of sound pressure within the listening space is actually much
more even with an NXT panel than with a conventional loudspeaker figure 14. So room
interaction is actually reduced figure 15."

 

[jkeny]

Can you please explain what you mean by "Low dynamic noise floor"? And how does one achieve such low dynamic noise floor?
Once we start inventing such concepts , especially those we deemed not measurable we are delving in metaphysics, IMO but... do entertain me nonetheless. I will in passing note that the room is likely the first to provide a low noise floor... Well isolated room with measured Low noise Floor

What I mean by "low DYNAMIC noise floor" is the noise floor while the system is processing a dynamic music signal. Traditional "noise floor" is how low the system is when measured at silence or when processing a single tone signal. If we have a noise floor that is fluctuating while playing music it seems to interfere with our auditory perception as it's an unnatural occurance not encountered in nature but simply happens due to the electronics & we seem to be sensitive to these sort of anomalies

I agree some with microstrip , not a first but not the norm either I would have prefered not to tack things all over the room . Would have prefered a room build in a way to provide the requisite acoustic environment for my chosen speakers. I am now of the opinion that room treatments are speaker dependent to a certain extent. MBL omnis and CD horns speakers would likely require different room treatments IMHO.

I had already come to the conclusion that room treatments were speaker dependent.

 

[JackD201]

I'm extremely skeptical John. Go look at probably the most visible bending wave speaker out there (Gobel) on youtube and I think you'll find treatments used are quite typical for dipole/bipole configurations. Gobel himself makes no claims to superiority other than not having to use a tweeter, so only XO to the dynamic bass woofers.

 

[jkeny]

I'm extremely skeptical John. Go look at probably the most visible bending wave speaker out there (Gobel) on youtube and I think you'll find treatments used are quite typical for dipole/bipole configurations. Gobel himself makes no claims to superiority other than not having to use a tweeter, so only XO to the dynamic bass woofers.

Not having heard a DML speaker recently I can't say whether their claims for the technology are accurate or not but so far my understanding of the technology makes sense.
I don't think it's claimed that DML speakers are IMMUNE to any room interactions, just that they are greatly diminished?

Here's what the Goebel speaker site says - I know it's marketing talk but if you read the NXT paper, it is showing measurements & blind test results that are coming from AES papers so some level of credence to their claims would seem warranted, no?

"Only the Göbel Carbon Excellence bending wave loudspeaker can eliminate the weak points of a conventional loudspeaker system. You will experience a soundstage with ultra high resolution and speed completely seamless over the entire frequency range that you never heard before. Fine details and textures are reproduced unbelievable naturally without any losses and with the highest possible dynamics.

The music is entirely detached from the loudspeaker, the walls of the room completely disappear and you will find yourself in the middle of a real emotional musical event. Amongst others, the absolutely natural sound reproduction achieved due to the continous bandwidth, the ideal dispersion range and the high dynamic of the Göbel Carbon Excellence bending wave loudspeaker:"


Anyway, my whole reason for introducing the ideas behind bending wave speakers (DML) was to give a higher level view into speaker-room interaction & room treatments

 

[JackD201]

Yeah well, I've found "disappearing room" stuff happen in even untreated rooms from all sorts of other speakers as well. Here's the thing that makes me skeptical. Think of a cone attached to it's coil, hung by its basket with the coil moving in and out of the gap. Sure you'll think it is purely pistonic but we so know that that isn't perfectly true. There is driver membrane flexure there as well. Something easily proven with a strobe light and a tone generator. They may not be multiple exciters on one membrane but single exciters like say a German Physic, Ohm Walsh or other "benders" with single exciter Multiple "petals" like MBL, regular cones have "bender" properties as well. Conventional drivers, and more so planars have uncorrelated output too.

Ultimately there's no getting around the acoustic output of a non pistonic bender being a pressure wave itself. Will it behave differently when these waves hit a boundary? I really don't think so especially if we are thinking more of air molecules in a fluid dynamic sense where molecules collide with adjacent molecules chaotically under compression and rarefaction as opposed to the neater but also grosser simplification of a say a trace or wave representation of what is really happening. In my mind at the point the random points of origin sum up and begin to propagate they now begin to act as a point source. The point just got bigger. In this case the random positions on a bending wave which like wise may cause differences in reflection points is still limited by the size of the excited panel itself. The diffuse nature simply will require a little less diffusive surface area. Diffusion is cheap and sometimes even free. Like our friend from Capetown says you're going to have to hand the low end to a dynamic driver anyway so no I don't think that going back to the OP that going with a bender will solve reflection patterns in any way that is really significant. Pure because it lacks a crossover? Sure. More flexibility in terms of rooms they can perform well in just because they are benders? I doubt it.

Plug in the numbers in the precedence effect formulas and it quickly begins to be apparent that the advantage is that the high frequencies now share the dispersion characteristics as one would with a tweeter with the same characteristics as the upper crossover of its adjacent or hand off driver. Today loudspeakers with at least 180 degrees of even dispersal are pretty common. The thing is, the other way would be to not hit a wall to begin with so you don't need to mess with wall treatments at all with the use of speakers with controlled directivity.

 

[ddk]

Not having heard a DML speaker recently I can't say whether their claims for the technology are accurate or not but so far my understanding of the technology makes sense.
I don't think it's claimed that DML speakers are IMMUNE to any room interactions, just that they are greatly diminished?

Here's what the Goebel speaker site says - I know it's marketing talk but if you read the NXT paper, it is showing measurements & blind test results that are coming from AES papers so some level of credence to their claims would seem warranted, no?

"Only the Göbel Carbon Excellence bending wave loudspeaker can eliminate the weak points of a conventional loudspeaker system. You will experience a soundstage with ultra high resolution and speed completely seamless over the entire frequency range that you never heard before. Fine details and textures are reproduced unbelievable naturally without any losses and with the highest possible dynamics.

The music is entirely detached from the loudspeaker, the walls of the room completely disappear and you will find yourself in the middle of a real emotional musical event. Amongst others, the absolutely natural sound reproduction achieved due to the continous bandwidth, the ideal dispersion range and the high dynamic of the Göbel Carbon Excellence bending wave loudspeaker:"


Anyway, my whole reason for introducing the ideas behind bending wave speakers (DML) was to give a higher level view into speaker-room interaction & room treatments

One thing I learnt over the years is that when it comes to "space management" (thank you Jack, my favorite term now!) most of the same fundamentals hold true for most speakers. Aside from corner horns that have additional requirements the space dictates the same treatment for every type of speaker, wether, dynamic, horn or panel. Don't know if you read 6moon's interview with the designer of now apparently defunct Podium loudspeakers and follow up review, you'll see in the last paragraph that the room interaction doesn't change with DML designs but they seem to have some unique sonic attributes.

http://www.6moons.com/audioreviews/podium/1.html

david

 

[jkeny]

Yeah well, I've found "disappearing room" stuff happen in even untreated rooms from all sorts of other speakers as well. Here's the thing that makes me skeptical. Think of a cone attached to it's coil, hung by its basket with the coil moving in and out of the gap. Sure you'll think it is purely pistonic but we so know that that isn't perfectly true. There is driver membrane flexure there as well. Something easily proven with a strobe light and a tone generator. They may not be multiple exciters on one membrane but single exciters like say a German Physic, Ohm Walsh or other "benders" with single exciter Multiple "petals" like MBL, regular cones have "bender" properties as well. Conventional drivers, and more so planars have uncorrelated output too.

Hmmm, it is my understanding that traditional speakers which operate based on a cone pushing/pulling according to the signal at the voice coil mostly produce correlated signal. Any flexure of the cone is considered a resonance best avoided, no?

Ultimately there's no getting around the acoustic output of a non pistonic bender being a pressure wave itself. Will it behave differently when these waves hit a boundary? I really don't think so especially if we are thinking more of air molecules in a fluid dynamic sense where molecules collide with adjacent molecules chaotically under compression and rarefaction as opposed to the neater but also grosser simplification of a say a trace or wave representation of what is really happening. In my mind at the point the random points of origin sum up and begin to propagate they now begin to act as a point source. The point just got bigger. In this case the random positions on a bending wave which like wise may cause differences in reflection points is still limited by the size of the excited panel itself. The diffuse nature simply will require a little less diffusive surface area. Diffusion is cheap and sometimes even free. Like our friend from Capetown says you're going to have to hand the low end to a dynamic driver anyway so no I don't think that going back to the OP that going with a bender will solve reflection patterns in any way that is really significant. Pure because it lacks a crossover? Sure. More flexibility in terms of rooms they can perform well in just because they are benders? I doubt it.

Ok, I hear your skepticism & as I say I haven't yet experienced one to give my opinion on whether the reality lives up to the theory but so far I like what I see in the theory & the published results

Plug in the numbers in the precedence effect formulas and it quickly begins to be apparent that the advantage is that the high frequencies now share the dispersion characteristics as one would with a tweeter with the same characteristics as the upper crossover of its adjacent or hand off driver. Today loudspeakers with at least 180 degrees of even dispersal are pretty common. The thing is, the other way would be to not hit a wall to begin with so you don't need to mess with wall treatments at all with the use of speakers with controlled directivity.

Yes, controlled directivity is one way to avoid the worst of the side wall reflections (not the back wall) but that implies a narrow sweet spot, no?

 

[ddk]

Hmmm, it is my understanding that traditional speakers which operate based on a cone pushing/pulling according to the signal at the voice coil mostly produce correlated signal. Any flexure of the cone is considered a resonance best avoided, no?

Ok, I hear your skepticism & as I say I haven't yet experienced one to give my opinion on whether the reality lives up to the theory but so far I like what I see in the theory & the published results

Yes, controlled directivity is one way to avoid the worst of the side wall reflections (not the back wall) but that implies a narrow sweet spot, no?

From the descriptions it seems that DML is anything but directional, actually more diffuse that most.

david

 

[jkeny]

One thing I learnt over the years is that when it comes to "space management" (thank you Jack, my favorite term now!) most of the same fundamentals hold true for most speakers. Aside from corner horns that have additional requirements the space dictates the same treatment for every type of speaker, wether, dynamic, horn or panel. Don't know if you read 6moon's interview with the designer of now apparently defunct Podium loudspeakers and follow up review, you'll see in the last paragraph that the room interaction doesn't change with DML designs but they seem to have some unique sonic attributes.

http://www.6moons.com/audioreviews/podium/1.html

david

But David, from what I remember of those Layered Sound Podium loudspeakers, his theory is that they are an adjunct to traditional speakers & so are used in conjunction with traditional pistonic directive cone speakers, so it's not surprising that the same room treatments are in evidence - the same traditional speakers are being used but just supplemented by DMLs

 

[jkeny]

From the descriptions it seems that DML is anything but directional, actually more diffuse that most.

david

Yes, David, that's what I'm saying - the controlled directivity I'm talking about is in reference to traditional cone speakers