Properties of speakers that creates a large and precise soundstage

[sigbergaudio]

What is the science behind a big and precise soundstage and making the speaker dissappear, in the context of designing a speaker?

Forgive me for being difficult here, but I am a bit confused. Are you subtly asking a different question than what is the topic of this thread, which we've been discussing for 53 pages now? Or is it the same?

The thread is about "properties that creates a large and precise soundstage". You are asking about "the science behind". I'm not sure how that's different, if it is.

I think it's fair to say that it's not a perfect science, we don't know exactly what properties makes it happen, and we also don't know how to measure it - otherwise we wouldn't have over 1000 posts in this thread. Why this is the case has been debated several times in this thread already (it is dependent on the room, the recording, the listener, placement, etc, before you even come to the speaker design).

I shared my initial thoughts on it in post #1, and have also shared some other reflections throughout the thread. I shared very recently in post #1034 (!) what I think the key elements are for the SBS.1 speaker specifically.

You are adding "and making the speaker disappear" to the question, but I think that's part of the same / comes with the territory. A speaker that does not disappear, will not convey a big and precise soundstage.

Finally you're concluding your question with "in the context of designing a speaker". I am not sure how that is different to the discussion we're already having, if it is. What other context is there?

 

[Pearljam5000]

Forgive me for being difficult here, but I am a bit confused. Are you subtly asking a different question than what is the topic of this thread, which we've been discussing for 53 pages now? Or is it the same?

The thread is about "properties that creates a large and precise soundstage". You are asking about "the science behind". I'm not sure how that's different, if it is.

I think it's fair to say that it's not a perfect science, we don't know exactly what properties makes it happen, and we also don't know how to measure it - otherwise we wouldn't have over 1000 posts in this thread. Why this is the case has been debated several times in this thread already (it is dependent on the room, the recording, the listener, placement, etc, before you even come to the speaker design).

I shared my initial thoughts on it in post #1, and have also shared some other reflections throughout the thread. I shared very recently in post #1034 (!) what I think the key elements are for the SBS.1 speaker specifically.

You are adding "and making the speaker disappear" to the question, but I think that's part of the same / comes with the territory. A speaker that does not disappear, will not convey a big and precise soundstage.

Finally you're concluding your question with "in the context of designing a speaker". I am not sure how that is different to the discussion we're already having, if it is. What other context is there?

Sorry, My English is not perfect

 

[Salt]

Lol
He said his speakers have a big soundstage and that they dissappear
So I guess he knows and can explain in one comment, and I can't read 53 pages so...

I followed this thread from the beginning ...

 

[sigbergaudio]

Sorry, My English is not perfect

I think you will find the thread interesting and learn a lot if you start from the beginning, even if you don't read all the 53 pages.

 

[thewas]

I think you will find the thread interesting and learn a lot if you start from the beginning, even if you don't read all the 53 pages.

And then again ask if loudspeaker A or B is better, although dozens of people have explained him over and over for years that everything is compromise and there cannot be absolute better but it depends on the individual priorities, preferences and listening room characteristics so even if someone tells him he prefers A it doesn't really help him but only understanding the basics behind to make his own informed choice.

 

[Arindal]

the horn is what produces the H/V pattern (and the narrow vertical dispersion).

Absolutely agree, but that means the horn has to be rather big in order to achieve both vertically narrow and even horizontal dispersion down to lower frequencies. And a broad horn in theory can also be localized as a broader source. Another question that was arising when I checked some MEH concepts, was how the midrange slots would be integrated in order not to cause edge diffraction of the treble waves in the horn. Or how the treble part of the horn would maintain broad horizontal dispersion while trying to tackle the aforementioned problem.

I fully appreciate the conceptional sophistication as well as the theoretical perfection of such concepts. From practical point of dealing with various contradictions, I would say they are not for me.

What is the science behind a big and precise soundstage and making the speaker dissappear, in the context of designing a speaker?

Cannot speak for Sigberg or his products, but would say from own experience and studying a lot of speakers on the market, the following technical parameters contribute to that:

- least of interchannel differences in response (both frequency and group delay/phase), both between several speakers and at several points of a potential listening window over all frequencies except the bass
- minimum width of (diaphragm) area which localizable frequencies are originating from
- all localizable frequencies (approx. 400 - 7,000Hz) originating from one spot or from positions very close to each other vertically, so they cannot be localized as separate sources (neither directly nor indirectly via reflections)
- frequency-independent response over the whole sphere (aka constant directivity), as well as over designated angles most prone to causing those reflections defining tonality of the indirect soundfield (like pointing at floor, ceiling, side walls) for localizable frequencies, which includes absence of lobing and decreasing dispersion angle
- sufficiently high overall directivity index to meet the requirements of room reverb and listening distance

As mentioned, these are my personal conclusions. Others might find other parameters important. For example i have not included group delay and phase issues other than interchannel differences, as I never had congruent experience with their importance on soundstage and ambience.

 

[audiofooled]

- least of interchannel differences in response (both frequency and group delay/phase), both between several speakers and at several points of a potential listening window over all frequencies except the bass

I agree, but If bass can be included, it also becomes an important part of soundstage precision and spatial quality.

 

[Arindal]

If bass can be included, it also becomes an important part of soundstage precision and spatial quality.

Absolutely agree, and I am not meaning to say that bass is not important. It is just difficult to precisely formulate related conditions for the speaker alone, as it vastly depends on the room and how the two interact with each other.

 

[audiofooled]

Yes, and we wouldn't want to discriminate smaller speakers or ones that are designed to be used with subs. Rooms included is another can of worms.

 

[Arindal]

we wouldn't want to discriminate smaller speakers

In a way, compact as well as slim speakers come with some huge disadvantage already, as they are not big enough to create sufficiently high directivity index below 1K by using conventional methods (like waveguides), but tending towards omnidirectional behavior the lower you go in frequency. In some cases, that might be gentle and low enough to have it equalized, but that is not always the case.

To solve this problem, you either have to achieve higher midrange directivity by cancellation (like dipoles or cardioids do), or expand the diaphragm area solely in one dimension and make it longer (the result is basically a line array or any sort of linesource derivate). I personally tend to the latter concept for various reasons, but other people have other methods, like @sigbergaudio - that is perfectly fine.

 

[Bjorn]

Like @gnarly points out, a vertical narrow directivity is important for a precise image. For those don't have such speaker, treatment of the reflections in the ceiling is often the biggest improvement. I'm sharing that based on feedback from customers who treat their rooms. It's also related to the fact that most speakers suffer from polar lobing and crossover in the sensitive area. But having speakers that either greatly minimizes or more or less avoids vertical reflections is a great benefit.

 

[Sokel]

Like @gnarly points out, a vertical narrow directivity is important for a precise image. For those don't have such speaker, treatment of the reflections in the ceiling is often the biggest improvement. I'm sharing that based on feedback from customers who treat their rooms. It's also related to the fact that most speakers suffer from polar lobing and crossover in the sensitive area. But having speakers that either greatly minimizes or more or less avoids vertical reflections is a great benefit.

At my setup the untreated ceiling demolishes the whole sound stage both at height and depth vs the treated one.
It's easy to listen to with the arc test.

Almost the same with the dead front wall but the effect is more about height.

As one of my room's disadvantages is that I have the whole rig at the long dimension I already loose some spatial quality with the side walls 4 meters apart from the speakers so soundstage could already suffer without the treatment in general, no matter the speaker.

The next best thing I could do according to my installers was a small booth at MLP but as a classical listener and somehow claustrophobic I avoided that

 

[Bjorn]

At my setup the untreated ceiling demolishes the whole sound stage both at height and depth vs the treated one.
It's easy to listen to with the arc test.

Almost the same with the dead front wall but the effect is more about height.

As one of my room's disadvantages is that I have the whole rig at the long dimension I already loose some spatial quality with the side walls 4 meters apart from the speakers so soundstage could already suffer without the treatment in general, no matter the speaker.

The next best thing I could do according to my installers was a small booth at MLP but as a classical listener and somehow claustrophobic I avoided that

You can regain spaciousness with quality diffusion that effects the phase.

Very audible at particular side walls, most rooms are wide enough for placement at least at the opposite side wall reflections. And great for classical.

 

[Curvature]

I agree that CBT lines and planars are a way to obtain even and apparent narrow vertical coverage.

CBTs do not produce narrow directivity. They explicitly use the floor reflection as part of the design. Below is a simulation of a full array, i.e., with the bottom half being virtual due to floor reflections.

 

[Bjorn]

CBTs do not produce narrow directivity. They explicitly use the floor reflection as part of the design. Below is a simulation of a full array, i.e., with the bottom half being virtual due to floor reflections.

View attachment 456810

View attachment 456811

While it uses the floor as a mirror, the result is avoidance of floor reflections in practice. As for the uppwards directivity, it's narrow and depends on the design.

The CBT36 was as the name indicated 36° but this can be designed in various ways. With a normal ceiling height, I saw reflections from the ceiling being below -20 dB without any treatment with the CBT36.

 

[Arindal]

CBTs do not produce narrow directivity. They explicitly use the floor reflection as part of the design.

I agree that they use some kind of groundplane total reflection concept, but this is increasingly less effective in terms of adding SPL hence reducing directivity index, above the frequency the curved line is showing line source behavior itself (250Hz in your example). Otherwise the one you have linked would show 90deg of beamwidth window and not 45deg.

And, yes, CBT are less narrow in vertical radiation, tending more towards constant directivity than a comparable straight linesource, but I would still classify them as narrow beamwidth. The ones which are available on the market, are covering much less than the 45deg of the experimental unit, rather in the region of 20deg.

 

[Curvature]

While it uses the floor as a mirror, the result is avoidance of floor reflections in practice. As for the uppwards directivity, it's narrow and depends on the design.

The CBT36 was as the name indicated 36° but this can be designed in various ways. With a normal ceiling height, I saw reflections from the ceiling being below -20 dB without any treatment with the CBT36.

You're playing with semantics here. It is not true narrow vertical radiation. The net effect is, yes, that the typical floor and ceiling cancellations disappear. But they don't disappear because of beamforming.

This anechoic measurement of the JBL CBT1000 does not reflect what happens when all of those drivers play at once in a small room. See the attached extract from a presentation by Keele.

 

[Bjorn]

You're playing with semantics here. It is not true narrow vertical radiation. The net effect is, yes, that the typical floor and ceiling cancellations disappear. But they don't disappear because of beamforming.

This anechoic measurement of the JBL CBT1000 does not reflect what happens when all of those drivers play at once in a small room. See the attached extract from a presentation by Keele.

I think you are the one playing with semantics
The result in practice or what you call net result is of course what matters when placed in a room. The other is more of theoretical interest.

 

[gnarly]

CBTs do not produce narrow directivity. They explicitly use the floor reflection as part of the design. Below is a simulation of a full array, i.e., with the bottom half being virtual due to floor reflections.

I agree that they don't produce narrow directivity, and is why I used the phrase apparent narrow vertical coverage.
Imo, speakers operating as a line array don't really fit with the usual idea of narrow vertical coverage, that we ascribe to speakers with spherical radiation.
I think a true line has smooth even vertical coverage off any axis perpendicular to the line, except at the ends of the line, where only there does the HF/VHF attenuation take on the more conventional idea of directivity.
The tighter the center-to-center spacing of the line needed for HF/VHF extension, the more abrupt the change in HF/VHF pattern at the ends of the line. As when standing up and listening to full-range electrostats above their height...bye bye VHF.

Like @Bjorn says, and your good sim shows, i see the CBT as a clever way of using a line to counter floor reflections, but that otherwise it still behaves as a line.

CBT's and lines are really fun to play with DIY. I was able to use the same driver baffle for both curved CBT, and straight line boxes. With DSP and multi-amping a lot of neat experimentation is possible.

 

[Curvature]

I think you are the one playing with semantics
The result is practice or what you call net result is of course what matters when placed in a room. The other is more of theoretical interest.

The CBT is a unique speaker that does not function like typical multiways. It is simply not a useful comparison.

Look, I don't think there are many speakers out there that spit out true constant, narrow vertical beam outside of PA speakers, but those never fire alone, only in arrays. I don't know why people started in the last while saying that vertical reflections are so harmful to clarity and so forth. It sure isn't that clear-cut in the research, where the conclusions I've gathered suggest more or less that the effects range from a very slight benefit/neutral to harmful in experimental settings. Outside of artificial experimental settings, there are so few examples of available speakers that actually allow a person to isolate the effect of vertical reflections without other factors confounding that judgement.

Personally, I've heard consistent and inconsistent vertical directivity combined with good and bad horizontal directivity. I think we are all in agreement that poor, inconsistent horizontal directivity has plenty of bad effects. The only arguments on this point concern what kind of radiation pattern is optimal (wide, narrow, constant, sloping, stepped).

On vertical directivity, we don't even have something resembling a consensus. There are plenty of circumstances in which inconsistent vertical directivity becomes objectionable and plenty where it does not. It is just hard to tell what is good vs. bad when looking at measurements. There hasn't been enough research done on the topic which isn't limited in one sense or another. Consistent vertical directivity on an otherwise excellent speaker I've never had the chance to hear. I would love for an owner of the large Perlisten speakers or for Erin, Amir or any other reviewer to include in their listening some report about how speakers sound at different heights.

My experience is that I will never again buy standard multiway towers, bookshelves or monitors with vertical lobing. But all noncoaxial speakers are impacted by lobing to some extent. How to assess that is the question, and I don't think the right design answer is solely narrow vertical beams.