"The phase coherence of harmonics in the vocal formant range, ~630Hz to 4000Hz"

[weltersys]

Have you ever considered an even narrower directivity speaker (20°x30°) for home theater?

The DSL SH 25 has a 25° x 25° pattern, most would find that tight of a pattern to limit the "sweet spot" to too small an area for home theater.

That said, if your home theater is very deep and narrow, the SH 25 could be right for you.

 

[lolo]

Now try it with the Orions lolo.
Go ahead, don't be scared

I just finished a long 5 hours session.. It didn' work..

I placed absorbers behind the speakers to take the back wave out of the picture, and whatever I tried I did not managed to get a coherent sound. Surely, on some recordings I had super nice, precise and wide effects, nearly 180°, Roger Waters, Jarre's Oxygen and such, that worked much better than stereo. But for anything else, there just was a cluster of sounds from center surrounded by reverb, totally unrealistic. I use the electro-music DSP pluggin. I shall try a passive separation. The Orions+Watson gives this far a way better result.

 

[Melo theory]

I just finished a long 5 hours session.. It didn' work..

I placed absorbers behind the speakers to take the back wave out of the picture, and whatever I tried I did not managed to get a coherent sound. Surely, on some recordings I had super nice, precise and wide effects, nearly 180°, Roger Waters, Jarre's Oxygen and such, that worked much better than stereo. But for anything else, there just was a cluster of sounds from center surrounded by reverb, totally unrealistic. I use the electro-music DSP pluggin. I shall try a passive separation. The Orions+Watson gives this far a way better result.

You are using too much cancellation.
Try more attenuation, I find the best results are when I have the speakers at 20 degrees spread, delay at 31.2us and RACE attenuation at 4.5.
This should give you a 60 degree window (like stereo triangle) but with appropriate center imaging and correct pinna cues.
I personally don't care about a huge wide window. I'm more concerned about what happens between the speakers.
On recordings that use phase tricks, you will get a larger stage like stereo.
So, fiddle with the settings in order to achieve a stereo triangle soundstage.
You want pinna cues to be an average between dead center and the edge of the sound spread.....this is the reason that the speakers should be placed between 20 and 30 degrees apart.
If you put them right next to each other and try and stretch the stage to 180 degrees, this will give horribly confusing cues to the pinna.
I'm sure you are not going to that extreme but just try the settings I've suggested and tweek from there.

 

[Melo theory]

By the way, I really like the Watson solution.....but I think the mains should be closer together.
I have hopes that SL will continue on this journey of experimentation, it will influence a trend towards the problems with stereo.
But seeing that this thread is getting 10x more action than the Watson thread, I can see that people are still stuck in there ways.
Its great to see you are giving it a go lolo

 

[ScottG]

I personally don't care about a huge wide window. I'm more concerned about what happens between the speakers.

On recordings that use phase tricks, you will get a larger stage like stereo.

That's one of the best effects of well-done binaural - eliminating the small room acoustic.


..On the other hand you are effectively "re-mastering" the original - so yeah, why not add-in some phase tricks as well.


To me RACE just isn't compelling, (it bunches up the images toward center , displaying depth better but not width - with a few exceptions). The basic format requires low pressure between the ears derived from narrow directivity. (..even barriers don't work well for me.) RACE in combination with narrow directivity speakers - sure, but it's not RACE that is doing the "heavy lifting" (..or at least the cross-talk elimination portion of it).

 

[Melo theory]

Well, Scott.....of course I cannot agree with you on this.
Some of the reasoning you are giving is incorrect.
I don't carry a torch for ambiophonics for no reason.
I didn't believe in it at first or even like it for that matter.
After spending a lot of time understanding it and tweaking it (as far as setting on RACE and speaker set up), I find that it is superior to blumlen stereophonics.
After eliminating crosstalk and hearing the results of the improved phantom imaging, when I went back to stereo, all I could hear was the 6ft wide blob of confusion between the speakers, also there was a huge lack of depth.

 

[ScottG]

After eliminating crosstalk and hearing the results of the improved phantom imaging, when I went back to stereo, all I could hear was the 6ft wide blob of confusion between the speakers, also there was a huge lack of depth.

Hmm, "blob of confusion" - like it , but don't agree with it.

Lack of depth however, yes! (..but that improvement is usually the case when emphasizing a mono presentation.)

 

[lolo]

I'm sure you are not going to that extreme but just try the settings I've suggested and tweek from there.

Ok, will try again! Thanks for the help and sorry for the OT..

It did seem though that I may need narrower directivity.

 

[David Wareing]

Ok, will try again! Thanks for the help and sorry for the OT..

It did seem though that I may need narrower directivity.

Apart from the possibility of not finding the right combination of angles and settings, there are a couple of other things to consider.

The speakers need to be much closer than you would use for stereo. For sounds to the sides the direct sound is much reduced relative to the speaker feeds, and room response. A dry, mono centre image is essentially reproduced as such, with no cancellation at the speakers. (The cancellation is cancelled before it leaves the RACE VST)

Although I am not particularly keen to have sounds way off to the sides, it is the ability to do this which gives the low interaural correlation which leads (IMO) to the range of depth you can get with Ambiophonics. If you are not hearing this from the recording, it is probably that it is swamped by the room generated reflections.

The whole thing relies on the principle of superposition. This assumes that the two speakers act independently. For small, ineffecient speakers with some air around them, this is essentially true. For larger speakers, they tend to end up touching each other before you get a sufficient direct to reverberant sound ratio. It is more likely then that one speaker will affect the output of the other.

Try putting them next to each other with a baffle between them. This is not the same function as the 'Glagal mattress', although you could merge the two functions..

 

[Barleywater]

Hi Barleywater
I am not sure you looked at the phase part of the curve, there is no “all pass” crossover phase shift like Butterworth, linkwitz riley and other named slopes produce.
The high pass hf crossover alone for example has a 4th order ultimate slope which normally would put 360 degrees phase rotation centered around 1200Hz which is not present. The phase response is as if it were one driver, not 7 with a 3 way passive crossover.

Here is an old link to some square waves if curious;
http://www.diyaudio.com/forums/multi-way/71824-making-square-waves.html

Yes, I looked at phase, and time reference and windowing play into display; PDF of SH-50 from your site shows full 360 degrees smoothly over bandwidth:



This is quite an accomplishment with passive crossover, and horn version of slanted baffle, that goes further by folding up an WMTMW. Likewise your 250Hz, 1kHz, and 2.5kHz show all classic motifs of phase effects present with 4th order passive filtering; soft shoulders, droop, and significant overshoot; but fairly clearly produced from square wave source.

DSP correction has been commonplace in commercial sound for a long time and for one single location, it can perform miracles and can appear to be “perfect acoustic bondo”, but does not fix root or acoustic source problem.
The problem is that if one has separate sources producing the same signal (like a multi-way speaker at crossover), one has separate path lengths to the ear.
DSP can easily fix time and can correct a multi-way loudspeaker but the larger the spatial problems it’s is accounting for (the larger the acoustic spacing relative to a quarter wl), the smaller the “corrected zone” is and usually the result is worse everywhere else.
A multi-way speaker that produces an interference pattern (lobes and nulls) will still be producing an interference pattern with DSP correction because it can’t fix problems in horizontal or vertical placement unilaterally, only locally for one point in space.

Not just path length difference, but actual different paths. Fixed point correction at listener end is self inflicted trap of "digital room correction" Multiple path correction spanning multiple wavelengths does lead to single point solution. Yuck.

Think on the large scale like concert sound, it usually sounds good or fair at the mix booth and different everywhere else.

Yes, easy for desk heads to get good sound, potentially at near total loss for rest of venue.

The SH-50 (Synergy horns) are unusual in that they can be very largely phase correct without DSP and by radiating a segment of a sphere over a wide band act / measure /sound like as if it had one crossover-less driver and so it presents a very uniform spectrum across the listening area.

Phase plot has relatively smooth slope, thus fewer large inflection points, really approaching limits of physical design with analog processing.

While the coherent addition of drivers makes it an ideal thing to unilaterally correct the remaining time/phase with DSP (and that works great!),

Absolutely.

...the market demand is much more for a passive speaker “if” it sounds good without being active.

Market is very slow boat indeed; at consumer end nearly stationary. Caps and coils for power applications cost; insertion losses cost power; and increased failure rates due to lack of control hit hard.

I guess I would say the goal here was to fundamentally fix the acoustic source radiation and you fix many problems like lobes and nulls etc all at once.

Again, absolutely.

The speakers I mentioned are much more powerful than hifi speakers and are normally used say 30-100 feet from the audience or larger distances. As you probably have observed, most loudspeaker problems become larger, faster than the signal you want so if your audience is 19 times farther away, you need 100X the acoustic power to reach the same level.
The audience plane is usually as wide or wider than the coverage of a single box and so, the object is to have the sound field be as identical as possible everywhere within the pattern.

Also, confining as much of the total acoustic power to the design radiation angle is a very important thing, the larger the room, the less natural absorption there is and the more of a limiting factor reflected and reverberant sound is so far as understanding words so a constant/ high directivity design was also needed. In a living room, the directivity means the mag/phase response and impulse response at the listening position is much more like the 1 meter measurement. When you can confine most all of the energy into the front pattern, the direct field and intelligibility zone is maximized in large spaces..

Even in living room articulation is lost in lower voice range, and modulation envelope of most sound below 200Hz gets clobbered.

If I recall the picture of your speakers, they would be nearly / mostly onmi directional up to the higher frequencies and would radiate from nearly a single point in space with a simple pattern.
If they only had a tweeter that was smaller still but covered the entire frequency range, then the radiation would for the most part be a simple sphere and then portion of a sphere, largely a single point in time and space.. From that (the shape of the point source radiation envelope) it would seem that your point source speakers are actually similar to the Synergy horns which is curious, those being more or less the whole pie, while the Synergy horn is as much as possible just a slice of pie..
While the company is so far not interested in hifi, I am and that is what drives the designs, why I mentioned it here..

The Synergy horn radiates like that except the angle is bounded by a solid wall (tangent pressure boundary forms an acoustic mirror image of the rest of the sphere) with a confined angle less than a flat baffle.
What radiates begins at highest frequencies at the apex at a dimension too small for the sound to have any directivity and so the angle is set by the horn wall.
AS it progresses out of the driver into the horn and at a dimension suitable for lower frequencies, the mid energy is added in synchrony with the highs and then further down, again according to the acoustic dimensions, the low frequency energy is added.
That time /phase offset the crossover normally causes is offset by the drivers inverse physical locations so the result is what is in time and space like one driver and not a 3 way system.
What radiates is a segment of a spherical radiation, not the entire sphere and as if it were a single (but impossible) horn driver.

The “spherical-ness” is audible too when you place two of them side by side hard packed, you cannot hear a seam where one box ends and the other begins, only possible by radiating as if it were a point at the very back of the cabinet (in fact from a point where the horn walls would intersect).

Best,
Tom

Yes, we both subscribe to 1/4 wave approach and spherical wavefront. For small speaker convergence is short, enabling impulse measurement from inches. All sound passing through this point is corrected. To degree that this point represents behavior of neighboring points on spherical wave front determines overall performance.

For large speaker, flying on mast with microphone further back forms good basis for correction. For SH-50, and it's preferred environment relative to listeners, I'd guess at flying 15-20 feet with microphone the same and 10-20ft from speaker to acquire reflection free impulse via swept sine over desired bandwidth. Quiet as possible, including air movement. Yes, DSP works great once groundwork of good design is done.

Regards,

Andrew