Omnidirectional speakers

[xschop]

For the coaxial design would be simple to execute. I was originally pondering (still am) machining a conical stand-off connected via the mid-woofer's polepiece. The tweeter would be located within that inverted cone and it's insulated wires ran up thru the pole-piece extension. No stanchions at all on the perimeter is the idea, except the tweeter dispersion where I can easily change to a sphere shape and experiment there. I have some more large diameter all-alloy tubing to build these to match my new billet amp case.

 

[Newman]

Just checked the stereo source DSP program surround options for my Yamaha surround receiver—two of the three you noted are included:

Amsterdam
Vienna

Other available ones:
Freiburg Church
Munich Hall
Royaumont Church
Chamber
Village Vanguard
Warehouse Loft
Cellar Club
Roxy Theater
The Bottom Line
9 channel stereo

Maybe my soundstage immersion and such problem has just been solved? Will know soon, plus the surround and 2 channel systems are seperate so easy to do instant level matched A/B comparison.

Hi Jim,

I have all those on a v3900, and YMMV, but I certainly wouldn't like to have any one of them turned on as a permanent/default setup for 2-channel playback. They seem very 'strong'. Although fully adjustable on my unit (I haven't explored this aspect).

It has crossed my mind that they might work better if my room was modified to be super-dead, near anechoic. But with a 'normal' room, maybe the sound of two rooms are summing and it's excessive. I don't know if the average omni fan likes to keep his listening room 'extra live' to get the omni effect, but if so, it would only compound the problem.

I have also tried the Dolby and DTS upmixing that comes with my old v3900. The way they create a pseudo centre channel doesn't work for me: least objectionable being DTS Neo Music. YMMV but others have reported similar impressions. Even Toole is no fan of these unsophisticated early upmixers. It has crossed my mind to tell my AVR that there is no centre speaker, and see how it upmixes from 2 to 4 channels. Maybe I should explore this more. Lazy of me.

Toole has reported some personal success (defined as preferred over straight 2-channel) from upmixers by Lexicon and by Auro (Auro 3D). Dolby have a more recent (2012) upmixer called DSU, which I believe has been further improved approx 2022. One day I will modernise my AVR and explore the latest.

cheers
Grant

 

[jim1274]

Hi Jim,

I have all those on a v3900, and YMMV, but I certainly wouldn't like to have any one of them turned on as a permanent/default setup for 2-channel playback. They seem very 'strong'. Although fully adjustable on my unit (I haven't explored this aspect).

It has crossed my mind that they might work better if my room was modified to be super-dead, near anechoic. But with a 'normal' room, maybe the sound of two rooms are summing and it's excessive. I don't know if the average omni fan likes to keep his listening room 'extra live' to get the omni effect, but if so, it would only compound the problem.

I have also tried the Dolby and DTS upmixing that comes with my old v3900. The way they create a pseudo centre channel doesn't work for me: least objectionable being DTS Neo Music. YMMV but others have reported similar impressions. Even Toole is no fan of these unsophisticated early upmixers. It has crossed my mind to tell my AVR that there is no centre speaker, and see how it upmixes from 2 to 4 channels. Maybe I should explore this more. Lazy of me.

Toole has reported some personal success (defined as preferred over straight 2-channel) from upmixers by Lexicon and by Auro (Auro 3D). Dolby have a more recent (2012) upmixer called DSU, which I believe has been further improved approx 2022. One day I will modernise my AVR and explore the latest.

cheers
Grant

I’m actually relieved to hear that, wondering if I wasted 400+’hours chasing the elusive soundstage aspects with 2 speakers when the 7.4.1 ATMOS capable surround rig sitting idle could match or best it. I will test it out in the name of science, but earlier experimenting had me abandoning it quickly. Phew…

 

[MattHooper]

But wouldn't it be nice for some people if there was ALSO a two-channel solution which only needed the venue spatial cues already present on the recording, instead of relying on the relatively small selection of multi-channel recordings and/or a processor whose settings might need to be adjusted from one recording to the next?

Yup.

The refrain from some to “just go multichannel” is often either impractical, ironic or both.

It’s highly impractical for most audiophiles to suddenly limit their music to the truly teeny proportion of music recorded for surround.

But if the suggestion then is “just choose to upmix all your two channel music to surround” then ….what happened to this whole drum-beat about reproducing the signal accurately again?

“Pick a lane” as the saying goes

 

[Duke]

The intial scale from these old graphs are compressed in the beginning and not linear...

If the diffuse energy arrived after only 10 ms [behind the direct sound], it wouldn't have said it was arriving after 18 ms.

@Bjorn, I wrote to Peter D'Antonio (one of the book's authors) asking whether the horizontal scale was linear and whether the initial time-delay gap was 10 milliseconds or 18 milliseconds.

I quote here his reply:

"RFZ is 10 ms linear scale"

Here is the image again, so that people don't have to scroll back to find it:

 

[Flaesh]

No stanchions at all on the perimeter is the idea, except the tweeter dispersion

You may use ring radiator like

Someone has already used it

In Visaton Fontana small cone is simply glued to tweeter's phase plug:

 

[jim1274]

Yup.

The refrain from some to “just go multichannel” is often either impractical, ironic or both.

This is impractical for many folks, those who don’t even have a multichannel system (assuming DSP multichannel creation from stereo sources is even preferable) and those, like me, whose systems are only 2 channel stereo outside the living room multichannel rig.

It’s highly impractical for most audiophiles to suddenly limit their music to the truly teeny proportion of music recorded for surround.

That’s for darn sure.

But if the suggestion then is “just choose to upmix all your two channel music to surround” then ….what happened to this whole drum-beat about reproducing the signal accurately again?

“Pick a lane” as the saying goes

Maybe a good test of this is to try, say, a live orchestral recording in stereo with whatever spacial information is built into the 2 channel recording, then try a DSP multichannel using the same hall venue DSP program and see which sounds closer to sitting in the audience?

Does that make any sense?

 

[Newman]

Ok, since Jim has 'bought into' Matt's false dichotomy, I'm going to have to correct it. (No, to answer the obvious question, I'm not a masochist, it just looks like it. I'm actually taking one for the team. )

The refrain from some to “just go multichannel” is often either impractical, ironic or both.

That's right. Everyone knows that as soon as you implement a great MCH system, it can't play 2CH any more.

Oh, wait.

It’s highly impractical for most audiophiles to suddenly limit their music to the truly teeny proportion of music recorded for surround.

That's right. Everyone knows that as soon as you implement a great MCH system, all your 2CH software self-destructs in protest.

Oh, wait.

But if the suggestion then is “just choose to upmix all your two channel music to surround” then ….what happened to this whole drum-beat about reproducing the signal accurately again?

That's right. Those upmixers don't have an off button.

Oh, wait.

“Pick a lane” as the saying goes

Actually a false dichotomy, presented without nuance. Nuance, Matt, nuance.

Anybody who has read Toole with sensitivity, instead of translating him into a series of black-and-white false dichotomies, will already understand that the key message is that, despite the fact that the Circle of Confusion can be worked on with 2CH just as much as MCH, and it's important to work on that if you are interested in experiencing the sonic and musical art at its best, there are a couple of issues that are so dire that it's advisable to make adjustments. One is the fundamental inadequacies of 2CH in the areas of spatial cues and phantom centre colourations. Attempting to manage this with two speakers is largely futile, whereas upmixing has much more potential, and is much more, ahem, nuanced. The other issue is poor mastering. The best option, he suggests, is a well-implemented tone control.

Clearly, from the above, one thing Toole is NOT is some kind of fundamentalist kneeling before the altar of purity at all costs. (Don't paint his or my arguments in that light, unless your sole motive is malicious pointscoring.)

In fact, it's the person who tries to extract spatial from 2CH with weird and wacky dispersion speakers, who is locking himself into a sound effect unnecessarily. It's the person with MCH, an upmixer and a tone control who doesn't have to 'pick a lane'.

 

[xschop]

You may use ring radiator like

Someone has already used it

In Visaton Fontana small cone is simply glued to tweeter's phase plug:
View attachment 349828

So no cone needed over the ring tweeter? That'd be the ticket. Thanks for sharing.

 

[jim1274]

Ok, since Jim has 'bought into' Matt's false dichotomy, I'm going to have to correct it. (No, to answer the obvious question, I'm not a masochist, it just looks like it. I'm actually taking one for the team. )


That's right. Everyone knows that as soon as you implement a great MCH system, it can't play 2CH any more.

Oh, wait.

That's right. Everyone knows that as soon as you implement a great MCH system, all your 2CH software self-destructs in protest.

Oh, wait.

That's right. Those upmixers don't have an off button.

Oh, wait.

Actually a false dichotomy, presented without nuance. Nuance, Matt, nuance.

Anybody who has read Toole with sensitivity, instead of translating him into a series of black-and-white false dichotomies, will already understand that the key message is that, despite the fact that the Circle of Confusion can be worked on with 2CH just as much as MCH, and it's important to work on that if you are interested in experiencing the sonic and musical art at its best, there are a couple of issues that are so dire that it's advisable to make adjustments. One is the fundamental inadequacies of 2CH in the areas of spatial cues and phantom centre colourations. Attempting to manage this with two speakers is largely futile, whereas upmixing has much more potential, and is much more, ahem, nuanced. The other issue is poor mastering. The best option, he suggests, is a well-implemented tone control.

Clearly, from the above, one thing Toole is NOT is some kind of fundamentalist kneeling before the altar of purity at all costs. (Don't paint his or my arguments in that light, unless your sole motive is malicious pointscoring.)

In fact, it's the person who tries to extract spatial from 2CH with weird and wacky dispersion speakers, who is locking himself into a sound effect unnecessarily. It's the person with MCH, an upmixer and a tone control who doesn't have to 'pick a lane'.

I’ve had an “ah-ah” moment, at least provisionally, subject to much more testing. Some of the discussions here are paralleled on another thread covering a lot of the same territory. I just minutes ago did some quick tests, cycling through all the DSP modes that create a multichannel output from a two channel source. I’ll link that rather than repeat, but want to add that the “9 channel stereo” mode is actually more promising than even initially thought. I am playing it right now on an orchestral track known for soundstage, and it presents a pretty immersive and huge soundstage. I would encourage anyone who has a surround sound rig to try the “9 channel stereo” compared to just 2 speaker stereo.

Post 861 here:

Properties of speakers that creates a large and precise soundstage

Some years ago I tried setting up a 7.1 with my Yamaha DSP a-1000. I was actually quite impressed by how much engineering had been put to this and the various effects it offered. The sound was truly immersive on some tracks, especially live performances. On majority of other tracks the effects...

audiosciencereview.com

 

[Duke]

... it's the person who tries to extract spatial from 2CH with weird and wacky dispersion speakers, who is locking himself into a sound effect unnecessarily. It's the person with MCH, an upmixer and a tone control who doesn't have to 'pick a lane'.

The greatest variation in the "sense of space" from one recording to the next that I have encountered, including from one song to the next on the same album, has come from extracting spatial information from two-channel via "weird and wacky dispersion speakers". I don't say this to convince you, but to put into the record my objection to your characterization of such as "locking [one]self into a sound effect unnecessarily."

... one thing Toole is NOT is some kind of fundamentalist kneeling before the altar of purity at all costs.

Agreed.

In September of 2021 I attempted to hire @Floyd Toole as a consultant. He declined, but he and I subsequently exchanged messages. I did not ask for permission to quote him so I won't, but his response to what I described was positive.

 

[Eurasian]

I agree with you, actually. One of my planned experiments is to create a multi-speaker setup to see if delayed and attenuated sound can be used to simulate reflections and enhance the feeling of spaciousness and immersion. My problem is that I have run out of DAC channels and I lack suitable speakers to try this experiment (I will need to borrow more speakers). There is an entire chapter in F. Alton Everest's "Master Handbook of Acoustics" devoted to late reflections outside the Haas fusion zone, and mentions Olive and Toole's anechoic chamber experiment with two speakers - one delivering direct sound, the other delivering the "reflection" with delay and attenuation as variables.

The question is - how would you create multichannel sound from stereo? I am planning to do it by simply copying the 2 channel signal and playing it back on extra speakers with delay and attenuation baked in. I would point the speakers away from the listening position towards the corners so that I get as much diffusion as possible. I am not sure how low the speakers need to go, my suspicion is as low as possible (need to do more reading on that). Does this seem like the right approach to you, or do you have another suggestion?

ADS did exactly this with their Model 10 digital Acoustic Dimension Synthesizer. All you needed was a stereo amplifier and a pair of decent speakers mounted above ear height, aimed at the ceiling and placed behind the listening position. If you can find a copy, the owner’s manual provided a fantastic acoustics and perception introduction and is definitely worth the read. The device itself is amazingly sophisticated and powerful. I strongly recommend that you try one if you can find a working unit.

 

[Newman]

The greatest variation in the "sense of space" from one recording to the next that I have encountered, including from one song to the next on the same album, has come from extracting spatial information from two-channel via "weird and wacky dispersion speakers". I don't say this to convince you, but to put into the record my objection to your characterization of such as "locking [one]self into a sound effect unnecessarily."

Perhaps I should have said "locking oneself into an added sound effect unnecessarily". OTOH Toole didn't describe them as "added sound effect generators"...perhaps it was taken as read.

 

[ernestcarl]

It has crossed my mind to tell my AVR that there is no centre speaker, and see how it upmixes from 2 to 4 channels. Maybe I should explore this more. Lazy of me.

I don't know the details of what some upmixers do in other audio processors for the center channel mix, but it looks like from the simple L/R in-out sweeps I've done through JRiver and it's "pseudo-surround" mode in my HTPC, it basically just copies the left and right to the center channel at a much lower level -- of course, there could be something more going-on that's not entirely obvious from my simple in-room acoustic measurements.

Regardless, it doesn't work well for all content being played back. So I do find myself lowering the volume of the upmixed center (and surrounds) with presets to taste. In some cases where the upmixed center vocals is particularly, prominently loud/boomy or overly diffuse or just sounds wrong, easiest fix is to simply mute/disable center upmixing altogether.

 

[xschop]

I don't know the details of what some upmixers do in other audio processors for the center channel mix, but it looks like from the simple L/R in-out sweeps I've done through JRiver and it's "pseudo-surround" mode in my HTPC, it basically just copies the left and right to the center channel at a much lower level -- of course, there could be something more going-on that's not entirely obvious from my simple in-room acoustic measurements.

Regardless, it doesn't work well for all content being played back. So I do find myself lowering the volume of the upmixed center (and surrounds) with presets to taste. In some cases where the upmixed center vocals is particularly, prominently loud/boomy or overly diffuse or just sounds wrong, easiest fix is to simply mute/disable center upmixing altogether.

View attachment 350483 View attachment 350484

I'm trying to follow the conversation (and learning some concepts) and it dawned on me if, the acoustic 'delay' some like or dislike may have contributed to Polk's SDA designs(Interaural crosstalk cancellation)? I have built and experimented with them and for most modern recordings, it is a great benefit to achieve a wider soundstage. For some other recordings (aka mono mic'd piano, I don't like the "effect". Just my 2 cents.

 

[ernestcarl]

I'm trying to follow the conversation (and learning some concepts) and it dawned on me if, the acoustic 'delay' some like or dislike may have contributed to Polk's SDA designs(Interaural crosstalk cancellation)? I have built and experimented with them and for most modern recordings, it is a great benefit to achieve a wider soundstage. For some other recordings (aka mono mic'd piano, I don't like the "effect". Just my 2 cents.

Yeah, not all too surprised with the variability of results given the differences in recordings. I have only read other people shared experience with those speakers, but never heard them in person myself.

 

[jim1274]

Had an “ah ha” moment tonight with the Omnis after trying a speaker placement previously untested.

To set the table, I had been experimenting with BMR box speaker postioning in an attempt to optimize the soundstage, finally ending up with an 8’ equilateral triangle position, now 8’ from the front wall and 3.5 from side walls. So I then moved the Omnis inside the BMRs, retaining 8’ from the front wall and what ended up being about 4.5’ from the side walls. When doing an A/B, The penalty in clarity with the Omnis was clearly noticeable, enough that any soundstage effect was not sufficient to prefer the Omnis. Then it dawned on me, moving the Omnis closer to me and even further from reflective surfaces would increase the ratio of direct to reflected energy, increasing clarity. Since the “clarity gap” was large, I decided the repositioning needed to be large too. Without repositioning my coffee table with my DAC, amp, and A/B box, I was still able to reduce my listening triangle by half, now 4’ between speakers and create a 4’ equilateral triangle to the listening position (which also moved them a couple feet further from side walls and front wall) Well, the increase in clarity was so much that it was now very close to the BMR box speakers in that characteristic. What surprised me just as much was literally no soundstage penalty. The Omnis still completely disappeared, their soundstage still deep and wide, sometimes sounding like it started well behind the speakers and extending back to the front wall. This varies by recording, just like the BMR box, but had much more depth and no noticeable penalty on width (beyond the previously noted tendency on some recordings to collapse a tad toward the center). The soundstage depth with the box speaker was not even close, on some recordings sounding like it was mostly sound coming right from the speakers and all on the same plane.

I was just about to conclude that the Omnis loss in clarity when compared to the box was maybe a deal breaker, but no longer. I’ve done A/B on several dozen songs now and find the Omnis preferable on most songs so far.

I’m still thinking maybe a dipole is the “sweet spot”, reducing the extra sidewall reflected energy added by the Omnis, increasing direct to reflected energy ratio for clarity, but still retaining enough reflected for the added soundstage spaciousness aspects, also allowing more placement flexibility and closer to sidewalls. I’m thinking swap the BMR box out next for the AMT dipoles, starting at the 8’ triangle initially.

 

[xschop]

Very good write-up. I'll keep these experiments in mind. I find it very interesting that your experiences/reporting coincide with mine when I built a small set of SDA's. I actually preferred them further away from walls and a smaller triangulation than what is normally done for room set-up, almost near-field if you will.

That said, do you think omnidirectionals would be good for desk-top, near-field in general?

 

[Duke]

Then it dawned on me, moving the Omnis closer to me and even further from reflective surfaces would increase the ratio of direct to reflected energy, increasing clarity.

Yesss!!

You also increased the time gap between the arrival of the direct sound and the strong onset of reflections.

 

[jim1274]

Very good write-up. I'll keep these experiments in mind. I find it very interesting that your experiences/reporting coincide with mine when I built a small set of SDA's. I actually preferred them further away from walls and a smaller triangulation than what is normally done for room set-up, almost near-field if you will.

That said, do you think omnidirectionals would be good for desk-top, near-field in general?

That’s an interesting thought, but see two challenges:

1. Getting them far enough away from the wall behind them (front wall) to reduce/delay early reflections

2. Finding a suitable desktop size omni speaker.

There are not many desktop Omnis that I’m aware of—have these myself:

360 PEAK Music System By Level10 – soundmatters

soundmatters.com

Harman Kardon Aura Studio 4 | Bluetooth home speaker

Brilliant visuals. Beautiful Harman Kardon sound. Set your musical mood with the transparent dome and themed lighting of the Aura Studio 4 Bluetooth speaker.

www.harmankardon.com

These are designed to be stereo from one unit, so suspect you were thinking seperate L & R Omnis?

Those two speakers are what took me down the Omni path, resulting in scoring the Duevel Planets then Enterprises to test.

The 360 Peak still gets regular use—it’s my primary “mobile” portable Bluetooth speaker indoors. It’s perfect for when you are working and moving around in a room and want the whole room to be a “sweet spot”. When cooking, I just throw it on the end of the “L” counter island section and have good sound everywhere in the workspace.

The HK one has more SPL capability but tethered to wall power. I’ve used that a lot when working in the garage. Can’t recall if mentioned here or a different thread, but had a new garage door installed not too long ago, asking the crew “tunes or no tunes?” Tunes requested, so I threw the HK Omni on a workable off to the side a bit. After a couple songs, the crew chief stopped and said “ok—where in the heck is the music coming from—sounds like everywhere and see no speakers”. Pointed to it on the table with some other stuff and he just looked at me. He inquired about it, telling him I got from Amazon. He stopped installing, mumbled something, ordering one on the spot.

Omnis may still be controversial to many, but I say they do things no other speaker can and are unparalleled in providing music across a wide listening area. Like one member said much earlier in the thread, the perfect “party” speaker.