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omnidirectional loudspeakers = best design available

Hello people,

Surfing the internet, I was pleasantly surprised to find a serious topic on omni directional speakers. Inspired by a talk from Siegfried Linkwitz, I became very interested in the subject. This resulted building my own omnidirectonal speakers. It’s a bit uncommon design based on a polyhedron.


Here is a small paper on this design and I hope for some useful comments:
 

Attachments

  • Omni Directional Speaker-2.pdf
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Happy New Year! I'm having a lazy New Year's Day, so here is a verbose reply:

This is an interesting dilemma. You want to impress listeners, who are probably inexperienced, hoping that they will think that you have a superb audio system, or that you have exquisite taste in recorded music, or both. There is no way to know the details of cause and effect, in what it is that impresses them. Maybe your system is flawed, but the choice of music impresses in part by not revealing the flaws – that is what I was describing as a certain category of “audiophile” music. Impressive in its “ultra-clear simplicity” but not challenging to the system. Maybe your system is magnificently neutral, and a demanding program sounds impressive because the listener has never heard such music reproduced with such transparency.

Audiophile notions of “resolution”, “detail”, and the like are mind exercises having a lot to do with the program and often less to do with the technical performance of the playback system. Double-blind tests have a way of revealing such things. As I have said before, the sound quality ratings go up as the audible evidence of resonant colorations goes down. Colorations in the playback system mask details in the music, but only if the music has the bandwidth and spectral density to reveal the problems. The only conclusion, therefore, is to use music that is capable of revealing problems, because when the problems are not heard, the result is that all your desirable factors are available to be appreciated.

Here is your summary of desirable factors: “Clarity. Vividness. Smoothness (not harsh). Wide frequency range. Rich (the sound has body, weight, not thin). Exciting dynamics/sense of impact. Timbral nuance and complexity. And, ideally a sense of spaciousness, and perhaps a sense of dimensionality to the sonic "images."

Most people live their lives experiencing insufficient bass quality and extension, a fact of life. We now know that low frequencies account for about 30% of overall listener preference in sound quality. So, clearly impressive bass is an essential starting point. Neutrally balanced bass is not a necessity, as mildly excessive bass is impressive and, even if recognized as such, a forgivable sin. So, forget about string quartets as program material. A good kick drum is a better start, combined with some synthesizer low bass that exercises the low end of subwoofer system, gently shaking the body. Many people will never have heard such sounds from an audio system, and you will immediately have their attention.

The second technical factor that impresses novice listeners is sound level. Most people have never lived with systems capable of “realistic” sound levels that utilize the full audio bandwidth. A good audio system can reproduce crescendos without sounding “loud”.

Beyond this, it is likely to be a matter of how well you have anticipated the musical taste of your audience. Recordings do vary in quality, but in my personal observations, the variations have reduced over the years. Modern microphones, studio electronics, monitor loudspeakers and room treatments in control rooms have become more similar and together capable of capturing, mixing and mastering sound with all of the inherent desirable sound qualities intact. There are occasional exceptions, but for me most of the compromised recordings are from the “good old days” that technically were not really all that good – nostalgia notwithstanding.

I had a shock when I visited a massive climate-controlled vault of archival tape recordings, many years ago. Analog tape recordings degrade with time, and are occasionally re-recorded or digitized for preservation. That is all understandable, but my greatest disillusionment came when I learned that many original studio master tapes had been scrapped and what was saved were the LP cutter tapes – compromised in various ways to allow the content to be cut into the inherently limited LP medium. Consequently, some of the first generation CDs sounded bad because they contained the pre-distortions necessary for LPs to be playable – mono bass, amplitude compression and high frequency rolloff to allow for inner groove tracking. Thinking at the time was clearly that the LP was the ultimate format. Wrong. Some “classic” master recordings gone forever.

You said: “But since we not only have "reality" as a reference, but now a history of reproduced artificial sound that has molded people's preferences, “

I grew up in the age of “High Fidelity”. Looking back, it is clear that reproducing reality was never a realistic goal. Back then, sound quality in microphones and loudspeakers was not neutral, 78 rpm records were noisy and distorted. Sound quality was obviously lacking, and in my youth, stereo did not exist. Once it was recognized that recordings had to be mixed from multiple microphones, the recording studio and control room became the dominant factors in what ended up in recordings. Recording engineers had arguably more influence over what we heard than musicians, and it was true at a time when all sounds that were captured were “live” voices and instruments. The “circle of confusion” reigned supreme.

Voices and instruments radiate sound in many directions, in reflective spaces, but a microphone captures only a tiny sample of the total sound, only at a single angular perspective, and much closer to the performer than any audience member is likely to be in a live performance. The “reality” as a reference notion was an unrealizable fantasy. I have never had my ear as close to a vocalist’s mouth as microphones are. I am visualizing Elton John “chewing” the windscreen on his mic. Classical music is multimiked at locations close to and often above the musicians, not 12 rows back in the audience. As you said: “"closer to real" was the guiding goal”, but while recorded sound quality has definitely improved, there has been no truly persuasive sensation of spatial “envelopment” to transport the listener to the recording venue, only hints. That requires multichannel. That would truly impress your listeners – it can still send chills down my spine when I hear it.

I can listen to stereo through a pair of Revel Salon2s and then add in some amount of Auro3D simulated surround through my 7.4.6 system of timbrally similar Revels. Guess which I prefer for the vast majority of recordings? I fantasize about a better upmixer; my old favorite the Lexicon Logic 7 is history, and I am “making do”.
Thank you Dr. Toole for your time and attention. I feel selfish just asking you a question. I have seen posited that timbre isn't a thing and that a center channel that matches the L/R mains is unimportant, but in your post you mention your "7.4.6 timbrally similar Revels." Does that mean you do think the center channel of a surround sound system should match the mains, as in come from the same brand and model line?

Thank you.
 
Thank you Dr. Toole for your time and attention. I feel selfish just asking you a question. I have seen posited that timbre isn't a thing and that a center channel that matches the L/R mains is unimportant, but in your post you mention your "7.4.6 timbrally similar Revels." Does that mean you do think the center channel of a surround sound system should match the mains, as in come from the same brand and model line?

Thank you.
The center channel is the most important channel in the system - in movies it does most of the work. Ideally it should be "identical" in performance to the L & R, but in reality it cannot be a tall floor stander, so it is reconfigured to be horizontal, creating a challenge for the engineer. It can be done, and done well, as can be revealed by spinoramas. Once you have access to spinoramas you will soon see that it is possible to mix and match models, even brands, that have used the same performance objectives. So, while sticking to the same brand and model line is easy, a labor saving device, it is not the only way to get timbrally similar L,C and R.
 
[For trained listeners] omnipolarity testing apparatus; the more stable the sound when moving, the better the design:
1704291273490.png
 
An interesting poll conducted here a year or so ago showed that a third of our members use a 2.0 channel audio system and a slim majority use more than 2.channels. This poll seems to indicate a significant gap between those who are employing 2 channels and those who use more than 4 or 5 channels plus a sub. I was surprised by the results. Almost 60% of respondents indicated they use a 2.x passive speaker setup. Therefore it seems to me that we can draw a conclusion that 40% or less use a powered dedicated Subwoofer.

Here is the Poll, for an insight on this community. Note that only 311 people voted. So a very small percentage of our community. Maybe we can get the OP to post another Poll and see if the numbers have changed? How about it @Rick Sykora ?

 
I was surprised by the results. Almost 60% of respondents indicated they use a 2.x passive speaker setup.
Which of the numbers below did you add up to get "almost 60%"?

1704320032865.png

Therefore it seems to me that we can draw a conclusion that 40% or less use a powered dedicated Subwoofer.
I have to wonder whether voters were understanding the vote card differently to you, and thought "passive stereo 2.x" includes passive speakers with a powered sub.

26.4% + 10.0% = 36.4% use no subwoofer

Therefore 63.6%* use a subwoofer, and my money would be on almost all of them employing a powered subwoofer, including those who voted "passive stereo 2.x".

cheers

* I don't know what to do with the bottom 4.2%, so I left them in for now.
 
Which of the numbers below did you add up to get "almost 60%"?

View attachment 339498

I have to wonder whether voters were understanding the vote card differently to you, and thought "passive stereo 2.x" includes passive speakers with a powered sub.

26.4% + 10.0% = 36.4% use no subwoofer

Therefore 63.6%* use a subwoofer, and my money would be on almost all of them employing a powered subwoofer, including those who voted "passive stereo 2.x".

cheers

* I don't know what to do with the bottom 4.2%, so I left them in for now.
I added the top 3 respondents into the almost 60%. Passive 2.x, Active 2.0 and Passive 2.0. Agree that I may be misinterpreting the categories. 36% definitely don’t use a subwoofer. I took Passive to mean all 2.x are externally powered. Feel free to start a new Poll and let’s collect more data.
 
i humbly add the axiom audio LFR series. these are floorstanding front/rear bipole designs with hybrid active/passive crossovers (active front/back, passive vertical). they also have a newer model that uses fully active crossovers. i have LFR1100s, which are a bipolar design based on their M100 unipolar floorstanders. the effect isn't towards surround sound but ridiculously wide sweet spot and room filling sound for larger spaces -- mine is 500sqft with lots of weird corners and doors.

available integrated with their own class D amplifier series for fewer boxes.

i humbly add the axiom audio LFR series. these are floorstanding front/rear bipole designs with hybrid active/passive crossovers (active front/back, passive vertical). they also have a newer model that uses fully active crossovers. i have LFR1100s, which are a bipolar design based on their M100 unipolar floorstanders. the effect isn't towards surround sound but ridiculously wide sweet spot and room filling sound for larger spaces -- mine is 500sqft with lots of weird corners and doors.

available integrated with their own class D amplifier series for fewer boxes.

Just curious—have you tried a true Omni like Morrison or Duevel in your room to compare to the LFR bipolar? I ask because a Definitive Technology bipolar was suggested to compare to my Duevels over in the other Omni thread.
 
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