That's a 45.5" L x 1.5" H countertop that juts out 11" past the kitchen wall.
Subject: Center Speaker Recommendations for Main Horn Speakers
- Thread starter ajant
- Start date
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
I crossed the Radians over at 1.4 kHz in the speaker shown in lower photo in post #62.
I wouldn't worry about the Altec's intermodulation distortion unless you play to play extremely loud.
It's the same data presented different ways. Notice the top few off-axis curves, they are bunched up much closer in the horizontal family of curves than in the vertical family of curves.
The vertical coverage is a bit narrow up high, but you could tilt the SEOS-15 back maybe five degrees or so still have good vertical coverage when you stand up.
The Pyle 612 is pretty good, that's what's underneath the grille cloth in the upper photo in post #62, crossed over to a 12" woofer at about 1.5 kHz. I used the Celestion CDX1-1731; I didn't like the titanium-diaphragm Selenium that was populare with DIYers. Imo you're probably not going to get low enough with that horn. Not sure it's even still available, but Parts Express sells a copy of it.
Thanks!
I don't understand this, but I don't think I need to.
Got it - thanks! Imo in order to get good coverage across a seating area as wide as the speaker's spacing, we'd want a horizontal radiation pattern width in the ballpark of 90 degrees.
Time/intensity trading is the technique of crossing the speaker axes in front of the listening position in order to widen the listening area. I first mentioned it i
n Post #18 but didn't explain it; my apologies.
First a bit of background: The ear determines the direction of a sound source by two mechanisms: arrival time, and intensity. So if a sound arrives at the same time from both speakers but is louder from one of the speakers, the image location will be pulled towards the louder speaker. If the loudness is the same from both speakers but arrives earlier from one of them, the image location will be pulled towards the first-arrival speaker.
Time/intensity trading is a clever (though somewhat counter-intuitive) way to exploit these characteristics of human hearing to increase the width of the listening area within which you get a good soundstage.
You'd use a pair of speakers with a fairly narrow and well-behaved radiation pattern and toe them in aggressively such that their axes criss-cross in front of the normal central "sweet spot". The situation from well off to one side of the centerline is this: The listener is very far off-axis of the near speaker, but on-axis, or nearly so, of the far speaker. So the output of the near speaker arrives FIRST, but the output of the far speaker is LOUDER. The net result is that the two localization mechanisms (arrival time and intensity) approximately cancel one another out, so we still have a pretty good spread of the instruments in between the speakers, with the center vocalist roughly in the center. The image locations are not as precise as from listening locations up and down the centerline, but the imaging is still enjoyable.
The SECRET to time/intensity trading being successful is this: The output from the near speaker must fall off SMOOTHLY and RAPIDLY as the listener moves off-axis. In my experience time/intensity trading does not work well with conventional speakers; their radiation patterns are too wide and usually have too much variation, such that timbre is degraded at locations well off-axis.
Credit to Earl Geddes for teaching me the technique. I've been using it for more than twenty years.
At this link is an online paper describing time/intensity trading:
http://libinst.com/PublicArticles/Setup of WG Speakers.pdf
Thanks to time/intensity trading, the home theater system shown in the upper photo in Post #62 does not need a center-channel speaker. In "phantom center" mode the soundstage depth and sound quality are both better than they were with a dedicated center-channel speaker. But there is this potential dowside: If one of the viewers has a significant hearing imbalance (much better hearing in one ear than in the other), you might need a center-channel speaker to anchor the dialogue on-screen for them.
Last edited:
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
Thank you.
Imo the reflections from the vertical surface underneath that countertop will arrive too early for listening positions near it. See the attached .pdf file. Sound travels about 1.1 feet per millisecond, so a reflection from less than 5 feet past the direct sound will arrive earlier than the 10 milliseconds target. (Ten milliseconds is not a hard-and-fast cut-off point; it is a fuzzy transition zone, and I can explain the thinking behind it if you'd like).
Maybe put diffusion on that vertical surface, or maybe absorption. The issue with absorption is it's impractical to make it deep enough to be truly broadband, so we'd end up with a reflection that has had the high frequencies removed, and any subsequent energy that strikes the absorptive panel also has its high frequencies removed. But room acoustic treatment is not my area of expertise.
Would you be okay with me suggesting a different location for the speaker set-up?
Last edited:
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
Well, imo there are trade-offs either way.
800 Hz and 1200 Hz are effectively in two different categories, as far as available waveguides and suitable compression drivers.
For an 800 Hz crossover we'd have to use at least a 1.4" throat waveguide and then choose a suitable compression driver. I am not aware of any off-the-shelf 1" throat waveguides and horns suitable for an 800 Hz crossover.
For a 1200 Hz crossover there are a few off-the-shelf 1" throat waveguide/compression driver combinations that would work.
If we end up staying with the 90-degrees-ballpark radiation pattern width as our target, I'm thinking the 80-degree-pattern B&C ME90 looks the most promising for an 800 Hz crossover. The SEOS-15 and Pi Speakers H290C, both 90 degrees in the horizontal plane, look to me like viable options for a 1" throat compression driver with a 1200 Hz crossover.
Imo the advantage of an 800 Hz crossover is that we have a bit more of the overtone region covered by a single driver (which is imo desirable), and of course the power handling is higher, but the downside is that the radiation pattern will narrow somewhat in the top octave. Therefore top-octave coverage across the entire listening area will be less uniform than the coverage further down the spectrum. Also, there will be more of a radiation pattern discontinuity in the crossover region because the woofer's pattern will be wider than the waveguide's pattern.
Imo the advantage of a 1200 Hz crossover is that we can use a 1" throat compression driver which will give us more uniform coverage in the listening area in the top octave, along with better pattern-matching in the crossover region (assuming a 90-degrees-horizontal waveguide). The trade-off of course is that we don't get the benefits of an 800 Hz crossover.
There are only a small handful of compression drivers suitable for covering the region from 500 Hz on up, and imo no suitable off-the-shelf waveguides, except maybe a big SEOS in fiberglass from Autotech in Poland. That would probably be a semi-custom build, and expensive.
Imo it's inevitably a juggling of trade-offs. Neither the perfect waveguide nor the perfect compression driver exist.
My opinion is that a large Oblate Spheroid waveguide would be the closest approach, but even that would involve trade-offs. To the best of my knowledge oblate spheroids are not an option aside from having something custom made.
Just in case knowing how I juggled the tradeoffs might be useful to you: My most recent custom Oblate Spheroid waveguide design uses a 1" throat compression driver which can go lower than most, and the waveguide itself is pretty big, so a 1 kHz crossover looks feasible in a home audio application. The coverage pattern is 80 degrees; in my application I think an 80-degree pattern has a minor advantage over a 90-degree pattern.
Last edited:
You may suggest an alternate placement location though I'd be less likely to decline if the room was at least 50% bigger. Sadly, this is a stifling apartment on grossly overpopulated, over school taxed Schit Island; hardly the likes of Big Sky Country. I have a 65" TV further north along the east wall and two other Rythmik F12 subs along the north wall, which, as per Toole & Geddes http://www.gedlee.com/Papers/Philosophy.pdf, I want to utilize wil the other two subs via a multichannel DAC to minimize room modes. I also may want to use those subs with second pair of speakers-and if space permits a center channel speaker-for TV sound.
As for the acoustical problem generated by that space under the countertop, looking at the attached sketch, there's 1.) no listener's chair placed in line with the corner and 2.) I thought the speakers and subs were to be toed in? If so, would they then not be firing at that countertop and therefore cause little if any early reflections?
Otherwise, once the speakers are here I plan to hire someone like Mitch Barnett. https://accuratesound.ca/about/ When remote controlling my pc and instructing me to take live recorded system measurements, his subsequent evaluations will presumably lead him to prescribe surface mount materials to minimize the destructive effects of that and other troublespots-even though my speakers will have passive crossovers rather than DSP active crossovers. And as all of my music sources are computer based, further correction may be possible via the use of convolving software. However, your opinions on these approaches to room correction and multiple subwoofer bass management vs. speaker relocation are welcomed.
Last edited:
But much upward tilting of the horn before coherency with the midwoofer is reduced? Would rather opt for a horn with greater vertical coverage so I wouldn't need to do that, but few such horns available.
Last edited:
https://www.kartesian-acoustic.com/product/cmp50_vpa-s
https://josephcrowe.com/blogs/news/kartesian-cmp50-vpa-1-compression-driver
https://josephcrowe.com/products/es-800-bi-radial-wood-horn
Other ideas https://www.diyaudio.com/community/...n-to-800hz-for-a-2-compression-driver.398732/
But please list any existing tradeoffs even with a relatively large budget for this project.
But doesn't this imply that a speaker, or horn and/or driver can mask a recording's low level detail even when playing at moderately loud or lower SPLs? https://josephcrowe.com/blogs/news/...rious-hf-drivers?_pos=21&_sid=76f408801&_ss=r
Granted, it took 90db SPL at one meter (3.21ft) to produce those IM distortion levels, so assuming I'm listening at 9 ft from the speakers
, that's 81db SPL, which is certainly a lot louder than I'd want to here anything at ~ 1kHz in that room at that distance.
Sound Pressure Level (SPL) Calculator | AtlasIED
Sound Pressure Level (SPL) Calculator for precise audio measurements. Optimize your setup try our tool for accurate sound analysis today.
www.atlasied.com
Sound Attenuation Calculator - Inverse Square Law | WKC Group
Sound attenuation and the inverse square law. Calculate the sound attenuation over distance based on a starting sound pressure level.
www.wkcgroup.com
NOTE: Pierre's room is ~ 20 ft x 20, drivers center-to-center 8.5 ft, 10 ft listening distance. Post 15266.
Beyond the Ariel
Hi Lynn Olson, thank you for the explanation in your post. If I understand correctly your other posts, you plan to use a passive cross-over. Should its resistance not be added to that of the output resistance of the amplifier and the conductors? I think that apart from that, I have all the...
But the ear's sensitivity also varies with frequency. https://en.wikipedia.org/wiki/Equal-loudness_contour and I'm hoping to play my midwoofers down to ~ 80Hz before having to cross them to my subs. So-assuming this is wise- if we reduce the required SPL @ 1kHz to ~ 75db, then for the midwoofers to reach 80Hz with minimal distortion the (revised) equal loudness curves says the midwoofers would have to play at ~ 87db for their loudness to be perceived equally with 1kHz @ 75db. Thus, how much lower than 90db at 1 meter can the compression driver play and still enable this?
Of course, my point it that to avoid a driver from masking a recording's detail the crossover point must be optimized to keep the driver producing its minimum IM distortion numbers.
Btw, how to read that spectral content pattern? From that graph, how is Troy computing what values at 400Hz and 2kHz to get -65db and -52db,
respectively?
Last edited:
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
Sounds like you've narrowed it down to the best combination of performance and practicality already. I attached a quick sketch, but I don't expect it to be practical.
You could tilt both the midwoofer and the horn. Or you could use a horn with better vertical coverage, just like you said.
That's a really nice looking compression driver. I hadn't seen it before. I wrote to Kartesian and asked what the exit angle of that compression driver is.
It's not obvious to me that intermodulation distortion is going to be an issue in the system you're building. That being said, this is YOUR project, not mine! If you want to minimize intermodulation distortion, I'm not going to try to talk you out of it.
Among off-the-shelf horns, I'm now thinking the B&C ME90 horn might be the front-runner because it uses a 1.4" throat compression driver so it can be crossed over around 800 Hz, it has good coverage across 80 degrees horizontally, AND it has good vertical coverage for when you stand up. If you go that route, I would suggest getting your crossover designer's input on the compression driver choice.
I don't know.
Last edited:
Thanks for that alternative placement sketch. Presumably, you did so because it allows for ample and symmetrical side wall reflections. Is that what would produce the "you are there" illusion by maximizing imaging quality? I will present this countertop generated acoustical problem to these guys. https://www.diyaudio.com/community/forums/room-acoustics-mods.169/
If they can't suggest an effective solution then will go with your solution. Not happy about the TV on the south wall but audio quality is priority.
Yes, the B&C ME90 looks like it hits all the right buttons. Otherwise, what do you think of this?
www.bcspeakers.com
If they can't suggest an effective solution then will go with your solution. Not happy about the TV on the south wall but audio quality is priority.
Yes, the B&C ME90 looks like it hits all the right buttons. Otherwise, what do you think of this?
ME464 - Horns - B&C Speakers
www.bcspeakers.com
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
I was aiming for more time delay for the sidewall reflections.
But the more I think about it, the less sure I am that my alternative placement would be better than yours. The front wall reflections would be worse with my alternative placement. Not sure that's a good trade-off.
And the more I think about it, the less bad I think the reflection from the vertical surface under the counter would be. It's a contralateral reflection, meaning that it arrives at the opposite ear from the direct sound from that speaker, and that allows the ear/brain system to process it as ambience (according to Earl Geddes).
I think your original idea is probably better than my alternative suggestion because yours does a better job with the front wall reflections.
The "you are there" illusion theory I subscribe to goes something like this:
In the home audio listening room, there is a competition between two sets of ambience cues: The venue ambience cues on the recording (whether they be real or engineered or both); and the "small room signature" cues inherent to the playback room. When the playback room's cues "win" this competition, which often happens in small to medium-sized rooms, the presentation tends towards "they are here". When the venue ambience cues on the recording "win" this competition, we can end up with a plausible "you are there" presentation.
So imo we want to minimize the "small room signature" cues of the playback room while promoting the "venue ambience" cues on the recording.
The earliest reflections are the ones which most strongly convey the "small room signature" of the playback room. If we can push those first reflections fairly far back in time, we can disrupt the small room signature. (The floor and ceiling reflections are fairly benign from the standpoint of spatial quality.) Imo we do not want to use absorption on the first reflections any more than we absolutely have to, because we want that energy to survive long enough to become "late reflections".
I believe that sufficiently late reflections convey the "venue ambience cues" on the recording without also conveying strong "small room signature" cues. And I believe that ten milliseconds after the first-arrival sound is sufficiently late (later would be better, but ime 10 ms works). These reflections should have the same spectral balance as the direct sound, or nearly so.
With the kind of speakers you're building, the good news is that their radiation patterns can be aimed to avoid strong early sidewall reflections, and the reflections they do produce will be spectrally correct (or nearly so). The bad news is, they don't produce a whole lot of that beneficial late-arriving reflection energy.
The approach I use in my some of my designs is to add more late-arrival energy to the in-room reflection field via additional drivers which are aimed away from the listening area. Imo this can help to enable a "you are there" presentation if done right.
what do you think of this?
ME464 - Horns - B&C Speakers
The ME464 is a diffraction horn. That vertical slot is a diffraction slot. Maybe it wasn't practical to simply scale up the ME90.
Here is why I don't like diffraction horns: There will be a reflection (or diffraction) at the slot because it's a sharp change in the wall angle. This reflection widens the radiation pattern at high frequencies, so this technique is often used in prosound horns to combine constant-directivity behavior with the low-end extension of having a deep horn.
The bad news is, part of that reflection propagates back down the throat all the way to the diaphragm, where it is reflected back out again. When this reflection off the diaphragm reaches the slot, again it is reflected, with some of that reflection once again propagating back down the throat to diaphragm. This continues until it fades away. My understanding (from Geddes) is that this type of reflection may not be audible at low SPLs, but as the SPL increases, it can become increasingly audible and objectionable. And, this is not the sort of problem EQ can fix.
If you want a big enough horn to enable a crossover frequency down around 500 Hz, imo a viable low-coloration alternative might be a big SEOS waveguide from Autotech. Maybe plan on both waveguide & Altec being tilted back a few degrees to give better coverage when you stand up.
Last edited:
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
@ajant, much of my thinking on speaker/room interaction, as it relates to spatial quality, is informed by psychoacoustician and researcher David Griesinger. He studies concert hall acoustics and psychoacoustics, but imo the principles are still applicable to home audio.
Here are some relevant Griesinger quotes; I have assembled these based on subject matter from multiple papers or lectures, so in some cases he didn't say these sentences in exactly this sequence, but he did say them all:
"Presence depends in the ability of the ear and brain to detect the direct sound as separate from the reflections. When presence is lacking the earliest reflections are the most responsible."
“Localization – and the perception of clarity – is a high-frequency phenomenon in reverberant spaces. The information content of speech and much music,and the sense of sonic distance, the perception of clarity, the ability to sharply localize instruments, and the ability to separate multiple sound streams, all depend critically on the harmonics above1000 Hz.”
"Envelopment is the Holy Grail of concert hall design. When reproducing sound in small spaces [home listening rooms], envelopment is often absent. Envelopment is perceived when the ear and brain can detect TWO separate streams: A foreground stream of direct sound. And a background stream of reverberation. Both streams must be present if sound is perceived as enveloping." [Duke's note: A time gap between the direct sound and the reverberation is necessary in order for the ear/brain system to separate the two, and imo/ime 10 milliseconds is sufficient. And technically "reverberation" would be the wrong term in a home audio setting; "onset of the reflection field" would be more accurate.]
“Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough.”
“Perceiving envelopment is only possible when the direct sound can be separately perceived, and clarity of the front image is a vital part of this process.”
"Where the background stream is easily separated from the foreground stream, envelopment is about 6 dB stronger for a given direct-to-reverberant ratio."
While none of this directly addresses how to get the "venue ambience cues" on the recording to be perceptually dominant over the "small room cues" of the playback room, ime the application of these ideas contributes to that happening.
Here are some relevant Griesinger quotes; I have assembled these based on subject matter from multiple papers or lectures, so in some cases he didn't say these sentences in exactly this sequence, but he did say them all:
"Presence depends in the ability of the ear and brain to detect the direct sound as separate from the reflections. When presence is lacking the earliest reflections are the most responsible."
“Localization – and the perception of clarity – is a high-frequency phenomenon in reverberant spaces. The information content of speech and much music,and the sense of sonic distance, the perception of clarity, the ability to sharply localize instruments, and the ability to separate multiple sound streams, all depend critically on the harmonics above1000 Hz.”
"Envelopment is the Holy Grail of concert hall design. When reproducing sound in small spaces [home listening rooms], envelopment is often absent. Envelopment is perceived when the ear and brain can detect TWO separate streams: A foreground stream of direct sound. And a background stream of reverberation. Both streams must be present if sound is perceived as enveloping." [Duke's note: A time gap between the direct sound and the reverberation is necessary in order for the ear/brain system to separate the two, and imo/ime 10 milliseconds is sufficient. And technically "reverberation" would be the wrong term in a home audio setting; "onset of the reflection field" would be more accurate.]
“Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough.”
“Perceiving envelopment is only possible when the direct sound can be separately perceived, and clarity of the front image is a vital part of this process.”
"Where the background stream is easily separated from the foreground stream, envelopment is about 6 dB stronger for a given direct-to-reverberant ratio."
While none of this directly addresses how to get the "venue ambience cues" on the recording to be perceptually dominant over the "small room cues" of the playback room, ime the application of these ideas contributes to that happening.
So then the SEOS-15/Kartesian combo or the B&C 90 or 464 horn and a 1.4" driver that Troy would recommend.
Duke LeJeune
Manufacturer - Illusio Audio and AudioKinesis
Sounds good!
The big one is a diffraction horn. The small one is not, but it beams the highs pretty badly (not shown in the published data but I've measured it), and it's too small. `
Hello Duke
Not in my experience. I can stand up walk into them as a stereo pair and move off axis one speaker no issues I can notice aside from some HF shading if you get too close. Not saying your suspicion is wrong but in actual use it's not obvious and the in room balance is very stable. If you get a chance you should give them a listen.
`
That is correct no DSP in the crossover just a PEQ boost 26hz Q2 0, +3, +6 selectable at box tuning like the older JBL BX-63 used in the B380, 460.
Rob
I believe I recalled some years ago when James Romeyn proposed this a rear firing tweeter array at Lynn Olson's thread at diyaudio.com, though perhaps this wasn't meant to accomplish the same thing. But from what you seem to be saying here:
And imo the interaction between the loudspeakers' off-axis response and the room means that the end result is neither entirely up to the speakers nor entirely up to the room.
https://www.audiosciencereview.com/...directivity-vs-speaker-radiation-width.46479/ And since all my music are on WAV or other computer files, is it possible to produce that late-arriving reflection energy via DSP software? Maybe this is something Mitch Barnett can do when I eventually seek his help for doing room correction and multisub bass management. https://accuratesound.ca/
Also, I found some info on SEOS horns. https://www.avsforum.com/threads/at-last-the-seos12-measurements.1369780/
Too bad the vertical directivity narrows a bit but otherwise very good I suppose. https://horns-diy.pl/horns/seos/seos-18-1/
I don’t want to go bigger than a 1/4” throat/3” diaphragm as Weltersys and Arez that all you gain from 4” diaphragms are more SPL output at lower frequencies and you lose the diaphragm breakup point of the 3” at higher frequencies. But apparently Autotech will cut/not cut the neck to match the driver throat exit.
https://horns-diy.pl/wp-content/uploads/2015/07/SEOS-221.pdf
https://horns-diy.pl/wp-content/uploads/2015/07/SEOS-242.pdf
But I couldn’t find any sonograms on the SEOS 22 and bigger waveguides.
Actually, it’s just as well that the ME464 gets ruled out as the sheer acoustic power of that huge thing almost invites some ear damaging high SPL accident. Sadly, this is even more so why unless well designed and built multichannel attenuators were installed between the output of my DAC interface and the inputs of biamping power amps and subwoofer plate amps, I’d be against using DSP or any kind of active crossovers, as these high efficiency drivers would be directly connected to my 25 wpc power amps. This is something I’d have to make clear to Mitch.
But what about the ME90, as it has no diffraction slots, albeit not quite 90 x 60?
https://www.bcspeakers.com/en/products/horn/1-4/0/me90
Last edited:
Thanks for helping me avoid the X120’s problems. Is the bigger horn satisfactory or pass? https://www.eighteensound.it/en/products/horn/1-4/0/XR1496C
Last edited:
How would you reply to this assertion?
https://www.audiosciencereview.com/forum/index.php?threads/compression-drivers.29697/post-1301000
https://www.audiosciencereview.com/forum/index.php?threads/compression-drivers.29697/post-1301000
Similar threads
 | Steve Williams Site Founder | Site Owner | Administrator |  | Ron Resnick Site Owner | Administrator |  | Julian (The Fixer) Website Build | Marketing Managersing |