Pros and Cons of Sealed Listening Rooms
- Thread starter Ron Resnick
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Agreed.
When I demoed the Odeon No. 26, however, I started at 4 or 5m and ended up about 3m away. I always found myself wanting to lean into the soundfield. This tells me they might be good for near field listening.
In my experience this is generally true but it depends on the specifics, such as crossover point(s) and vertical spacing between the drivers. I have seen a hybrid horn system (woofer + horn) which was coherent at a little over arm's length, something I was not expecting.
If I had to take a guess based on crossover frequencies and vertical driver spacing, I'd guess that the Odeon 33's could be coherent down to somewhere between 6 and 7 feet (ballpark 2 meters). But guesses are no substitute for experience.
The 2 way pap horns I have in a bound room near-field setup with a listening distance 2.5 metres away (speakers positioned 2 metres out from the front wall), but even so I can easily lean forward and they are still comfortably coherent at a listening distance even down to the 2 metre mark. I still have a touch over another 2.5 metres behind me to the rear of the room. Would love to try them though in a much bigger room (say even 12+ metres deep) but that might be where I go with a DIY build for 3 way horns and an ob sub.
Well, if that does not work out, maybe try a vertical line array or electrostatic speaker with narrower dispersion characteristics.
Optimum dispersion in speakers
https://whatsbestforum.com/threads/optimum-dispersion-in-speakers.29773/
At least the reflected sound off the glass wall will be more equal in frequency than with conventional dynamic drivers.
https://www.audiophilenirvana.com/audiophile-equipment-reviews/altec-lansing-model-14/
I don't know if all horns have similar patterns or if you need one of those orange wafers (phase plug) inside.
https://www.audiophilenirvana.com/audiophile-equipment-reviews/altec-lansing-model-14/
I'm not sure what the correct search terms would be or if one of our experts has a few images they could post, but I'm not seeing in my searches what I want regarding: polar plot, dispersion radiation pattern, lobe, directivity, polar response and so forth.
I want a side by side comparison of all the major speaker types.
I think electrostatic speakers would be the right choice but not everyone likes them.
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I have always believed intuitively that tall ceilings are good, but this is the first objective explanation I have ever seen as to why.
Here is another good vid.
Room acoustics nice and practical.
Its my last system hurdle, a custom audio room .
And it ll be realized in 1 - 2 years i reckon .
But its gonna be good
Room acoustics nice and practical.
Its my last system hurdle, a custom audio room .
And it ll be realized in 1 - 2 years i reckon .
But its gonna be good
Some horns have similar patterns, but the radial phase plug has little if anything to do with the exceptionally uniform radiation pattern of the Altec Model 14 as shown in their ad. Rather, the controlling factor is the geometery of the horn that Altec used, which they called the "Manta Ray".
The Manta Ray was a constant-directivity diffraction horn; that is, the horn had deliberate, aggressive discontinuities
(internal slots and/or sharp angles or edges) which strongly diffracted the output causing the pattern to widen. So instead of the sound "beaming" at high frequencies and being concentrated on-axis, it was spread around fairly evenly within the coverage pattern. Since then many companies have used diffraction horns.
Let me back up and give a brief and incomplete overview of horn designs.
In the early days when amplifiers were weak, the most important characteristic of a horn was acoustic amplification. These early horns were typically very long and large, and had narrow radiation patterns. Their length and large mouth size helped them to be effective down to lower frequencies.
Sectoral horns were an early attempt to widen the coverage pattern. These use slots or vanes or cells to help spread out the high frequencies more uniformly.
Diffraction horns like the Manta Ray use diffraction to spread the highs around, and diffraction horns have been widely used in prosound ever since, and are used in some high-end audio designs. Altec was one of the first to also incorporate "pattern matching" in the Model 19/Model 14 series. This is where the woofer's radiation pattern approximately matched the horn's pattern in the crossover region. The Model 19 used the same woofer and horn as its predecessor, the Valencia, but the crossover frequency was considerably higher, so that the woofer's pattern had narrowed enough to match the horn's pattern. The landmark JBL model 4430 studio monitor came along a few years later and was arguably a more "purist" application of this concept.
Meanwhile over in the high-end home audio world, much more gentle horn profiles began to show up: Tractrix, Exponential, Hyperbolic, Spherical, Le'Cleach, and so forth. These all have a trumpet-like profile, with a very gentle curvature back near the compression driver, and then the curvature accelerates near the mouth. One characteristic of this sort of profile is that the directivity of the high frequencies is controlled by the walls of the horn in the first few inches (where the angle is narrow), while the directivity of the lower frequencies is controlled by the walls of the horn near the mouth (where the angle is wider). So typically their radiation pattern gently narrows as we go up in frequency. One advantage of concentrating the highs into a smaller angle is higher efficiency; the amount of high-frequency energy available at the top end is often a limiting factor as far as the efficiency of a horn system goes, and a narrow pattern in the top octave results in higher on-axis efficency than you would get with a diffraction or multicell horn.
Waveguide-style horns are focused on radiation pattern control rather than acoustic amplification. Their profiles have most of their curvature near the throat, except for the round-over at the mouth. They tend to have pattern uniformity rivalling diffraction horns, but don't offer as many pattern shape options as diffraction horns do. Like diffraction horns their highs are spread out over a wider area, which lowers their on-axis efficiency at the top end. Waveguide-style horns tend to be fairly short so they don't have good acoustic loading down very low, but usually they are pattern-matched with a woofer anyway so it's seldom an issue.
I have tried to avoid comments about horn sound quality here; that's a complicated and controversial topic. Perhaps another day.
Imo the most informative type of directivity graph is the polar map, which uses color to convey intensity. Here is a paper on the subject:
http://www.gedlee.com/Papers/directivity.pdf
Audioholics uses polar maps in some of their reviews; here's one:
https://www.audioholics.com/bookshelf-speaker-reviews/monolith-k-bs-1/measurements
There is so much variation from one model to another that only the broadest of generalities could be conveyed, with a veritable plethora of exceptions being the norm. And it is often these exceptions which are the most interesting.
Still I can see how what you are asking for would be useful. If I come across something along those lines I'll post a link.
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In retrospect I should have compared a trumpet style horn to an ESL which in the context of the room being discussed were the two options that popped into my mind as options, with perhaps a vertical line array being a 3rd option.
Not my room, not my problem but will be interested in the results in a few months I'm sure.
Thank you for the short version of horn design Duke LeJeune, always a pleasure to read such posts.
With horns you can change the dispersion by changing the horn. But as an ex Martin Logan summit owner and general fan of electrostatic mids and highs, I can tell you that beryllium horn drivers like Radian and TAD provide the see through transparency, decay, mids and highs of electrostatics, imo better, because they are more dynamic and agile and have better SETs based tone. They also can provide similar style of wide staging without requiring same level of space behind the speaker. Horns universum is based on the Radian beryllium, Cessaro are based on TAD. Even JBL drivers are sometimes used with beryllium diaphragms. So it's not only about comparison of trumpet style or some other style horn
I've seen some dipolar electrostatic drivers in catalogs intended for use in horn designs that interests me.
That would perhaps be the only way I would get into a horn, as I've found them to be piercing like a scornful woman's voice over long periods of listening. And any lack of sound-stage depth would be frustrating for me.
I have not heard the wall mounted M/L's that I posted earlier, and suspect they for Home Theater only.
I have no answer for this room, which is why I'm eager to hear back if the horns did the trick. And remember these are mixed driver horns which may complicate any conclusions.
I don't think that I've heard these yet, will keep an ear out for them.
Last time I was at Paragon in A2 they had some big green horns on consignment. I might have to sneak in there and see if they set them up.
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I have a link to support my theory, see below.
Oh, and it applies to listening to live and studio performances as well as your stereo (I think).
almost everything you ever wanted to know about subwoofers
http://soundoctor.com/whitepapers/subs.htm
Well, Ive just gone from 99% sealed to 100% fully sealed. Just filled a simple small void. Well, they say the best things come in small packages. They were right. An upgrade that I'd hapilly have spent 1000x the sum on for the same effect. Not so much bang, as thermonuclear explosion, for yr buck.
It depends on the room and its acoustics. Some rooms benefit from exhaustion of frequencies. Others? It completely depends on the room. Depending upon the recording? Open it up. Others? Seal it in.
Yes
This is recording dependent.
That is the very thing, Ron. Depending on the recording? That allows one to either make or break a sealed room or a "make shift" room to respond to said acoustics. Some recordings need to "let go" of some acoustics. Others. you very well "want" to keep in the room.
I hope this makes sense. to you sir.
The Bliss happens when everything comes together within your subs/mains/.pre/source.....whatever the "magic" may be.
If you have said singer before you, the band where it should be and everything else in place? What difference does it make whether or not the room is sealed or not?
You tell me.
Tom
This was really strange and dramatic. Whatever this blocking of 12 cub ft void did, maybe eliminating a node, or suckout, an inappropriate Helmholtz Resonator or infinite sub (virtual uninterrupted connection to 20,000 cub ft main space below)...it has totally evened up bass performance in the room, meaning I've been able to take my Zu subs output right down (initially 50Hz 6/10 level to 39Hz 1.5/10). This has taken smeared lower mids out of the equation. Most interestingly in some ways has been the solidifying of imaging. It's almost as if I'm running 3-channel stereo with a centre spkr, so beefed up is the image between my Zus.
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