Funny story with that gloss-I was having horrible issues with the teak veneer, coat after coat there were hundreds of waxy dots migrating through the finish even after washing the veneer extensively with acetone etc. After 5 or six coats and sand-downs, I switched to a different varnish and it worked to contain things. So I returned to my satin varnish and it looked really good after I applied it and I felt so happy and relieved.
Came back 2 hours later and was shocked to see the varnish was still completely wet and shiny. That’s when I realized I hadn’t stirred the varnish for 3 days and the matting agent had all settled out. I really didn’t want gloss but at that point I was pretty over caring.
Beaming in the sense that Crowe's horns have increasingly less constant directivity with increasing frequency? See these plots.
https://cdn.shopify.com/s/files/1/0...BMS_4591-8_off-axis3_480x480.png?v=1649504045
https://cdn.shopify.com/s/files/1/0...ot_2023-10-14_170306_480x480.png?v=1697317415
However, doesn't the driver that the horn is paired with also greatly determine the final directivity pattern?
Unfortunately, of course, it's not always cost effective or otherwise easy to choose the best driver for the horn to minimize variation level versus frequency and angle.
https://www.diyaudio.com/community/attachments/img_6718-jpeg.1355887/
Two guys using their 425 horns/15" cabinets for TV audio. HELP! I have to decide on a 55 or 65" Sony TV before Dec 31st or I lose $1200. in Sony card points when the Rewards program terminates on that date. I'm looking at getting this beauty. https://electronics.sony.com/tv-video/televisions/all-tvs/p/xr55a95l
The current problem is that I don't want to use horns with a size, shape and/or color
https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670 that shout at my eyes while I'm trying to watch the screen, which will be behind my black midwoofers https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed , and with me then seated ~ 11.5 ft away from the screen.
I do keep my living dimly lit so I guess if the 425 horns were painted black (or is that brown?) like Gary Dahl did then I may not notice them very much.
https://www.diyaudio.com/community/attachments/img_3796-jpeg.1193321/
Any other suggestions?
BUT in case I didn't want to actually paint them how else to make the horns black? Use flat black gaffer's tape?
https://www.bhphotovideo.com/c/search?q=BH #PRGT12B&sts=ma
As you can see in comparative polar plots, the driver affects the directivity primarily only above 10kHz.
Gaffer's tape looks fuggly, simply put a black grill cloth in front of the horn.
For complicated horn shapes, a breathable nylon and polyester spandex fabric can be stretched directly over the horn, and tacked or gaffed out of sight.
Haven't built a horn without a grill since 1979.
I prefer to have the screen distance to my eyes around the same as it's diagonal, otherwise I still notice black speakers in the periphery.
Get the bigger one, your eyesight won't improve with age, and 11.5' is a long distance for screens that small 😉 .
Art
I love the idea of stretching fabric over a horn, never thought of it. How about black nylon stockings? Might take two layers but could do the trick. If you decide to paint, hopefully not Troy's beautiful wood ones, short quick sweeping pulses with spray paint is easy to pull off. Do the deepest part of the throat from the back and don't overdo it, then quickly flip the horn over and work from the center out to the edges in a circular or spiral pattern. Not too heavy or you'll have runs! I love the way Gary did his in gloss black, very classy.
By the way I don't use my rig for the TV, it has to make do with a soundbar 😉
By the way I don't use my rig for the TV, it has to make do with a soundbar 😉
I'm not sure I follow. While diffraction could be used to augment dispersion, my point was simply about preserving the wavefront in a productive manner and not letting it run unmanaged.
The loading profile may not support this.
90 x 60 adds to the challenge of spacing. The narrow angle needs to be taller and longer so that it maintains control to the same low frequency (since a wider vertical gives more control for the same height and requires less termination).
Wide, not narrow, results in a closer vertical spacing to the woofer while allowing the same low cross.
This is not the complete truth. This is only true in small rooms. In large rooms this is not the case. Rising DI horns create similar off axis sound, as large rooms, but in a small room. Large rooms are generally said to be more acoustically pleasing than small rooms.
If you place a two-way using a constant directivity horn or waveguide in a very large room like for example, a large movie theater... The power response will reflect that of a loudspeaker that has a rising DI
Matter of fact, if you were to place that same two way in a small room that was heavenly dampened you have a good chance of ending up at the same place since sound dampening becomes increasingly ineffective as frequency lowers
The lack of indirect sound always leads to higher clarity. Outside of listening window size, constant directivity is trying to sell you on the idea of having a constant amount of clarity while the traditional exponential rising DI horns, have more clarity in areas where the DI rises higher than the constant directivity horn, can be used lower thanks to loading thus being able to bring directivity increases, lower into the spectrum where as a constant directivity horns size and driver performance typically limits waveguiding to what, about 900hz?
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In larger room like big cinema we use constant 70° horizontal and something more narrowing like 30/40 that of course will be partially constant in vertical comparing to the range where the horn is horizontally, the rest is acoustics treatment, to create reflection on wall where it need, and avoid to generate a specular reflections especially in early reflection, but its room acoustics.
Adapting coverage to the room doesn't mean we no more needs to pays attention of room acoustics treatments, this need remain.
It need to be coherent about energy, we try to have this kind of things (it's at listening position) :
And not this where the energy is present bellow 2.5khz but upper energy it's only present in direct field :
There is a unbalance, sweetspot is very present, and sound stage is not the same across all bandwidth, in this case, in HF, the speaker can sound "tiny" due to lack of reflection and no respect of the 50/50 or 60/40 about direct field and reverberated field.
There is no disadvantage to use a constant horn if the directivity (the opening coverage) is adapted to listening distance (so called Critical Distance).
For the sound-stage we have to keep wall reflections (you can read about brain TPI too, the Time Period of Integration) until a certain point but of course it depending of listening distance and room. the greater the listening distance the more we reduce the coverage basically, but we stay constant at least horizontally.
I don't understand about 900hz ? We can load and use 90*60° constant horn down to 700Hz, not in 1" but in 1.4", 48cm wide, yes:
Use diffraction to "improve" directivity is a bad idea, it broke the wavefront, there is plenty of others solutions, smoother, to push directivity control higher without creating a succession of accidents. Midrange narrowing or midrange beaming describe accident like this :
Adapting coverage to the room doesn't mean we no more needs to pays attention of room acoustics treatments, this need remain.
It need to be coherent about energy, we try to have this kind of things (it's at listening position) :
And not this where the energy is present bellow 2.5khz but upper energy it's only present in direct field :
There is a unbalance, sweetspot is very present, and sound stage is not the same across all bandwidth, in this case, in HF, the speaker can sound "tiny" due to lack of reflection and no respect of the 50/50 or 60/40 about direct field and reverberated field.
There is no disadvantage to use a constant horn if the directivity (the opening coverage) is adapted to listening distance (so called Critical Distance).
For the sound-stage we have to keep wall reflections (you can read about brain TPI too, the Time Period of Integration) until a certain point but of course it depending of listening distance and room. the greater the listening distance the more we reduce the coverage basically, but we stay constant at least horizontally.
I don't understand about 900hz ? We can load and use 90*60° constant horn down to 700Hz, not in 1" but in 1.4", 48cm wide, yes:
Use diffraction to "improve" directivity is a bad idea, it broke the wavefront, there is plenty of others solutions, smoother, to push directivity control higher without creating a succession of accidents. Midrange narrowing or midrange beaming describe accident like this :
Bingo! And all this time I thought the rule was that putting any kind of grill cloth over a horn was an acoustical no-no. Like this?
https://www.joann.com/p/rip-stop-nylon/2637809.html
I normally keep my room dimly lit, allowing me to dial down the TV's brightness. But utility rates, like property taxes and housing prices here are obscene. And I will like to use my Class A amp with the speakers. So a 65" TV it will have to be.
The SMPTE agrees with you that the screen should fill "30° of your field of vision, which means viewing distance should be 1.2-1.6 times the screen's diagonal measurement." That's 8.7 ft max. What's strange is that the 32" Toshiba CRT TV in my bedroom has never been very uncomfortable to view from 10 ft. And I only wear glasses for reading. Furthermore, at my sister's last week I measured 10 ft and change from my eyes to their 55" TV. It did look nice but just a bit too close for me. Stranger is that both Nancy and Walter think that 65" is too big even for 11.5 ft away. They don't wear glasses either for TV viewing, though irrelevant to those SMPTE guidelines.
Thus, with reference to earlier discusssions about 1/4 wavlength vs. 70Hz target response for the Altec midwoofers, the cabinets should be 2.0095 ft from the front wall. That's ~ 6 inches closer to the wall than Pierre's woofers, so with the TV directly behind them I could at least sit that much closer. TV + TV stand depth is 8". Cabinet depth + horn/driver depth is ~2 ft. And if speakers should be 8 ft (?) apart with the 4.875 ft wide TV between them then I guess ~10.5 ft from the TV it will have to be.
Yes, the way you described the essential steps for avoiding a painted disaster Gary handled it masterfully. But I wonder if he ever thought of the black nylon; only way for me as gaffered around the back of the horn mouth would be a snap.
I was so expecting you to be using the speakers for DVD, BD or streaming movie sound. And my question would then be for such a 2.0 system how much would you miss a dedicated center speaker for dialogue.
This is the only part of your very long response you touch on the topic that I brought up.
You say twice now, that vocals/HF being tiny, when the power response of the room is low in the upper spectrum, as it is with a speaker that has rising DI, and needing constant directivity, to fix it. This an inconsequential issue.... this aspect exists with rising DI horns in small room, it exists in movie theaters, even with constant directivity loudspeaker.... which is just another way of saying that this issue is not an actual issue.
No one is complaining about a lack of reverberation from HF in the theater.
Large or Small, When both are
Acoustically treated, I think the majority of people will prefer the large room in particular due to the reduction of early reflections, by delaying them in time and and reduction of spl.
This is what happens to the HF of a typical exponential horn, it creates a tapering room power response, and the outcome is a smaller sweet spot and a room that acoustical sounds as if its bigger.
Hello Camplo
Not sure what you are trying to say here. Off axis a CD system maintains it on axis target curve for a much wider arc than a non cd system by virtue of it's flat DI curve.
A non CD system has rising DI with frequency, The DI doesn't rise on the lower end of the horns bandwidth. Look up a 2360 bit lower than 900hz.
If you EQ and level match a non CD vs CD system on axis the differences are moot. When you move off axis with a non cd system the upper bandwidth rapidly degrades which makes the sound power into the room audibly different.
More Clarity? how does this work? A traditional exponential horn has rising DI which in turn acts as EQ to flatten the on axis. With a CD system you use EQ to flatten the on axis response. If they are level matched with the same target curve on axis why would one have more "clarity"
CD system vs non CD exponential horn comparison. Over all guess who won IMHO
Rob 🙂
Attachments
@camplo I made a long response to try to explain why it's important, you made a focus about constant or not constant and forgetting that the opening is choose in function on the listening distance, of course it's better in bigger room. As the Schroeder Frequency is lower in bigger volume so the modal field begin lower, and when the room is big enough there is even no more modal field, it's harder in medium/small room as our room as the modal field is in the audibility range with a Schroeder Frequency around 300/400hz.
When a horn is not constant it's hard to give a coverage as it's never the same according to frequency, it narrow more the frequency goes up.
First just adapt your opening coverage to your listening distance (and your room in some cases) then the horizontal coverage should be constant (directivity cannot by corrected, it matter), the rest will be a mater of preferences and the result will be greatly influence by the RT (Reverberation Time) of your room, so the treatment so the size of the room, etc.
When a horn is not constant it's hard to give a coverage as it's never the same according to frequency, it narrow more the frequency goes up.
First just adapt your opening coverage to your listening distance (and your room in some cases) then the horizontal coverage should be constant (directivity cannot by corrected, it matter), the rest will be a mater of preferences and the result will be greatly influence by the RT (Reverberation Time) of your room, so the treatment so the size of the room, etc.
Are you therefore arguing that CD horns offer no more better sound quality-at least subjectively-than exponential horns, like the JMLC, because the latter horn's delivery of real or apparent power response in its smaller sweet spot? If yes, then does this also give the illusion of a wider sound stage? But if not a wider sound stage that would an also somewhat rising DI horn like the ES290 do the former but also give real sound stage width?
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Most of the "acoustical no-nos" regarding grills are related to diffraction from frames, not the material itself.
That said, I doubt rip stop nylon would be "breathable", the main requirement for grill cloth. Non-breathable material reflects sound waves, not good.
And many organic material absorbs sound
I've found if you can breath through it easily (a lot easier than Covid masks...), grill cloth will generally have less than 1dB reduction in HF output at 16kHz.
You really need to do your own comparisons. On axis same target frequency response and level matched in the sweet spot little difference on direct sound. Sound power will be different. As you move off axis the on the non cd exponential the image and soundstage collapses well before the CD design.
Do you want a head in vise system with a really small sweet spot?
I don't YMMV
Rob 🙂
Whats hard about it? Maybe the problem is that you need to understand what the sweet spot is and why its important to a person who is interested in critical listening. The sweet spot "refers to the optimal listening position in a room, where the stereo image is most accurately perceived and the overall sound quality is best. As you move away from the center, the soundstage will gradually lose its focus, the tonal balance may shift, and the overall clarity and detail may diminish.". Lets focus on Tone, since that what Constant Directivity seems to be about most. If Voicing starts to change, as one moves away from dead on axis, you can say you have left the sweet spot. I personally like to use -3db. Similar to F3, -3db being significant in the terms of a change in spl. I also chose to look at the most narrow beam which is at 20khz....actually I looked at 17khz since I don't think I can hear above that. When 17khz dropped -3db from 0 axis performance, I said this is the end of the sweet spot, and recorded the beam angle (In simulation at this point)... Later I was told by some design professionals on this board that I was being way too strict. Which is what I intend to do anyway but I am trying to make a point. I was told that truthfully I could use ~7000hz (IIRC) as my reference point to judge effective listening window. Case and point, anything outside the sweet spot, is unoptimal and should not be used for critical listening. I personally want to use my system for high precision EQ work. Signal Design. Hearing the signal without adulteration has been my goal
I would look at the above polar and say the sweet spot is no wider than it is at 20khz, which is about 30 degrees wide. At 7khz the sweet spot is about 60 degrees wide.
This Elliptical tractrix Horn Doesn't reach 60 degrees wide until about 6khz and is somewhere near >40 degrees at 20khz
Depending on how strict one wants to be, The elliptical tractrix horn in this example has a wider sweet spot if being literal and judging by 20khz, the top of the register. Constant directivity horns and Horns with Rising DI need to be judged case by case. I have just shown a real world example of a Rising DI horn that has wider coverage than your Constant Directivity horn. Your horn, like almost any horn/waveguide, needs to be listened to within the sweet spot in order to hear all of the signal undistorted in tone. If judging by 7000hz, both horns are Equal in achieving a ~60degree beamwidth.
So we could say the Elliptical Tractrix horn has Wider or Equal Coverage.... There are other horns that have non Constand Directivity that provide wide Coverage.
The only Waveguides I've seen keeping Constant Directivity to 20khz is probably Mabats which I think require a modified phase plug. My point, again, is to show that your comment "it's hard to give a coverage as it's never the same according to frequency, it narrow more the frequency goes up." is simply wrong, evidence being, I quickly pulled up a waveguide with wider sweet spot, than your CD horn, Sweet spot, being the beamwidth in which Frequency response stays with -3db of dead on Axis, according to my strict definition of the term. So we can let go of this idea about coverage.
Coverage is specific to a specific designs. One could build a Constant Directivity horn with the intentions of maintaining a 20 degree beamwidth. Constant Directivity is an design type that has no requirement to reach any particular beamwidth.
For critical listening, staying in sweet spot is whats desirable. The off axis performance of the system only needs to happen smoothly and free of large peaks/nulls, an excellent example would be something like below. This prevent the room response from being colored in a way that have any one particular note stand out be be hidden versus another. Every polar in this post, fits that criteria
Below is a Tractrix 200 from autotech, God knows what 200 means but non the less, This is a more traditional design where DI reaches higher than what We are seeing in Contemporary horns and waveguides. From ~4000hz on up, the beamwidth of the sweet spot is 40 degrees and diminishing. We know that above a certain frequency the Compression Driver owns directivity. The BMS 4950 is a modern driver and creates a ~20 degree beamwidth by 20,000hertz.
Your horn has the slightly wider coverage as this Horn in the most strict sense. If we relax the criteria we can easily say your horn has wider coverage. The Tractrix Horn shown above, maintains a higher DI than your horn over a larger part of the spectrum. If we place these 2 horns in the same room. Your horn will accommodate more people more people to hear the same frequency response. The Tractrix will only provide the intended to a very small audience. If using the strict expectation of -3db at 20khz, and 1 meter distance, the tractrix basically becomes a 1 man experience but then again so does yours.
If we look at 7000hz and -3db instead, which is what is supposedly commonly accepted for Quality sound, it becomes 40degrees vs 60degrees. 4.37ft coverage vs 6.93ft at 6ft.
Yes? No? It all depends on how you define sweet spot. -3db or -6db as limit? 20khz or 7000hz as limit? First we have to say what we mean by Sweet spot and how its limits are determined. My criteria is more strict than what some professionals on this board say need be, but, I intended to be strict in order to hedge the bets in my favor. As I said, I chose the highest frequency I could hear confidently, 17khz and tried to determine the beamwidth.
OK now that we've thought about that, lets look at the other side of the coin "Tractrix Horn shown above, maintains a higher DI than your horn over a larger part of the spectrum". The sweet spot has been discussed. The above polar shows higher DI from about 1000hz and up vs versus the Constant Directivity horn. Based on that, I would expect higher clarity from 1000hz and up. There will be less off axis sound from the tractrix horn in this example. The difference between these 2 waveguides, in my opinion are near negligible to be honest.
If we switch over to the vertical axis then what? For critical listening to the -3db limitation we must stay on axis, Horizontally and vertically.
I don't think the difference between the Tractrix 200 and the Constant Directivity horn are as huge as some may think. The Difference between the elliptical and the Biradial blur the lines even more. The pictured Elliptical horn is small so of course its going to lose directivity sooner. Crude comparisons, maybe, but Higher the DI, the less indirect sound creation is not an opinion. Having a Rising DI in a small room where the DI is higher than a comparable Constant directivity horn, I personally would likely chose that horn over the CD horn, as I am more concerned with ultimate accuracy, and not so much, pleasing an audience.
Maybe Like crotch rocket versus a fast 4 door car. Depending on how stritch you want to be, the CD horn isn't allowing any much larger coverage than the other two horns shown. That is judging by -3db at 20khz. If you are like me, only concerned with Accuracy/Imaging, May the Higher DI over the most spectrum win....
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Dear sirs. As a total amateur I can't believe "7khz sweetspot" could possibly be considered an acceptible baseline even for mid-fi. Speech maybe, as in cinema dialogue; musical instrument tonality requires 7-10khz to be as ruler flat as possible; +/-3dB is a different musical instrument, one that might not exist. The two plots above that go 70deg (35 each side of axis) up above 10khz and >30deg approaching 13khz, seem amazing to me. Until recently my listening sweetspots (reproducing live concert front-row) weren't head-in-vise but certainly not much bigger than a basketball.
I've posted/boasted quite a bit too much about my out-of-the-box speaker experiments (~20 in Fullrange photo gallery last 10 pages). Common theme being time-aligned minimalist-or-no-XO wide-even-dispersion -- kind of similar spirit and goal as Ariel thread but without horn. Sorry I can't make rigorous measurements given my nomadic situation etc. but perhaps one of you experts can do a simple experiment LX or reflector-point-source.
I've posted/boasted quite a bit too much about my out-of-the-box speaker experiments (~20 in Fullrange photo gallery last 10 pages). Common theme being time-aligned minimalist-or-no-XO wide-even-dispersion -- kind of similar spirit and goal as Ariel thread but without horn. Sorry I can't make rigorous measurements given my nomadic situation etc. but perhaps one of you experts can do a simple experiment LX or reflector-point-source.
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@camplo,
The opening coverage of a horn is given where he is constant as it's usually in our sensible part of hearing.
Be constant is not only useful to allow several listening position, in room (in will not be the case outside, without wall) it guarantee the 50/50 direct field/reverberated field in the range of our hearing sensible part, where it need, audibility is important :
Psychoacoustics of Dr Floyd Toole should be add to this.
It why Geddes or Toole said to be constant until 7/8khz, Geddes said form 700 to 7000hz if I remember well (it may be inside a video he make), as anyway our sensibility decrease seriously after 8/10khz we are not very sensible (depending to your age but I guess you are more than 20 years old), we still ear but the signal need +10/+20dB from the average to be "registered" by our brain.
All bi-radial is narrowing like this vertically by nature, mine is free of accident, that is not the case of old ones, bi-radial don't excite floor and ceiling, and all need to be listen at a relatively fixed position in height, they all have a sweet spot vertically due to their behavior bellow 7kHz, but not horizontally.
Our room and our physical hearing system is asymmetrical by nature between horizontal and vertical, it should be taken in account but it not means there is only one ideal solution to deal with it and we have to be careful as in fact our brain already corrected some things.
If you want a horn that provide no sweet spot on both axis, huge loading and stay close in terms of center to center spacing with the woofer, as you apparently know well my website, take an X-Shape.
It's a matter of preferences but it's important to be constant horizontally in the plain audibility range as I or other specialist or acousticians said.
And to remember that energy is not free, if she is present somewhere , she will be less present somewhere else.
The opening coverage of a horn is given where he is constant as it's usually in our sensible part of hearing.
Be constant is not only useful to allow several listening position, in room (in will not be the case outside, without wall) it guarantee the 50/50 direct field/reverberated field in the range of our hearing sensible part, where it need, audibility is important :
Psychoacoustics of Dr Floyd Toole should be add to this.
It why Geddes or Toole said to be constant until 7/8khz, Geddes said form 700 to 7000hz if I remember well (it may be inside a video he make), as anyway our sensibility decrease seriously after 8/10khz we are not very sensible (depending to your age but I guess you are more than 20 years old), we still ear but the signal need +10/+20dB from the average to be "registered" by our brain.
All bi-radial is narrowing like this vertically by nature, mine is free of accident, that is not the case of old ones, bi-radial don't excite floor and ceiling, and all need to be listen at a relatively fixed position in height, they all have a sweet spot vertically due to their behavior bellow 7kHz, but not horizontally.
Our room and our physical hearing system is asymmetrical by nature between horizontal and vertical, it should be taken in account but it not means there is only one ideal solution to deal with it and we have to be careful as in fact our brain already corrected some things.
If you want a horn that provide no sweet spot on both axis, huge loading and stay close in terms of center to center spacing with the woofer, as you apparently know well my website, take an X-Shape.
It's a matter of preferences but it's important to be constant horizontally in the plain audibility range as I or other specialist or acousticians said.
And to remember that energy is not free, if she is present somewhere , she will be less present somewhere else.