I don’t see why everybody is pooping on the idea of a real front horn on the drivers?
A line array placed in a corner is this, only with a slightly less aggressive horn.
You could even have (adjustable possibly) radial baffles to create a vertical multi cell horn. This would be ideal for shaping the pattern.
Absorbant baffles sounds like a very bad idea.
It would involve a hell of a lot of EQ. Possibly more than even a line array could take. And result in a sweet spot, that wouldn’t be pleasant for anything else than “head in a vise” listening.
You’d be better served with headphones or small near field speakers and an under the seat sub, if that is your style of listening.
I wouldn’t worry too much about the window. The wall on the opposite side will be about as reflective. A set of blinds could be the cure for critical listening, if it really turns out to be a problem.
The grayed out absorbent felt baffle space, on the first plan (here part of the horn on the outside), would IMHO be better used for a oversized “infinite” baffle approximation.
Well padded and with absorbent material it would work quite well as such.
A line array placed in a corner is this, only with a slightly less aggressive horn.
You could even have (adjustable possibly) radial baffles to create a vertical multi cell horn. This would be ideal for shaping the pattern.
Absorbant baffles sounds like a very bad idea.
It would involve a hell of a lot of EQ. Possibly more than even a line array could take. And result in a sweet spot, that wouldn’t be pleasant for anything else than “head in a vise” listening.
You’d be better served with headphones or small near field speakers and an under the seat sub, if that is your style of listening.
I wouldn’t worry too much about the window. The wall on the opposite side will be about as reflective. A set of blinds could be the cure for critical listening, if it really turns out to be a problem.
The grayed out absorbent felt baffle space, on the first plan (here part of the horn on the outside), would IMHO be better used for a oversized “infinite” baffle approximation.
Well padded and with absorbent material it would work quite well as such.
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I don't know if that was the intention of other posters, I would say that a properly designed waveguide in front of the line is actually a good idea.
Something that has become apparent with other corner lines has been that if it is in the corner without a waveguide other than the walls then there is early reflections off surrounding surfaces which can be detrimental.
I think this is part of crumboo's idea of absorbing material in front.
I don't really understand the thinking behind this comment. If the absorbent is broadband enough you would get even polar control through that range and below the room will be dominant anyway. EQ cannot fix polar issues so no amount would make a difference.
I don't necessarily think it is better than a real waveguide but I don't think the idea is inherently bad.
I agree with fluid. My first thought, though, was the original horn was too narrow; 2nd thoughts on how well absorber would work. If I had infinite time and patience, I'd try a diffraction slot in front of the cones to get a wide beam. Beaming has got to be an issue with a 3.5" wide horn throat.
It’s too aggressive. It’s quite hard to make a true broadband absorber.
The uneven absorption will affect the room interaction in unpredictable ways.
The whole idea of cutting the room out for some frequencies, while others are left to roam, and the idea of a very directive speaker (in some part of the spectrum) is old fashioned and has been proved troublesome and “wrong” many a time.
Same with early reflections. Just like with certain types of distortion, it has been proven to have far less effect on the quality of sound (as perceived by humans) than what was previously thought.
It’s better to make the speaker work with the room in a more homogenous way.
The waveguide/horn here would be steep, but it could work I think. It would be worth trying with some adjustable baffles at least.
It's not hard to make a broadband absorber down to transition, but it does take some space. 90mm is pushing it though.
That is why any absorption should be broadband to avoid that issue, a line array of these drivers has good polar response so it would not be a good idea to make that worse with selective absorption.
Nothing to disagree about there
Or here
Lot's of thinking have been going on for the last few days. I have been under the impression that early reflections are something bad (always) that could distort imaging etc. and should be delt with. After some googling I now see that this may not be the case at all (see this article by Toole). Most important is that the reflections have a similar spectral content as the direct sound. Also I learned that the kind of absorbers I was planning are much less effective for a shallow angle of incidence as in this case.
This, together with your helpful comments, has led me to rethink this project and I am now leaning towards the idea of moving the speakers forward, in line with the book shelf.
This, together with your helpful comments, has led me to rethink this project and I am now leaning towards the idea of moving the speakers forward, in line with the book shelf.
Be careful how you interpret the term "early reflections" 
.
I'd say the first reflections falling in a 0 to 3ms window would be very damaging to things like imaging. Vertical parallel planes near to the array falling into that category quite easily.
The reflections from say 6-7 ms on are way less damaging to imaging and are probably what Toole was talking about. At least that's what I get from it when viewing the Harmon listening spaces. (my space doesn't look anything as nice as that)
Personally I like having strongly reduced levels of reflections up till about 15 ms where a Haas kicker comes in, from lateral angles.
.I'd say the first reflections falling in a 0 to 3ms window would be very damaging to things like imaging. Vertical parallel planes near to the array falling into that category quite easily.
The reflections from say 6-7 ms on are way less damaging to imaging and are probably what Toole was talking about. At least that's what I get from it when viewing the Harmon listening spaces. (my space doesn't look anything as nice as that)
Personally I like having strongly reduced levels of reflections up till about 15 ms where a Haas kicker comes in, from lateral angles.
I was just reviewing the first couple of pages in your thread...
Personally, I don't believe/think the rods were the problem. Lots of other stacked constructions have cracked too, without any rods in them. There's just no stopping the wood from moving (expanding/contracting with humidity changes) and with a birch ply panel, the thickness is the one direction where this change will be the most severe. See: https://www.diyaudio.com/forums/full-range/349408-translam-cabinets.html#post6085073 for more of my comments.
I would not hesitate to go for a stacked array build if I would ever need to start over again. I'd build small(er) stacks and use something in between that can move and plan to go for the outer fiberglass matt/ epoxy ahead this time. Actually, the original plan included fiberglass matt/epoxy. Until I saw how good that naked birch ply stack looked after sanding. I just had to try to preserve that. I don't mind it happening like this though, because I bet even the fiberglass matt/epoxy would not have stopped the wood from moving. The smaller sections were the real answer.
More thinking... With the baffle moved forward it would look like this (see picture). The first lateral reflection will hit the listening area about 0.1 ms after the direct sound. Maybe this is so short that it could be considered as “direct sound”? The path/time difference will however result in destructive interference starting at about 4 kHz. But since it is about 60 deg off the driver axis the level should be about 5 dB less according to the spec sheet. Getting the driver as close to the wall as possible seems to be a priority here, and the same time make a smooth transition between the baffle and sidewall/bookshelf.
The first contralateral reflection will be delayed about 5.7 ms to the direct sound and will hit the listener for a more lateral angle. Should I care...?
The first contralateral reflection will be delayed about 5.7 ms to the direct sound and will hit the listener for a more lateral angle. Should I care...?
That short path difference reflection from the near side wall is why those of us who have been down this path recommend some absorber there. I built my arrays with the driver as close to one edge of the angled baffle as I dared in the hopes of avoiding the need for that absorber but all I managed to do was minimize the thickness required, which is a good thing.
The opposite side wall reflection is why so many recommend absorption at point of first reflection. You should care for two reasons. First, the delay is on the short side. Second that reflection will get in the way of taking clean measurements at your LP for use in DSP EQ.
The opposite side wall reflection is why so many recommend absorption at point of first reflection. You should care for two reasons. First, the delay is on the short side. Second that reflection will get in the way of taking clean measurements at your LP for use in DSP EQ.
Be careful how you interpret the term "early reflections"
I'd say the first reflections falling in a 0 to 3ms window would be very damaging to things like imaging. Vertical parallel planes near to the array falling into that category quite easily.
The reflections from say 6-7 ms on are way less damaging to imaging and are probably what Toole was talking about. At least that's what I get from it when viewing the Harmon listening spaces. (my space doesn't look anything as nice as that)
Personally I like having strongly reduced levels of reflections up till about 15 ms where a Haas kicker comes in, from lateral angles.
Sound traveling at one meter per millisecond, this was definitely not what Toole and others where talking about.
The lesson was that early reflections of any kind are hardly ever harmful to sound quality.
Hence the sustained popularity of bipolar and dipolar speakers in opposition to accepted “good science”.
Borderline echoes from a back wall is not good though. But never really seems to be a problem, since the sound seems to be attenuated enough by the time it gets back to the listening position, that it is only perceived as ambience, and not muddling.
Diffraction from sharp edges near field though can be bad, since it can have enough energy to significantly shape the directionality of the sound.
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I'm so glad I have the freedom to make up my own mind . I have waisted enough time behind the keyboard not to repeat it here. One has to remember. Some make speakers for a living. Others are a little more obsessed. I would fall into the latter category but I know not to expect any one else being as crazy as I am.
'Control the room and you will control the sound'
That would be my quote for the DIY crowd willing enough to find their own thruth. While you will not hear any significant change from early reflections (*), they do tend to give away the position of the speakers. Avoiding early reflections, say those happening at less than 6 ms, (I went for 20 ms for good reasons, we can learn valuable lessons from the Studio guys) and avoid diffraction as much as possible. Be sure to have/add headroom, lots of it.
(*) = Tonally, because our brain has spend most of our life learning to filter out these effects for us. Something you can 'unlearn'. Not recomended though. Imaging is quite a different story. That does change a lot with early reflections present. It kinda becomes a sauce being spraid over each and every recording. Not my cup of tea. I'd rather be transported back to the environment as recorded. Even if it's just artificially created.
. I have waisted enough time behind the keyboard not to repeat it here. One has to remember. Some make speakers for a living. Others are a little more obsessed. I would fall into the latter category but I know not to expect any one else being as crazy as I am.'Control the room and you will control the sound'
That would be my quote for the DIY crowd willing enough to find their own thruth. While you will not hear any significant change from early reflections (*), they do tend to give away the position of the speakers. Avoiding early reflections, say those happening at less than 6 ms, (I went for 20 ms for good reasons, we can learn valuable lessons from the Studio guys) and avoid diffraction as much as possible. Be sure to have/add headroom, lots of it.
(*) = Tonally, because our brain has spend most of our life learning to filter out these effects for us. Something you can 'unlearn'. Not recomended though. Imaging is quite a different story. That does change a lot with early reflections present. It kinda becomes a sauce being spraid over each and every recording. Not my cup of tea. I'd rather be transported back to the environment as recorded. Even if it's just artificially created.
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This must be lost in translation
I think the type of program material plays a big role in how well it translates in the presence of a given level of reflected sound. In all of those type of experiments the biggest change factor came from the program being used to evaluate the effect.
I built both of Linkwitz's best speakers (Orion and LX521) partly because he was a brilliant man and knew a huge amount about sound and spoke authoritatively on the topic. It took me a long time to realise that he was an ardent classical music fan and all of his experiments and improvements were evaluated with that source material.
I was only ever pleased with them while listening to music that incorporated space, jazz, acoustic, audiophile type test recordings. As soon as it turned heavy and distorted it all went downhill so I started to look for alternatives from those who had put equal thought and effort into their designs. Dipoles do not work for me with what I want to listen to. If they are in a big enough room far enough away from boundaries then some of these issues reduce.
This is one of those things that you really do have to try for yourself in your own space to decide if the benefits or tradeoffs of absorbing reflections works for you.
Toole has written a few chapters in his third edition book to explain some of the misconceptions that have arisen from his earlier writings, his thoughts are not quite so black and white as you have suggested.
As an example Kevin Voeks of Revel has a personal setup where much early reflections are absorbed, so not everyone who knows what they are talking about agrees on their own personal preference.
What they do all agree on is that any absorption should be as broadband as possible to avoid EQ'ing the reflections.
I'm glad you did tooI'm so glad I have the freedom to make up my own mind
Sorry, that came out wrong. Sound travels about a foot or 34cm per ms, so three milliseconds is about a meter. So very much near field and relating to the walls near the speaker.
If what you want is an absolutely precise mirror of what came into the microphones in the studio or event, use headphones or near field speakers.
Wesaysos line array is strangely not leaning overly towards that kind of near field "dry" experience by nature, by virtue of only having linear drop-off in SPL as you move away from them in a normal room. The room is going too contribute at lot whether you like it or not in this case. Unless you live in an anechoic chamber.
While Roger Russel who popularised the type of speaker in modern times, describe it as the nearest equivalent to headphones, he also says: "The IDS-25 with all wide-range drivers comes closest to this new experience heard with headphones but without having the sound inside of your head".
My Experience with Column Systems
The sound inside your head effect comes partly from the stereo imaging really being a gimmick, or an approximation at best.
Your outer ear and your head is a highly personal frequency modulator, and can only be crudely approximated by binaural recordings.
Even then, you miss the all important imaging cues that comes from slightly moving your head.
But the (controlled) room contribution, also plays a really important part in avoiding that "in head feeling".
The head mounted open baffles that pops up from time to time, where drivers are put at an angle in from of the ears, would be far more popular amongst proponents of the clean, dry sound otherwise (apart from making the wearer look silly).
The effect of listening to a highly directional speaker in a heavily dampened room, is certainly striking and can give you some sense of depth and a momentary illusion of "being there", when you hit the sweet spot.
But it is not what I would describe as pleasurable or actual high fidelity.
It is in short an expensive gimmick.
This is a complex subject that isn't really suitable to brief explanation and discussion on a message board. The literature is right there on the web and in your local technical library though with a little searching.
Anyone taking the time and expense to build an expensive speaker like this, should take the time to peruse, reasonably understand and internalise the relevant literature.
What makes you think that any of us didn't read that literature?
However, personally I am not after a 'dry near field' or 'studio sound'. I never was. But avoiding/absorbing early reflections with reduced/avoided diffraction, while introducing later lateral reflections (Haas Kicker) goes a long way to avoid any of the unpleasantness while still having the "I'm there" feel (in spades).
Look up what the Studio guys have to say about Haas kickers. For their task it would not be a wise choice to have it. But for pure entertainment/listening pleasure it works very well.
Crumboo will have to find his own preferences. All I'm warning about is that not all early reflections are alike. Certainly not with arrays, which are a different animal all together when it comes to parallel planes. Avoid/absorb at least the first 6 ms of reflections and it will have good imaging and a live/dynamic feel. From there on the journey becomes a bit harder to achieve. At least in something resembling a living room. Still it is easier to do so with arrays than most speakers. Find out the why and the attraction of arrays becomes more clear.
Well for a start the original poster seemed like he learned a thing or two.What makes you think that any of us didn't read that literature?
If you look at other IDS-25 clones you'll see they are setup in a number of ways, none of them employing near field absorbers or diffusers.
I don't know about your setup? I frankly don't have the time to search through all 560 or so pages. ;-)
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