Another corner line array, 28 TC9FD18

[Squeak]

One of the pictures showing up does seem to be quite familiar .
Looks can be deceiving though. This is my room:

Or as seen in the search:

Oh no, no absorbing panels in sight! That must sound awful. Or not, maybe Toole is right . However, measuring the room and presenting it in a way so we can see what happens over time:

Huh? what happened? I can see some bumps, representing reflections, but they do seem a bit lower in SPL level.... how is that possible?

It must be tuned to a single microphone position, right? That must be what's at fault.

Sorry to disappoint, the early reflections have been significantly reduced, by absorbing the most obvious first reflections with huge panels, though they are hidden from plain sight. Would you believe nothing was needed (but actually was tested extensively) behind those arrays? It would have looked dreadful to place anything there. So what about the wall beside the right speaker? No damping/absorbing there? Well, the front of that array is ever so slightly in front of that chimney (10 cm to be precise) for it to not show up in measurements at all. The only remainders of reflections are from behind the listening spot. Because the absorbing panel (which looks like a poster) still is a tiny bit too small to catch them all. It hits the microphone at just over 6 ms. A tiny bit louder reflections for the right speaker than for the left.
If you know where to look, it's easy to find them in my measurements.
Measurements are there that show way more than the sweet spot center alone. And it's not half as bad as what most would predict. In fact, it is quite well behaved in a wide area. Once you get what arrays can do in a room it all starts to make a little more sense. We have a whole bunch of little drivers, all with a specific position in the line. Each and every obstacle will create a series of reflections, but most of them don't coincide. However parallel planes do come closer to having identical distances as seen from a listeners ear. The bent over CBT array spreads this even further and thus will be even more insensitive to boundaries. Meaning it will require even less room adjustments while having great potential for good sound. Only one thing holding it back. As you need to shade the output of the CBT, you end up with not much more sensitivity than that of a single driver.
While with these straight arrays we get to keep more of their joint potential. Sure, even that comes at a price. Comb filtering between all those little drivers and ones ear is a true phenomenon. But at the listening distance, and even much closer, it won't be easy to detect. You can still see it in measurements though. Going with smaller drivers can have benefits, but you also lose some bottom end extension.
We can correct the timing of those little drivers back to what presents a decent IR with FIR filters. Especially at the listening distance. This is done out in the room, but preferably after proper treatment of early reflections. If you cannot do all of that, multiple measurements around the area of interest and re-combined into a single pulse has been known to be a working solution.

Where one stops, or what is enough is up to the end user entirely.

In a nutshell, this is what was done in at least one of those rooms in that image search. I presented it here for Crumboo so he might still benefit from this rather strange discussion.

I take no responsibility for those other line arrays as seen in a Google image search. In fact, in my thread I've never mentioned the IDS-25. That does have a reason that I might go and explain in my own thread.

I'm sorry Wesayso, while there are many interesting sub observations in your post, I fail to glean an overall point?
I don't think anyone here has said anything against padding the back wall. Also one of my sub points, as you show, is that most normal dwelling rooms are already sufficiently damped.

 

[wesayso]

And what is your point exactly? I've seen a lot of warnings about measurements and what not. A downplay of the effect of early reflections... but what I am missing is the point you're trying to make. I've seen my room with and without treatment. I've seen the measurements from way more arrays with and without treatment. Believe me it is obvious and helps us get to great results.

My results that lead to a happy me, were all based on in-room measurements. Followed by analysis, DSP and listening. Rinse and repeat.

Some of the things you keep repeating just don't bode well with me. My last post has one goal and one goal only. To keep some sense for Crumboo to follow. Showing that measurements can lead to listening joy. Rather than shooting in the dark and going in blindly. Loosely based on interpretations of thing said by the great names in the industry.

To get two things right at once: treating early reflections/diffraction can go a long way to get stellar imaging and sweet tonality. You can measure your way there, it has been done more than once.

What help do you have to offer to Crumboo?
I will stick around and help out, in any way I can to make sure he gets satisfaction out of his build. Will you do the same?
It isn't the first time I have offered this kind of help and if it's up to me it won't be the last time either.

 

[koldby]

Surprisingly often even seasoned professionals and professors talk provably nonsense, or cling to old notions and ideas, because the question is slightly out of their specialty, or "that's the way had always been".
I've seen it countless times.

Not that I wouldn't rather listen to an expert saying something wrong for the right reasons, than listen to a crank, or a self proclaimed expert.

Comb filtering due to early reflections is a complex subject. Electronic audio engineers are taught to avoid it like the plague, because "they know how it sounds", due to being able to reproduce it at will.
While realworld comb filtering is more broadband/diffuse in nature and the psycho acoustic experience is totally dependent on the placement in the room, intensity and number of sources.
For example, a normally furnished room is going have completely different characterics WRT to comb filtering, with the same amount of bare hard wall near the speaker, than an unfurnished one.

 

[Squeak]

My point, which I think was pretty clear, was not to go with the old adage of a little too much damping is better than too little.
It seems OP hadn't heard of Toole et al too.
In his original plan he suggested going nuclear with damping near the speakers.
The later posts about measuring and listening was secondary and more responses to others.
You know, a conversation...

 

[Squeak]

 

[wesayso]

My point, which I think was pretty clear, was not to go with the old adage of a little too much damping is better than too little.
It seems OP hadn't heard of Toole et al too.
In his original plan he suggested going nuclear with damping near the speakers.
The later posts about measuring and listening was secondary and more responses to others.
You know, a conversation...

Well, that's just it. every boundary that near to that speaker will have a way more detrimental effect on things like imaging etc. than the rest of the room has. No matter how many pictures you can show us of IDS-25 speakers that fail to do anything about that.(*)
The rest of the room would still produce reflections valid to call them early reflections. Avoiding problems goes a lot further than trying/having to solve them, as we can't EQ out the room, we might as well start working with it.

(*)= I see enough so called HiFi setups with speakers I could never afford placed in environments that make me cringe. Sure, their high dollar cables will negate those problems making it irrelevant.

 

[Squeak]

Well, that's just it. every boundary that near to that speaker will have a way more detrimental effect on things like imaging etc.

I thinks it's time for some quotes from Toole:
Room Reflections & Human Adaptation for Small Room Acoustics | Audioholics

Reflections within listening rooms are real and numerous. Some would argue that they all are problems to be eliminated. Others take a more philosophical view that they just provide information about the room, and the brain can figure it out. I’m somewhere in the middle, but leaning towards the latter. The science that has been done so far seems to be on my side.

They (sidewall/lateral reflections) fall into a region where there are varying amounts of "image shift" - the image is either perceived to move slightly or to be stretched slightly in the direction of the reflection. I, and others, spent hours in anechoic chamber simulations of direct and reflected sounds and can confidently state that the effects, while audible in direct A vs. B comparisons, are rather subtle. Was it ever unpleasant? No, the apparent size and/or location of the sound image was just slightly changed. The effect was smaller than tilting the head a small distance left or right of precise stereo center.

In a listening room, we need to know what happens to a sound from a loudspeaker that reflects from this material when it is placed at the point of reflection, as seen in the preceding illustration. In that situation we are interested in knowing how much of a sound that arrives from, say, 45° is reflected towards the listener. Illustration (b) shows this as an attenuation of the sound. If we use the data in (a) we would possibly expect something like the dashed curve that falls rapidly above about 100 Hz, essentially eliminating everything above 400-500 Hz. What we actually get is something quite different because resistive absorbing materials change their absorption properties as a function of the angle of incidence. They also change when the fibrous absorber is covered with an acoustical fabric – the one shown here is probably the most widely used fabric in the industry (Guilford of Maine FR701), and it is clearly not acoustically transparent at very high frequencies. This absorber has not eliminated anything, it has simply turned the treble down – the off-axis performance of the loudspeaker has been “redesigned” especially if it is a well-designed wide-dispersion system.

This is information that is almost never known by people offering opinions about the audible effects of these reflections, yet it is known to be critical to the listening experience. If the spectra of the direct and reflected sounds are significantly different, the reflections are likely to be more noticeable, from subtle timbral effects up to a premature breakdown of the precedence effect, at which point listeners may be aware of two simultaneous sound images, one located at the loudspeaker and one located at the point of reflection. This is obviously not good. Over the years this is likely a factor in listeners rating loudspeakers with uniform directivity more highly than those with uneven directivity. Wide dispersion seems to be good, but especially if it is uniform with frequency and the spectra of the reflections is not substantially altered. Hundreds of loudspeakers auditioned by hundreds of listeners in double-blind evaluations have demonstrated this; it is monotonously predictable.

Humans evolved while listening in reflective spaces, and are comfortable listening in them. In fact, it is now widely recognized that we perceptually "stream" the sound of the room as separate from the sound of the sources

Sorry if the quotes are a bit long. I emphasized what I saw as the main point WTR to this thread, and left the rest for context.

Treating the stereo imaging information as the holy gospel to be preserved at all costs, I think is something to do for studio engineers, and a bit naive to do for the end listener of the recording.
Thinking that you can take a frozen facsimile of a sound field with two mics, and then recreate it reasonably with two speakers of differing designs in any room, with or without the appropriate treatment is a popular fantasy, but when you think about it quite silly.

Stereo is "something", but The Truth ™ it is not.
This of course, has also been written about extensively.

 

[wesayso]

A word upfront, my quotes are even longer...

Yawn... I already stated to be aware of the quotes from Toole, didn't I? Maybe Crumboo will get something out of it, but first I'd have to ask what your experience with line arrays is... They are quite a bit different in engaging with the room, you may have noticed a couple of Array builders with hands on experience reacting to some of your wordings. They too have listening experience with arrays and (very) early reflections. Which is why they chime in to help out.

Anyway, I have already drawn my own conclusions on this subject and only offer some well meant advise for Crumboo, pointing out what he should be aware of. As I've heard both the untreated vs the treated room and have way more freedom and success to get the latter version to sound to my liking.
This isn't the only part where I differ in opinion from Toole. And personally, I am not really bothered by that. It doesn't mean I'm not taking what he has to say seriously, it just means that I have a different opinion.I doubt he will come by and tell me how wrong I am, unlike some people feel the need to.

As said by fluid, Tool is an aficionado of classical music, big orchestra's etc. People that like Studio recorded music might have a different opinion or preference on this subject, read up on Geddes quotes too, he has stated his opinion more than once right here on this forum. I can find many quotes from him stating it's one of those things where he and Toole don't quite see eye to eye.

Following the discussion that was starting about here; https://www.diyaudio.com/forums/multi-way/277519-fixing-stereo-phantom-center-83.html#post4996662

I figured why not ask Geddes directly why he and Toole did not see eye to eye on the subject of (very) early reflections:

I actually am very curious if this is the main reason of a difference of opinion between Dr. Geddes and Toole on the subject of early reflections. Not having heard what they hear in their preferred environment I can only guess at it though.

For the record, I recently talked with Floyd on this exact point. I believe that he has softened his position (although he claims that people misquoted him and that he was never fixed in his opinion on early reflections.) It appears now that he and I both agree that Very Early Reflections (VER) are a compromise. While they add spaciousness, envelopment and enhance ASW, they will degrade imaging on more dry studio type recordings. Floyd now recommends the ability to either have VER or not with adjustable side curtains. Since my listening is almost 100% studio work, I do not see the need to have "options". Floyd is virtually 100% large venue recordings and hence his earlier beliefs that enhanced spaciousness was a major benefit.

So basically this discussion about VER has no real resolution as it entirely depends on what one is looking for and not everyone will be the same. Suffice it to say that if orchestral pieces recorded in a large venue are your goal then you will want wider directivity and/or more reflective side walls. If studio work with precise imaging is your goal then narrower directivity is beneficial to avoid VER without the need for side wall absorption. If your speakers do not have controlled and narrow directivity and you want good imaging then absorptive side walls are probably essential.

So, which one should we follow? What is your listening preference? What should we do?

As said, as much as I have enjoyed reading (and listening to) Toole, I don't feel I'm obliged to follow all his rules to a tee, if they don't quite fit my needs. Anyone else will have to make up their own mind. For me, the words of Geddes weigh in at least equally and I saw it as my task to try it both ways and pick my winner. Again, emphasizing that this works quite a bit different with arrays as opposed to most speakers placed near boundaries.

We can also ask another highly regarded member here, on the subject of very early reflections, here's Lynn Olson's view on the topic:

Hard reflecting surfaces and edges have destructive effects on image quality and timbre - especially when the dimensions involved are similar to head, shoulder, and pinna dimensions, which are essential for localization of sound. Vocal timbres in particular are susceptible to artificial-sounding colorations, partly because human beings have such acute discrimination between voices, and also because vocal-tract dimensions can be similar to dimensions of loudspeaker diffraction effects (a few inches).

I can't emphasize enough the first millisecond (14 inches long) is the most crucial thing the loudspeaker does - although the first 3 milliseconds are pretty important too. Note that I'm discussing reflections that are in the 0 to 42 inches long, kind of awkward considering our speakers are the same size! Thus the importance of (any) smoothing techniques to soften the acoustic edges so they re-radiate less energy - and have smoother polar patterns.

What makes this more difficult is the dynamic range of the ear. A 20 dB reduction of edge reflection energy might seem a huge triumph, until we consider we really need 60 to 100 dB of reduction to say it's actually gone for good. This where we hope that auditory masking will save the day, so the quieter reflections fall below the auditory threshold.

Now why would he have that opinion, let's dig a little deeper:

Room size is an essential consideration here. When the sound is several wavelengths smaller than the smallest room dimension, the listener can separate the sound into direct-arrival and total-room-energy components. At wavelengths approaching room size, direct-arrival and total-room-energy merge together. What sounds unnatural are the direct-arrival and total-room-energy spectra diverging from each other, since this is something that rarely happens in nature (or a concert hall).

As mentioned earlier, the ear/brain/mind processes sound in different "slots" using cross-correlation techniques (the first 20 or so reflections are compared to the direct arrival), and can compare the direct-arrival spectra to the earliest reflections. This happens automatically all the time - in fact, it's working when you're asleep or awake, constantly analyzing the environment for threat or safety. The environment-processor is not only connected to the frontal lobes (the "adult" sense of self - responsible for planning-ahead) but to the limbic system, which reacts with emotion and activates the fight-or-flight system.

When a hifi system tampers with the early-arrival information, the ear/brain/mind discounts the artificiality and categorizes the sound as just another artificial creation, mimicking life but most certainly not the real thing, just as you'd never confuse a TV picture or movie with real-life. When you get that hair-raising "spooky" feeling with a hifi system, that means early-arrival information is arriving intact, and the auditory illusion of being somewhere else is working. The machine is really generating an illusion, something HDTV and IMAX are still a long way from doing successfully.

The reason that movies and TV shows "pull you in" is the light hypnotic trance generated by the quiet, darkened room - a modern replica of the environment where thousands of previous generations listened to stories told round the tribal campfire. For a really fun experience, listen to the ZBS radio-dramas on a top-quality system - the illusion of "being there" is far more intense than watching a movie, as your ears open up to the environmental sounds of Morocco at night, and the narrator weaves the story-line.

(lovely thread, full of information, even longer than my own thread (lol) but filled with lots of knowledgeable people chiming in. Highly recommended for everyone to read. Even though Lynn made it clear he does not like line arrays )

You want me to find more quotes from other big names in the industry to respute Toole's quotes? You should realise Toole isn't the only one in the game. As said, it's much more interesting to find what they can agree upon. Just look at all horn users that work on the horn's mouth to soften ill effects there, they too fall into the same category of wanting to eliminate very early reflections from the equation.

To me, it's clear what to do so I get a soundscape that's in line with my own preferences. I never tell people they should do as I do, more often I tell them to doubt every thing until you've been able to make up your own mind on the subject, that includes putting everything I say in that category as well. Don't trust me on my word, put it to the test yourself. See where you stand.

Now do tell us your line array experiences... good or bad...

 

[wesayso]

Crumboo, just say the word. If you're thread seems polluted with this debate I'd be happy to ask a moderator to clean it up, maybe move it elsewhere.

The line array owners I've seen chime in here:
- Perceval has (free standing) line array experience in his untreated room

- fluid has (free standing) line arrays and heard it both with and without treatment on early reflections.

- koldby has (free standing) line arrays and has treatment at first wall reflections. He's also heard mine with absorbing panels in place

- nc535 has (real corner) arrays and has heard his setup in a few different ways with and without absorbing panels

- mark100 has (free standing) arrays, he experimented with both CBT and straight arrays and has listened to them in an untreated room as well as outside to rid himself of reflections

Did I miss anyone? Yes...

- TNT has corner line arrays and I'll let him chime in if he has experienced them with treatment

- xrk971 has heard my line arrays in a treated room, here's his opinion on it: https://www.diyaudio.com/forums/full-range/242171-towers-25-driver-range-line-array-275.html#post4905160

Just so we know who is who in this thread... I could go on posting inside knowledge who of these gentlemen (that I know) have read Toole but they can certainly speak for themselves .

 

[perceval]

Hey guys, anybody seen line-array projects/images that are not in corners....neither flush in the corners or pulled out a bit but still predominantly in the room corners.

Where the speakers are on the long wall of the room and substantially away from corners?

The more i reminiscence my straight-line experiments, the more i want to try this sometime soon. Seems like it could solve the corner reflection difficulties pretty easily....????

A few years back...

They were on the long wall, quite away from any corner, and in listening position, they were pulled in about 1m from the wall behind.

These were not floor to ceiling, mirror-image line arrays, so they were missing some advantages there. Your head had to be placed within the line.
Also, at 16 drivers per line, they needed subwoofers for bass duty.

Still, they were loads of fun.

 

[Crumboo]

One of the pictures showing up does seem to be quite familiar .
Looks can be deceiving though. This is my room:

Do you have absorbtion panels behind both of those curtains or only behind one of them? How thick are the abrsorbers (I now it's somewhere in your thread somewhere...)? As in your case I have a big window to the left., The first contra lateral reflection point from the right speaker will be in that window which concerns me. The window niche is quite deep and will present a large vertical plane which is also of concern.

In my case I have several meters (about 4) to my back wall so those reflections would be significally reduced in energy and time. It's the side walls that I'm concerned about (the top-to-floor array solves the ceiling and floor reflections I understand).

I am pretty convinced that early reflections/diffraction close to the array should be treated. As of my room, I need to get the arrays close into the corners so I really need to work with it to get good results.

My goal here, or what I really wish to achive, is to reproduce the musical event as true as possible (well, that's what hifi is about isn't it?). I would like the front part of the listening room to dissapear leaving an opeing to the concert hall/stage. I listen alot to classical music: big orchestras, smaller ensambles, organ and choir. But then also more intimate jazz settings with only a few musicians.

I think, in my situation and room, that full range arrays have the potential to get me there. There is not enough room for big free standing multi-way speakers anyways.

You guys have so much experience than me on this subject, so I really appreciate all helpful comments and discussions. Then of course I need to make up my own mind in the end.

So here is a challenge : Given my room and other conditions - what would you do/how would you design (speakers/room) to reach my goal?

 

[wesayso]

Absorbing panels behind both curtains. About 3 inch in thickness with an airgap between panel and wall. Wool felt top layer over fluffy fiberglass insulation material.
I'll post my thoughts later today after work. With virtual Haas kickers/ambient speakers you get to pick the time delay you want/need. The room return (or in this case ambient speakers) should be diffuse in nature and decorrelated from mains.

Read up on some David Griesinger papers to get a feel of what it is you want. Highly recommended reading. He was the one behind the well known Lexicon reverbs.

 

[Joseph Crowe]

I suggest a throat width of 1.7” and use at least four drivers per horn.
This will provide decent treble coverage. I suggest a horn with a 250Hz Fc. This will provide the necessary off-axis pattern control.
I’ve attached off-axis polars of the Scanspeak 10F/8424 in such a horn versus a non horn setup. The driver’s power response into the room is much more balanced with the horn resulting in good overall timbre. The non horn sounds like it’s overly aggressive in the midrange despite efforts to flatten with PEQ.
Also, once you’ve applied PEQ on the horn the resulting %THD will drop to around 0.1%. The best I could do with a non horn configuration was around 0.8%.

 

[fluid]

I suggest a throat width of 1.7” and use at least four drivers per horn.
This will provide decent treble coverage. I suggest a horn with a 250Hz Fc. This will provide the necessary off-axis pattern control.

What does a your horn look like? It would be interesting if it could be made to work with a full line of drivers, the TC9's crumboo has are not wildly different to the scanspeak drivers.

 

[TNT]

I have tried a number of different setups with damping using felt fabric say 12mm thick. Wider and narrower pieces close and further away form the lines (2-30cm). Also on the baffle itself touching the side of the drivers (pic!). Now I play without any felt damping. In the end it was the best. It could be brutal but I have found ways to improve my electronics but more importantly worked with EQ. Just ordinary PEQ as I do not have access to enough power for a FIR party. My drivers are very cheap but the lines have superseded my expectations and they do some thing really well.

I will in the future most probable build a new pair. The baffle will be concave, maybe elliptic!? (pic2) This is to create a seem-less surrounding to the line, just a completely smooth transition to the side walls with no vertical edges or angles whatsoever.

 

[fluid]

I've been nothing but nice in this thread, and yet you decide to kick up dust and get aggressive and confrontational.
Why?

If that is truly your intention then I think it has been lost in some of your comments. You have managed to raise the hackles of a number of members who I know from previous interactions to be reasonable people.

If five people hearing your message get upset by it and that wasn't your intention, maybe you didn't say what you meant to. Tone is hard to read in this context.

I thinks it's time for some quotes from Toole:

I don't know if you have read the 3rd edition of Toole's book but if you haven't I suggest that you do, for anyone else it is a very good read and is significantly expanded in content and layout from the previous versions. He has gone into greater detail about a lot of this with examples of his own rooms including the current one which includes side wall damping from heavy curtains for those occasions where he feels it is beneficial. His opinion is not black and white but it is informed by a long history of double blind testing. That article from audioholics is part of the new book but it is much better when presented in the context of the whole book. This is why Toole himself goes to greater lengths to explain his thoughts and position more clearly across the whole book due to some quotes from him being used to represent something that he did not intend.

Treating the stereo imaging information as the holy gospel to be preserved at all costs, I think is something to do for studio engineers, and a bit naive to do for the end listener of the recording.

This is an interesting comment for me. Up until quite recently I had no real interest in "imaging" as a thing to chase in a speaker. I almost found significant panning to be distracting and not something I enjoyed. After having changed my setup to have the speakers point more directly at me than before (for an entirely different reason than imaging) I started to get a really clear picture of what those who place imaging as an important aspect of speaker performance are getting at.

Stereo is "something", but The Truth ™ it is not.
This of course, has also been written about extensively.

Indeed and Toole's circle of confusion shows that truth is hard to come by in recordings that you did not make yourself in highly controlled conditions. You can still get a lot of enjoyment out of that available content though.

I am pretty convinced that early reflections/diffraction close to the array should be treated. As of my room, I need to get the arrays close into the corners so I really need to work with it to get good results.

My goal here, or what I really wish to achive, is to reproduce the musical event as true as possible (well, that's what hifi is about isn't it?). I would like the front part of the listening room to dissapear leaving an opeing to the concert hall/stage. I listen alot to classical music: big orchestras, smaller ensambles, organ and choir. But then also more intimate jazz settings with only a few musicians.

I think, in my situation and room, that full range arrays have the potential to get me there. There is not enough room for big free standing multi-way speakers anyways.

You guys have so much experience than me on this subject, so I really appreciate all helpful comments and discussions. Then of course I need to make up my own mind in the end.

So here is a challenge : Given my room and other conditions - what would you do/how would you design (speakers/room) to reach my goal?

I think the arrays can get you to where you want to go too.

My experience matches in with most of what I have read from a number of different sources that lateral reflections that occur within 6ms of the direct sound are the ones than are likely to cause timbral degradation. As these are fused with the direct sound and cannot be separated as separate events like the ear can do with later arriving reflections. Avoiding those can be achieved by having more than 1 metre distance to any reflecting surface making the overall path length difference 6ms plus. Full range arrays need to be closer to the front wall for reinforcement 50cm from wall to front baffle has always worked the best for me for the uniformity of response below 200Hz.

In your setup that is not so practical so you are left with directivity or absorption to deal with them. Which is where your original idea stemmed from.

If your main musical listening is to classical, jazz and acoustic styles then I would advise against too much damping overall as these are the types of music that are much more tolerant of reflections and can often benefit from them (still trying to avoid the sub 6ms ones).

Using the ambience channels for an artifical Haas kicker is another way to inject back some of that room sound while also making it controllable. Maybe you have the space to make that work worth thinking about at least.

You may be able to make a free standing array and place it further out from the bookcase to peek out much like wesayso has done from his right hand niche, you could then meaure in situ and damp the areas that need attention. Angling the speakers to point directly at the listening position can have a beneficial effect in that the direct sound field is stronger that way and you benefit from the natural drop of of the TC9 at offaxis angles. 75mm fibreglass of medium density with 10mm felt over the top and an air gap behind is a pretty good panel for reflection control at least down to 500Hz. Making the panels only as wide as is needed to control the reflection can also help to avoid making the room overly dead, they do need to be full height with an array to have maximum effectiveness. From my own experience a few panels in strategic positions makes things quieter and more controlled without making the room feel uncomfortable or dead.

 

[Squeak]

If that is truly your intention then I think it has been lost in some of your comments. You have managed to raise the hackles of a number of members who I know from previous interactions to be reasonable people.

If five people hearing your message get upset by it and that wasn't your intention, maybe you didn't say what you meant to. Tone is hard to read in this context.

If you don't like what is being said, discussion often degrades into a discussion of tone, or Grahams level DH2: How to Disagree
It was mainly Perceval that responded in what I consider, lets say, a less than rational way.
Please point to places where my tone has been harsh or aggressive, and I'll try to better myself from those examples.
Raising hackles to a certain degree is one of the main reasons for forums. If it was just a big echo chamber and list of references, it would all be a bit pointless. No?
Disagreement and misunderstanding is not fighting. At least among reasonably civilised people.

I don't know if you have read the 3rd edition of Toole's book but if you haven't I suggest that you do, for anyone else it is a very good read and is significantly expanded in content and layout from the previous versions. He has gone into greater detail about a lot of this with examples of his own rooms including the current one which includes side wall damping from heavy curtains for those occasions where he feels it is beneficial. His opinion is not black and white but it is informed by a long history of double blind testing. That article from audioholics is part of the new book but it is much better when presented in the context of the whole book. This is why Toole himself goes to greater lengths to explain his thoughts and position more clearly across the whole book due to some quotes from him being used to represent something that he did not intend.

Toole has never been dogmatic or put out credos. Neither have I in this thread. You are building straw men.
I have the book right here in front of me. And the small article is not, not representative of his views. Of course you get a lot more answers and food for thought in the book, but the article is not a bad starting point.
Neither is this video:
YouTube

I think the arrays can get you to where you want to go too.

Sure, no one has said otherwise.
They are not without problems, and I don't think they are for me. But I can sure hear they have some quite magical things going for them, from the few encounters I've had with them.

 

[Squeak]

A word upfront, my quotes are even longer...

Yawn... I already stated to be aware of the quotes from Toole, didn't I?

You didn't state why really. He's language is not magic and especially prone to getting twisted. And as long as the context is accessible, what's there to complain about really?

Maybe Crumboo will get something out of it, but first I'd have to ask what your experience with line arrays is... They are quite a bit different in engaging with the room, you may have noticed a couple of Array builders with hands on experience reacting to some of your wordings. They too have listening experience with arrays and (very) early reflections. Which is why they chime in to help out.

Well, I have listened to a few line arrays and I know the physics pertaining to them.
I also know that they don't bend the laws of physics or play tricks with the basic laws if psychoacoustics.
I can't see how sidewall reflections should be any more pronounced or fundamentally different than with "normal" speakers.
If I'm mistaken, enlighten me.

As said by fluid, Tool is an aficionado of classical music, big orchestra's etc. People that like Studio recorded music might have a different opinion or preference on this subject, read up on Geddes quotes too, he has stated his opinion more than once right here on this forum. I can find many quotes from him stating it's one of those things where he and Toole don't quite see eye to eye.

I don't really buy the notion that some genres or types of recording should call for different speakers.
Demands on dynamic range is a different matter altogether. But a good speaker and setup of them, should be good for most types of recording.
Most genres include subgeneres, variation and parts where they could be said to go into another territory.

As said, as much as I have enjoyed reading (and listening to) Toole, I don't feel I'm obliged to follow all his rules to a tee

Again, you are going after a straw man. No one here is dogmatic about his "teachings" least of all the man himself.

There will always be opposing views (at least seemingly opposing) or approaches to almost anything. That shouldn't, and doesn't stop anyone from posting what they think right here.
Toole, Linkwitz etc. have an approach and ideals/ideas that are very well founded in years and years of research and thinking. You'd be foolish not to at least consider them and know about them.
That's all I'm saying here really.

 

[Crumboo]

I suggest a throat width of 1.7” and use at least four drivers per horn.
This will provide decent treble coverage. I suggest a horn with a 250Hz Fc. This will provide the necessary off-axis pattern control.
I’ve attached off-axis polars of the Scanspeak 10F/8424 in such a horn versus a non horn setup. The driver’s power response into the room is much more balanced with the horn resulting in good overall timbre. The non horn sounds like it’s overly aggressive in the midrange despite efforts to flatten with PEQ.
Also, once you’ve applied PEQ on the horn the resulting %THD will drop to around 0.1%. The best I could do with a non horn configuration was around 0.8%.

Yes, please tell us more about those horns. I have no experience with horns and not very familiar to the advantages/disadvantages with them.

 

[Crumboo]

I have tried a number of different setups with damping using felt fabric say 12mm thick. Wider and narrower pieces close and further away form the lines (2-30cm). Also on the baffle itself touching the side of the drivers (pic!). Now I play without any felt damping. In the end it was the best. It could be brutal but I have found ways to improve my electronics but more importantly worked with EQ. Just ordinary PEQ as I do not have access to enough power for a FIR party. My drivers are very cheap but the lines have superseded my expectations and they do some thing really well.

I will in the future most probable build a new pair. The baffle will be concave, maybe elliptic!? (pic2) This is to create a seem-less surrounding to the line, just a completely smooth transition to the side walls with no vertical edges or angles whatsoever.

Thank you. I have also been thinking about a concave baffle to get a really smooth transition to the side wall and book shelf. With a stacked design (and a friend with a cnc router) any shape should be possible. It should smear out the very early reflection making it less prominent I guess.