Hi folks!

As some of you may have noticed, last few weeks have seen an intense round of treatment to my humble retrofitted living room.

The before/after is startling. To say the least. Feels like I've done the same sort of upgrade that I did when going from no treatment to well treated room..




The room a few weeks ago above and as measured last night below. Was measuring at low level, so the noise floor is high, making for the less than ideal end of the reverb tail. The schroeder integral is actually scaringly flat all the way down to noisefloor.

Still got some tweaking to do to the response, but it's getting very close to the goal. I thought the room was 90% there in the first picture.. W R O N G. It was more like 50% there in terms of what it feels like listening to it..

Done lots of work to get some more life into the room while also cleaning up the destructive clutter at 0-20ms. It's more precise now, less destructive early interference, while also having more life and euphonic fun to it. From 150 to 210ms RT60 and still growing!

The Haas trigger at 19ms was actually surprisingly easy to achieve. Beats me why I didn't do it a long time ago. It's the result of four reflectors on the rear wall, two for each speaker. The outermost reflectors crisscross each other, with the left reflector taking the right speaker and vice versa. The middle reflectors are straight, in that left speaker in is left reflector out. Thought it may be a bit better, more enveloping, than having the each side of the rear wall dealing with the corresponding speaker only. Any thoughts on this?


This is the best development I've ever achieved in acoustics! Yay!

Very very happy now.


Better graphs to come after more tweaking.. Still room for improvement.


A huge *THANK YOU* to SAC/Mark for making this possible! Wouldn't have gotten even remotely close to this without his effort in explaining LEDE rooms and measurement basics.


Cheers,

Andreas

pics!

This is the "dead end"! Didn't thought it would have to be that live. It was deader. What happened was that the sound went from speaker to rear wall and forward again. When it hit the dead end, there was a significant drop in energy. Then back to the rear (live) end, back to the front, another drop in level.. The reverb tail tended towards a stair step pattern! So I've crammed lots of reflectors in there. Still room for some more reflectors, but it's getting difficult to find more spots to treat without creating unwanted early reflections.





Sidewall absorber/reflector combination. The absorber closest to the speaker eats that reflection, while the sheet of parquet reflects the sound from the othere speaker rearwards. Gotta preserve that precious room energy!





Closeup of sidewall absorber. Another cool thing is that it lets me place rockwool exactly where it's most needed - at one fourth room length. Without eating too much room. The angle of the reflector also makes for a little bit less absorption when the reverb comes forward again from the rearwall.





Close up of the funny reflection free console. It's as close to a transparent work surface that I could make up in half an hour of nailing and sawing bits and pieces of wood. It's an old contraption by now. Had a big aha moment years ago when trying to listen without the desk in front. Never going back to a big reflective surface right in front! So I threw together this weird console using whatever I had at hand and it's just been sticking since then. Keep thinking that I should build something better looking, or get someone to weld a better console frame in metal. But you know how it is with such things.. It looks weird, but works very well! This must be one of the few occasions when having few pieces of hardware is an asset. Going to run into a problem when amassing more gear! Edit: computer is hidden behind rockwool in the front mid. It's built to be extremely silent and behind the rockwool it's totally gone. Also makes for defined in/out air paths, avoiding sending hot out air into the intake.




Live end/rear wall seen from front. Shows how live the live end is! Used to have a lot of absorption in a ceiling grid that extended all the way back to the first diffuser. They went somewhere else. It wasn't compatible with my current room plan of avoiding semi-anechoic condition. Vinyl should probably go, from an acoustics standpoint, but.. It's good mojo! Don't actually do any DJ'ing these days, but I still love to spin records and do the occasional scratch.





Rear wall closer. Diffusers, more diffusers, some random reflectors and the aimed Haas trigger reflectors in the upper middle strip. Notice that the room is asymmetrical. The door is bad enough, but the other side actually have an angle in the corner where the house pipe goes. No guessing that the asymmetry bugs me a bit..



It used to be that I thought all rockwool was good rockwool and that a deader room was better. It's now the opposite! The rockwool is a problem in that it steals precious room energy. It needs to be there to tame bass and eat early reflections. But it's sure a bit of work to find places for the absorbers where they work well and then dress them up in reflective surfaces to avoid eating too much life without creating more early reflections. If dressing the absorber with reflector is an option at all, which it's obviosuly not at early reflection points.

Wish I had the space to use more splayed walls and less absorbers..

Thanks for posting the photos. It puts context to all the discussion.

I was trying to figure out how you could talk about "reverb tail" with a LEDE design room. But you really don't have an LEDE at all anymore. Perhaps a bit deader on the front end.

I notice you are using 2D diffusers, which should lose a lot of energy to the floor/ceiling. I thought that a lot of designers use only 1D diffusers on smaller, low-ceiling rooms, to preserve the energy in the horizontal plane, and not lose it to the difficult-to-deal-with low ceiling. Sometimes I see 2D on the ceiling, but not on the back/side walls usually.

Nice to see your room and hear of its development. Very organic .

Coupla comments. I know you've gone through a lot of moving things around
but are your monitors really in the best place acoustically ? I would have
thought that in the corner and on the wall, as opposed to in the wall, would
be about the worst possible spot.

I notice you have two subs. Did you place them to minimize mode energizing ?

Paul P

Oh man - this is art! It's so good to read that you are preserving the room tone. I believe this is the most musical and honest way of treating yourself and the room. It's all about controlling the acoustics without killing the sound. I went the other way and added too much absorption in my CR. I have my (home) studio at home and it's only for me and my friends. I have a day job. I'm slowly changing my path and removing a lot of absorption. I would love to achieve something similar to yours. I'm using my CR for recording both my voice and other instruments and I want to make my room come alive without taming too much (absorption). I just want to make the room more controlled and not so problematic... But still with some personality to the sound. I don't want to add artificial reverb because the room is too dry and boring.

Good work - even if you are from Norway!

/The Swede!

very nice Andreas,

you continue to be an inspiration.

What exactly is a "Haas trigger"?

-R

With all due respect, SAC, sometimes I wonder if you're being intentionally obtuse. Maybe I just need somebody to explain it to me as if I'm five.

But thanks for trying.

-R

To aid in anybody searching for LEDE info, you will sometimes see ISD gap referred to as ITD gap (initial time delay, as opposed to initial signal delay). The Haas triggers are also sometimes referred to as Haas kickers.

Although the original implementation of LEDE may be "dead," the principles have indeed contributed greatly to the development of the newer "RFZ" model. It can be thought of as essentially an updated and refined LEDE, but does not, strictly speaking, meet the LEDE criteria. One of the things that is less common these days is the traditional Haas kickers. I don't miss them. RFZ tends to use more diffusion and less specular reflection. Another thing that is no longer common is the asymmetric outer shell.

One rationale for the development of LEDE concerned being able to hear a performance in the studio uncolored by the control room. There is a time delay between the direct energy arriving at the microphone and the reflected energy from the room boundaries. Because the smaller control room created its own reflections much sooner than that of the studio, the control room reflections would be heard before the studio reflections, masking the sound of the studio.

LEDE tried to eliminate early reflections at the listening position, using a combination of absorption, especially in front, and a highly diffuse rear (with complex side and ceiling reflections too), including “Haas kickers” to sharply delineate the end of the ITD (ISD) gap and beginning of the ambient decay. This approach achieved a time delay in the control room large enough so that the engineer could hear the studio reflections before hearing the control room reflections. The intent was to allow the engineer to hear precisely what was happening in the studio without any masking from the control room.

It should be kept in mind that what you're saying applies more to control
rooms than live or listening rooms. LEDE and RFZ both make more sense
for control rooms in which you may be prepared to sacrifice spaciousness
for clarity.

Paul P

True, but Paul's point about live rooms is valid. LEDE was developed for the control room (or critical listening room with speakers), not the recording space.

Great book. One of the first I ever got. The acoustics and LEDE info are but a small part of this book. There is a bunch of other great audio info too.

Slightly off topic, Lupo, but I like the look of your desk with the slightly sunken monitor...What is it? does the low profile help cut down audio reflection from the screen?

Sorry - just read your post again...nice work!

Hi!

Thanks for the many thumbs ups!


Sorry for the late replying. Life bit me in the back and wouldn't let go..

It's very much deader in front than in the rear. The front 2/5's of the ceiling is absorption and there's the ceiling/wall corners and sidewall absorbers. About ~10 square meters(100 feet^2) of non-covered absorption. Still too much! Going to see what I can do about that.

Glad you mentioned the word reverb. It's a term that's very tempting to use to describe the tail in the room. In the same way, it's very tempting to describe the response change achieved in terms of RT60, as I did in the first post. The extensive use of diffusion makes the tail look a bit like reverb. Just want to point out that I'm doing a technical error by using the term "reverb". There is no reverb in such a small room! Reverb is a situation with random incidence. The response in a small room can't be random. It'll be a definite series of distinct reflections. The term "RT60" does not apply to small rooms as such. "Series of late reflections" is more descriptive.

Think you're right in this. Didn't knew when building the diffusers. Though they sure do create a pretty complex tail for being such a small room! Am thinking of replacing the lower rear wall ones with 1D's to have more energy in the horisontal plane.

The thought have also occurred to have diffusers with parabolic shape for the Haas triggers. Would be a difficult build though. Better yet, if I had the math skills, would be to force the pattern to send the overall energy in a certain direction. Avoiding spatial diffusion while still giving temporal diffusion.



Think the wide angle lens and the acoustic treatment makes them look closer to the wall than they really are. Acoustic center of speaker is about 85 and 65cm's off the side and rear walls.

They're placed to interact well with the mains. There's no cross over. Mains play the full range down to about 40Hz and subs are LPF'ed at 40Hz. Rolloff is pretty soft. The overlap makes the overall response flatter above 40Hz. Phase timing with the mains is also important. This works well with 90' phase lag.

Though I'm not sure it's the best setup for the subs.



It's also easier to get the job done as the sound stage is more refined.

Think most people in here have been there and done that!

Must have been the good influence from my Swedish parents.


Thanks for chiming in on the topic. The specific point above would be interesting to hear more about. By traditional, do you mean specular reflection?



Please don't stop expounding the general topic! Would to see this thread deal more with the generalities than the practicalities of my particular situation.


Haven't tried raising or lowering the screen to check what happens with the screen higher up. It works fine as a practical viewing angle, about the same as having a book on a desk.

There's also a psychological effect of "looking" straight at the sound field without having anything disturbing the field of view. Have a shortcut on the keyboard that blanks the screens. The single best placebo effector there is. Just about every visitor comments the big change that happens in focus and the subjective experience of having a pure sound field when the screen goes off. It's like the sound turns on when the screen goes off.


To be continued..

funny, i had a similar situation happening last week, while teaching our guitar player how to track. I was using and ART MPA Gold on the snare, and while getting levels, he kept telling me it's clipping. i told him, well, it's a tube pre, so the clipping isn't a problem unless it's audible and ugly. he insisted that it was. so i "turned down heh" the input and repositioned my chair so he couldn't see the meter. "oh that's better" he says. sure it is.

Yes. As alluded to when I said RFZ tends to use more diffusion instead of specular. I, like others currently, think diffuse reflections are preferable after the RFZ window, rather than specular.

Great to see the pics Lupo, having already seen the ETC plots

Have read the entirety of this thread and other like it with very great interest, and I am also keen to hear why jayfrigo doesn't miss the Haas kicker.

Really - thanks to all who are participating in all this I'm learning ever so much.

And well done Andreas!

I second this.

The recent proliferation of (similarly) related topics has been absolutely riveting. This acoustics forum has certainly grown legs over the last year or so. Life is good!

-MM

Please excuse the terrible lack of punctuation in that last post - it was late

Thanks! Have realized there needs to be more..

Been pondering what to do with the specular reflection Haas triggers. Replacing them with 1D diffusers is an obvious move, but it will take a bit to reach high enough level. How much? Is it possible to guesstimate a minimum area coverage to achieve sufficient level of a diffuse Haas trigger/ISD termination in this room?

Also given that there needs to be more energy sent backwards, ie: less absorption in the front area.

Have also seen a note that specular reflection works best amidst diffused reflections at about same level. Specifically stating that it should not be the first loud reflection. Hard to measure without cross correlation tools.. Though, it'll be worth a try when I get around to having a decent diffuse Haas trigger.

Have obviously only tried the specular variety!

Know it's a bit of stretch to put such things in words, but I wonder if you can make an attempt at recalling what sort of aural difference it makes? Or say something more about the change in general..?




Regarding diffuseres. Have a pinch for PRD's. RSA encryption math, specular suppresion, nonsymmetrical shape, unique depth for each well and all that. Something I'm overlooking? Any reason to avoid 1D PRD's over 1D QRD's in this context? Complexity of build is not an issue.

Had a bit of calculations and found a prime 41 sequence to be suitable:


The generally recommended minimum well width is one inch, 25mm's. Am thinking a divider less design will be less suspect to viscous losses. With 20mm wells, upper cutoff is close to 10kHz. The diffusion range for such a prime 41 1D PRD will be about three times the range of a prime 7 QRD at the same width, with orders of magnitude more complex response.

Have also been thinking about making the diffuser response more parabolic. Keeping the time diffusion asset while concentrating the burst of energy towards the middle. Creating a parabolically shaped diffuser will be extremely difficult, given that the beams needs to be conically shaped. An alternative could be to offset the array so that the middle of the diffuser is deeper than the ends. Shaping the diffuser into an U form.

Ie: a normal prime 13 QRD diffuser is
0-1-4-9-3-12-10-10-12-3-9-4-1. Shaping it into a U would could give
0-1.1-4.2-9.3-3.4-12.5-10.6-10.6-12.5-3.4-9.3-4.2-1.1. (prime 13 QRD used for this example, am thinking about doing the same to the prime41 PRD). Seems logical to me that this would avoid some of the spatial dispersion while keeping the temporal dispersion asset. Any thoughts on this?

Placebo is underrated as a deliberate tool.

In this case, it's more than placebo! Even with eyes closed, bright fluorescent light from the screen backlighting leaking through the eye lids still makes a difference.

Overall lightning is an important aspect of room comfort and concentration. Have a well rooted relation to 15w clear light bulbs(typically used in ovens). Wonder what to do when they run out of supply! Have a bunch of them, and some 25w's, in spots arund the room. No visible bulbs, all hidden in spotlights pointing towards the ceiling, giving indirect diffuse lightning from above. Daylight provides a productive bright environment at the right times, the soft lightning gives the right setting at night.

You moved from Sweden to Norway that's art - Your pizza is super expensive.

Hey I really enjoy this thread - wish I had more time and bigger brain when it comes to room acoustics. Must be cool to have a good sounding room man.

Keep us posted on the progress and please share more pictures. Great stuff baby!

Bra jobbat amigo/gutt!

Hi Andreas,
As a redirect from Q 4 Avare thread...

You mentioned you still have modal issues under 100hz, yet your set up has a prominent ISD termination. I realize the ISD termination is not part of modal region and is suggested as a seperate entity .I have some typical treatment installed, however the -100hz region is atrocious. My thoughts are to attempt designing absorbers in tandem to implement reflection directivity for the ISD termination. The angles and placement is where I'm trying to get a grasp to direct the energy, though difficult due an existing door . I can hear SAC saying: you gotta measure it !!
By the pictures you have extensive clouds. Is the front wall all porous absorbers with reflection controlling panels in front ?

Yep, those are separate issues.

Good idea! Though you have make sure that there actually is a high pressure modal activity region where the early reflections occur. Those you want to redirect with the reflecting action of the deep end absorbers surface. The first axial modes occur pretty much across the whole of the incident surfaces, so they should be pretty safe to target if it is incident on some of the early reflection points.

Perhaps a too short explanation. Do you follow?

Correctly deducted! The front is pretty much all absorbers of various thickness, though not as thick as the rear wall. Most of the front is, as can be seen, covered in reflective sheeting.

The cloud is a bit too much and a bit too concentrated. Am going to do something about that, spreading it more across the ceiling, while also adding more reflecting surfaces to keep more life in the room.

Got it, Suppose I need to make the left front corner somewhat portable where the door is. Above(vertical) that I should be fine. The pesky high pressured ones are +20 db or so are at the front side walls and I may look into a similar approach to what you have.

Thanks Andreas !!

Dear Lupo,
looking at your room photo's, I wonder if your not getting some of that back reflections of what would appear to be hardwood Haas kickers beside each monitor. I would think you would want a RFZ panel there to prevent monitor and rear wall reflections from hitting you. Am I seeing that wrong?
Regards

Hello!

Thanks for the concern!

The reflections from the wall next to the speakers meets sheets of absorption, as normally expected. The reflections that would normally bounce on the far side wall meets the angled reflectors. They serve a dual purpose. They send the early energy towards the back of the room and avoids overdamping the response when the energy from the rear wall flows forward again.

It did take a bit of work to make the angles work correctly! The response in the early reflection structure is now as good as when using an absorber in the same place. With the added bonus of keeping some extra energy in the room. And it fits pretty nicely with the esthetique!

Could you show the first 50ms in greater detail? I am working on a similar goal and would like a better look.

LEDE / RFZ ideas applied to a critical listening room