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Acoustics tips and help, please

23K views 37 replies 8 participants last post by  atledreier 
#1 ·
I've been hijacking so many threads in this forum I think it's time to start my own.

My room:
390cm wide by 530cm long, 230cm ceiling.
Floor is concrete (basement) with laminate wood on top. Walls are panelled wood(sp?) for the sides and ceiling. Front wall is plaster with wallpaper, and rear wall is plaster/wallpaper, but with a big glass door to my office.
Some carpeting on the floor, and three bookshelves with books and DVDs. A dysfuntional fireplace and a bit of clutter as well.
A three seat sofa is pretty much all the furnishing in the little room.

There is a 3' opening to a hallway and stairwell in the right wall, just rear of the 1st reflection point. That is covered with a light drape.

My system is off center in the room, after advice I got here, and it works really well. Smoothed out the response and kept imaging, so I'm happy with it. That also made access to the back of the room better.
I have my subwoofer located behind my listening position.

I have in total 5 sheets of 1,5" rockwool acoustics panels, and 3 sheets of 4" Rockwool.
I have treated the sidewall 1st reflection of both fronts with 1,5" panel, and also the reflection off the front wall with 1,5" panels. The 4" panels and a 1,5" panel are straddling corners as basstraps.


I have more acoustic panels on the way, and will make proper floor to ceiling bass traps in every corner of the room.
I have some nasty dips in my response, and I wouldl liek to have them smoothed out. I have had my current setup for about two months now, and I think my house curve might need some adjusting, there's just too much low-end level now. I have a +10dB hard knee curve. It's very cool to have my sofa shake and jump around for action movies, but sometimes it just gets too much. I think I'll try to go with +3dB and live with that for a while and go from there. Or it could be that it's just a little bloated from too long decay or something. I don't really know. I've also though about maybe making some diffusors. I don't wan the room too dead, but I'm an imaging nut, so I want crisp and sharp without being harsh. I know my components can do that, so it's all in the room.

Anyways, maybe some tips to what I can do better? I can post any measurement you like, including REW and trueRTA, so just let me know what you need to assess my mess.. ;)

A picture says a thousand words, so here comes a few thousand words worth of pictures of the room. I had no thought for proper photography when I took these, so bear with me.. :p















My current sweetspot response in green here:
 
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#3 · (Edited)
You should feel it in a nearfield position like I have it... :hsd:

I am not too fuzzed about aestethics.. Maybe I could hang some panels on the doors themselves?

Even though I use it for HT, the main concern is overdampening the room. I listen most critically to music. Maybe some diffusion somewhere?
 
#4 ·
You should feel it in a nearfield position like I have it... :hsd:
Mine rattles the floor on some movie scenes. What more could a bass-lover ask for? :daydream:

Maybe I could hang some panels on the doors themselves?
Sure.

the main concern is overdampening the room. I listen most critically to music. Maybe some diffusion somewhere?
Looking at your photos I don't think that's a problem.

--Ethan
 
#6 ·
Ok, got my panels just now. Going to get the materials and wood I need to get some cornertraps going. Hopefully done over the weekend. I have moved some stuff around, mainly the subwoofer, and the fronts are symmetrical again. Not sure I like it, I'm going to give it a little time and see if I just need to 'unlike' my old setup.. :p
 
#14 ·
Since the thread is revived, I will respond to this. I replaced an 18"x40" coffee table with a 33"x33" ottoman. However, I opened the bottom of the ottoman by removing the cloth, filled it with OC705 and replaced the cloth.

Wow! This sits in the approximate center of my room so, in addition to replacing a hard reflecting surface with a soft transmissive one, I think it is damping some midbass (80-100Hz) energy effectively. Comfy, too.
 
#10 ·
I just finished three more acoustics panels. My four corner chunks were located stacked in the front corners before. Now I have one in each corner, with a 4" panel straddling the corner on top of each of those. That means floor to ceiling basstraps in all four corners! And it really made a difference too! I have another set of small-ish corner chunks that I'm going to finish up today and see if I can find a use for. I'll probably replace two of the corner-straddling panels sith the chucks and use the panels somewhere else. I have another two panels that I need fabrick to cover, so they will come at a later stage. I'll get fabrick tomorrow, probably. Those will go in the ceiling to kill the 1st reflections from LCR. They are also 4".

So now I have 4" panels behind the mains, 3" behind the center, 1,5" on sidewalls, and chunks in all four corners, floor to ceilig! And it sounds rather good to my ears!
 
#11 ·
Ok, finished all the materials I have so far. I'd like some input as to the most effective use of the stuff I have. So I'll list it all;

5 pcs 1 1/4" 2'x4'
6 pcs 4" 2'x4'
4 pcs 3'4" corner chunks, 2' face
2 pcs 2'6" corner chunks, 2' face

Currently I have the 4 larger corner chunks on the floor in each corner.
In the front corners I have one 4" panel straddlign the corner on top of the chunks, so they fill floor to ceiling.
In the rear corners (where I have my sonotubes) I have the smaller chunks stacked on top of the larger chunks, with one 4" panel straddling the corner in front of the smaller panel (if that made any sense).

One 4" panel in the first reflection point from the left speaker. This covers the reflection from the center as well, on the left wall.
Three 1 1/4" panels stacked in front of each other, making one 3 3/4" panel on the right wall in the first reflection from the right speaker. I have a door here that prevent me from killing the center channel reflection on the right wall. I'll live.

Two 4" panels upright against the front wall behind the main speakers, and two 1 1/4" panels next to those, toward the center, and the last 1 1/4" panel horizontal behind the center speaker. So my front wall is covered up to 4' high with at least 1 1/4" and up to 4" (some of the front wall panels overlap)

I plan to get another case of three 4" panels and mount them in the ceiling to kill the 1st reflection from the left, center and right speakers.

The room sounds awesome as it is now. Going floor to ceiling really helped, as opposed to the 6' stacks I had before. Ceiling height is just over 7', but covering that last foot really helped.

I feel maybe having the small chunks behind the 4" panels is overkill and could be put to better use, but then the subs are right against those corners and I figure they can use all the absorbtion they can get back there.

Any views or suggestions as to what I should do? I enjoy the room as it is now, but things can only get better, right? :)
 
#12 ·
Ok, been a while since I posted in my thread now.

Recently made some changes to the lineup. Sold the Dalis and got a set of Klipsch THX Ultra 2 speakers. KL650 front and center, and the KS525 dipole rears. Also changed my screen to a 106" Dreamscreen ProCurve with UltraHD screen material. In the process of putting up a new false front wall and get the speakers behind the screen. Also, since the screen is curved I need to make a shallow stage to accomodate the curve. I will make some other changes to the room as well, trying to move my subs up front in the room, behind the screen wall and see if that works out.

I will keep the corner treatments, and probably try to get some more treatment behind the screen now, and some rear wall diffusion to keep the room lively.

I'll post some pictures shortly.
 
#15 ·
Hybris: Yes, it is definetly timeto do some new measurements. I've done a lot of changes, all the speakers except subs have been replaced, listening position has changed slightly, and the subs have also moved slightly. I will try with the subs up front again, so I will have to do more measurements and comparisons then. I also have to clean up the room and do some photography.

Kal: Great idea! I will definetly try something like that, my midbass definetly need cleaning up!
 
#16 ·
Got around to moving the subs the other day, and did some measurements today.
I used to have the subs behind the listening position, now they are up front, near the corners. I have chunk style traps in all four corners, and got the subs as close to that (touching) as possible.
I sacrifice a little extension for smoothness. It's really not a problem, the subs reach pretty low anyway, just not QUITE into the single digits, and I really like the smoothness of them now.
Also got the new speakers, obviously. Currently sitting on empty cardboard boxes for stands. I will get proper stands for them, and I'm sure the midrange will clear up a bit. The boxes have a pretty high resonance, well into the midrange. The screen fabric needs replacing as it's just too tight now. I could get more of what I have, but the v2 (free upgrade) is due in Q1 2010 anyway, so I won't bother for now.

No pictures of the setup yet, it's not in a photogenic state right now, but some measurements should be in order:

The sweetspot measurement. This is with Audyssey active. I never play without it anyway. 6dB/oct smoothing.




I averaged all the measurements Audyssey used (as close as I could get) and averaged them. This graph has no smoothing.




I accidentally made my first measurement with Audyssey DynamicEQ engaged. This was with master volume at -27dB. Adds quite a bit down low... :hsd:

 
#17 ·
Great low-end response but relatively uneven. How about posting the graph at 15-200hz and no smoothing, easier to see the bass response in detail then. :)

Very interesting to see the effect of the Dynamic EQ on the last graph by the way. That's kind of house curvish. :)
 
#18 ·
Here they are.

Notice that the frequency axis is different in the two graphs.
Also not that Audyssey do NOT target a flat-as-possible response for a single location, but rather a best perceived response in all measured positions. Doing all 8 measurements in the same position give smoother measurements but sounds like ... well, not near as good as a proper measurement.

I am very happy with the way it sounds now, and it's pretty much the smoothest I've seen in my room, so I'll stop fiddling with it for a while.

The DynamicEQ will adjust frequency response to compensate for our ears' varying sensitivity vs levels, so at 0dB master volume the curve will be uncorrected, then as volume goes lower, more and more compensation is added.



First graph is the standard frequency response, unsmoothed and 75dB target. Notice the frequency axis extends to 5Hz.




Waterfall with default settings of the measurement above. You can easily see where my treatments stop working... :hissyfit:

 
#22 ·
It appears you mounted your projector the same way I did (threaded rod)... I slid aluminum tubing over the threaded rods to dress it up and made my equipment racks the same way as the projector stand.
 
#23 ·
Not trying to revive an old thread, but you said you bought the KL650's?

I was dinking around and saw them on Klipsch site, are they worth the money?
 
#24 ·
I no longer have them.

I thought they were great up about 5dB below reference, then they became harsh. Mine were driven by Behringer EP4000, one channel for each, so they should have enough power on tap. They got pretty harsh whenpushed, and I haven't had that happen with any other speakers on the EP4000, so I can only conclude it was the speakers that didn't handle it.
I loved them up to that point, though. Puncy and detailed, but a little on the small side. There's only so much two 6,5" drivers can do...
 
#25 ·
Yeah I thought the stats seemed a bit underwhelming for the price myself, which is why I asked
 
#27 ·
Oh, didn't say that but for the money, it would seem they're better options available.

What are you running now?
 
#28 ·
DIY Beyma LCRs

Two 15p80nd and a TPL-150h in each. 200liters, tuned to 45Hz. The have the SPL capability and sound quality that I've been looking for a long time. They are managed by a MiniDSP 10x10 and an EP4000 to drive each of them. Bulid thread is in my sig. inConcert Miles after the guy who originally designed the configuration, I adapted it for frontmounted slotports.

 
#29 ·
atledreier,

Impressive speakers, these inConcert Miles. I am in the proces of building a house with HT myself. Subs are done, LLT as in sig. I was going to build DTQWT-12 by Troels Gravesen for LCR, but I am having doubts that they will do reference level without desintegrating. Problem is the midrange JA8008. Troels wrote on his website that a 95 dB speaker should not be fed 400 solid state Watts. Which is exactly what I have (Emotiva XPR-5)...

So I am looking for other options, maybe buying active speakers such as the new Emotiva Pro Stealth 8 (also uses the Air Motion type tweeter). Or build an other speaker all together, so your's got my attention. Seems like TangenAVDesign is no longer in business though? I also think going active would be more complicated. Do you think an electric noob like me could pull it off? I see you're an engineer..

Also, what are your surrounds?
 
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