Case Study in Very Small Room Acoustics

sbnx

Well-Known Member
Mar 28, 2017
187
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60
#21
half a meter to the sidewall is sufficient for the vivid woofers. I know a person who has G1's less than a meter from the sidewall and it sounds great.
 

kach22i

WBF Founding Member
Apr 21, 2010
1,500
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Ann Arbor, Michigan
www.kachadoorian.com
#22
I added two absorber panels (2'X5"X 7" thick) to the side walls at the point of first reflection. This does two things. First it absorbs that nasty reflection from the side wall and second, it help s with the modal ringing of the width modes...........

The equipment was spread across the front wall between the speakers. Although the speakers were about 1' in front of it, moving the equipment to the side wall toward the rear of the room would be beneficial. It would not interfere acoustically between the speakers and would allow greater flexibility in speaker placement.
Question-1:

Can you post a photo of entry door with 7" deep absorber mounted to it?


Question-2:

The more reading I do, the more I understand your design of this room.

I assume the 7-inch deep first reflection side panels are full range which is as I understand is how it should be, but does this actually narrow the room at that point?

Question-3:

In my small room my DIY early reflection curved diffractors may be giving me ringing as you describe, but is far less damaging than my attempts at absorption at same point.

In your opinion can curved products from Acoustic Geometry, Flex-48, and others serve both as diffusers of highs and mids plus serve as absorbers of low frequencies?

I've read the charts in product testing PDF's but lab tests involve 8'x8' arrays of multiple diffusers and not single units at sidewall locations.

Question-4:

Appears that you know equipment side wall location after the early reflection points is best. Yet equipment is on front wall. Was this because of the client request/ demand/expectation?

Was this a future battle, one you did not want to fight right now?
 

sbnx

Well-Known Member
Mar 28, 2017
187
111
60
#23
Question-1:

Can you post a photo of entry door with 7" deep absorber mounted to it?


Question-2:

The more reading I do, the more I understand your design of this room.

I assume the 7-inch deep first reflection side panels are full range which is as I understand is how it should be, but does this actually narrow the room at that point?

Question-3:

In my small room my DIY early reflection curved diffractors may be giving me ringing as you describe, but is far less damaging than my attempts at absorption at same point.

In your opinion can curved products from Acoustic Geometry, Flex-48, and others serve both as diffusers of highs and mids plus serve as absorbers of low frequencies?

I've read the charts in product testing PDF's but lab tests involve 8'x8' arrays of multiple diffusers and not single units at sidewall locations.

Question-4:

Appears that you know equipment side wall location after the early reflection points is best. Yet equipment is on front wall. Was this because of the client request/ demand/expectation?

Was this a future battle, one you did not want to fight right now?
Hello kach22i. I posted a pic of the door side. This picture is at an angle so it looks like the panel sticks into the room farther than it actually does. It is not mounted to the door. A room this small has some space challenges. The panel is placed over half the door and half the wall. We put furniture sliders on the bottom so he could slide it in and out of place easily when he goes in to listen to music. Not ideal but you gotta do what you gotta do.

So on the topic of sidewall treatment. The speaker is very close to the sidewall (as you can see) so the sidewall delay is less than 5ms. Without the absorber it sounds really harsh and pingy. Of course one can get rid of the high frequency ping with a much thinner absorber but in this case we also need the low frequency absorption to help smooth the overall low frequency response. This 7" absorber is absorbing 60% at 100Hz. A diffuser would not do this. If your room is big enough that the sidewall delay is >10ms and your speakers have smooth off axis response then a diffuser works.

The equipment between the speakers is a compromise for sure. I guess you could say we are slowly walking down the path. I make a bunch of suggestions. I fix one thing -- make suggestions, he hears how good that sounds and then want to take the next step. So far we have been really focused on fixing the bass. As until that sounds good the rest will not really be as noticeable. I actually gave two suggestions on the equipment position. The first is simply to move it to the side wall. The main issue here is cables (which he has quite a bit invested in). The second suggestions was to put the equipment in another room. On the other side of the front wall is his home office. We could just set everything up along that same wall (on the other side). Drill two holes through the wall to run the speaker cables and Bob's your uncle. Would be a little inconvenient when using the TT but no issues at all when streaming which is what he does 95% of the time.

One other point. The stuff in the very front (curved diffusers and Aurelex) was not mine. I don't think it does any harm and is probably better than just a bare wall. I would prefer to see some type of skyline diffuser in this space.

How big is your room? Don't worry if it messes things up when you treat the sidewall reflection. With acoustics I find that in many cases it is an iterative process. Treat the sidewall. Treat the corners. Then find the best place you can sit. Then position the speakers (adjust sidewall if needed). You may also find another reflection point that needs to be treated. And as you work you zero in on a fantastic sound.
 

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kach22i

WBF Founding Member
Apr 21, 2010
1,500
172
225
Ann Arbor, Michigan
www.kachadoorian.com
#24
Quote:
The panel is placed over half the door and half the wall. We put furniture sliders on the bottom so he could slide it in and out of place easily when he goes in to listen to music. Not ideal but you gotta do what you gotta do........End Quote.

Simple is good, I too have a door at the wrong spot. First reflection is right at the door handle.

Link:
https://www.whatsbestforum.com/threads/kach22is-system.30259/

I do not have bass issues at the moment because my small room is not yet closed off.

Right now I am struggling to have zing without the ping.

May have to get more serious about absorption, have been reluctant and using only what I have on hand from other projects to explore mostly diffusion.

To go further I will have to get supplies such as mineral wool from the local big box home improvement store.

I think some LVL's and brackets are going to come first though so I can remove a post located right where my left speaker wants to be.
 

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sbnx

Well-Known Member
Mar 28, 2017
187
111
60
#25
It looks like your speaker is too close for the cylinder to work well. If you want to dry diffusion maybe something like a couple of the GIK Gotham 23's. you could also try something with a lot of flexibility like the Vicoustic totem. You can mix and match to tune to the sound you are looking for.
 

kach22i

WBF Founding Member
Apr 21, 2010
1,500
172
225
Ann Arbor, Michigan
www.kachadoorian.com
#26
It looks like your speaker is too close for the cylinder to work well. If you want to dry diffusion maybe something like a couple of the GIK Gotham 23's. you could also try something with a lot of flexibility like the Vicoustic totem. You can mix and match to tune to the sound you are looking for.
Great recommendations of what to look into.

If I combine several of my sketchbook ideas together the ViscTotem looks close to an idealization of them.

The videos of what I think is a Frenchman explaining the construction of the Totem and the corner bass trap are most illuminating.

I also found an interesting product by Wenger, see below.

 

Loheswaran

Well-Known Member
Dec 20, 2014
337
50
78
#27
Good thread - I have a small room in my loft which I have had fully soundproofed.
Whwn I had Yamaha NS1000M's they overpowered the room, not just that but the mid and treble drivers were bouncing off the walls. I then bought a pair of Roksan DArius S1's - it has worked wonders - the ribbon tweeter with it's more direct dispersion helps an awful lot as does the smaller bass driver.
I have a drop at 95 hz and this is after front and sidewall panels being used.
I am thinking about a small sub - but I'm wondering if I can find one to deal wit hthe deepest dip at 97hz
 
Dec 29, 2015
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0
31
#28
The speaker he has in the room is about as large a speaker that would logistically fit into a room that size. I would have no objection to a small 3 way speaker (or even 4 way like the Giya G4). The main goal of this would be to spread the "load" that is carried by the woofer in a 2 way design. But whatever speaker that is chosen it needs lot be already lean in the bass for a room this small. I think the Magico Q1 would be awesome. A sealed design is best as we are trying to roll off the bass anyway. I don't need a port trying to boost the bass output of the mains. Another good choice would be the YG Carmel 2.
Interesting stuff.
I have a 13' x 13' x 8' listening room.
Your comment about a two-way with a lean bass presentation is spot on.
I use the fabulous Hales Signature Two to great advantage.
It's a fairly big speaker but works great.
I use two Genesis 12" Subs for stereo effect and a center Revel B15 for the down and dirty bass notes.
No crossover with the Hales. These subs have many control parameters to tweak.
I'm flat down to about 22 Hz with zero bass boominess.

The concrete floors are covered with a 1/2" thick pad and an interior rug.
For the corners I use rolled up floor carpets from floor to ceiling.
On the walls and ceiling, I use a combination of Acoustic foam, cardboard wine packing holders and tons of toilet paper and paper towel interior cardboard holders (mini poly's).
My room is a REAL conversation piece.
The Hales LOVE a dead room and mine is definitely deceased!
 

sbo6

Well-Known Member
May 19, 2014
1,033
122
135
Round Rock, TX
#31
Great job! You might find that raising the subs off the floor makes quite a difference in the articulateness of the bass. 1-2 feet is a common distance to raise them and experiment.
 

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