Case Study in Very Small Room Acoustics

sbnx

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Mar 28, 2017
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#1
I thought I would post this to encourage anyone who only has a small room (perhaps a second bedroom) for a hifi system. It is possible to get really good sound in a small room. This past weekend I set up a system for a person in a room that was 11'X10'X9'. Not exactly a cube but pretty close. The system consisted of a pair of 2 way' vivids, a pair of 10" subwoofers, a Luxman integrated and both a digital and analog source. In the end the sound was open and warm with very nice imaging and soundstage.

There is a pic of the axial room modes. As the room is almost a cube they come in groupings of 3. The first length, width, height modes are at 51Hz, 57 Hz and 62 Hz, The second group is at 102 Hz, 112, Hz and 125 Hz. The third group is at 153 Hz, 169Hz, and 187Hz. The fact that the three lowest modes are close but have a little spread means that although there is a large bump in the bass it is also more spread out. When I integrated the two subwoofers we ended up with a very broad bump rising from 90Hz peaking at 60Hz and then dropping down to 20Hz. The sound of this was not objectionable at all. But I am cutting to the end.

I took an initial measurement of the room at the listening position (MLP) and where the speakers were initially located. You can see this in the pic called baseline. This is really not so good. The large peak in the 60Hz region, a peaks in the 110Hz region and the peak at 190Hz. With a big gulf between 120 and 180Hz. Note all of the modal ringing from 90hz to 150hz and again at 180Hz. The ringing causes voices, piano or really anything to sound really thick and not very natural.

We added corner traps to the back corners. The impact of this is seen in the pic labeled "CornerTraps". All of the ringing has been reduced quite a bit. although still not good enough. Note the "ringing" at 120 Hz seen in the waterfall that is not decaying. This is the ceiling fan. This was barely noticeable in the previous baseline. For measurements after this the ceiling fan was turned off. Still have some pretty severe frequency response issues to address.

The next step was to expore how to improve the frequency response issues. I moved the listening position forward. Initially, the ear was about 10" from the rear wall. Once I found the smoothest bass response from 80-300 Hz this is where we planted the chair. This improvement can be seen in the pic labeled "MoveLP". Still not super great but the best within the constraints of the room. The Gulf moved a little higher up in frequency.

I added a 3'X5' 10" thick bass trap mounted on the wall with a 2" gap directly behind the listening chair. This does two things. First, it helps more with modal ringing and second it helps with hf bounce from the rear wall causing listening fatigue. The improvement can be seen in the pic "absorber Behind LP". This really cleared up the ringing at 127Hz and helped a bunch with the 52Hz Mode. Only one mode left to clear up. The one at 112Hz.

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. You can see this in the pic labeled "Absorb Sidewalls". This cleared up the ringing at 112Hz. The waterfall now looks very respectable up to 200Hz (and above) with the exception of the 52Hz fundamental length mode. I know some like to debate the merits of absorbing the sidewall reflection. In this case the speakers are so close to the wall that without them the sound is very hard and edgy. I don't believe anyone would choose to listen without the side panels in place.

The next step is to really dial in the speaker placement. I had moved them a little prior to this but now we are getting down to business with fine tuning precise position, toe-in, level & rake angle. The speakers ended up about 3' from the front wall and about 22" from the side wall. The toe-in was pointed almost directly at the listeners ears. And the speakers were raked up about half a degree. The speakers are farther apart than the listener to the speaker meaning he is sitting a little near field. This coupled with the high toe-in really helps minimize the room effects even further. The final result can be seen in the pic "Speaker Placement Tweaks".

The subs were integrated and unfortunately I don't have a graph of this as I didn't hit save. But as I mentioned the bass gradually rises from baseline and peaks 5dB over at 60Hz and then gradually drops back to baseline by 20Hz. Not optimal but not offensive. Definitely not one-note bass. One interesting thing is that the Luxman has tone controls. These were useful to help flatten the response even further. We could bump up the bass knob which gave a more visceral bass. This is a great feature to have for anyone in an acoustically challenged space.

There are a couple further things that could be done but the customer was finished for now. Bass trapping could be added to the front corners which I feel would greatly smooth the 52Hz mode and enable an overall flatter bass response. Also there is a rather high reflection occurring 7.2ms after the direct sound. This needs to be investigated. 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. Using the JL Audio CR-1 would destress the 30W amp and woofer. If this were used then flat bass could be achieved using the subs at least up to 80Hz.

All-in-all, it sounded really good. I hope anyone with a small room can read this and find direction and hope in achieving audio bliss.

~Todd
 

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sbnx

Well-Known Member
Mar 28, 2017
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#2
The Other pics
 

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Likes: Scott W

JackD201

WBF Founding Member
Apr 21, 2010
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Manila, Philippines
#3
Good job!
 

Scott W

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Apr 20, 2010
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Texas
www.suprahifi.com
#4
Here are a few pictures of the room;
IMG_4991.JPG IMG_4997.JPG IMG_4998.JPG
 

Scott W

Well-Known Member
Apr 20, 2010
245
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Texas
www.suprahifi.com
#5
For me the key to integrating the subs in this this super small room and getting a very amazing sound overall, is the Xilica combined with Todd's crossover specifications. IMG_4995.JPG
 
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kach22i

WBF Founding Member
Apr 21, 2010
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Ann Arbor, Michigan
www.kachadoorian.com
#6
My new listening room is 11 feet wide x 23 feet long with a large Kallax/Ikea record rack dividing the room at the 17 foot mark for an 11'x17' listening space/area.

I am going to attempt a guest seat for side by side listening.

Right now system is not set up, but I am expecting to shift the chairs as needed when solo so I can sit in the center or darn well close to it.

Your project is an inspiration, thank you for posting it.

I think my sub is going to end up just for movies as it will be a two channel and HT room, two systems in one room. We shall see. The concrete floor (carpet) might make taming the bass easier, just do not know yet.
 
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wookie1

New Member
Dec 12, 2019
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#7
Looks like you picked an appropriate sized speaker for a room of this size. The usual trap of trying to shoe horn too large a floor standing speaker is what typically trips up people. Adding small and fast subs is a great way to even out the bottom end response...so long as some kind of acoustic treatments are utilized...which i see you did. A very large floor standing speaker in too small a room is almost always going to sound much worse than a small stand mount or floor stander in a small room. The small speaker wont have the bragging rights of the large behemoth, but it will almost always sound better....
Fitting a system into a small room is...horses for courses.
 
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Scott W

Well-Known Member
Apr 20, 2010
245
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175
Texas
www.suprahifi.com
#8
Looks like you picked an appropriate sized speaker for a room of this size. The usual trap of trying to shoe horn too large a floor standing speaker is what typically trips up people. Adding small and fast subs is a great way to even out the bottom end response...so long as some kind of acoustic treatments are utilized...which i see you did. A very large floor standing speaker in too small a room is almost always going to sound much worse than a small stand mount or floor stander in a small room. The small speaker wont have the bragging rights of the large behemoth, but it will almost always sound better....
Fitting a system into a small room is...horses for courses.
Exactly what we found wookie1(new strategy, let the wookie win ;)). And we knew going in we would need subs for a smooth bass response and this made chosing the smaller 2way speaker the best right choice.
 

sbnx

Well-Known Member
Mar 28, 2017
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#9
Time for an update on this room. Part 1: This person decided to try the JL Audio CR-1 after some encouragement and he has zero regrets. Even a 2 way speaker was way overexciting the fundamental 51Hz room mode making the bass not as clear and precise as it should be. (See Picture labeled baseline) With the CR-1 I could roll the mains off to the point where the 51 Hz mode was more than 20dB down. Then the subs could be integrated using the xilica to provide very flat bass response. The bass is now very articulate, punchy, fast. Using the CR-1 has the added benefit of taking some of the load of the 30W integrated as well as not requiring the 6" driver to move as far. This is now making the midrange even better. (See the final results graphs). We still have a little work to do. There is too much structural resonance in the room below 30Hz to support a flat response. Will give that a 3-6 dB rolloff. Also need to work a little in the 100Hz range for a little better resonse there.
 

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sbnx

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Mar 28, 2017
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#10
Part 2: The dip in the 200Hz range needs to be fixed. A dip in the 200Hz range is not good as this is in the middle register of the piano. This is largely due to floor bounce. I placed a couple panels on the floor and you can see in the graph that the majority of the issue is resolved. Of course panels on the floor is not an ideal option. Will likely get some kind of ottoman to absorb/deflect the bounce.
 

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May 3, 2020
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#11
Looks like you picked an appropriate sized speaker for a room of this size. The usual trap of trying to shoe horn too large a floor standing speaker is what typically trips up people. Adding small and fast subs is a great way to even out the bottom end response...so long as some kind of acoustic treatments are utilized...which i see you did. A very large floor standing speaker in too small a room is almost always going to sound much worse than a small stand mount or floor stander in a small room. The small speaker wont have the bragging rights of the large behemoth, but it will almost always sound better....
Fitting a system into a small room is...horses for courses.
i actually thing going for a small speaker in a small room is another trip up. size has to be within reason, for example, magico q7's or something that size in this room would be insane but a small room shouldn't limit you to just bookshelves and two-ways (though they have a certain type of magic that many listeners - myself included find very appealing). i say this because i run s5's in a medium sized room - bigger speakers just scale in a way small ones can't. for a room this size the s5 would be too much but i think you could probably run an s3 in there. especially at those price points, speakers play extremely well at low levels. if you like near field listening then you probably have even more choices as you can pull out the speakers a bit more.

however, this is a beautiful system on it's own and i hope the owner is enjoying some great music. for a reader already encouraged by OP's post, i wanted to add further encouragement that you can pull off a bigger speaker :)
 

sbnx

Well-Known Member
Mar 28, 2017
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#12
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.
 
Likes: Skanda
May 3, 2020
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#13
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.
yep the carmel 2 and q1's would be my go-to rec for a room that size. aesthetically i think they would look great too.
i've heard great things about the vivids but unfortunately havent been able to hear for myself.

do you have any thoughts on using dsp or even roon equalizer to even out bass response? i'm using a simple roon parametric eq to lower the output on the 50hz area of my s5's as i have a room node there. with that simple change (all tuned by ear and a simple fr app on phone) i had detail POURING out of the speakers. i didn't realize the lower freq's were muddying this since the node was only being triggered on a few tracks - but this change really opened everything up. for what it's worth, my fr output from the app looks more or less just like the stereophile measurements for my speaker
 

defride

VIP/Donor
Mar 28, 2013
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#14
Congrats on getting good sound from a challenging space.

I'm in a similar position. When we moved I went from a 20x13x8 ft room with limited scope for set up as it was also a living space to a dedicated 10.5x14.5x8(or 9 I've not measured!) space.

My speakers are Kharma 2.3ce, bigger than compact floorstanders. Initial fears that they'd overdrive the room were confirmed. Sounded awful in a completely untreated room set up hurriedly in a manner similar to the last place.

Once in I've had plenty of time to experiment. Heavy curtains either end of the room and diffusion at the first reflection. I don't have measuring equipment so it's all been by ear but I've managed to get the system working better than it ever did at the last property.

I concur, it's definitely possible to get a small room singing!
 
May 3, 2020
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#15
Congrats on getting good sound from a challenging space.

I'm in a similar position. When we moved I went from a 20x13x8 ft room with limited scope for set up as it was also a living space to a dedicated 10.5x14.5x8(or 9 I've not measured!) space.

My speakers are Kharma 2.3ce, bigger than compact floorstanders. Initial fears that they'd overdrive the room were confirmed. Sounded awful in a completely untreated room set up hurriedly in a manner similar to the last place.

Once in I've had plenty of time to experiment. Heavy curtains either end of the room and diffusion at the first reflection. I don't have measuring equipment so it's all been by ear but I've managed to get the system working better than it ever did at the last property.

I concur, it's definitely possible to get a small room singing!
this (the 20x13x8) is more or less the same set up of my room. are you in nyc by any chance? that's a very common "living room" dimension here
 

defride

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Mar 28, 2013
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#16
No, I'm in the UK

Think that's fairly common for local living rooms also. Good size for all but the largest of speakers

In the new place it's called a 'Drawing Room' and would be perfect at 15x26x9, I've been banished (but not complaining)
 
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May 3, 2020
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#17
No, I'm in the UK

Think that's fairly common for local living rooms also. Good size for all but the largest of speakers

In the new place it's called a 'Drawing Room' and would be perfect at 15x26x9, I've been banished (but not complaining)
it can work well especiall against the long wall, you sacrifice depth but don't have pesky reflections. on my old contour 1.4 le's i had the short wall set up and near field which was amazing but ultimately, I prefer the bigger speakers. the wall behind the speakers is always annoying to deal with...i'm tempted to make some planars work in here but i might be playing with fire
 

sbnx

Well-Known Member
Mar 28, 2017
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#18
i've heard great things about the vivids but unfortunately havent been able to hear for myself.
Vivid’s have a very special sound to me. The top end is extended but very smooth. They are extremely dynamic. They have a huge soundstage, and i can just listen to them forever. Vivid, YG and Magico all have very different sound. You might try and find somewhere to listen to a pair of vivids just for the experience.

And since we are talking small rooms the tweeter is the same in all of them. So a small vivid sounds like a big vivid.
 

defride

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Mar 28, 2013
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#19
Vivid’s have a very special sound to me. The top end is extended but very smooth. They are extremely dynamic. They have a huge soundstage, and i can just listen to them forever. Vivid, YG and Magico all have very different sound. You might try and find somewhere to listen to a pair of vivids just for the experience.

And since we are talking small rooms the tweeter is the same in all of them. So a small vivid sounds like a big vivid.
The only Vivid's I've heard were at dealer some years back. The original B1, they were set up in free space in the shop with fairly modest equipment and sounded wonderful. A rare shop demo's that left an indelible memory.
 

defride

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Mar 28, 2013
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#20
it can work well especiall against the long wall, you sacrifice depth but don't have pesky reflections. on my old contour 1.4 le's i had the short wall set up and near field which was amazing but ultimately, I prefer the bigger speakers. the wall behind the speakers is always annoying to deal with...i'm tempted to make some planars work in here but i might be playing with fire
I also started out in the bigger room on the short wall with Dynaudio 52's. The floorstanders I used there all worked better down the room.

Here the seating position is nearfield, the tweeters are approx 150cm from the frontwall, 45cm from the side wall and the listening position 180cm from the back wall. I like the presentation however there's a valid argument for sitting further back. Mid hall v front row presentation, in this system I have a preference for front row.

I wonder if Vivid G4 would work in here, similar height but the side mounted woofers might be a problem?
 

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