REW Beta Release REW - Small Room Advice

[rawn027]

Looking for some advise for my small listening room. The focus of this room is a critical listening environment.
This is currently an untreated room. Walls and ceiling are sheetrock, floors are hardwood on a suspended floor with an area rug/pad on top.

Equipment: MacBook Air + REW 5.19 b7a
Room: 11' W x 12' 4" L x 10' H
Speakers: Decware HR-1 Hybrid Radial

• 92.5 dB with 1 watt at 1 meter
• 32Hz ~ 22kHz
• 6 inch radial driver
• 6 inch mid-range driver
• 4 inch ribbon planar tweeter
• 8 inch passive radiator

 

[rawn027]

Used a UMIK-1 with calibration file. Mic was positioned facing the drivers and I used the 90 deg cal file.

 

[Matthew J Poes]

Used a UMIK-1 with calibration file. Mic was positioned facing the drivers and I used the 90 deg cal file.

You want the mic facing the ceiling with the 90 degree file. That is also the correct orientation for room Measurements. It won't make a massive difference but you should adjust and measure again.

 

[Matthew J Poes]

Looking for some advise for my small listening room. The focus of this room is a critical listening environment.
This is currently an untreated room. Walls and ceiling are sheetrock, floors are hardwood on a suspended floor with an area rug/pad on top.

Equipment: MacBook Air + REW 5.19 b7a
Room: 11' W x 12' 4" L x 10' H
Speakers: Decware HR-1 Hybrid Radial

• 92.5 dB with 1 watt at 1 meter
• 32Hz ~ 22kHz
• 6 inch radial driver
• 6 inch mid-range driver
• 4 inch ribbon planar tweeter
• 8 inch passive radiator

View attachment 4808 View attachment 4809

It looks like there are a few issues. I won't interpret anything up high until I see your new measurements in case that is an artifact. I see what looks like comb filtering up high.

Down low it looks like you have significant SBIR cancelation. I would consider two options to address that. First is a different speaker location. However just to be sure of what we are looking at, can you take more measurements at multiple locations at least 24" apart? I would also take at least one measurement at a higher elevation and one at a lower elevation. Your room ratio places the room modes so close together that I want to be sure that I am seeing SBIR (Which won't change with mic position, or modes (which will), or both.

Your room ratio is 1:1.1:1.22, and if you.go here you will see that this is a tough ratio of dimensions for bass eveness. http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=best

Is your listening position dead center of the room or very close to it? If so it would be a good idea to move it some. Different placement of you and the speakers may help reduce that null.

I would also consider treatments to help but the bass null is so low that most panels won't do much. It's also a very small space and so the general advice is more absorption and a lower RT60 than is preferable in a larger space. My suggestion is to consider bass traps covering most if not all of the front wall behind the speakers.

Normally I suggest a range of treatments to avoid making an uneven RT60 and overly dry space. In spaces like you have (my last listening space was similar to this but with lower ceilings), I find you need a lot more dedicated bass traps to get things smoothed out and sounding better.

If you are a DIYer, feel free to diy. If not, please choose whoever you like and don't feel like these recomendations are seeking to sell you on anything (I don't work for Gik). However since I know Giks lineup well I will share my suggested treatment plan.

Front wall: four monster bass traps consider using two range limited and two full range. If you can handle six, that's better and I might suggest 4 as full range.
http://www.gikacoustics.com/product/gik-acoustics-monster-bass-trap-flexrange-technology/

Front corners: four soffit traps
http://www.gikacoustics.com/product/gik-acoustics-soffit-bass-trap/

Ceiling: four 24"x48" 6A alpha panels with 1D diffussion. You could go with 2D if you want but in small spaces with a set listening position it's not as valuable. It is preferable to mount these as a cloud which will extend the Lf absorption.

Side walls: two to three 24x48 panels of 6" depth. I would use either the Monster bass trap or 6A alpha again. You could use a 242 panel to save money but remember you need a lot of bass trapping. The 242 doesn't offer a lot of bass trapping, but this side location is less critical than the front, rear, and ceiling.

Rear wall: two or more monster bass traps range limited. If you have the ability, soffit traps or corner traps in the rear are also good. As crazy as it sounds, covering nearly the entire rear wall with bass trapping can be beneficial in small spaces. It absorbs the bass wave hitting the rear wall and reduces the impact of length axial modes.

If you know you like a lively room feel free to use more of the 6A alpha panels, but know you lose some bass trapping which you need. Because you are trying to address SBIR caused by the front wall and ceiling, the front wall is most important to treat with bass trap panels.

With omni-Radiation pattern speakers it's good to know that this treatment approach is going to absorb much of their reflections. You could add diffussers between the speakers or at the side wall, but I worry you will lose needed bass trapping.

As with anything in audio, you don't have to do this all at once. If I had to prioritize I would do the wall behind the speakers and side walls first. You could do less than I suggested to start, the results just won't be as dramatic.

 

[rawn027]

Ok quick update. Attached is the latest mdat file with the proper calibration file and mic orientation. I have also included the two responses in a single image. The red line is the untreated room.

 

[rawn027]

It looks like there are a few issues.

Wow, what a fantastic reply, thank you for your insight and help. The room layout is a bit tough based on a window and entry way which really restrict my ability to place the speakers in a different location.

I started with bass trapping, with only 4x IsoThermal Tube Traps I have noticed a huge improvement. Hopefully my new measurements will help.

Thanks again,
Ron

 

[Silverprout]

Hello,
At first you should make a drawing of your room (horizontal and vertical), your loudspeakers (size and position of each emitting points on the two drawings) and you listening area (also on the two drawings).
Then perform a vertical and horizontal matrix measurement batch in order to make a first rough attack plan.

 

[Matthew J Poes]

Ok quick update. Attached is the latest mdat file with the proper calibration file and mic orientation. I have also included the two responses in a single image. The red line is the untreated room.

What are the two responses?

Isothermal tube traps are good. I have a business relationship with Art. I like his products but his stuff is a little more expensive.

I found that I could give nearly identical generic advice for rooms like yours that always lead to very good success. The reason is simple, small nearly square rooms always suffer the same problems and they are always the biggest problems. Bass! Lots of modes close together and lots of SBIR close together leading to a bad bass response.

 

[Silverprout]

I have a business relationship with Art.

You have a company ?
Could you tell the name ?

 

[rawn027]

What are the two responses?

The green line is with the tube traps, the red line is without the tube traps. Both are from the same position, the listening position.

Eventually I would like to have 9 total IsoThermal 13" tube traps in my three available corners.
I plan to do 2x 24" x 48" x 4" on each side wall from GIK.

Would you treat the front or side wall next knowing that I have the 6' of tube traps in the corners behind the speakers?

 

[Matthew J Poes]

You have a company ?
Could you tell the name ?

It's just me. I do business under the name Poes Acoustics. It's a side business doing acoustic consulting. I've mostly done commercial spaces in the past. A recent acquaintance is helping me take it more seriously and I'll be putting together a website and such. I'm not quite to the point of doing complete room renderings, my services are primarily before and after measurements and treatment suggestions. For small home projects I can help with design, construction, and installation of custom treatments. For larger commercial projects I use professional companies like GIK or ASC.

Art does custom panel designs for me to meet specific needs. The most common is treating a targeted problem area in the bass. Very large stubborn peaks or nulls in the bass at very low frequencies are best treated with tuned traps, but generic tuned traps won't target the problem area and can do more harm than good if it's really a narrow problem. Gik can make some modifications to their tuned traps, as I understand, but ASC has been willing to make completely custom treatments. For instance my first use of him was for a rear wall membrane trap tuned to 37hz. It worked out well so the client asked about a front wall that provided scattering at higher frequencies, but tuned to address SBIR. He did a customized version of this:
https://www.acousticsciences.com/products/attack-wall


However let me just be up front in saying I get no money from these companies and make no money recommending their products. I freely give acoustic advice here and only charge for acoustic consulting under formal circumstances.

 

[Silverprout]

It's just me. I do business under the name Poes Acoustics. It's a side business doing acoustic consulting.

To be honest, i'm a tad dubitative about you methodology... and about "raw 027" measurements, the traps seems to have no effect at all on the FR amplitude.

 

[Matthew J Poes]

The green line is with the tube traps, the red line is without the tube traps. Both are from the same position, the listening position.

Eventually I would like to have 9 total IsoThermal 13" tube traps in my three available corners.
I plan to do 2x 24" x 48" x 4" on each side wall from GIK.

Would you treat the front or side wall next knowing that I have the 6' of tube traps in the corners behind the speakers?

I would still suggest going with a Gik bass trap product for either. The standard 4" panel still has a lot lessow frequency absorption than the slightly thicker bass trap.

In terms of which to treat next, it's a tough question. Corner traps or tube traps in the corner have minimal effect on the SBIR issues. I would probably use the same product to treat behind the speakers as I would to treat the side walls. Because of the type of speaker I would want to experiment before committing. As such I would buy either the Alpha panels in 6" or the actual bass trap in full range. I would start with them behind the speakers to see. Move them more toward the center between the speakers and see. And finally try them on the side walls. The wall behind the speakers should have the most significant impact on the LF null at 80-90hz.

Silverprout mentioned something earlier that can be important when you start selectively treating. You may want to write down a diagram of your room. Place the speakers and yourself in the diagram and do fairly precise measurements of the distance or both you and the speakers to all other walls (including the ceiling and floor).

After you have done that you can use that information to identify the source of your peaks and nulls. You can mock up your room in REW room modeler. This let's you play around with both treatments and speaker/listener placement, as well as visualize the modes. You can selectively add absorption to each wall and look at the impact. Remember that the room will look anechoic if you treat every wall with 100% absorption. It will look awesome, but is both unrealistic and undesirable in practice. Treat each wall as a composite when adding absorption. You have to fudge the numbers for the absorption of each wall to roughly equal what you get in practice by adding just 16-20 square feet or absorption to each wall with negligible absorption of the bass. I can't say this is right, but using the extended absorption data that companies like Gik publish, I will average the values between ~60hz and 500hz and use that for my wall value. I usually lower the number a bit to account for the fact that the whole wall isn't being treated. For front and rear walls, the correct method is to average the absorption of the treated area with that of the untreated area (absorption =0) and use that as your composite. For side walls SBIR effects are area specific so I'm ok using a higher value as if the whole wall is treated. It will show an over absorption of width modes, but you can also reduce the value for the width as a comparison.

Here is an example model I made for something.


Now the problem with this approach is that it can be hard to read this data and figure out what is what. As such I do something else as well.

SBIR calculator:
http://tripp.com.au/sbir.htm

Plug in all that data about room dimensions and speaker placement here (you need to convert to mm) and look at the values. Line up those values with your peaks and nulls. This is important because you can treat SBIR with speaker position and targeted treatments.

Here is an example of the output for Sonnies room with the recent speaker test in the near wall position (actually a meter from the front wall):

Look at the nulls whose frequencies are near each other. Pretend like those nulls are really deep EQ bands. Say equal to -60 db at those frequencies. Thing about a speakers response if you chain together these negative EQ bands and you can see how cancelation effects that are near each other can cause really wide nulls in the bass. In Sonnie's room you have nulls at 94 and 93hz, 191hz and 200hz, as well as 69 and 64hz. These are estimates and real rooms will shift these a few Hz. Now look at Sonnies measurements from the speaker event.



You can see that the nulls line up fairly well. He has peaks at 96hz, 120hz, and 191hz. Again you see good alignment.

Hopefully this is helpful for you to now explore the sources of your bass distortions and make decisions on where to treat.

 

[Matthew J Poes]

To be honest, i'm a tad dubitative about you methodology... and about "raw 027" measurements, the traps seems to have no effect at all on the FR amplitude.

That's fine you don't have to agree. His measurements show small improvement because he doesn't have enough bass traps to show a big improvement. This is normal. Additionally corner traps don't have much of any impact on SBIR.

I have plenty of case studies of my treatment consultations yielding massive improvements and very happy clients (understanding that bass never looks perfect with just acoustic panels in even the best rooms).

If you feel there is a specific flaw in my recommendation I'm happy to have you point it out and explain your rationale.

 

[Silverprout]

Sonnie's room.

The measurements are averaged ?
How many ?
Why don't you use CSD in order to locate ringings, and judge the real effect of the treatements ?
There are peaks of 20dB of amplitude under 200Hz and peaks of 10dB of amplitude over 200Hz, you ears should bleed !

 

[Matthew J Poes]

The measurements are averaged ?
How many ?
Why don't you use CSD in order to locate ringings, and judge the real effect of the treatements ?
There are peaks of 20dB of amplitude under 200Hz and peaks of 10dB of amplitude over 200Hz, you ears should bleed !

Silverprout I'm happy to discuss this with you. Discourse is fine with me, but I suggest we do it elsewhere and leave such discussions out of this or similar threads so it can stay on topic.