Improving sound in high reflective room, help needed

[Miguelón]

Hi everybody!

For dust mites allergy, I have a quite nude living room. Cannot be considered “moderately reflective” because no carpets nor curtains.

My room is approximately 5 x 5 meters, you can see a sketch with main elements in different colors:

-Green: glass windows and door at the top, a TV large screen at right I can move with wheels and place were I want, normal position in that place.

-Yellow: a kitchen bar 1 m high at top left, bookshelves at top right with a little column, a false wall with wardrobe at bottom slightly on the left.

-Blue: big sofa, only absorbent surface in the room.

-Red: speakers on floor stands, circle with L an office chair where I listen analytically.

I ask for advices on room reflections, mainly from the floor (impossible to put carpets, should equalize?), the corners between the rear wall and kitchen bar (less problematic) and the most conflictive one: at top right with 3 levels of bookshelves and the column (yellow little square) with a messy mids reflections and bass “tramp”.

I can use only foams or other acoustic treatment, no curtains or other fabrics. I consider both EQ and treatment, if possible minimum EQ for room modes.

Thanks for help!

P.S: I didn’t show the table on the sketch because except for eating or studying is folded, my apartment is very little and use free space for yoga and other exercises.

 

[Duke]

This is just my opinion...

If feasible, I would look for narrow-pattern speakers whose off-axis response closely matches their listening-axis response.

"Narrow pattern" so that the direct-to-reverberant sound ratio remains fairly high even though the room is highly reflective.

"Off-axis response closely matches their listening-axis response" so that the in-room reflections do not degrade the sound quality. An unamplified acoustic guitar probably sounds great in your room because the reflections are spectrally correct. Imo that same principle can apply to loudspeakers.

Regarding room treatment, my instinct is to rely more on diffusion than on absorption, unless you can use truly broadband absorption. Here's why: Foam panels which are not thick enough to be truly broad band attenuate the short wavelengths far morso than the longer ones, so they degrade the spectral balance of the reflections. The ear/brain system looks at the overtone structure to correctly identify reflections as such. If too much of the overtones are removed, the reflections cease to be recognizable as "signal" and become "noise".

 

[kemmler3D]

Since fabric is off the table, I would suggest using BAD (binary amplitude diffuser) panels backed with foam or rockwool. These are effective for both scattering and absorption, often for pretty wide frequency bands, and you don't need to use cloth coverings.

Or you could go further and just do a lot of hard surface diffusers.

This won't decrease the overall decay time too much but it does make reflections less problematic.

 

[Miguelón]

This is just my opinion...

If feasible, I would look for narrow-pattern speakers whose off-axis response closely matches their listening-axis response.

"Narrow pattern" so that the direct-to-reverberant sound ratio remains fairly high even though the room is highly reflective.

"Off-axis response closely matches their listening-axis response" so that the in-room reflections do not degrade the sound quality. An unamplified acoustic guitar probably sounds great in your room because the reflections are spectrally correct. Imo that same principle can apply to loudspeakers.

Regarding room treatment, my instinct is to rely more on diffusion than on absorption, unless you can use truly broadband absorption. Here's why: Foam panels which are not thick enough to be truly broad band attenuate the short wavelengths far morso than the longer ones, so they degrade the spectral balance of the reflections. The ear/brain system looks at the overtone structure to correctly identify reflections as such. If too much of the overtones are removed, the reflections cease to be recognizable as "signal" and become "noise".

Speakers are Genelec 8030C, I’m not going to change them because I like so much how they sound: even quite aggressively equalized (-8.5 dB needed on 70 Hz in the right speaker and -7 dB at 150 Hz).

Probably a sub will improve under 100 Hz response, because will avoid the most severe mode at 70 Hz. I tried F Two and the system get much better, just I returned because I discovered 7050 to be better and cheaper. I’m waiting for the money back to get it.

The right side is by far the acoustic nightmare, if I sacrifice soundstage and put speakers closer and more to the left the sound improves so much.

Sorry for the mess, here is the floor stand at right, I’m moving things now.

Should I put the diffraction panels on the wall at this corner?

Post edited: I’m not a soundstage super fan, most of time I listen music when I do other things I prefer just mono reproduction on just one speaker (out of sweet spot stereo sounds quite messy), and the advantage of floor stands I chose is that I can get them to the front on a rainy day when I’m going to listen music or watching movies, and remake the living room moving the TV to get a proper image in front of the sofa.

 

[Miguelón]

Since fabric is off the table, I would suggest using BAD (binary amplitude diffuser) panels backed with foam or rockwool. These are effective for both scattering and absorption, often for pretty wide frequency bands, and you don't need to use cloth coverings.

Or you could go further and just do a lot of hard surface diffusers.

This won't decrease the overall decay time too much but it does make reflections less problematic.

Since fabric is off the table, I would suggest using BAD (binary amplitude diffuser) panels backed with foam or rockwool. These are effective for both scattering and absorption, often for pretty wide frequency bands, and you don't need to use cloth coverings.

Or you could go further and just do a lot of hard surface diffusers.

This won't decrease the overall decay time too much but it does make reflections less problematic.

I see, this will improve over 250 Hz irregularities, I tried to put a lot of books on the bookshelves but are quite bad attached to the wall and had to reinforce by two exercise bars (see image) on the bottom one. Over the others I can put panels and perhaps between the first and second one, depending on thickness.

 

[dedobot]

Something like this on the floor ? :

No fabric , its a an soft rubber. You can wash it easily when needed.

 

[Miguelón]

Something like this on the floor ? :
View attachment 429583

No fabric , its a an soft rubber. You can wash it easily when needed.

Interesting, now I have some elements that can move by wheels (TV, chairs) so perhaps will disturb my daily life because I move them quite often. But is a good suggestion and take into account.

 

[dedobot]

Interesting, now I have some elements that can move by wheels (TV, chairs) so perhaps will disturb my daily life because I move them quite often. But is a good suggestion and take into account.

It's a for kids. I had same but with different print in my son's room. Its very lite, but thick and stable and is pleasure to walk on it.

 

[markstein]

If you need absorption you could look into Basotect foam absorbers which are available also in white and look good without fabric cover. They should be thick enough though (min. 100mm). Can be used especially for the ceiling. Also available in circular form factor with suspension, so you can build a visually appealing cloud.

Basotect

plastics-rubber.basf.com

 

[markstein]

Unfortunately a German site, but the principle becomes clear:

Deckensegel aus Basotect® Kreise (ohne Stoffbespannung) 2 Stück

Preis gilt pro Set (2 Stück) Sind Sie wegen der Farbauswahl unsicher? Dann bestellen Sie eine Muster Platte. Diese Artikel wird individuell für Sie gefertigt. Bitte beachten Sie die AGB.

xb-acoustics.de

 

[Miguelón]

Unfortunately a German site, but the principle becomes clear:

Deckensegel aus Basotect® Kreise (ohne Stoffbespannung) 2 Stück

Preis gilt pro Set (2 Stück) Sind Sie wegen der Farbauswahl unsicher? Dann bestellen Sie eine Muster Platte. Diese Artikel wird individuell für Sie gefertigt. Bitte beachten Sie die AGB.

xb-acoustics.de

Is not better a diffuser than an absorber?

 

[markstein]

I am no expert, however, from my understanding both absorption and diffusion need to be used carefully and strategically not to worsen the situation (overdamping, changing reflections spectrally, damping "good" reflections...). There is no "one fits all" concept. Other people might have the knowledge to provide your more detailed guidance.

 

[Soniclife]

Nearfield listening reduces the impact of the room.

You can use subs to absorb bass, which is hard to do with anything less than extreme treatment. DSP helps a lot at the bottom end, but isn't good for this problem as you go up in frequency.

 

[Randolf]

Hi,

I guess you are running on limited space and budget. I would start with an actual measurement. Looks like you already have an audio interface and probably a computer, perhaps even a suitable microphone. Get free REW software and eventually a measurement microphone (USB UMIK-1 or even cheaper perhaps Behringer ECM8000 attached to your audio interface). This way you can easily measure the actual in room response, you can also measure the speaker's quasi anechoic response above ~300Hz using a time gated measurement. This could already help to configure your equalization (in WiiM ?) more properly. You may think about building a cheap Helmholtz resonator to suppress the strongest room mode (https://homeaudio.jimdofree.com/). It could be as simple as a square box with some holes, you can also use it as a sofa table. You could also use REW to simulate room modes for you actual room dimensions, speaker and listener position. This may help you to optimize your positioning. If you want to know what excellent room correction could do for you you can get a free DiracLive trial license for 14 days on your PC. Cheapest DiracLive hardware to day probably is Pioneer VSX-LX305 or miniDSP DDRC-24 (if you can integrate it well into your system).

Best regards
Randolf

 

[markstein]

I would recommend multiple subwoofers (at least 2, better 3) plus optimization using MSO software (free download) for bass management.

If "room equalization" is done, I recommend the MMM method using pink noise and no equalization above approx. 500 Hz (above only if you really know what you are doing).

 

[Miguelón]

Hi,

I guess you are running on limited space and budget. I would start with an actual measurement. Looks like you already have an audio interface and probably a computer, perhaps even a suitable microphone. Get free REW software and eventually a measurement microphone (USB UMIK-1 or even cheaper perhaps Behringer ECM8000 attached to your audio interface). This way you can easily measure the actual in room response, you can also measure the speaker's quasi anechoic response above ~300Hz using a time gated measurement. This could already help to configure your equalization (in WiiM ?) more properly. You may think about building a cheap Helmholtz resonator to suppress the strongest room mode (https://homeaudio.jimdofree.com/). It could be as simple as a square box with some holes, you can also use it as a sofa table. You could also use REW to simulate room modes for you actual room dimensions, speaker and listener position. This may help you to optimize your positioning. If you want to know what excellent room correction could do for you you can get a free DiracLive trial license for 14 days on your PC. Cheapest DiracLive hardware to day probably is Pioneer VSX-LX305 or miniDSP DDRC-24 (if you can integrate it well into your system).

Best regards
Randolf

Thanks, effectively I’m running on limited budget

Biggest issue is the two modes that resonate more time than other sounds, mainly 70 and 140 Hz but cannot trust accurately because I used a older mic that was not made to calibration, and the iphone mic: more or less coincide on the main lower end modes frequencies but not on the decibels.

I will purchase a Umik 1 as soon as I have my subwoofer (Genelec 7050 ordered). When rolling off on 85 Hz left and right channels on WiiM Ultra (just by activating sub output automatically applies the roll off filter) things improve a lot, leaving just one mode at 140-150 Hz and the messy reflections on the right speaker.

Thanks for the suggestion about Dirac live, but I find some fun on hand made corrections, so for instance I think that should go with REW and UMIK 1 or Behringer.

I have the impression, maybe just my imagination that a lot of EQ give some unrealistic feeling or is just WiiM auto correction is very inaccurate. I can tolerate imperfections and some resonances, that make part of what happens when I play my piano but don’t like when prolongated “hummmms” invade the room and disturb mids and highs.

Eventually I correct another 3d mode that appears at 310-330 Hz, I suppose is a mode and not a reflection because this prolongation sound and appears both in left and right speakers, or if I place one just at the middle of the room.

I had a Genelec F Two some days for trial and another very little 42 Hz mode appeared, but was easy to correct.

I will try to fill the bookshelves by toys and some gym light material to help diffusing sound from the right, yesterday au discovered that also placing a chair on the corner attenuated low end (unfortunately not adding clarity, just dumping the lows)

Post edited: nice to read REW simulator on rooms acoustics, I enjoy learning a little of that field when trying to improve my music experience, that makes part of the fun! A reason to avoid automatic software for instance, I can live with imperfections but I can’t live without knowing where and why they appear.

 

[Randolf]

...
Thanks for the suggestion about Dirac live, but I find some fun on hand made corrections, so for instance I think that should go with REW and UMIK 1 or Behringer.

I have the impression, maybe just my imagination that a lot of EQ give some unrealistic feeling or is just WiiM auto correction is very inaccurate. I can tolerate imperfections and some resonances, that make part of what happens when I play my piano but don’t like when prolongated “hummmms” invade the room and disturb mids and highs.
...
Post edited: nice to read REW simulator on rooms acoustics, I enjoy learning a little of that field when trying to improve my music experience, that makes part of the fun! A reason to avoid automatic software for instance, I can live with imperfections but I can’t live without knowing where and why they appear.

Using REW and UMIK-1 to understand the problem and trying to improve it with your own (or REW generated) PEQ is for sure great and you will probably learn a lot. On the other hand I doubt that in a more complicated case you can manually achieve results as good as DiracLive does, at least I can't. It is doing a lot more that just fixing some low frequency room modes, for me the midrange and stereo image improvement was the most outstanding benefit. In contrast to my own PEQ it never degraded the sound noticeable for me. DiracLive seems to focus on impulse response and combines IIR and FIR filters. Theoretically you could do all that by your own. I found reading https://www.dirac.com/wp-content/uploads/2021/09/On-equalization-filters.pdf very interesting. Therefore using the free DiracLive trial is a great option to find out, if DSP correction is beneficial in your situation and something you like or dislike. You could even inspect the frequency response of a DiracLive filter if you want, I did it simply by measuring my DDRC-24 after DiracLive calibration.

 

[Miguelón]

Using REW and UMIK-1 to understand the problem and trying to improve it with your own (or REW generated) PEQ is for sure great and you will probably learn a lot. On the other hand I doubt that in a more complicated case you can manually achieve results as good as DiracLive does, at least I can't. It is doing a lot more that just fixing some low frequency room modes, for me the midrange and stereo image improvement was the most outstanding benefit. In contrast to my own PEQ it never degraded the sound noticeable for me. DiracLive seems to focus on impulse response and combines IIR and FIR filters. Theoretically you could do all that by your own. I found reading https://www.dirac.com/wp-content/uploads/2021/09/On-equalization-filters.pdf very interesting. Therefore using the free DiracLive trial is a great option to find out, if DSP correction is beneficial in your situation and something you like or dislike. You could even inspect the frequency response of a DiracLive filter if you want, I did it simply by measuring my DDRC-24 after DiracLive calibration.

But DIRAC needs a dedicated DSP or a streamer compatible with it, am I correct?

In the future I will try it, I know you’re trying to express when noticing the degradation of sound when trying to correct midrange by ear.

At first trials I thought that was just the fast Fourier transform and reverse process that losses information but a kind member told me that actual DSPs are well above significant audible effects. So it wast just a failed trial to approximate a frequency amplitude that has primary reflections influences and should be measured and pondered from various room points, I don’t know how to do this.

For instance I will try to learn as much as I can for the main issues at standing waves levels, surely after I will go to a Dirac compatible DSP.

I’m considering to move with time, currently chosen a little apartment at very centric location close to my job, but space is a problem to many things including acoustics. A lot of pollution for nose allergy and very noisy, so probably I will go to the surroundings close to sea

 

[Randolf]

But DIRAC needs a dedicated DSP or a streamer compatible with it, am I correct?
...

You can run DiracLive in Software of your Computer. This limits you to the using the computer as the source for you music. For just testing it this is probably fine, for every day usage probably not for most of us. For this version you can get a free trial licenses. Otherwise you need a pre amplifier, amplifier, AVR or one of the miniDSP products supporting DiracLive. On https://homeaudio.jimdofree.com/dirac-live/ I am maintaining a list of the more "affordable" options.

 

[krabapple]

This is just my opinion...

If feasible, I would look for narrow-pattern speakers whose off-axis response closely matches their listening-axis response.

"Narrow pattern" so that the direct-to-reverberant sound ratio remains fairly high even though the room is highly reflective.

And/or, listen in the near field with speakers toed in

He likes his Genelecs (which are excellent) so he won't be changing speakers.

"Off-axis response closely matches their listening-axis response" so that the in-room reflections do not degrade the sound quality. An unamplified acoustic guitar probably sounds great in your room because the reflections are spectrally correct. Imo that same principle can apply to loudspeakers.

Regarding room treatment, my instinct is to rely more on diffusion than on absorption, unless you can use truly broadband absorption. Here's why: Foam panels which are not thick enough to be truly broad band attenuate the short wavelengths far morso than the longer ones, so they degrade the spectral balance of the reflections. The ear/brain system looks at the overtone structure to correctly identify reflections as such. If too much of the overtones are removed, the reflections cease to be recognizable as "signal" and become "noise".

Smart/informed audiophiles don't use 'foam panels', they rockwool that is 4" or more in thickness.