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Room measurements with KEF R3

Jdunk54nl

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As for the acoustic treatment - I don't have anything on the back wall, it's totally "naked"... Would it be a good idea to hang some panels there and which frequencies would potentially benefit?

You could try hanging a heavy blanket temporary to see if it makes any difference, but with your seating position away from the back wall near the center of the room, I doubt it would do much.
 
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Marcin

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Sorry for spamming with graphs again but I'm still in measuring mode...
I decided to do some movements of the speakers today. Started with 22cm from the front wall (like KEF suggests in the manual as minimum distance). Then I moved it a little bit from the front wall, then also from side walls in two directions, more toe in etc. Finally after many measurements I picked "the best" and this is it for this moment.
KEF's are now placed 32 cm from front wall (measuring from the back of the cabinet), 136 cm from side walls, 230 cm apart. Mic set about 170 cm from back wall.
Green is the new placement, red is old (this time I measured L+R at the same time)
1642168211239.png


1642168275663.png


What do you think of this now?
 
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Jdunk54nl

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Sorry for spamming with graphs again but I'm still in measuring mode...
I decided to do some movements of the speakers today. Started with 22cm from the front wall (like KEF suggests in the manual as minimum distance). Then I moved it a little bit from the front wall, then also from side walls in two directions, more toe in etc. Finally after many measurements I picked "the best" and this is it for this moment.
KEF's are now placed 32 cm from front wall (measuring from the back of the cabinet), 136 cm from side walls, 230 cm apart. Mic set about 170 cm from back wall.
Green is the new placement, red is old (this time I measured L+R at the same time)
View attachment 179000

View attachment 179001

What do you think of this now?

Looks amazing to me. I still feel a subwoofer and some dsp for low frequencies would help there. But not much at all to do with the rest.

More important, how does it sound to you?
 

Jdunk54nl

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Also, don't apologize, this is what forums are for.
 

Dj7675

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Looks to me you are at the point of doing lots of listening and a/b of a few filters. If you want to try to “fix” any remaining room issues, I would recommend doing 1 filter at a time and a/b testing with it on/off to just shoot for audible improvements and/or fixing an issue you find bothersome... but I would think those would sound very good not doing too much to them above where the room starts to affect the sound.
 

ernestcarl

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Sorry for spamming with graphs again but I'm still in measuring mode...
I decided to do some movements of the speakers today. Started with 22cm from the front wall (like KEF suggests in the manual as minimum distance). Then I moved it a little bit from the front wall, then also from side walls in two directions, more toe in etc. Finally after many measurements I picked "the best" and this is it for this moment.
KEF's are now placed 32 cm from front wall (measuring from the back of the cabinet), 136 cm from side walls, 230 cm apart. Mic set about 170 cm from back wall.
Green is the new placement, red is old (this time I measured L+R at the same time)
View attachment 179000

View attachment 179001

What do you think of this now?

Good that you're able to recover some of the bass below 100Hz. And since you've already tried moving the speakers, why not try experimenting with moving the sofa/MLP a little bit forward/back just as well. The benefit may be small, but it may be worth it.

With regards to acoustic treatment panels, given that the walls are bare-naked I'm sure putting at least a few will improve the sound. It is possible that you may not see any obvious improvement at all in the magnitude/amplitude graphs overall, but you are very likely to see some in the time domain graphs e.g. increased clarity and cleaner spectrogram. You could start with a bale or two of some rigid rockboard or comfortboard 60/80 -- no need to create frames as this is just for "testing". Temporarily position them around the room by leaning them against the walls and corners (maybe use an ad hoc spacer with whatever material you can find at home) and measure and compare before and after treatment. I recently vertically placed and staggered two 1.5 inch layers behind my sofa with about a six-inch spacing from the rear wall and several more layers in the rear corners. This raised the clarity (C50) below 400-500Hz on average 5dB more for the rear channels and about 2-3dB for the fronts, though there was no real obvious net effect below 100Hz which was also kind of expected. Though, admittedly, the clarity levels in my room is already mostly in the +20-30dB range so the additional panels were somewhat unnecessary anyway -- I just wanted to do a quick and cheap experiment.
 
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Larry B. Larabee

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In the first graph(post#1) if the green line is the left channel, which I assume it is since my room is similar and has an assymetrical boost at low frequencies, can you show your graphs that include the ports stuffed and if you haven't already done so the graph with only the left speaker port stuffed. That should give you a better match between speakers below 100hz. Also, does the right speaker measure louder than the left from the exact center measuring distance? Again, wondering about room assymetry effects.
thanks
 

hemiutut

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Sorry for spamming with graphs again but I'm still in measuring mode...
I decided to do some movements of the speakers today. Started with 22cm from the front wall (like KEF suggests in the manual as minimum distance). Then I moved it a little bit from the front wall, then also from side walls in two directions, more toe in etc. Finally after many measurements I picked "the best" and this is it for this moment.
KEF's are now placed 32 cm from front wall (measuring from the back of the cabinet), 136 cm from side walls, 230 cm apart. Mic set about 170 cm from back wall.
Green is the new placement, red is old (this time I measured L+R at the same time)
View attachment 179000

View attachment 179001

What do you think of this now?
It is necessary to set the measures of each channel separately and if there is no possibility of putting acoustic treatment, it is necessary to use a manual, powerful and customizable equalization.
Equalization will always be used to a greater or lesser extent.
If you can put acoustic treatment, it is very easy to get a result.
that is very noticeable.
I recommend this channel of this engineer,short and understandable videos.
very well.

Written with translator

Greetings
 
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Marcin

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In the first graph(post#1) if the green line is the left channel, which I assume it is since my room is similar and has an assymetrical boost at low frequencies, can you show your graphs that include the ports stuffed and if you haven't already done so the graph with only the left speaker port stuffed. That should give you a better match between speakers below 100hz. Also, does the right speaker measure louder than the left from the exact center measuring distance? Again, wondering about room assymetry effects.
thanks
Correct, left side is louder in terms of low frequencies. This is because the left and front walls are outer walls that are 50cm thick. Right side wall is only 10 cm thick...
If you stand in the corners of the left wall you can hear deep bass rumbling which you can't really experience on the other side.
So this is a real issue and I can't figure out how to fix it. I tried moving the left speaker in every direction but it didn't help much. The only good thing is that I have curtains on the left side that are covering walls and I could hide some absorbers there. Already tried with rolled carpets in the corners but I couldn't hear big improvements...
 

Kvalsvoll

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Just some of my thoughts...

There is room for improvement beyond what DSP can offer. What's often missing here is an analysis of how the in-room time domain performance can be improved. If planning to acoustically optimize the measured listening position(s) further, at least aim to improve the clarity (C50) below 500Hz with acoustic treatment. The magnitude response below 100Hz may be improved perhaps by experimenting with positional adjustments -- also consider specialized diaphragmatic panels -- but, generally those are rather quite large and expensive, and require much more careful planning. Above that, acoustic absorption panels as thick as 4-6 inches will definitely help.

View attachment 178520
Try aiming for 5-10 dB

View attachment 178530 View attachment 178531
Just to show the difference compared to a controlled directivity speaker in a treated room - C50 is around 30dB, quite a significant difference compared to the 0 to 10dB typically seen in non-treated environments.
 

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  • rom2 F205 clarity C50.png
    rom2 F205 clarity C50.png
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ernestcarl

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Just to show the difference compared to a controlled directivity speaker in a treated room - C50 is around 30dB, quite a significant difference compared to the 0 to 10dB typically seen in non-treated environments.

I can sort of understand clarity in untreated rooms can be much lower, but what caught my attention here is how some of the low-end actually alarmingly hovers below zero which seems like a good indicator of a need for some physical acoustic kind of intervention. Even my untreated main living room’s bass with what I consider to be not so great acoustics — but quite acceptably ‘okay’ — is mostly in the 5dB range.
 
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Marcin

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I can sort of understand clarity in untreated rooms can be much lower, but what caught my attention here is how some of the low-end actually alarmingly hovers below zero which seems like a good indicator of a need for some physical acoustic kind of intervention. Even my untreated main living room’s bass with what I consider to be not so great acoustics — but quite acceptably ‘okay’ — is mostly in the 5dB range.
My common sense tells me that left corners are the reason for the issues you are talking about. What would you recommend for acoustic treatment to get rid of the "boominess" in those corners? Would mineral wool help? I could fill the space in both corners behind the curtains with something up to 20 cm thick and at least 100 cm wide.
 

abdo123

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My common sense tells me that left corners are the reason for the issues you are talking about. What would you recommend for acoustic treatment to get rid of the "boominess" in those corners? Would mineral wool help? I could fill the space in both corners behind the curtains with something up to 20 cm thick and at least 100 cm wide.
Unfortunately that will not help below 100Hz, but it will improve the situation above 100Hz.
 

ernestcarl

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My common sense tells me that left corners are the reason for the issues you are talking about. What would you recommend for acoustic treatment to get rid of the "boominess" in those corners? Would mineral wool help? I could fill the space in both corners behind the curtains with something up to 20 cm thick and at least 100 cm wide.

I really don't know how much of an effect this is going to have, but a single bale/package (200 lbs weight?) of comfortboard 80 has a depth of around 9" or 23cm -- without any frame built for it yet, of course. It's just about impossible to find Rockboard or Comfortboard 60 in our regular hardware stores which is the reason why I just picked the 80 myelf. Dunno what the return policy is of the stores in your place, but the Homedepot about 5 minutes from me allows one to return items if unused. For a quick test, I would just prop the whole unopened package vertically against the corner and take measurements. Even if it does not make a whole lot of difference below 100Hz and you decide you don't want it there, you can still use and cut these into smaller pieces to create individual panels to place all around the room.
 
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EEE272

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I agree with the discussion around room treatment. Before testing it, I was very sceptical, but was surprised how positive the effect is.

Regarding the graphs, I am actually surprised about the treble. It seems to me that the high frequencies seem to fall off rather quickly. Maybe this could be room related but I wondered if your loudspeakers are really oriented towards the listening position? If not, it might explain the falloff and it could be good to change their orientation.
 
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Marcin

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The speakers are on-axis.
It's not the room. I did a test with mic standing 60 cm from the speaker and HF fall was still there for both speakers. I think it is the characteristics of my amp. I have an Atoll IN200 Signature and Cambridge Audio CXN V2 streamer. The measurements were taken with my laptop connected to CXN via USB cable. When I connected the laptop directly to Atoll via mini jack the curve was a bit lower till 10khz and a bit higher after 10khz, but it was actually a smoothing effect in REW. Without any smoothing CXN graph was much broader in db after 10khz, therefore smoothing averaged the curve more to the bottom.
 

EEE272

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The speakers are on-axis.
It's not the room. I did a test with mic standing 60 cm from the speaker and HF fall was still there for both speakers. I think it is the characteristics of my amp. I have an Atoll IN200 Signature and Cambridge Audio CXN V2 streamer. The measurements were taken with my laptop connected to CXN via USB cable. When I connected the laptop directly to Atoll via mini jack the curve was a bit lower till 10khz and a bit higher after 10khz, but it was actually a smoothing effect in REW. Without any smoothing CXN graph was much broader in db after 10khz, therefore smoothing averaged the curve more to the bottom.
Above 10k, I would not worry too much, but there is a lot of fall off even before. While one can expect a tilted slope, it does seem quite strong and maybe it is sounding related.
Would you have the near field measure still available? Did you smooth it more than 1/3? Usually, I would try to opt for +-2dB for on axis in the near field. With time windowing, you can typically easily check the behavior of direct sound down to ~1000 Hz in the room.
 

abdo123

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Above 10k, I would not worry too much, but there is a lot of fall off even before. While one can expect a tilted slope, it does seem quite strong and maybe it is sounding related.
Would you have the near field measure still available? Did you smooth it more than 1/3? Usually, I would try to opt for +-2dB for on axis in the near field. With time windowing, you can typically easily check the behavior of direct sound down to ~1000 Hz in the room.
I showed in a graph earlier that the tilt is optimal. Roughly -5dB around 10-20KHz
 
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Marcin

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2022-01-18 11_25_31-Window.png


RMS average on both channels:
2022-01-18 11_27_16-Window.png


No comment needed I guess... :D
 
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Marcin

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Now I see that something got messed up in REW with magnification... This is the graph with correct one. It's still an improvement IMHO.
2022-01-18 12_07_10-Window.png
 
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