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Tool for identifying room treatment?

nebunebu

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Sep 20, 2022
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Hi all,

This question has probably been brought up before, i'm sorry to bothering you with this - once again.

I've watched some youtube videos from community members here on how to do a measurement of room with REW and UMIK-1 microphone.
The videos i've found contains knowledge on how to use the tool and the effect of doing a proper room treatment, however I can't seem to find a "tool" that says:

- If you are experiencing long decay time in this area - do this treatment.
- If you are experience this other thing - do this treatment

Again, sorry for probably bothering you all with a question that has been reapeated endlessly..

As I mentioned, I've performed a measurement of my Klipsch RP600 MK2 (I know not exactly high end hifi, but it suits my purpose and budget).

Below shows the waterfall graph for the measurement and my questions are highlighted with number 1 to 3.

1. What type of treatment would be best to attack decay time in this range?
2. What type of treatment would be best to attack decay time in this range?
3. If I understand correctly, if I reduce this with EQ I might also reduce decay time as its "overpowering" compared to the other frequencies?
1727891808384.png


1727892058797.png


Room measurements are: 6m (19.68inch) length x 4m (13.12inch) width x Ceiling height max 3.8m (12.4 inch).
1727892856963.png


This is the start of my journey building a room for listnening =)
 
I've watched some youtube videos from community members here on how to do a measurement of room with REW and UMIK-1 microphone.
The videos i've found contains knowledge on how to use the tool and the effect of doing a proper room treatment, however I can't seem to find a "tool" that says:

- If you are experiencing long decay time in this area - do this treatment.
- If you are experience this other thing - do this treatment
I don't believe such a tool exists, at least, not that I'm aware of. There are rules of thumb and simplistic calculators out there, but what you are looking for comes from knowledge of the topic and attention to what you are hearing.

Below shows the waterfall graph for the measurement and my questions are highlighted with number 1 to 3.

1. What type of treatment would be best to attack decay time in this range?
2. What type of treatment would be best to attack decay time in this range?
3. If I understand correctly, if I reduce this with EQ I might also reduce decay time as its "overpowering" compared to the other frequencies?
View attachment 396168

View attachment 396169
A few comments that may or may not be helpful: 1) FFT analysis trades time resolution for frequency resolution and the settings in that waterfall are such that you are seeing very poor resolution in the time domain, so I would not use that specific graph to assess much of anything in the way of decay times.
2) If decay times are in fact too long at middle and higher frequencies, resistive absorbers are what you would typically use (i.e. fiberglass, open cell foam, fabrics, etc). If it's too long at low frequency, reactive absorbers (i.e. resonators, diaphragms, etc) or special processing of multiple low frequency sources is the usual go to.
3) You are correct that EQ can usually be used to reduce low frequency decay.
Room measurements are: 6m (19.68inch) length x 4m (13.12inch) width x Ceiling height max 3.8m (12.4 inch).
View attachment 396174

This is the start of my journey building a room for listnening =)
It's a small room, so I wouldn't be too concerned about decay times, personally.

If it were me, I'd EQ the bass down some, and maybe put a large, thick, absorber behind the couch. Then reassess. But that might be all I'd do. Then again, I don't know what that room sounds like, so may sound ok as is.
 
This question has probably been brought up before, i'm sorry to bothering you with this - once again.

Do you have the .mdat file from those measurements that you can post here or on a filesharing site like Google drive?
 
The best tool - if I can call it that, and if you have the patience - is the combined experience and willingness to help of the membership here
 
Or contact one of the treatment suppliers, ie GIK, and have them make recommendations for your room, etc. They may want pictures, room dimensions, equipment, etc. I don’t recall as it’s been years since I went through this exercise. Best part, it’s a free service
 
I can give you some ideas to start with.

You have a lot of reflective surfaces. The decay times in the upper frequencies are likely coming from back and forth reflections from your front/rear walls, and the left speaker is probably more at fault. So some treatment to the front or back seems in order. A fabric wall hanging perhaps? If you can hang a blanket, that's a good test of concept.

I'm not sure what the other side of the room is like, but you might also get some issues from left and right.

Is the space above the speakers open to other spaces? If so, you could TRY flipping your speakers and angling them very slightly upward, try to send more reflections out of the room. Sometimes that can help, though there are downsides.

You could also raise the speakers a bit, and angle them down slightly. So more towards couch, with reflections going towards the floor (a thicker rug, but also consider a felt rug pad under what you have-- piling blankets or clothes on your current rug is a good test of what might happen) and then towards the system (with treatment behind it.)

Pulling down the bass is easy to try with EQ or tone controls. But the right speaker looks pretty close to a corner, than can increase bass, so maybe try the speakers a touch closer together with less toe in, see what that does to the bass measurements and your decay times (likely very little effect on those, but might make it worse with less toe).

For now, concentrate on what you can do, see how what you do changes the measurements and the sound (better or worse to YOU matters). Think in terms of moving towards improvements, not fixing things. Once you know how changes you can try easily work, then you can think about more permanent solutions for improvement. Once you make some improvements, you can decide if you want to go full out (like professional treatment) or live with what you have, or do something in between.

This slow approach will also let you learn a lot about your particular room, which can make the end treatment better. Every room is different, and asymmetrical rooms do some odd things. Odd as in tiny changes can produce outsized effects when room issues line up just right (just wrong).

Good luck!
 
A seating position right in front of a wall is generally considered less than ideal as it provides strong reflections leading to comb filtering, a bit like the detrimental effect of early reflections. While the couch will be absorbing some sound, the area behind your head remains critical, so some absorption would be useful there. Also, there's the whole issue of flutter echo between front and back walls. I can't quite tell whether L/R asymmetry could be an issue as well, but it seems likely as the right speaker seems fairly close to the wall.
 
Thank you for your reply @No. 5 @sam_adams @JeremyFife @madrac @Pareto Pragmatic @AnalogSteph.

After reading through your answers I asked my self: What is the best way to test out how much acoustic treatment I would need to do.
So I did what any sane person would do and bought some packages of something called Hunton (https://huntonfiber.co.uk/)

I'm not sure if you have this product abroad, but its commonly used as a acoustic treatment material here.

------- Skippable ------
First a bit about mye stereo setup.
My contemperary goal is to have a fully analog setup, from source to loudspeaker.

Turntable Dual 704 with shure v15 III (Christmas present from my brother)
Dynamic Precision DP400H (400w in 8ohm) Amplifier https://www.dpguiden.no/pdf/Datablad/DP400H_db_uk.pdf (Recieved as a gift some years back)
Dynamic Precision Balance Passive Controller (Bought used for cheap)
Klipsch RB600 MK (bought new for fair price, 600$.

This means that EQ is a bit of hard to perform at the moment, but i'm leaning towards that the high bass level might be a colorization from the amplifier.

------- Continue ------

The attenuator i'm using can change major level by -10dB and minor level for each channel by 1dB.
Note that for SPL meter in REW before starting with acoustic treatment it was at 75dB.

1727981253856.jpeg


1st Measurement - clean room (no acoustic treatment)
Name: Baseline
1727981568482.png


1727981397559.png


2nd Measurement - with acoustic treatment on rear wall (2 panels)
Name: 2 Panel rear
1727981633812.png

1727981680019.png

1727981706307.jpeg


3rd Measurement 2 Panel (100mm thickness) + 2 Corner Panel (150 mm thickness)
Name: 4 Panel rear

1727981866474.png

1727981825643.png

1727981894914.jpeg


4th Measurement: Loudspeakers thugged a bit out in the room
Name: 4 panels + speaker out

1727982006746.png

1727982030916.png

5th Measurement: 4 panels rear, speaker thugged out, panels behind speaker
Name: 4 panel + spkr + fr
1727982112514.png

1727982136306.png

1727982157773.jpeg


6th measurment: 4 panel, speaker thugged out, panel behind speaker and panel behind amplifier.
1727982237047.png

1727982279294.png


Conclusion:
6th measurement
The dB level on SPL meter decreased by 2dB (down to 73dB).
The room is quite dead and a bit unpleasant to be in as its not as natural as one would like it to be.

5th measurement
I immediately removed the panel behind amplifier and some of the natural acoustics came back.
What I'm experiencing now is that sound doesn't reflect much around but it might be a thad to dead as a bit of the "natural element" seized to exist.
However, its also nice to hear a nice and tight sound that doesnt travel.

2th measurement
Tried to remove 2 rear panels in the corner. Bass got a bit sloppier, but overall sound a bit more "lively". Would like to have a tighter bass though.

In terms of waterwall on all of the measurements, I can't really say that acoustic treatment has had any effect on it?

What is your take on this?

I have included the REW file.

Regards
Nebu
 

Attachments

  • hifi attic test of acoustic treatment.zip
    3.3 MB · Views: 30
The best tool - if I can call it that, and if you have the patience - is the combined experience and willingness to help of the membership here

So, you're calling us a bunch of tools? ;)
 
Buy some heavy Curtains for the windows to be used while listening, the glass is not good due to the high reflectivity.
 
I don't believe such a tool exists, at least, not that I'm aware of. There are rules of thumb and simplistic calculators out there, but what you are looking for comes from knowledge of the topic and attention to what you are hearing.


A few comments that may or may not be helpful: 1) FFT analysis trades time resolution for frequency resolution and the settings in that waterfall are such that you are seeing very poor resolution in the time domain, so I would not use that specific graph to assess much of anything in the way of decay times.
2) If decay times are in fact too long at middle and higher frequencies, resistive absorbers are what you would typically use (i.e. fiberglass, open cell foam, fabrics, etc). If it's too long at low frequency, reactive absorbers (i.e. resonators, diaphragms, etc) or special processing of multiple low frequency sources is the usual go to.
3) You are correct that EQ can usually be used to reduce low frequency decay.

It's a small room, so I wouldn't be too concerned about decay times, personally.

If it were me, I'd EQ the bass down some, and maybe put a large, thick, absorber behind the couch. Then reassess. But that might be all I'd do. Then again, I don't know what that room sounds like, so may sound ok as is.

It is my understanding that a large thick absorber on the front wall between the speakers my help also. I mention this only so others more knowledgeable than I may comment and/or verify.
 
Treat the wall immediately behind the mic, and the wall opposite the mic. See what happens.

I would set the mic up on the cushions, not the back of the couch to better be near where my head would be. Personally, I use the mic pointed up (90 degree calibration file) for room effects, I use the 0 degree more for gear measurements, which I almost never do.

While the decay might not seem to move much, you have changed 400, 1k and 2.5-5k levels quite a bit in your measures. So something happened.

I think the ringing is from couch wall/speaker wall back and forth reflections, parallel walls will do that particularly with speakers pointed at one of them. So I would concentrate my trials with that in mind. An up/down tilt on the speakers should break some of that up, if it is the issue.
 
Buy some heavy Curtains for the windows to be used while listening, the glass is not good due to the high reflectivity.
Neither is the picture, maybe a velour picture but surely not a wood and glass one.
Perhaps a tapestry with the foam backing that goes under a carpet attached?
 
Treat the wall immediately behind the mic, and the wall opposite the mic. See what happens.

I would set the mic up on the cushions, not the back of the couch to better be near where my head would be. Personally, I use the mic pointed up (90 degree calibration file) for room effects, I use the 0 degree more for gear measurements, which I almost never do.

While the decay might not seem to move much, you have changed 400, 1k and 2.5-5k levels quite a bit in your measures. So something happened.

I think the ringing is from couch wall/speaker wall back and forth reflections, parallel walls will do that particularly with speakers pointed at one of them. So I would concentrate my trials with that in mind. An up/down tilt on the speakers should break some of that up, if it is the issue.
Thanks, I changed the calibration file to 90 degree and moved the mic further in on the seating area.
What could be the cause of the major dip from 60 to 80 hz thats been showing on all measurements?

1727992137409.png
 
What could be the cause of the major dip from 60 to 80 hz thats been showing on all measurements?
70hz waves are about 16 ft/4.88m. So an 8ft/2.44m room dimension will cause cancellation, and this is common in many rooms given ceilings are often this tall.

Do you have a room dimension that size? Maybe floor to the lower bit of ceiling above the speakers, or from that ceiling corner to the floor/wall corner behind the couch?
 
Thank you for your reply @No. 5 @sam_adams @JeremyFife @madrac @Pareto Pragmatic @AnalogSteph.

After reading through your answers I asked my self: What is the best way to test out how much acoustic treatment I would need to do.
So I did what any sane person would do and bought some packages of something called Hunton (https://huntonfiber.co.uk/)

I'm not sure if you have this product abroad, but its commonly used as a acoustic treatment material here.
Happy to help.

Empirical testing! A good idea.
My contemperary goal is to have a fully analog setup, from source to loudspeaker.

Turntable Dual 704 with shure v15 III (Christmas present from my brother)
Dynamic Precision DP400H (400w in 8ohm) Amplifier https://www.dpguiden.no/pdf/Datablad/DP400H_db_uk.pdf (Recieved as a gift some years back)
Dynamic Precision Balance Passive Controller (Bought used for cheap)
Klipsch RB600 MK (bought new for fair price, 600$.

This means that EQ is a bit of hard to perform at the moment, but i'm leaning towards that the high bass level might be a colorization from the amplifier.
Nothing wrong with wanting to go full analog. If the higher bass level ever does get to you, you can use an analog tone control to bring it down some.

In terms of waterwall on all of the measurements, I can't really say that acoustic treatment has had any effect on it?

What is your take on this?
There is some effect in there. Here's a comparison of your baseline and 4 panels:
baseline.jpg

LR 4 panel.jpg

But the bigger question is: do you like the sound of it with some absorption? You can make your room really dead, but if that prevents you from enjoying listening to anything... I wouldn't call that a win.
It is my understanding that a large thick absorber on the front wall between the speakers my help also. I mention this only so others more knowledgeable than I may comment and/or verify.
Yes, absorption in that location will also have an effect. I mentioned having it behind the listening position simply because my preference is to have it deader behind me than in front of me, other preferences/goals are certainly valid.
 
Do you have a room dimension that size?
Ok, maybe that short ceiling to floor, given the room dimensions you provided.

More generally, if reflected sound travels 8ft further to get to the mic than direct sound, that should cancel at 70 to some degree. I would think you would see more variation in the dip by speaker if this was the issue.

One 10db room null is not that bad, really, as a place to start. Pulling down the peaks on either side of 70 will help things a lot.
 
There is some effect in there.
Looks like -100ms in many areas. Nothing to sneeze at.

Nothing wrong with wanting to go full analog. If the higher bass level ever does get to you, you can use an analog tone control to bring it down some.
I could use bass tone controls and be pretty happy with the results for this situation. My analog eq has 500hz and 1k, so that elevated midrange would be problematic given my current analog options and listening preferences.
 
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