• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Am I ruining my sound with insulation?

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
#1
I have a 9.2.6 system in a 16x25x9 home theatre. Long story short I have a front wall with left, center, and right channels and these are surrounded and backed by 15-25" of insulation. See the photo below. A screen goes in front of the speakers. The insulation was placed based on the following assumptions:

1. Reflections off the front wall in a home theatre are generally bad (correct, I think).
2. Materials that only absorb high end frequencies are problematic as they disproportionality impact the high end. Therefore, thicker materials that absorb lower frequencies are preferred (correct, I think).
3. I had tons of material (true), so why not
4. "baffle" walls for home theatres are a common thing so surrounding speakers with insulation can't be that bad (don't know if correct)
5. The majority of sound from speakers comes from the front, so having insulation behind or around them isn't a big deal (don't know if correct)

FYI the subwoofer is ported and the driver and ports are facing the center speaker in that gap.

I'm wondering if I messed up here with this system.

Is placing insulation so close to my speakers a problem? Should I just remove a lot of it to free space?

How does insulation so close to speakers effect frequency response and dispersion or other qualities? Data from actual measurements would be especially helpful!

12.JPG
 

Beershaun

Major Contributor
Forum Donor
Joined
Oct 3, 2019
Messages
1,074
Likes
991
#2
Hi. Have you tried taking seating position measurements with and without the insulation in place? REW with a umik-1? I think this would give you the definitive answer and give you a tool to measure any room treatments you put in place and the affect they have.
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#3
Is your screen that you use acoustically transparent? I know your other thread had some REW data that was not great.

You are definitely getting very little bass reinforcement below 150hz and a lot of high frequency issues (Bad screen choice could easily cause that).

https://www.audiosciencereview.com/...uld-i-be-looking-for-in-rew.25445/post-865812



Picture from other thread linked above, for what @Snoochers thinks is L+R but it didn't seem like he 100% knew that.
1628027419115.png
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#4
This blue line would be the harman target (there is variation that can be with this curve, this is just generalized like Amir does it for the predicted in room response). Obviously this can be shifted up/down depending on where you start, and usually a lot of people like more bass than this too.
Screen Shot 2021-08-03 at 14.52.17.png


Here it is slightly down, with, what I would consider big, problem areas boxed in red.
Screen Shot 2021-08-03 at 14.56.08.png
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #5
Hi. Have you tried taking seating position measurements with and without the insulation in place? REW with a umik-1? I think this would give you the definitive answer and give you a tool to measure any room treatments you put in place and the affect they have.
This blue line would be the harman target (there is variation that can be with this curve, this is just generalized like Amir does it for the predicted in room response). Obviously this can be shifted up/down depending on where you start, and usually a lot of people like more bass than this too.
View attachment 145323

Here it is slightly down, with, what I would consider big, problem areas boxed in red.
View attachment 145325
Thanks for this. I will take some measurements later today and post them. These previous measurements I’d take with a grain of salt since both speakers were likely playing at once, which I know can skew things a lot. I also need to move the mic around I think. And I can look at my EQ settings.

is the general idea that insulation is OK if measurements look good?

does it not affect directivity or anything? I can’t measure that with my mic for sure
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
11,493
Likes
12,080
Location
Riverview FL
#6
These previous measurements I’d take with a grain of salt since both speakers were likely playing at once, which I know can skew things a lot.
Maybe.

Left, Right, and both here, mic centered at the listening position, uncorrected:

1628029742592.png



With DSP correction. The dip at 48Hz is standing wave phase cancellation at the listening position due to asymmetrical rear of room.

Yeah, the target was "flat".

1628029897740.png
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #7
Maybe.

Left, Right, and both here, mic centered at the listening position, uncorrected:

View attachment 145334


With DSP correction. The dip at 48Hz is standing wave phase cancellation at the listening position due to asymmetrical rear of room.

Yeah, the target was "flat".

View attachment 145335
In the next few hours I should have some measurements !
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
11,493
Likes
12,080
Location
Riverview FL
#9
Just remember, multiple speakers playing together should be louder across all frequencies.

If you have cancelations caused by multiple speakers, something is off.

Both of those situations are present in my measures above.

Add 6dB for both speakers playing the same signal, and the cancellation at 48Hz for both speakers that is not present with either left or right singly.
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #10
Is your screen that you use acoustically transparent? I know your other thread had some REW data that was not great.

You are definitely getting very little bass reinforcement below 150hz and a lot of high frequency issues (Bad screen choice could easily cause that).

https://www.audiosciencereview.com/...uld-i-be-looking-for-in-rew.25445/post-865812



Picture from other thread linked above, for what @Snoochers thinks is L+R but it didn't seem like he 100% knew that.
View attachment 145322
Both of those situations are present in my measures above.

Add 6dB for both speakers playing the same signal, and the cancellation at 48Hz for both speakers that is not present with either left or right singly.

I don't know if I should be replying here or in my broader REW thread, but I took some more measurements tonight. ARC GENESIS shows me the general curve I'm aiming for (but haven't tinkered with much) while REW shows me something very different. Thoughts? I'm using the ARC microphone.

Screen Shot 2021-08-03 at 8.21.28 PM.png
Screen Shot 2021-08-03 at 8.16.50 PM.png
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #12
Does the arc microphone come with a calibration file? If so is it loaded in REW?

Are these moving microphone measurements or single spots?
I've been doing some reading and no it is not calibrated for use in REW, which means anything above 1khz gets sketchy. I've tried moving the mic and being stationary, no big difference.

Now I'm wondering whether I should get a UMIK-1 or say forget it and just run ARC and hope it is good.
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#13
Both of those situations are present in my measures above.

Add 6dB for both speakers playing the same signal, and the cancellation at 48Hz for both speakers that is not present with either left or right singly.
I don't see the cancelation by multiple speakers in your graphs? All of your together is louder than single speakers, except where you apparently have room/something cancelations (in single speaker and in together measurements), but those are not multiple speaker issues.
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#14
I've been doing some reading and no it is not calibrated for use in REW, which means anything above 1khz gets sketchy. I've tried moving the mic and being stationary, no big difference.

Now I'm wondering whether I should get a UMIK-1 or say forget it and just run ARC and hope it is good.
Usually low end and high end is where the biggest correction areas I've seen in "cheap" measurement microphones. That is also where your two graphs differ the most.
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #15
Usually low end and high end is where the biggest correction areas I've seen in "cheap" measurement microphones. That is also where your two graphs differ the most.
Are you suggesting the Arc Genesis microphone from ANTHEM is not good? I haven't heard that before and the manufacturer and such seems reputable and obviously the amp cost 4000$ lol.

I could just get a UMIK-1 but if I recall correctly I might need to buy it from a special place that calibrates it? Or can I just buy it anywhere?
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
11,493
Likes
12,080
Location
Riverview FL
#16
Thoughts? I'm using the ARC microphone.
The ARC software may contain a generic "calibration" for the microphone that goes with it.

REW would not have access to that calibration and would show the raw response of the mic, which may not be very flat.

A calibration file tells the software how much to adjust the readings across the frequency band.

Example calibration curves (adjustment) for a group of UMIK-1 measurement microphones (which are reasonably flat uncalibrated)

1628038645119.png
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#17
No, not suggesting that at all. But all "cheap" microphones need calibration files. Almost every Avr has the calibration files built in.

I say "cheap" because even the eathworks microphone capsules are like less than $10. But their other sorcery and time makes them worth more. They come with calibration files, but usually they are really flat out of the box.
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #18
The ARC software may contain a generic "calibration" for the microphone that goes with it.

REW would not have access to that calibration and would show the raw response of the mic, which may not be very flat.

A calibration file tells the software how much to adjust the readings across the frequency band.

Example calibration curves (adjustment) for a group of UMIK-1 measurement microphones (which are reasonably flat uncalibrated)

View attachment 145367
Yes so the question is do I need to buy another microphone for use with REW or should I simply be confident in knowing my anthem receiver Is EQing well?
 
OP
S

Snoochers

Active Member
Joined
Mar 28, 2020
Messages
147
Likes
52
Thread Starter #19
No, not suggesting that at all. But all "cheap" microphones need calibration files. Almost every Avr has the calibration files built in.

I say "cheap" because even the eathworks microphone capsules are like less than $10. But their other sorcery and time makes them worth more. They come with calibration files, but usually they are really flat out of the box.
Yes so the question is do I need to buy another microphone for use with REW or should I simply be confident in knowing my anthem receiver Is EQing well?
 

Jdunk54nl

Senior Member
Joined
Aug 5, 2020
Messages
495
Likes
491
Location
Arizona
#20
That is a question only you can answer. Is it worth it to you?

If you do go that route, I'd suggest a motu m2 or focus rite 2i2 interface with a Dayton emm-6 microphone.

You can do a lot more with that setup than a USB microphone. Biggest benefit is easy loop backs. Then you can run Open Sound Meter.
 

Similar threads

Top Bottom