John Sayers' Recording Studio Design Forum Archive

Hi Everyone!

I recently "completed" construction of a new studio and i am getting into the control room adjustments.
I've made other rooms before and always only used my ears, never really REW before but i thought it would give me a better idea of what i am hearing.

The first time i set up the speakers i was ofc coure.... super nervous.. afraid of getting hit in the face by uncontrollable low end inconsistencies...
To my surprise the low end of things seemed to be pretty even compared to most other rooms that i've been in in the past.
To my ears i could hear some strange 3.5 k build up that made vocals and other instruments more aggressive ( in a bad way ) .

At the time i had attributed that to the missing cloud over the mix position, windows partially covered behind the speakers and the control room window to my right.
I have attached a video link to a quick tour and explanation of how the room was build, the dimensions are in the video description as well.

I do see dips and peaks in the lower end but honestly I did not hear them as much as the graph shows, my speakers 8" woofers are not bass heavy at all but i went through a lot of bass heavy material during the listening
and never felt much uneven low end tones.

On the higher end of things i do see some comb filtering that might be due to the mixing desk, just an opinion.. i am open to suggestions!

I think the 3.5 k harshness is probably due to the missing cloud and the missing heavy drapes behind the speakers.


I have attached screenshots of the REW tests.
I would be very happy if anyone with more experience in testing and investigating problems could chime in.

Thank you so much!

here is the video link

https://www.youtube.com/watch?v=4kGlmAPlCHc

Ale

Forgot to apply smoothing
to the higher freq screenshot!

I would need the actual MDAT file to be able to fully analyze the data, and I'd also need to know exactly how you did that test (location of the mic, speakers, etc.), as well as the dimensions of the room, and the position the acoustically important things in it, such as the desk, sofa, etc., and also details of the treatment in the room. Photos would help too!

never really REW before but i thought it would give me a better idea of what i am hearing.

REW will do a lot more than that! It will enable you to tune your room correctly, precisely, so it meets the specifications for control rooms, such as ITU BS.1116-2 and others. Here's an example of what how a well tuned room should look, in REW graphs: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471

To my surprise the low end of things seemed to be pretty even

It's not too bad, as far as I can see, but without knowing all the other details, it's hard to say. There's clearly a large modal problem at about 48 Hz, which is right in the range of bass guitars, large kick drums, the low end of keyboards, and even come electric guitars. I'm surprised you can't hear that. There are also dips at around 80 and 120 Hz, which might be SBIR, or might be something else (floor bounce, maybe, or ceiling bounce). The rest of the low end looks reasonable, but it does seem rather dry and dead. The decay times seem to be rather fast, although once again, it's hard to say for sure without fully analyzing the MDAt file.

That's the low end. But the high end is a huge mess! You have very major swings of over 20 dB in the high end! That's very strange, and very hard to explain....

i could hear some strange 3.5 k build up

I'm not seeing that at all in the data. In fact, there's a clear dip between 2 k and 6 k, bottoming out around 3.5 k! I would suspect a phasing issue of some type, reflections, flutter echo, or something that just isn't evident in the limted set of basic graphs that you posted.

At the time i had attributed that to the missing cloud over the mix position, windows partially covered behind the speakers and the control room window to my right.

Possibly, but I'm not convinced. There are many other things that could be causing this, and the ones you mentioned would not be very high on my list of culprits!

I have attached a video link to a quick tour and explanation of how the room was build, the dimensions are in the video description as well

I'll take a look at that one day when I have time, but in the meantime it would be better to see an actual diagram of the room layout, a few photos, and at least the basic dimensions.

I do see dips and peaks in the lower end but honestly I did not hear them as much as the graph shows, my speakers 8" woofers are not bass heavy at all but i went through a lot of bass heavy material during the listening and never felt much uneven low end tones.

I'm surprised about that, because the graphs are showing clear issues that should be audible. Even simple sine sweeps should highlight those issues clearly.

On the higher end of things i do see some comb filtering that might be due to the mixing desk,

In a properly designed and laid out room, artifacts from the desk and console generally show up in the low end of the mid range, not in the highs. That would be very unusual.

My number one suspect for your problems would be the way the room is laid out, in terms of room geometry: position of the speakers with respect to the walls, floor, ceiling, desk, mix position. My second suspect would be incorrect speaker mounting. Third would be incorrect treatment in the front end of the room, or objects in the front of the room. My fourth suspect would be the speakers themselves, or the signal chain: What speakers are they (make and model)? How do you have the controls set? What else is in the signal path? Did you perform the entire REW calibration procedure?

I think the 3.5 k harshness is probably due to the missing cloud

I doubt it! There's not much energy that far off axis at 3.5k with most speakers. At 3.5k, the Q is pretty much a beam, with not a lot of energy at high angles off-axis, where the cloud usually goes.

and the missing heavy drapes behind the speakers.

I'm not sure I understand: Why would you want drapes BEHIND the speakers? On the rear side of the speakers, most of the energy (and all of the problems!) are in the low end, not the high end. Drapes can help a bit for high frequency treatment, but do nothing at all for lows. SBIR coming off the front wall, for example, would not even notice drapes, no matter how heavy they are. Drapes would be no use at all on the front wall.

What other treatment do you have on the front wall?

Please provide the MDAT file, photos, diagrams, and dimensions.


- Stuart -

Soundman2020 wrote:I would need the actual MDAT file to be able to fully analyze the data, and I'd also need to know exactly how you did that test (location of the mic, speakers, etc.), as well as the dimensions of the room, and the position the acoustically important things in it, such as the desk, sofa, etc., and also details of the treatment in the room. Photos would help too!

never really REW before but i thought it would give me a better idea of what i am hearing.

REW will do a lot more than that! It will enable you to tune your room correctly, precisely, so it meets the specifications for control rooms, such as ITU BS.1116-2 and others. Here's an example of what how a well tuned room should look, in REW graphs: http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471

To my surprise the low end of things seemed to be pretty even

It's not too bad, as far as I can see, but without knowing all the other details, it's hard to say. There's clearly a large modal problem at about 48 Hz, which is right in the range of bass guitars, large kick drums, the low end of keyboards, and even come electric guitars. I'm surprised you can't hear that. There are also dips at around 80 and 120 Hz, which might be SBIR, or might be something else (floor bounce, maybe, or ceiling bounce). The rest of the low end looks reasonable, but it does seem rather dry and dead. The decay times seem to be rather fast, although once again, it's hard to say for sure without fully analyzing the MDAt file.

That's the low end. But the high end is a huge mess! You have very major swings of over 20 dB in the high end! That's very strange, and very hard to explain....

i could hear some strange 3.5 k build up

I'm not seeing that at all in the data. In fact, there's a clear dip between 2 k and 6 k, bottoming out around 3.5 k! I would suspect a phasing issue of some type, reflections, flutter echo, or something that just isn't evident in the limted set of basic graphs that you posted.

At the time i had attributed that to the missing cloud over the mix position, windows partially covered behind the speakers and the control room window to my right.

Possibly, but I'm not convinced. There are many other things that could be causing this, and the ones you mentioned would not be very high on my list of culprits!

I have attached a video link to a quick tour and explanation of how the room was build, the dimensions are in the video description as well

I'll take a look at that one day when I have time, but in the meantime it would be better to see an actual diagram of the room layout, a few photos, and at least the basic dimensions.

I do see dips and peaks in the lower end but honestly I did not hear them as much as the graph shows, my speakers 8" woofers are not bass heavy at all but i went through a lot of bass heavy material during the listening and never felt much uneven low end tones.

I'm surprised about that, because the graphs are showing clear issues that should be audible. Even simple sine sweeps should highlight those issues clearly.

On the higher end of things i do see some comb filtering that might be due to the mixing desk,

In a properly designed and laid out room, artifacts from the desk and console generally show up in the low end of the mid range, not in the highs. That would be very unusual.

My number one suspect for your problems would be the way the room is laid out, in terms of room geometry: position of the speakers with respect to the walls, floor, ceiling, desk, mix position. My second suspect would be incorrect speaker mounting. Third would be incorrect treatment in the front end of the room, or objects in the front of the room. My fourth suspect would be the speakers themselves, or the signal chain: What speakers are they (make and model)? How do you have the controls set? What else is in the signal path? Did you perform the entire REW calibration procedure?

I think the 3.5 k harshness is probably due to the missing cloud

I doubt it! There's not much energy that far off axis at 3.5k with most speakers. At 3.5k, the Q is pretty much a beam, with not a lot of energy at high angles off-axis, where the cloud usually goes.

and the missing heavy drapes behind the speakers.

I'm not sure I understand: Why would you want drapes BEHIND the speakers? On the rear side of the speakers, most of the energy (and all of the problems!) are in the low end, not the high end. Drapes can help a bit for high frequency treatment, but do nothing at all for lows. SBIR coming off the front wall, for example, would not even notice drapes, no matter how heavy they are. Drapes would be no use at all on the front wall.

What other treatment do you have on the front wall?

Please provide the MDAT file, photos, diagrams, and dimensions.


- Stuart -

Hi Stuart!

As usual, very careful and detailed... thank you so much!

I've been tryint to upload the file but somehow i get an error, trying again now.
Also uploading the rt60 screenshot.

After the test i went back and listened using an oscillator and indeed confirmed the peaks and nulls.
They are so much more noticable with a generator...

It is also weird to me that i didn't here any masking in the low end, went back to listen to stuff
and felt again like i had clarity in the low end... ( unbalanced clarity but clarity).

So i discovered the rt60 graph and checked... I think the reason why i thought the low end was clean was the rt60 response, the low end seems to only raise by 0.4 after 100 hrz .. so i guess i was hearing a clean "upper low end".

The speakers I am using now are Mackies MR8 the very first model
https://www.recordingmag.com/productrev ... 03/25.html

Not great speakers but i know them pretty well.

I can't attach the MDAT it says: the extention MDAT is not allowed...

I've measured from the listening position, where my head would be, the speakers are lower than they should be
and will soon invest into supports...

The high frequency mess is most likely the bare concrete ceiling ( with beams ) Floor, and the last 2 feet of the side walls being bare as of now. I can actually hear some slight flutter echo up there.

I've explained treatment and dimensions in the video but i can summarize here.

Dimensions

142 1/2 inches wide
145 " tall
164" is the long wall where the speakers are firing, big BUT! the back wall is totally irregular with a huge bass trap acting as a false wall, a small pantry behind it and a bathroom further down so in reality the long wall is much longer than that at different points...

the 2 front corners are 2 superchunk bass traps with pink fluffy 12 tall and around 26 inches wide
10 of the 12 feet in height of the side walls are made by 3" roxul rockboard.
Back wall has 2 bass traps columns approx 10ft tall 5 inches deep and over a foot wide.
on top of those columns there is another bass trap on top approx 8 ft long .
Its very hard to explain but basically part of the back wall is an irregular giant bass traps
with 703 on the wider surfaces and pink fully in columns and wall to ceiling corners.
I will take pictures tomorrow and attach them here.

I also do think it could be sbir and need to play with placement ( speakers are ported in the back )
and right now i started with the speaker as close as possible to the back wall and eventually work my way back and re test.

Also having width and height of the room very similar it might be more of a modal issue?

I do have space on the upper side wall to ceiling and could tra more if needed, although
trapping 40hz.. unless i use pressure traps and get the q in the right spot...
As you can see i am a bit all over the place right now...

I will update with pics, and may be i can send you an email with the mdat file?


Thank you so much for you time!

Alessio

Also Steward.

Just saw the linked thread.
What a fantastic job!!!!!
I don't think i've ever seen a flatter low end response in a room!!!

Just saw the linked thread.
What a fantastic job!!!!!
I don't think i've ever seen a flatter low end response in a room!!!

Thanks! It wasn't easy to do, but it can be done, with careful design, careful testing, and careful tuning.

142 1/2 inches wide
145 " tall
164" is the long wall where

Well that explains the low end! The modal issue at around 48 is actually two at once: 0.0.1 axial and 0.1.0 axial, at pretty much the same frequency (46.8 and 47.6), because the profile is square! The cloud will help a little with that, provided that it is huge, hard-backed, and angled.

The one "around 80" is your 2.0.0 axial at 82.7 Hz., and the one "around 120" is your 3.0.0 axial, at 124 Hz.

In other words, you don't have enough bass trapping in the length and height axes, and width is also deficient.

Its very hard to explain but basically part of the back wall is an irregular giant bass traps

That's fine, but there still isn't enough in the low end.

I also do think it could be sbir and need to play with placement ( speakers are ported in the back )
and right now i started with the speaker as close as possible to the back wall and eventually work my way back and re test.

There's no need to play: Just set the up correctly!

Also having width and height of the room very similar it might be more of a modal issue?

Yep!

although trapping 40hz.. unless i use pressure traps and get the q in the right spot...

You'd be surprised... the wavelength at 40 Hz is 28.25 feet, so theoretically it is feasible to get usable trapping from 23" of porous absorber for normal-incident sound, and as little as 12" for randomly incident sound. Most people don't realize that porous absorption is effective down to rather low frequencies.

I can't attach the MDAT it says: the extention MDAT is not allowed...

Upload it to a file sharing service, such as Dropbox, then post the link here.

As you can see i am a bit all over the place right now...

First things first: A lot of your issues arecoming from the incorrect speaker placement. the very first thing you need to do is fix that. Your speakers need to go right up tight against the front wall, except for a gap of 4" where you will insert a panel of 4" 703, directly in between the rear corner of the speaker and the front wall.

They also need to go on stands... Heavy! Massive! Lots of weight! Some people stack up concrete blocks or bricks, others make it from hollow steel profile and fill it with sand. But whatever you do, it has to be HEAVY.

It also has to be built to the correct heights, such that the acoustic axis of the speakers ends up at 1.2m above the floor, which is 47-1/4". Or maybe a bit higher. Perhaps as much as 49", but not higher.

You also need turn your speakers the right way up! You have them laying on their sides, which is terrible, and is probably part of the problem with the frequency response in the high end.

And you also need to get the in the correct location with respect to the side walls: each speaker must go 39" from the side wall, in your room. Which means that they will be 64.5" apart. Once again, I'm talking about the acoustic axis of the speakers, NOT the top, bottom, or sides of the cabinet. Check the manual to find out where the acoustic axis is on your speakers.

OK, once you have your speakers set up correctly, you'll need to set up your listening position. For that room, you need to set up your chair such that your ears will be 61" from the front wall when you are mixing normally. Then set up your desk comfortably in front of that.

Now set up a vertical pole of some type (eg, mic stand) about 16" behind your head (in other words, 76" from the front wall), and carefully aim each speaker such that it points directly at the pole. Here too, I'm talking about the acoustic axis: The acoustic axis must point at the pole.

Double check all those measurements.

That's the theoretical ideal geometry.

Now calibrate your gain structure, and REW, such that each speaker is producing exactly 80 dBC with REW putting out a -10dB signal, and everything in the signal chain pegged at either 0 dB (analog gear) or -20 dBFS (digital gear). You will need a hand-held sound level meter to do this. If you do that correctly, when each speaker produces 80 dBC by itself, both of them together will automatically produce 86 dBC. With that situation,m calibrate REW to tell it that the level is 86 dBC when the meter is showing 86 dBC. Use the full-spectrum test signal in REW, NOT the sub-woofer test signal!

With that setup, run three REW tests: one for the left speaker alone (right one turned off), one with just the right speaker (left one turned off), and one with both.

Post the MDAT file with those three tests, with the room set up optimally.

- Stuart -

Soundman2020 wrote:

Just saw the linked thread.
What a fantastic job!!!!!
I don't think i've ever seen a flatter low end response in a room!!!

Thanks! It wasn't easy to do, but it can be done, with careful design, careful testing, and careful tuning.

142 1/2 inches wide
145 " tall
164" is the long wall where

Well that explains the low end! The modal issue at around 48 is actually two at once: 0.0.1 axial and 0.1.0 axial, at pretty much the same frequency (46.8 and 47.6), because the profile is square! The cloud will help a little with that, provided that it is huge, hard-backed, and angled.

The one "around 80" is your 2.0.0 axial at 82.7 Hz., and the one "around 120" is your 3.0.0 axial, at 124 Hz.

In other words, you don't have enough bass trapping in the length and height axes, and width is also deficient.

Its very hard to explain but basically part of the back wall is an irregular giant bass traps

That's fine, but there still isn't enough in the low end.

I also do think it could be sbir and need to play with placement ( speakers are ported in the back )
and right now i started with the speaker as close as possible to the back wall and eventually work my way back and re test.

There's no need to play: Just set the up correctly!

Also having width and height of the room very similar it might be more of a modal issue?

Yep!

although trapping 40hz.. unless i use pressure traps and get the q in the right spot...

You'd be surprised... the wavelength at 40 Hz is 28.25 feet, so theoretically it is feasible to get usable trapping from 23" of porous absorber for normal-incident sound, and as little as 12" for randomly incident sound. Most people don't realize that porous absorption is effective down to rather low frequencies.

I can't attach the MDAT it says: the extention MDAT is not allowed...

Upload it to a file sharing service, such as Dropbox, then post the link here.

As you can see i am a bit all over the place right now...

First things first: A lot of your issues arecoming from the incorrect speaker placement. the very first thing you need to do is fix that. Your speakers need to go right up tight against the front wall, except for a gap of 4" where you will insert a panel of 4" 703, directly in between the rear corner of the speaker and the front wall.

They also need to go on stands... Heavy! Massive! Lots of weight! Some people stack up concrete blocks or bricks, others make it from hollow steel profile and fill it with sand. But whatever you do, it has to be HEAVY.

It also has to be built to the correct heights, such that the acoustic axis of the speakers ends up at 1.2m above the floor, which is 47-1/4". Or maybe a bit higher. Perhaps as much as 49", but not higher.

You also need turn your speakers the right way up! You have them laying on their sides, which is terrible, and is probably part of the problem with the frequency response in the high end.

And you also need to get the in the correct location with respect to the side walls: each speaker must go 39" from the side wall, in your room. Which means that they will be 64.5" apart. Once again, I'm talking about the acoustic axis of the speakers, NOT the top, bottom, or sides of the cabinet. Check the manual to find out where the acoustic axis is on your speakers.

OK, once you have your speakers set up correctly, you'll need to set up your listening position. For that room, you need to set up your chair such that your ears will be 61" from the front wall when you are mixing normally. Then set up your desk comfortably in front of that.

Now set up a vertical pole of some type (eg, mic stand) about 16" behind your head (in other words, 76" from the front wall), and carefully aim each speaker such that it points directly at the pole. Here too, I'm talking about the acoustic axis: The acoustic axis must point at the pole.

Double check all those measurements.

That's the theoretical ideal geometry.

Now calibrate your gain structure, and REW, such that each speaker is producing exactly 80 dBC with REW putting out a -10dB signal, and everything in the signal chain pegged at either 0 dB (analog gear) or -20 dBFS (digital gear). You will need a hand-held sound level meter to do this. If you do that correctly, when each speaker produces 80 dBC by itself, both of them together will automatically produce 86 dBC. With that situation,m calibrate REW to tell it that the level is 86 dBC when the meter is showing 86 dBC. Use the full-spectrum test signal in REW, NOT the sub-woofer test signal!

With that setup, run three REW tests: one for the left speaker alone (right one turned off), one with just the right speaker (left one turned off), and one with both.

Post the MDAT file with those three tests, with the room set up optimally.

- Stuart -

Thanks Again Steward!

Great guidelines for setting things up right ( including the speakers...)

I assume you've seen the video, and those speaker stands are attached to the desk.. so i guess
i would have to decouple the speakers from the supports and decouple the desk from the floor?


Also i've always mixed with horizontal speaker placement but I will get them up and re test!
i am not able to find a diagram with the acoustic axis speakers.... any other way to find that out?


I am in the process of building the could, I was using 6 wooden grids (space couplers)
with 4 inch 703 stacked above them, so there would be no hard back on the cloud.
Could i close the cloud with anything like a 1/4 inch board what would that achieve?
Also i have downlights planned to be inside the cloud...
Since the ceiling is 12" tall i guess i could mount it at the 1/4 wavelenght to catch that mode?


I am a little confused, when you say we can dissipate modes down to 40hz with porus absorbers.
Wouldnt they have to be enormous? Unless using a perforated panel in front?


Again, thanks for all the suggestions. I will set things up as suggested ASAP then re test and send a new .mdat file!

Now, just for kicks... i attach a link to the first test, just so people can start yelling at me on the settings and then i eventually learn to measure correctly!

https://studio42brooklyn.wetransfer.com ... 613/0306b6

Appreciation!

Ale

I assume you've seen the video, and those speaker stands are attached to the desk.. so i guess
i would have to decouple the speakers from the supports and decouple the desk from the floor?

You need entirely separate speaker stands, not touching anything. Not the desk, or the wall, or anything else. They need to be completely stand-alone.

Remove everything from the desk that is not absolutely necessary: speaker stands, shelves, equipment, cables, video screens, etc. Just leave the absolute minimum equipment that you need.

It's not necessary to decouple the desk from the floor, but it would be good t decouple the speaker from the stand, using Sorbothane pads. That's the absolute bests stuff out there.

Also i've always mixed with horizontal speaker placement

Here's why that's a bad idea:
That's very probably part of the problem you are seeing in the mid/high. It peaks at the cross-over frequency for your speakers, and rolls off about an octave either side.

i am not able to find a diagram with the acoustic axis speakers.... any other way to find that out?

It will always be on the imaginary line that joins the middle of the woofer to the middle of the tweeter,and will be much closer to the tweeter. For your Mackie's, I would estimate that it would be about here:
Somewhere around 130mm from the top edge. I know that's not the exact same model you have, but the axis wont be far from there. It's not ultra-critical to have it perfect either. That would be a good approximation.

I was using 6 wooden grids (space couplers) with 4 inch 703 stacked above them, so there would be no hard back on the cloud.

That's not really a cloud! Take a look at that link I gave you yesterday: The cloud there is huge. It's the maroon monster across the entire front end of the room. There are several modules, some hard-backed, some not, and hung at different angles. You will need something similar. Your ceiling is high, so you have plenty of space to do that, and you'll be able to angle them well. You also have modal issues in the vertical plane: space-couplers won't to much to help that! You don't want the space above and below the cloud acoustically coupled: You want the opposite: Acoustically UN-coupled. Two different acoustic spaces with a large impedance mismatch in between.

Could i close the cloud with anything like a 1/4 inch board what would that achieve?

Much thicker. I would recommend 3/4" MDF. You need mass on that thing, if you hope to have much effect on modes.

Also i have downlights planned to be inside the cloud...

No problem! Take a look at the cloud in the link...

Since the ceiling is 12" tall i guess i could mount it at the 1/4 wavelenght to catch that mode?

Not necessary, and not all that useful.... and kind of hard to do! The quarter wave for your 47 Hz mode is 6 feet, so you'd have to hang it half way between the ceiling and the floor... it would sort of be in the way there, every time you stood up from the desk!

I am a little confused, when you say we can dissipate modes down to 40hz with porus absorbers.

A porous absorber that is as thick as 7% of the wavelength is sufficient to have a useful effect on normal-incident waves, and 3.5% thickness is good for random incidence. Not highly effective, of course, but still usefully so. The thicker you make it, the better it gets, and the further you move it away from the wall, the better it gets. The perfectly optimum distance is, indeed, a quarter wavelength away from the wall, but even at much smaller distances it still has some effect. The only place that it has no effect at all is right up against the wall.

Wouldnt they have to be enormous? Unless using a perforated panel in front?

If it has a perf panel in front, then it isn't a bass trap! It's a tuned trap, which might or might not be good for bass, depending on the tuning.

Porous absorbers work by taking away some of the acoustic energy of any sound wave that passes through them, and converting it into low-grade heat. Sound waves are basically just vibrating air molecules. They transfer energy to the fibers of the porous absorber by striking them, causing the to flex, which absorbs the kinetic energy of the wave and converts it to thermal energy. As long as the wave pass through a reasonable thickness of the absorber, there's a reasonable chance that some of the air molecules will strike some of the fibers. The greater the thickness of the panels, the better the chances, but even at 7% there's still a statistically decent chance that many molecules will strike many fibers.

Also, and maybe this is splitting hairs, but you can't "dissipate" a mode: All you can do is "damp" it. The mode is still there, but it just doesn't "ring" any more, because it is heavily damped.

- Stuart -

Thank Steward! I even learned how to quote!

You need entirely separate speaker stands, not touching anything. Not the desk, or the wall, or anything else. They need to be completely stand-alone.Remove everything from the desk that is not absolutely necessary: speaker stands, shelves, equipment, cables, video screens, etc. Just leave the absolute minimum equipment that you need.

I did most of the clean up, I will probably change stands as soon as some finances start coming back in...
If it is a completely stupid idea then.. I will do my best to improvise!

That's very probably part of the problem you are seeing in the mid/high. It peaks at the cross-over frequency for your speakers, and rolls off about an octave either side.

Placed speakers upright and took all the measurements, the weird 3.5 k madness is gone to my ear!!

Somewhere around 130mm from the top edge. I know that's not the exact same model you have, but the axis wont be far from there. It's not ultra-critical to have it perfect either. That would be a good approximation.

Yes its what i thought so i took measurements from there

That's not really a cloud! Take a look at that link I gave you yesterday: The cloud there is huge. It's the maroon monster across the entire front end of the room. There are several modules, some hard-backed, some not, and hung at different angles. You will need something similar. Your ceiling is high, so you have plenty of space to do that, and you'll be able to angle them well. You also have modal issues in the vertical plane: space-couplers won't to much to help that! You don't want the space above and below the cloud acoustically coupled: You want the opposite: Acoustically UN-coupled. Two different acoustic spaces with a large impedance mismatch in between.

It makes sense, but if I am not mistaken it'll be super heavy right?
I do not trust the concrete on the ceiling it was poured poorly and its thicn in some places and thick in others...
May be i can run 4x4's across from sidewall to sidewall and use those as support?
Another option/question: What if I use the 7% rule and use 24 inches of porus absorption on top of the couplers?
May be hanging the absorption rapped in black fabric a few inches away from the couplers ?
Just trying to see if there is a lighter option... but i know sometimes its about mass and mass, is mass...

If it has a perf panel in front, then it isn't a bass trap! It's a tuned trap, which might or might not be good for bass, depending on the tuning.

I guess my question was, wouldn't a resonator (tuned for 40hz) with insulation backing to widen the q be more efficient/smaller?
I can build most things, just pointing it out to see if you think its a better option for the room.

Also, and maybe this is splitting hairs, but you can't "dissipate" a mode: All you can do is "damp" it. The mode is still there, but it just doesn't "ring" any more, because it is heavily damped.

Yes I used the word dissipate thinking of sound being transformed in heat, I am aware of the concept but thank you for making sure!

The room is ready for a new test! Which will probably happen tomorrow late night!
Can't thank you enough for this, learning a lot and making my room better are two wonderful things!

Ale

- Stuart -[/quote]

Soundman2020 wrote:

Just saw the linked thread.
What a fantastic job!!!!!
I don't think i've ever seen a flatter low end response in a room!!!

Thanks! It wasn't easy to do, but it can be done, with careful design, careful testing, and careful tuning.

142 1/2 inches wide
145 " tall
164" is the long wall where

Well that explains the low end! The modal issue at around 48 is actually two at once: 0.0.1 axial and 0.1.0 axial, at pretty much the same frequency (46.8 and 47.6), because the profile is square! The cloud will help a little with that, provided that it is huge, hard-backed, and angled.

The one "around 80" is your 2.0.0 axial at 82.7 Hz., and the one "around 120" is your 3.0.0 axial, at 124 Hz.

In other words, you don't have enough bass trapping in the length and height axes, and width is also deficient.

Its very hard to explain but basically part of the back wall is an irregular giant bass traps

That's fine, but there still isn't enough in the low end.

I also do think it could be sbir and need to play with placement ( speakers are ported in the back )
and right now i started with the speaker as close as possible to the back wall and eventually work my way back and re test.

There's no need to play: Just set the up correctly!

Also having width and height of the room very similar it might be more of a modal issue?

Yep!

although trapping 40hz.. unless i use pressure traps and get the q in the right spot...

You'd be surprised... the wavelength at 40 Hz is 28.25 feet, so theoretically it is feasible to get usable trapping from 23" of porous absorber for normal-incident sound, and as little as 12" for randomly incident sound. Most people don't realize that porous absorption is effective down to rather low frequencies.

I can't attach the MDAT it says: the extention MDAT is not allowed...

Upload it to a file sharing service, such as Dropbox, then post the link here.

As you can see i am a bit all over the place right now...

First things first: A lot of your issues arecoming from the incorrect speaker placement. the very first thing you need to do is fix that. Your speakers need to go right up tight against the front wall, except for a gap of 4" where you will insert a panel of 4" 703, directly in between the rear corner of the speaker and the front wall.

They also need to go on stands... Heavy! Massive! Lots of weight! Some people stack up concrete blocks or bricks, others make it from hollow steel profile and fill it with sand. But whatever you do, it has to be HEAVY.

It also has to be built to the correct heights, such that the acoustic axis of the speakers ends up at 1.2m above the floor, which is 47-1/4". Or maybe a bit higher. Perhaps as much as 49", but not higher.

You also need turn your speakers the right way up! You have them laying on their sides, which is terrible, and is probably part of the problem with the frequency response in the high end.

And you also need to get the in the correct location with respect to the side walls: each speaker must go 39" from the side wall, in your room. Which means that they will be 64.5" apart. Once again, I'm talking about the acoustic axis of the speakers, NOT the top, bottom, or sides of the cabinet. Check the manual to find out where the acoustic axis is on your speakers.

OK, once you have your speakers set up correctly, you'll need to set up your listening position. For that room, you need to set up your chair such that your ears will be 61" from the front wall when you are mixing normally. Then set up your desk comfortably in front of that.

Now set up a vertical pole of some type (eg, mic stand) about 16" behind your head (in other words, 76" from the front wall), and carefully aim each speaker such that it points directly at the pole. Here too, I'm talking about the acoustic axis: The acoustic axis must point at the pole.

Double check all those measurements.

That's the theoretical ideal geometry.

Now calibrate your gain structure, and REW, such that each speaker is producing exactly 80 dBC with REW putting out a -10dB signal, and everything in the signal chain pegged at either 0 dB (analog gear) or -20 dBFS (digital gear). You will need a hand-held sound level meter to do this. If you do that correctly, when each speaker produces 80 dBC by itself, both of them together will automatically produce 86 dBC. With that situation,m calibrate REW to tell it that the level is 86 dBC when the meter is showing 86 dBC. Use the full-spectrum test signal in REW, NOT the sub-woofer test signal!

With that setup, run three REW tests: one for the left speaker alone (right one turned off), one with just the right speaker (left one turned off), and one with both.

Post the MDAT file with those three tests, with the room set up optimally.

- Stuart -

Hi There!

I've re done all the measurements!

And for the sake of science I did also L/R measurements with and without the 703 back panels behind the speakers.
I only had 3 inches... but given the results I WILL GET 4" for sure .

I hope these test will also help other people, i think they are incredibly useful!!

Here we go :

https://wetransfer.com/downloads/ce49fc ... 445/ebaa4c

Steward i would Love to get your opinion, I've re positioned everything as you described using a tape measure got things as accurate as i could.

Thank you!

ps: very interesting the difference between left and right speakers... seems almost unreal? How can that be?

I downloaded your zip file, but it is invalid. When I try to extract it, I get dozens of error messages like these:

Documents\new measurements studio 42 .zip: Attempting to correct the invalid file name
Documents\new measurements studio 42 .zip: Renaming new measurements studio 42 \L spkr 703.mdat to new measurements studio 42_\L spkr 703.mdat
Documents\new measurements studio 42 .zip: Cannot create new measurements studio 42 \L spkr no 703.mdat

Also, it looks like you didn't follow the instructions! You saved each new measurement into an entirely separate MDAT file, when what I really need is to have them all in the same MDAT file, to facilitate comparison. Yes, it would be dead easy to put them together (if I could actually extract the files), but it would be an awful to easier if you were just to keep the measurements all in the same file originally!

So please put all of the measurements in the same file, then put that on Dropbox WITHOUT compressing it in a zip file, and post the link.


- Stuart -

Soundman2020 wrote:I downloaded your zip file, but it is invalid. When I try to extract it, I get dozens of error messages like these:

Documents\new measurements studio 42 .zip: Attempting to correct the invalid file name
Documents\new measurements studio 42 .zip: Renaming new measurements studio 42 \L spkr 703.mdat to new measurements studio 42_\L spkr 703.mdat
Documents\new measurements studio 42 .zip: Cannot create new measurements studio 42 \L spkr no 703.mdat

Also, it looks like you didn't follow the instructions! You saved each new measurement into an entirely separate MDAT file, when what I really need is to have them all in the same MDAT file, to facilitate comparison. Yes, it would be dead easy to put them together (if I could actually extract the files), but it would be an awful to easier if you were just to keep the measurements all in the same file originally!

So please put all of the measurements in the same file, then put that on Dropbox WITHOUT compressing it in a zip file, and post the link.


- Stuart -

Ops.. Sorry about that!

I will do that now!

Soundman2020 wrote:I downloaded your zip file, but it is invalid. When I try to extract it, I get dozens of error messages like these:

Documents\new measurements studio 42 .zip: Attempting to correct the invalid file name
Documents\new measurements studio 42 .zip: Renaming new measurements studio 42 \L spkr 703.mdat to new measurements studio 42_\L spkr 703.mdat
Documents\new measurements studio 42 .zip: Cannot create new measurements studio 42 \L spkr no 703.mdat

Also, it looks like you didn't follow the instructions! You saved each new measurement into an entirely separate MDAT file, when what I really need is to have them all in the same MDAT file, to facilitate comparison. Yes, it would be dead easy to put them together (if I could actually extract the files), but it would be an awful to easier if you were just to keep the measurements all in the same file originally!

So please put all of the measurements in the same file, then put that on Dropbox WITHOUT compressing it in a zip file, and post the link.


- Stuart -

Here we go!
This should work!
https://studio42brooklyn.wetransfer.com ... 342/3eb0a3

OK, that one at least worked to download, but clearly you did not calibrate REW: it says you performed all of those tests at a level of 140 dBC!

That's a little hard to believe, since that's roughly the level you would hear if you stuck your head inside the tailpipe of a 747 jet engine just as it is pushed to maximum power for take-off...

There's also no sound-card calibration data ...

So please calibrate REW correctly, following the complete calibration procedure laid out in the manual, and using a proper hand-held sound level meter. The re-do the tests, and post the new results.


- Stuart -

Soundman2020 wrote:OK, that one at least worked to download, but clearly you did not calibrate REW: it says you performed all of those tests at a level of 140 dBC!

That's a little hard to believe, since that's roughly the level you would hear if you stuck your head inside the tailpipe of a 747 jet engine just as it is pushed to maximum power for take-off...

There's also no sound-card calibration data ...

So please calibrate REW correctly, following the complete calibration procedure laid out in the manual, and using a proper hand-held sound level meter. The re-do the tests, and post the new results.


- Stuart -

Yes i know... i had to hide during the sweep hahahaha
But REW wouldn't run the test saying it was too low..

I calibrated the level matching the db out of the speakers to the what the mic was hearing, so i guess the measurement even if loud should be valid?
Sorry about that...I thought it was strange...that i had to endure that loud torture...hahaha