Need help with vocal booth/ room dimensions

[Soundman2020]

1) Should I put plastic over the rear wall before putting the fabric over it in order to keep some of the mids/highs in the room?

Have you tested the room with REW? Both before you started treating (empty room) and again now that you have the back wall partly done. If not, then you won't really now what the treatment is accomplishing, and what else might need doing to it.

How to calibrate and use REW to test ant tune your room acoustics

and I definitely dont want to proceed without figuring out what would be best for the sound in the room.

Then run some REW tests!

My thoughts are... plastic would be quicker, and cheaper, but I really like the look of the slats - gives it a more polished professional look

Plastic and slats are two very different treatments. Even assuming that your slats are not tuned, they still perform very differently from plastic. Plastic is a thin foil, and reflects/transmits sound at different frequencies based on surface mass. Slats are solid reflective surfaces that reflect/diffract sound at different frequencies based on dimensions relative to wavelength, as well as area coverage, and density.

and then figure out a plan for adding slats if the room audio tests show it could use it.

Which "room tests"?

However, the hypotenuse of the superchunk would end up being a little over 21". I've read elsewhere that 24" traps should be in the front of the room, and 34" (if you have the space and budget) should be in the back of the room. ... Is it ok to use the existing materials I have to build the smaller 21" superchunks or is this not worth it?

Put up some of those panels vertically against the walls first, to get a 4" thickness of absorption, then build your 21" triangle in front of those, within the area created that they delimit. That gives you a superchunk that is 25" on each side. If you put up 8" against the walls first, then it would be 29"...


- Stuart -

[flyguyz]

1) Should I put plastic over the rear wall before putting the fabric over it in order to keep some of the mids/highs in the room?

Have you tested the room with REW? Both before you started treating (empty room) and again now that you have the back wall partly done. If not, then you won't really now what the treatment is accomplishing, and what else might need doing to it.

How to calibrate and use REW to test ant tune your room acoustics

Thanks, I am going to read this tonight! I didn't do any room tests yet as I am still in the construction phase, and assumed that the best use of that 6" void was to fill it in with insulation to help with the low end, regardless of how the space sounds without it. I assumed the same with the superchunks, No matter what, I figured having the superchunks floor to ceiling is only going to help with improving the sound. My initial plan was to put fabric over the rear wall, put the superchunks in place, then move my gear into the room and start running rew tests to see where to add wall panels and other sound absorption based on the test results. However, as I started thinking more into it and doing more research on this part of the build, I had the following questions that i posed in the last post and figured it would make sense to tackle those now before moving forward.

EDIT: I read through the REW link you attached, would the Galaxy Audio CM-130 Check Mate SPL Meter work or do I need a higher end option? https://www.guitarcenter.com/Galaxy-Aud ... L-Meter.gc

and I definitely dont want to proceed without figuring out what would be best for the sound in the room.

Then run some REW tests!
Will do, once I move my gear in. Was hoping I could at least get this part of the build complete before running tests, and use test results to improve room from that point on. Is it ok for me to proceed with the fabric on the rear wall, or do you think I would be skipping a CRITICAL step? I am using yamaha HS8 monitors and per manufacturing spec, I'm planning on positioning them 1.5 meters from the front wall. I will make an equilater triangle between the speakers and my listening position? Does this sound like a good starting point to run the REW test? Keep in mind I have a sliding patio door in front of my mixing desk (Center front wall). Initially I was going to place the monitors on my desk, but I know that is frowned upon, so if I may purchase some stands (soffit mounting was out of budget) to place the monitors on my behind my desk. My only question about this is, wouldnt the sound still reflect off the surface of my desk? If so, How much improvement would I really gain, is purchasing monitor stands worth it? My desk has a stand built in to the top of the desk for placing speakers at ear level. I can try to attach a picture later

My thoughts are... plastic would be quicker, and cheaper, but I really like the look of the slats - gives it a more polished professional look

Plastic and slats are two very different treatments. Even assuming that your slats are not tuned, they still perform very differently from plastic. Plastic is a thin foil, and reflects/transmits sound at different frequencies based on surface mass. Slats are solid reflective surfaces that reflect/diffract sound at different frequencies based on dimensions relative to wavelength, as well as area coverage, and density.

and then figure out a plan for adding slats if the room audio tests show it could use it.

Which "room tests"?

However, the hypotenuse of the superchunk would end up being a little over 21". I've read elsewhere that 24" traps should be in the front of the room, and 34" (if you have the space and budget) should be in the back of the room. ... Is it ok to use the existing materials I have to build the smaller 21" superchunks or is this not worth it?

Put up some of those panels vertically against the walls first, to get a 4" thickness of absorption, then build your 21" triangle in front of those, within the area created that they delimit. That gives you a superchunk that is 25" on each side. If you put up 8" against the walls first, then it would be 29"...

You lost me at first, but I figured out the layout you were suggesting now...Thanks again for the quick response. Truly appreciate it!

- Stuart -

[flyguyz]

Just a quick bump, looking for some insight, especially with the sound meter. Would this be ok to use for the REW test?

https://www.guitarcenter.com/Galaxy-Aud ... L-Meter.gc

Galaxy Audio CM-130 SPL Meter

[Gregwor]

Just a quick bump, looking for some insight, especially with the sound meter. Would this be ok to use for the REW test?

https://www.guitarcenter.com/Galaxy-Aud ... L-Meter.gc

Galaxy Audio CM-130 SPL Meter

That's a good one!

Is it ok for me to proceed with the fabric on the rear wall, or do you think I would be skipping a CRITICAL step?

Wait to cover insulation until you're positive you don't need to change anything.

I will make an equilater triangle between the speakers and my listening position?

The equilateral triangle positioning is a myth.

Does this sound like a good starting point to run the REW test?

Have you figured out your mix position via your SketchUp design? Place your mic where your head will be.

My only question about this is, wouldnt the sound still reflect off the surface of my desk?

Do your tests without your desk. Put your desk in near the end of your tests. By then, you should have your room sounding pretty great. Adding your desk at that stage will allow you to see if your desk is screwing up anything acoustically. From there, you can resolve any issues your desk causes.

How much improvement would I really gain, is purchasing monitor stands worth it? My desk has a stand built in to the top of the desk for placing speakers at ear level.

Monitor stands is worth it. A measurable improvement for sure.

Greg

[flyguyz]

So I've run into some techinical difficulties trying to calibrate my sound card in REW.

I am using Apollo 8 thunderbolt with iMac and I have a TRS to TRS cable plugged in from The L Monitor (output) to the Mic/LINE IN 1 (INPUT) to create the loopback for sound card calibration

when I go to select my input and output I see the following output options:

L (This is currently selected as Output)
R (This is currently selected as Timing Reference Output)
L+R
C
LFE
SL
SR
SBL

For input options I have 1-36
1 is currently selected as Input
2 is currently selected as (Loopback Input)

First and foremost, am I choosing the right settings here?

Secondly, when I go to calibrate the soundcard using these settings, I can see the -12 db output, and the highest my input will go is -14.1 db and that is with the preamp knob turned all the way up for the "Line 1" input on my Apollo 8

When I go to run the calibration I get a error for excessive clipping.

EDIT: I think I figured out what I was doing wrong, I didn't have the console input channel on mute so there was a feedback loop. I will post the REW results soon. Hopefully they will show that I did the test correctly

Thank you.

[flyguyz]

I have attached the mdat files from my first couple REW tests (the baseline test is with my desk pushed back slightly out of the way, and the "with desk" test is with my desk in the location it was originally planned on being)

Here is a dropbox link to the baseline test:

https://www.dropbox.com/sh/kvv6wuubs085 ... xT1wa?dl=0

Here is a dropbox link to the test with my desk in place:

https://www.dropbox.com/sh/akl4zurpoedu ... luJna?dl=0

And below are some pictures of the room and speaker setup (note, for the baseline test the desk was pushed back out of the way speakers some - not shown in pic)

Also, the super chunk bass traps are not filled with absorption yet. The only absorption is located behind the dark grey rear wall (6" of roux safe n sound)

Please let me know how the results look and what the next steps I should take to improve the sound in my control room.

Thank you !

[Gregwor]

Your room sure looks cool now!

I think you only measured up to ~ 2,200 Hz, not 22,000 Hz!

Please remeasure.

Thanks!

Greg

[flyguyz]

Haha thank you! And yes i definitely did, I’ll redo the test and repost results a little later today!

Quick question.

When placing my monitors I made an equilateral triangle using a point that is 16” behind my ears/head.

When I ran the REW test I placed the mic where my head/ears would be. Is this ok? Or should I be putting the mic at the spot located 16” behind my head/ears?

Just want to make sure I’m measuring from the correct point.

[Soundman2020]

When placing my monitors I made an equilateral triangle using a point that is 16” behind my ears/head.

When I ran the REW test I placed the mic where my head/ears would be. Is this ok?

You have the mic in the correct location, yes, and your speakers are aiming at the correct point, about 16" behind your head, yes, but the triangle does NOT need to be equilateral.... As long as the distance from left ear to left speaker is the same as the distance from right speaker to right ear, that's the only "triangle" you need. I can explain in more detail, if you want... But you have the mic and aim point correct, so that's good!

- Stuart -

[flyguyz]

Here is the link to the new baseline tests...

https://www.dropbox.com/sh/al0k6gvro4af ... upoKa?dl=0

[flyguyz]

When placing my monitors I made an equilateral triangle using a point that is 16” behind my ears/head.

When I ran the REW test I placed the mic where my head/ears would be. Is this ok?

You have the mic in the correct location, yes, and your speakers are aiming at the correct point, about 16" behind your head, yes, but the triangle does NOT need to be equilateral.... As long as the distance from left ear to left speaker is the same as the distance from right speaker to right ear, that's the only "triangle" you need. I can explain in more detail, if you want... But you have the mic and aim point correct, so that's good!

- Stuart -

Would it be more beneficial to move my speaker to the left and right more, or move them closer to me in order to avoid reflections from the top shelf of my desk. Take a look at my pics I posted earlier and let me know what you think.

[Soundman2020]

Would it be more beneficial to move my speaker to the left and right more, or move them closer to me in order to avoid reflections from the top shelf of my desk. Take a look at my pics I posted earlier and let me know what you think.

Your speakers should be right up against the front wall of the room, on either side of the door.

I wrote a long reply about speaker positioning for another forum member earlier today, where I covered most of the points that will be affecting you. Here's a link: http://www.johnlsayers.com/phpBB2/viewt ... 8&start=13

That should clarify several key issues about setting up your speakers and mix position.

- Stuart -

[flyguyz]

Would it be more beneficial to move my speaker to the left and right more, or move them closer to me in order to avoid reflections from the top shelf of my desk. Take a look at my pics I posted earlier and let me know what you think.

Your speakers should be right up against the front wall of the room, on either side of the door.

I wrote a long reply about speaker positioning for another forum member earlier today, where I covered most of the points that will be affecting you. Here's a link: http://www.johnlsayers.com/phpBB2/viewt ... 8&start=13

That should clarify several key issues about setting up your speakers and mix position.

- Stuart -

Interesting...I may have to sacrifice a bit as I do not want to have a trip hazard with the speaker wires being in the path between the door to the booth and my desk. I will think about this and may run a test with the speakers against the wall just to see what the difference in response is.

In the meantime, when you have a chance, could you please give me some feedback on the last baseline REW test results I posted? I Want to make sure I did the test right and see what my next step forward should be. I want to fill the superchunks with insulation next and rerun the test, and then get some input from you guys as to how many panels I should use to tighten up the room from there.

FYI, the LR--Baseline test did give a clipping error, not sure if that is normal or not, the single L and single R tests ran fine without clipping...

Thanks!

[Soundman2020]

Interesting...I may have to sacrifice a bit as I do not want to have a trip hazard with the speaker wires being in the path between the door to the booth and my desk.

Then run the wires in a different direction, and along the walls! You must be feeding power to your desk from somewhere, so run your speaker cables alongside that power cable over to the wall, then run them along the walls to the speakers.

I Want to make sure I did the test right

Yes, your data is valid, and you did the tests correctly.

and see what my next step forward should be.

The next step is to get your speakers and mix position set up in the correct locations.

Here's an example of one of the issues:

FLYGUYZ--REW--FR-20..500-baseline-SBIR.png

That's your low-end frequency response, below 500 Hz. You can see some very large dips in the response, at around 46 Hz and 65 Hz. I'm not sure how far your speakers are from the front wall, but I'm estimating that it is about 6 feet, so very likely the 46 Hz valley those is the first SBIR dip caused by that long distance. If the distance is a bit less, then it's the 65 Hz dip.

It is impossible (or rather, extremely difficult) to fix those with room treatment. They are purely geometric issues, related to the incorrect location of the speakers. If you leave the speakers in their current location, there's nothing you can do about that.

So, assuming you want good frequency response, the first thing you should do is to set up the geometry correctly, with the speakers and mix position in the proper locations.

Then after that is correct, you should start with large bass traps in as many corners of the room as you can, absorption across the entire rear wall, and absorption in the first reflection points. Each time you make a change to the room, do another REW test to check that the device is working properly, and to see what needs to be done next.

I want to fill the superchunks with insulation next and rerun the test,

First, geometry. Then treatment. As you can see above, there are some issues that cannot be fixed with treatment, and must be addressed with geometry.

FYI, the LR--Baseline test did give a clipping error, not sure if that is normal or not, the single L and single R tests ran fine without clipping...

That's might be an issue with the mic pre-amp: if so, try turning down the gain a bit on the pre-amp. But first, check your gain structure: Are you certain that the level in the room was 86 dBC when you measured with your hand-held sound level meter (NOT with REW, but with your hand-held meter)? Did you have your meter set to "C" and "Slow"?

- Stuart -

[flyguyz]

Interesting...I may have to sacrifice a bit as I do not want to have a trip hazard with the speaker wires being in the path between the door to the booth and my desk.

Then run the wires in a different direction, and along the walls! You must be feeding power to your desk from somewhere, so run your speaker cables alongside that power cable over to the wall, then run them along the walls to the speakers.
I will have to buy much longer speaker wires in order to do this, was trying to avoid having to do that, but after seeing the graph and response I think I'll run to the store and try it out! A couple questions first:

1) I believe the user manual for the Yamaha HS8 are reccomends the monitors be placed 4-5 ft away from the front wall. I believe they are rear ported and have a switch to compensate some if the monitors are being placed closer to the front wall. Should I ignore the manufacturer recommendation and move them close to the front wall anyways? If I do this, should I use the switch in the back to account for this?

2) Does it matter if one cable is say 50ft long and the other monitor cable is only 10ft long? Will this cause any delays, damage the stereo image, loss of quality or any other negative effects?

I Want to make sure I did the test right

Yes, your data is valid, and you did the tests correctly.

and see what my next step forward should be.

The next step is to get your speakers and mix position set up in the correct locations.

Here's an example of one of the issues:

FLYGUYZ--REW--FR-20..500-baseline-SBIR.png

That's your low-end frequency response, below 500 Hz. You can see some very large dips in the response, at around 46 Hz and 65 Hz. I'm not sure how far your speakers are from the front wall, but I'm estimating that it is about 6 feet, so very likely the 46 Hz valley those is the first SBIR dip caused by that long distance. If the distance is a bit less, then it's the 65 Hz dip.

I will let you know the distance when I get back to the studio, however, I have the monitor height at 47" from center of tweeter to the floor. I couldnt find any information on where the acoustical axis is, and the manual suggested having the tweeter lined up with your ear. Is this ok or is there a known acoustical axis point for yamaha hs8 that I should use instad, or should I use the midpoint between the woofer and tweeter as the acoustical axis?

It is impossible (or rather, extremely difficult) to fix those with room treatment. They are purely geometric issues, related to the incorrect location of the speakers. If you leave the speakers in their current location, there's nothing you can do about that.

So, assuming you want good frequency response, the first thing you should do is to set up the geometry correctly, with the speakers and mix position in the proper locations.

Then after that is correct, you should start with large bass traps in as many corners of the room as you can, absorption across the entire rear wall, and absorption in the first reflection points. Each time you make a change to the room, do another REW test to check that the device is working properly, and to see what needs to be done next.
I will try moving the speakers and rerunning the test, but just a theoretical question, if I know where the dip is in the low frequency, could i use some room acoustic software to correct that? Is there a way to have the software add it back in? Not that I want to spend any more money on more software, but just curious!

Also, could a workaround be to use headphones to check the low end also? I know the end goal is to have the room sound as good as possible, especially for playback purposes, but just thinking of workarounds.

I want to fill the superchunks with insulation next and rerun the test,

First, geometry. Then treatment. As you can see above, there are some issues that cannot be fixed with treatment, and must be addressed with geometry.
I plan filling all 4 corners with roxul safe n sound asap.

FYI, the LR--Baseline test did give a clipping error, not sure if that is normal or not, the single L and single R tests ran fine without clipping...

That's might be an issue with the mic pre-amp: if so, try turning down the gain a bit on the pre-amp. But first, check your gain structure: Are you certain that the level in the room was 86 dBC when you measured with your hand-held sound level meter (NOT with REW, but with your hand-held meter)? Did you have your meter set to "C" and "Slow"?

I had my meter set to "C", "Slow", but I had a level of 80db. Is "86" a typo, or should I run the next test at 86 db?

Thanks for the help and quick response! Im anxious to get up and running and am hoping I can at least get the baseline and monitor position established asap so that I can get back to making music this weekend and then work on tweaking/improving the sound in the room from there

- Stuart -