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Just moved in! New Studio Build
Old 8th August 2019
  #31
/\ That's horrible but most naked rooms look like this. The "good" news is that your 55 Hz mode is "relatively" high up. The bad news is you'll need a lot of treatment that works in the 70-80 Hz region.
Old 9th August 2019
  #32
Gear Head
 

Quote:
Originally Posted by johannburkard View Post
/\ That's horrible but most naked rooms look like this. The "good" news is that your 55 Hz mode is "relatively" high up. The bad news is you'll need a lot of treatment that works in the 70-80 Hz region.
I’ll take your word for it because I have no idea what I’m looking at. As mentioned, completely new to this software and it’s my first time treating a room.
Old 9th August 2019
  #33
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Quote:
As mentioned, completely new to this software and it’s my first time treating a room.
Are you SURE you followed the tutorial I linked you to, on how to calibrate and use REW? Because that's not what I'm seeing in your MDAT file...

- Stuart -
Old 9th August 2019
  #34
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Quote:
Originally Posted by Soundman2020 View Post
Are you SURE you followed the tutorial I linked you to, on how to calibrate and use REW? Because that's not what I'm seeing in your MDAT file...

- Stuart -
I followed the GK video tutorial for the time being as it was a bit more straight forward. I will do more accurate measurement with the link you provided this weekend when I have more time. Was tough to sit down and really give this process the time it needed during the week with work and dealing with city traffic. Also, I don't have the appropriate SPL meter needed to calibrate the speakers. I have a cheap one so will be heading to one of my works locations to rent the Galaxy CM-140.

I promise I will get you appropriate measurements this weekend Stuart!! Third times a charm! Also, I just realized that YOU are the original poster on that measurement post. How did I miss that!?

Hopefully, I can figure everything out this weekend.
Old 9th August 2019
  #35
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akebrake's Avatar
 

Quote:
Originally Posted by recaro19 View Post
... Also, I don't have the appropriate SPL meter needed to calibrate the speakers. I have a cheap one so will be heading to one of my works locations to rent the Galaxy CM-140....
It's nice to have a good SPL meter but not needed IMHO. Especially as you already have one... (Buy/ build bass traps in stead for the money)

If you rent a good SPL meter just compare it to the one you already have and note the difference. Done! Close enough for R& R

RE your measurement:
Your current (uploaded) measurement is probably a bit too loud. Too much distortion in the low end.(Pic below) No need to measure louder than ≈ 75-80dB SPL.

Always measure L & R speaker separately. We like to know how much they differ due to room assymetry or if one have a problem.

Best
Attached Thumbnails
Just moved in!  New Studio Build-dist-noise.jpg  
Old 9th August 2019
  #36
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Quote:
Originally Posted by akebrake View Post
It's nice to have a good SPL meter but not needed IMHO. Especially as you already have one... (Buy/ build bass traps instead for the money)

If you rent a good SPL meter just compare it to the one you already have and note the difference. Done! Close enough for R& R goof

RE your measurement:
Your current (uploaded) measurement is probably a bit too loud. Too much distortion in the low end.(Pic below) No need to measure louder than ≈ 75-80dB SPL.

Always measure L & R speaker separately. We like to know how much they differ due to room asymmetry or if one has a problem.

Best
I've attached an image of the exact dB reader I have. If you think it's okay then I won't bother with the trip to rent the CM-140. It's downtown and a bitch for me to get to. Here's the link: with Specs

https://www.amazon.ca/Decibel-Mengsh...05101004&psc=1

I'll be sure to lower the volume as well and follow Stuart's instructions for better measurements. I am planning on doing that all day Sunday (along with some grocery shopping).

As for the levels, I wouldn't have known I was distorting unless you told me so appreciate that. Look ofrward to getting this done.

On my way home I will be picking up the IVAR frames for the two bass traps I will be building. Slowly getting things done.
Attached Thumbnails
Just moved in!  New Studio Build-decibel.jpg  
Old 10th August 2019
  #37
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Quote:
I've attached an image of the exact dB reader I have.
That one only measures with "A" weighting. For loud sounds, you need one that measures with "C" weighting.

- Stuart -
Old 10th August 2019
  #38
Gear Head
 

Quote:
Originally Posted by Soundman2020 View Post
That one only measures with "A" weighting. For loud sounds, you need one that measures with "C" weighting.

- Stuart -
I’m assuming that would explain the distortion akebrake found in the mdat file? Clearly I measured 80dB in A weighting does that mean it’s much louder in c?
Old 10th August 2019
  #39
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Quote:
Originally Posted by recaro19 View Post
I’m assuming that would explain the distortion akebrake found in the mdat file? Clearly I measured 80dB in A weighting does that mean it’s much louder in c?
Right! If you calibrated at 80 dB using "A" weighting, then the actual level was much louder than 80, for sure. There's quite a big difference in the low end between A and C.

- Stuart -
Old 10th August 2019
  #40
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akebrake's Avatar
 

Relative measurements

Quote:
Originally Posted by recaro19 View Post
I’m assuming that would explain the distortion akebrake found in the mdat file? Clearly I measured 80dB in A weighting does that mean it’s much louder in c?
Now you have a SPL reference. Albeit with an A-curve.
You have 80dB of ”midrange” and a lot more bass. (Not visible with A weighting).

I think, you can insert that value into the REW SPL meter as a ref value.
REW Help

In the uploaded distortion plot I ”guesstimated” the peak level to roughly 95dB.

For the following measurements:

If you lower the monitor level say 5 dBA and measure L & R speaker separately I guess it will work fine (with lower distortion)

Also: Immedately after a sweep is performed, compare send & return signals in the Scope tab. Look for signs of overload.(REW 5.19)
(In v 5.20 b18) You'll find this function in ”Capture”

Best
Old 10th August 2019
  #41
Gear Head
 

Quote:
Originally Posted by Soundman2020 View Post
Right! If you calibrated at 80 dB using "A" weighting, then the actual level was much louder than 80, for sure. There's quite a big difference in the low end between A and C.

- Stuart -
Look at that! Learning already :P

Heading out to do some errands right now and pick up the db reader. I'll be working on measurements today.
Old 10th August 2019
  #42
Gear Head
 

Quote:
Originally Posted by akebrake View Post
Now you have a SPL reference. Albeit with an A-curve.
You have 80dB of ”midrange” and a lot more bass. (Not visible with A weighting).

I think, you can insert that value into the REW SPL meter as a ref value.
REW Help

In the uploaded distortion plot I ”guesstimated” the peak level to roughly 95dB.

For the following measurements:

If you lower the monitor level say 5 dBA and measure L & R speaker separately I guess it will work fine (with lower distortion)

Also: Immedately after a sweep is performed, compare send & return signals in the Scope tab. Look for signs of overload.(REW 5.19)
(In v 5.20 b18) You'll find this function in ”Capture”

Best
I'll probably just start over using Stuart's guide. Probably better for me to do it from scratch and do it properly then try and fix the wrong measurements. I don't even know if i did the current measurements i posted correctly.

Keep you both posted.
Old 10th August 2019
  #43
Gear Head
 

Alright. Just got back from errands. Picked up the decibel reader and followed Stuart's guide.

I hope i did this right. Measurements of the tip of the mic are as followed:

Distance from Front Wall - 52"
Distance from Left Wall - 70 1/4"
Distance from Right Wall - 66 1/2"

Should i have had the mic in the centre so the L & R measurements are equal? Does it matter that there is a 4" difference?

Also, please not that on the L&R speaker measurement I had to reduce the input gain on the mic as i was getting a notification that it was clipping. Hope that is ok as well.

Anyways let me know if you need me to run it again.
Attached Files
File Type: mdat Measurment 1 - Aug 10 2019.mdat (2.83 MB, 11 views) File Type: mdat Measurment 2 - Aug 10 2019.mdat (8.47 MB, 9 views)
Old 11th August 2019
  #44
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Quote:
Should i have had the mic in the centre so the L & R measurements are equal? Does it matter that there is a 4" difference?
Yes. And yes! Precision is important.

Quote:
Also, please not that on the L&R speaker measurement I had to reduce the input gain on the mic as i was getting a notification that it was clipping. Hope that is ok as well.
That's fine. Do keep the level low enough that there's no indication if clipping. If you have to bring the level down, then repeat all three measurements.

There still seems to be a problem with your calibration: The reported levels are very high, including the noise floor and the distortion. I'm pretty sure you are not hitting peaks of 125 dBC! And I very much doubt that your noise floor is at 60 to 70 dBC... unless maybe you live on a subway train...

I'd re-check the calibration procedure. Make sure you are getting no more than 80 dBC on each individual speaker, as measured on the meter set to "C" and "slow", and that you do then tell REW about that, by entering the exact level into the "SPL meter" calibration tab.

- Stuart -
Old 11th August 2019
  #45
Gear Head
 

Quote:
Originally Posted by Soundman2020 View Post
Yes. And yes! Precision is important.
That's fine. Do keep the level low enough that there's no indication if clipping. If you have to bring the level down, then repeat all three measurements.

Quote:
Originally Posted by Soundman2020 View Post
There still seems to be a problem with your calibration: The reported levels are very high, including the noise floor and the distortion. I'm pretty sure you are not hitting peaks of 125 dBC! And I very much doubt that your noise floor is at 60 to 70 dBC... unless maybe you live on a subway train...

I'd re-check the calibration procedure. Make sure you are getting no more than 80 dBC on each individual speaker, as measured on the meter set to "C" and "slow", and that you do then tell REW about that, by entering the exact level into the "SPL meter" calibration tab.
Ok i made the mic more centre. About to do this again. Can't believe i still don't have it right. Could it be my mic? I'm using the sonarworks XREF?

Also, the input meter when i do my sound check is not showing -18 as you state in the first step in checking the levels.
Old 11th August 2019
  #46
Gear Head
 

I think I may have figured it out. I went to mic/meter and selected "C weighted SPL meter" instead of "Mic or Z weighted SPL meter"

Hopefully that was the issue
Old 11th August 2019
  #47
Gear Head
 

Ok. Let's try this again.... I think i did it right. SPL levels look more normal. A lot lower. Pretty sure it was the mic setting i had.

New Mic measurements:

Front Wall - 51"
Left Wall - 68"
Right Wall - 68 3/4"

Also, as mentioned before I didn’t move any of the set up. Left speakers and everything where they were as I plan on putting treatment on the front wall.

Face of the speakers are about 19” away from the front wall so if I need to reposition and measure again that’s no problem
Attached Files
Old 11th August 2019
  #48
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akebrake's Avatar
 

Clocking

Quote:
Originally Posted by recaro19 View Post
I think I may have figured it out. I went to mic/meter and selected "C weighted SPL meter" instead of "Mic or Z weighted SPL meter"

Hopefully that was the issue
May be? BTW That "C" weighting can be switched off when examining plots.

A possible issue is the notch in the soundcard response. As I understand it the latest REW beta versions have warnings and functions for adjusting possible clock errors.

I can't give any tips how to do this unfortunately. It's new REW feature and I'm not a computer guy

If I got it right you have a XREF20 mic pointing at the front wall and an USB driven Komplete Audio 6 sound card/preamp connected to a Mac?
Attached Thumbnails
Just moved in!  New Studio Build-l-baseline-sndcard-clock-.jpg  
Old 11th August 2019
  #49
Gear Head
 

Quote:
Originally Posted by akebrake View Post
May be? BTW That "C" weighting can be switched off when examining plots.

A possible issue is the notch in the soundcard response. As I understand it the latest REW beta versions have warnings and functions for adjusting possible clock errors.

I can't give any tips how to do this unfortunately. It's new REW feature and I'm not a computer guy

If I got it right you have a XREF20 mic pointing at the front wall and an USB driven Komplete Audio 6 sound card/preamp connected to a Mac?
That is correct. Have the XREF20 pointed at the wall with an angle of approx. 60 degrees as recommended by Stuart in his guide.

Using the komplete audio 6 for now. Maybe a driver issue so I’ll check if I have the latest soundcard update. I’m pretty sure I do but worth exploring.

I also have an RME UFX with dangerous D-Box set up on the rack on the floor. Keeping the set up simple for now as I have yet to figure out how to incorporate the dangerous d-box in my set up. Focusing on acoustic treatement first and just making music at this point.

If I add the rme and dangerous later will I need to recalibrate?

That dip in the soundcard measurement looked a little off to me as well but I just assumed it was part of the reading. I didn’t download the latest beta version that prompts each time I open REW. I’ll take a look when I get home.
Old 11th August 2019
  #50
Gear Head
 

Just checked the device updater and it says the firmware is up to date.
Old 13th August 2019
  #51
Gear Head
 

Any other insight on akebrake's findings? Is tehre something wrong with my sound card reading which is why my results are poor?

Perhaps I should be starting over again and also using the rme with a more precise set up of my speakers?
Old 13th August 2019
  #52
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akebrake's Avatar
 

Quote:
Originally Posted by recaro19 View Post
Just checked the device updater and it says the firmware is up to date.
Have you tried a REW update also?
The latest one (5.20beta 19) came yesterday!

Before going into measurement details, you need a valid measurement.

And if no one here knows why there is a notch in your soundcard response
the guy you should ask is John Mulcahy (REW author) at AV Nirvana Forum

Best
Old 13th August 2019
  #53
Gear Head
 

Quote:
Originally Posted by akebrake View Post
Have you tried a REW update also?
The latest one (5.20beta 19) came yesterday!

Before going into measurement details, you need a valid measurement.

And if no one here knows why there is a notch in your soundcard response
the guy you should ask is John Mulcahy (REW author) at AV Nirvana Forum

Best
So, my last round of measurements are still not correct?

I'm confused... What is the issue? Sound card reading?

Should i try using the RME an Dangerous D-Box set up instead? If so, how do I calibrate through that?
Old 13th August 2019
  #54
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Quote:
Originally Posted by recaro19 View Post
Any other insight on akebrake's findings? Is tehre something wrong with my sound card reading which is why my results are poor?
DanDan mentioned in his sticky topic on measuring room acoustics about sound cards. Have you tried his suggestion?
Old 13th August 2019
  #55
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Quote:
Originally Posted by Starlight View Post
DanDan mentioned in his sticky topic on measuring room acoustics about sound cards. Have you tried his suggestion?
I have not as I wasn't aware of this information in his sticky. I'll take a look.

Here is what John said over at AV NIRVANA:

"Looks like there was a glitch or dropout during your soundcard cal measurement, it also rolls off quite early at the top end. I'd just remove the soundcard cal and measure without it.

Use single sweeps rather than 2 sweeps.

Look in Audio Midi Setup in the mac (in Applications -> Utilities) and check the sample rate the card is configured for, use the same rate in REW."


Does this make sense or does the soundcard calibration need to be included for a proper measurement?

I'm going to look into my audio midi set up first as he suggested as that is a good starting point. Didn't think to make sure of that. I'll do that and do the calibration again to see if the issues rectified. probably update REW as well.

Well, once again, I will be back! Determined to get things right...
Old 14th August 2019
  #56
Gear Head
 

Okay, I think i fixed the soundcard reading? Looks better now I think. Saved the file and will do the measurements over again on Thursday.

Now, in order to get the most accurate reading, should I move the monitors close to the wall or leave them where they are? Does it matter where they are set up for the initial measurements? If I plan on putting treatment in i'll most likely have to move them again so just curious how to go about this.

I want to ensure i do this properly as I've already made a few mistakes.
Attached Thumbnails
Just moved in!  New Studio Build-soundcard-08-13-2019.jpg  
Old 16th August 2019
  #57
Gear Head
 

Update: August 15 2019

Ok. At this point i feel like i did it wrong again but here goes nothing.

I rearranged my speakers a bit. Pushed them back as far as I could go without them touching the walls. Basically, the face of the speaker is now about 10.5 inches away from the wall and the rear of the speaker is just over 2" away from the wall.

I re did the measurements so I hope it's ok now. Please let me know if I messed up again.
Attached Files
Old 17th August 2019
  #58
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I guess people got fed up with my errors

If anyone is still out there i' d love some feedback.
Old 17th August 2019
  #59
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Don't give up!

The data is looking much better now, and you seem to have calibrated things properly. It looks like a typical untreated room now: ugly!

What does stand out is that there's quite a large difference between the left and right channels, below about 130 Hz. From there up the variations between channels are what you would typically expect in a small room, but below 130 there's some major differences. So symmetry is a problem. That could be related to the alcove off to your right, or the asymmetric rear wall... hard to say. Just checking here: are you certain that you have both speakers set up the exact same distance from the side walls, and the exact same distance from the front wall?

- Stuart -
Old 17th August 2019
  #60
Gear Head
 

Quote:
Originally Posted by Soundman2020 View Post
Don't give up!

The data is looking much better now, and you seem to have calibrated things properly. It looks like a typical untreated room now: ugly!

What does stand out is that there's quite a large difference between the left and right channels, below about 130 Hz. From there up the variations between channels are what you would typically expect in a small room, but below 130 there's some major differences. So symmetry is a problem. That could be related to the alcove off to your right, or the asymmetric rear wall... hard to say. Just checking here: are you certain that you have both speakers set up the exact same distance from the side walls, and the exact same distance from the front wall?

- Stuart -
I'm so relieved to hear i've made some progress! Much appreciated Stuart.

I just checked the measurements. Left speaker is 40" away from the left wall and right is about 39.5" away from the right. Both speakers inner rear corners are approx 2.5" away from the front wall.

I noticed that both measurements looked fairly similar as well till about 100 hz. I thought I had maybe messed up again b ut figured i'd post the readings here to get a second opinion.
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