First REW measurements - feedback appreciated :)

[viktorapo]

Hi everyone,

I've finally taken my first ever REW measurements and would really appreciate some feedback before I start moving speakers, changing treatment, or applying any EQ.

I'm completely new to REW and room measurements, so there's a good chance I've done something incorrectly. If you notice any mistakes in my measurement procedure or settings, please don't hesitate to point them out—I'm here to learn.

Room​

• Width: 3.5 m
• Length: 4.7 m
• Height: 3.0 m
• Listening distance: 1.6 m
• Monitors: Yamaha HS7

Acoustic treatment​

• 40 cm soffit-style bass traps in all four corners
• 15 cm rockwool panels on all walls with approximately a 5 cm air gap
• Three 15 cm ceiling clouds

The Yamahas are currently positioned about 25 cm from the front wall, almost touching the acoustic panels behind them, which are approximately 20 cm thick.

Files​

Room photos:

https://imgur.com/a/qcVxgbh

REW screenshots (1/12 octave smoothing):
https://www.dropbox.com/scl/fo/4cf5...ey=oi7njihjhomysmlpco4vsmtjl&st=ls9129mv&dl=0

Full REW measurement (.mdat):
https://www.dropbox.com/scl/fi/kxmj...ey=ucyznomoh4qysw7vuz2zi0qoz&st=i29qo3m5&dl=0

I've included screenshots for a quick overview, but also uploaded the full MDAT in case anyone wants to inspect the measurements in more detail.

Measurement notes​

• This is my first time ever using REW.
• The MDAT contains two measurements for each position, labelled "one" and "two."
• The only difference between them is the soundcard calibration (.cal) file I used. I wasn't sure which calibration file was correct, so I measured using both.
• If I handled the soundcard calibration incorrectly, I'd really appreciate someone explaining the proper approach.
• All measurements were taken one speaker at a time unless otherwise noted.
• I used a 512k sweep length with 4 sweeps/iterations, which resulted in roughly 43 seconds of sweep time per measurement.
• I don't have any "before treatment" measurements since this is the first time I've measured the room at all.

The main reason I'm doing these measurements is that I'm planning to upgrade my monitors to the Neumann KH310, preferably the MK2 version if it does indeed arrive later this year. There have been persistent rumors that it will include built-in DSP and room correction.

My understanding is that the sealed-box KH310s are generally more forgiving when placed close to the front wall, so the plan is to position them in essentially the same location as the Yamahas. With the larger speakers, however, I'll likely increase my listening distance to around 1.8–1.9 m.

The goal of these measurements is to understand whether my room is already in a good place for that upgrade, or whether I should spend more time improving the acoustics first. I'd really appreciate feedback on both the room itself and whether my measurements and REW setup look correct. Any suggestions on what you'd improve first would be greatly appreciated.

Thanks a lot to anyone willing to take the time to look through everything. I'm looking forward to learning from your feedback!

 

[Keith_W]

Firstly, have you read the eBook in my signature?

There are a few very strange things in your MDAT. Like, this sound card calibration file. This is clearly invalid. Look at this page in the REW manual - you have a feedback loop in your cal file. You will need to follow the steps in the manual to get rid of that feedback loop. If we want to examine the rest of your MDAT, we have to remove the soundcard calibration. Also, where is your mic calibration? Mics are electromechanical devices, and are far more susceptible to deviations than electronic devices like your sound card. My sound card (RME Fireface UC) is perfectly flat from about 1-2Hz up to Nyquist.

The eBook should answer the rest of your questions about your room. It seems to me as if your room might be overtreated (very low RT60) but there are procedures for determining that. Depending on room volume and application, it may be appropriate.

 

[viktorapo]

Firstly, have you read the eBook in my signature?

View attachment 542389

There are a few very strange things in your MDAT. Like, this sound card calibration file. This is clearly invalid. Look at this page in the REW manual - you have a feedback loop in your cal file. You will need to follow the steps in the manual to get rid of that feedback loop. If we want to examine the rest of your MDAT, we have to remove the soundcard calibration. Also, where is your mic calibration? Mics are electromechanical devices, and are far more susceptible to deviations than electronic devices like your sound card. My sound card (RME Fireface UC) is perfectly flat from about 1-2Hz up to Nyquist.

The eBook should answer the rest of your questions about your room. It seems to me as if your room might be overtreated (very low RT60) but there are procedures for determining that. Depending on room volume and application, it may be appropriate.

Thanks, I did doubted that the most. I also have Fireface UC and did the loopback but something smelled off. How did you set up ? I will try the "internal without cables" route like you did with ADAT. The interface on REW is a bit changed so I might've missed something there I will reupload proper measurements

 

[janbth]

I recommend that you take the time to learn how to produce plots (the camera icon on the top left) and show them inline in your posts. Posting an .mdat, or a link to an .mdat, is fine, but you will probably get much more feedback with plots.

 

[Keith_W]

Thanks, I did doubted that the most. I also have Fireface UC and did the loopback but something smelled off. How did you set up ?

From memory, I connected output 2 to input 1 with a physical cable. Turn 48V off. You have to make sure Totalmix does not loop back the input to the output.

I will try the "internal without cables" route like you did with ADAT. The interface on REW is a bit changed so I might've missed something there I will reupload proper measurements

No, you can't use that method as a soundcard calibration. The internal loopback function is ONLY for taking timing measurements. In any case, I wouldn't bother with soundcard calibration. I assure you it's flat, unless your RME has a problem. It's not likely, it's an RME after all! You should be more concerned about mic calibration.

There is no need to reupload proper measurements. I managed to unload your cal file and see the measurements without it. Your MDAT, as it is, is perfectly usable once the cal file is unloaded ... apart from the lack of a microphone cal file. But then, your question is about room acoustics, so the mic cal file isn't really needed. It's actually a pretty well taken measurement, and I can comment on it if you like. But it is better if you learn how to read it yourself, which is why I pointed you at the book.

 

[viktorapo]

I recommend that you take the time to learn how to produce plots (the camera icon on the top left) and show them inline in your posts. Posting an .mdat, or a link to an .mdat, is fine, but you will probably get much more feedback with plots.

thanks ! is there a general rule for that? like a guideline to follow (standards) regarding smoothing, what to include, etc.?

 

[viktorapo]

From memory, I connected output 2 to input 1 with a physical cable. Turn 48V off. You have to make sure Totalmix does not loop back the input to the output.



No, you can't use that method as a soundcard calibration. The internal loopback function is ONLY for taking timing measurements. In any case, I wouldn't bother with soundcard calibration. I assure you it's flat, unless your RME has a problem. It's not likely, it's an RME after all! You should be more concerned about mic calibration.

There is no need to reupload proper measurements. I managed to unload your cal file and see the measurements without it. Your MDAT, as it is, is perfectly usable once the cal file is unloaded ... apart from the lack of a microphone cal file. But then, your question is about room acoustics, so the mic cal file isn't really needed. It's actually a pretty well taken measurement, and I can comment on it if you like. But it is better if you learn how to read it yourself, which is why I pointed you at the book.

ok thanks! good to know! i will head up on your PDF right away, I do love learning about this - but the truth is I am insecure, same applies when mixing down my tracks, I feel like I have read so much and practiced a lot but i dont have the confidence. if you have the time, id like to hear your opinion, and then by reading the PDF and listening to it I can compare or even learn more (practical). thank you so much!

 

[Keith_W]

Sure, please supply the room dimensions and let us know what the system is for. Is it for recreational listening, or is it a studio? As for guidelines on how to post screenshots of measurements, that's also in the book.

 

[viktorapo]

updated the mdat file without the .cal file and cleaned up - also added images as inline

 

[janbth]

thanks ! is there a general rule for that? like a guideline to follow (standards) regarding smoothing, what to include, etc.?

There are some rules of thumb and convention. For frequency response plots I would suggest:

• X-axis: Span 20 Hz - 20k Hz if the focus is full range, 10 Hz - 200 Hz if the focus is bass.
• Y-axis: Span ca. 50 dB.
• Smoothing: Use Var smoothing unless you have a reason not to.
• You can put more curves on the same plot, especially if you are comparing responses. However, too many can be confusing, so exercise "good taste".

Other than that, try to find - and understand (!) - plots that others post around ASR (or elsewhere). With time, you will get a feeling for what is good practice.

 

[viktorapo]

Sure, please supply the room dimensions and let us know what the system is for. Is it for recreational listening, or is it a studio? As for guidelines on how to post screenshots of measurements, that's also in the book.

Room dimensions and images are in the post: https://www.audiosciencereview.com/...easurements-feedback-appreciated.72155/#-room

• Width: 3.5 m
• Length: 4.7 m
• Height: 3.0 m
• Listening distance: 1.6 m
• Monitors: Yamaha HS7

It is a studio, im producing electronic music mostly in the box with some old hardware synths and drum machines. I want to step up and have a better sound but also have a decent sounding room, to describe it better on a scale from 1-10 (1 being bedroom and 10 professional studio) id say on a level of 6-7, nothing super professional more like best value I can get from myself with DIY and of course - if its worth investing in the Neumann monitors with this room

 

[janbth]

... also added images as inline

Looks like these are attachments. You should be able to add them to show inline with Insert image. At least that's how it works on my end with Firefox.

 

[viktorapo]

L+R+LR

Left speaker RT60 Decay

Right Speaker RT60 Decay

Waterfall Left Speaker

Waterfall Right Speaker

Spectogram L

Spectogram R

 

[viktorapo]

Looks like these are attachments. You should be able to add them to show inline with Insert image. At least that's how it works on my end with Firefox.

i guess you meant like my reply above? need to step up my forum skills

 

[janbth]

i guess you meant like my reply above? need to step up my forum skills

Yes, that's exactly what I mean.

First impressions from the L+R+LR response plot:

• There is a dip at 80 Hz, almost certainly a room mode, probably due to an unfortunate listening posistion (because it is visible on both L and R). The solution is to move the MLP or use a sub.
• Another suckout at about 180 Hz. This is a bit too high for room modes, but could possibly be SBIR.

 

[viktorapo]

Yes, that's exactly what I mean.

First impressions from the L+R+LR response plot:

• There is a dip at 80 Hz, almost certainly a room mode, probably due to an unfortunate listening posistion (because it is visible on both L and R). The solution is to more the MLP or use a sub.
• Another suckout at about 180 Hz. This is a bit too high for room modes, but could possibly be SBIR.

yup, that 80hz worries me the most. speakers are placed around 25cm from the front wall and yamaha hs7 have rear port. theres an absorber of 15cm between the front wall and the speakers. listening position is around 1.8m from the front wall +-38% of the room.

 

[Keith_W]

Well let's start with what is good.

RT60 has been calculated for room volume (49m^3) and application (studio target 200ms). Your RT60 is bang on target. Note this is a single measurement of L+R, it is likely to be accurate from about 1kHz up. Below that is anybody's guess. There is a procedure in the book on how to take a proper RT60 measurement.

The first 20ms of the ETC is close to ideal. There is a loud reflection at 16.3ms, corresponding to a path-length difference of about 5.5m. You said that the listening distance is 1.6m, and the speakers are 25cm from the front wall (total 1.85m from the front wall). Room length is 4.7m. So (4.7-1.9) * 2 = 5.6m - that reflection is coming from the rear wall.

The Schroder frequency in your room is = 2000 * sqrt (RT60/V); RT60 is 150ms, and room Volume is 49m^3 = 110Hz. So we would expect the freq response above the transition zone (440Hz) to follow your speaker's anechoic response. Here is the published response from spinorama.org:

Your measurement looks similar, with the exception of the treble lift. In particular, that step at about 800Hz is present in both measurements. The lack of treble lift can be explained away by your lack of a calibration file and possibly wrong microphone orientation.

As for that 80Hz dip being SBIR: if it was, it isn't coming from the front walls. Speaker to front wall distance is 0.25m. The SBIR cancellation wavelength is 4x this distance, so the wavelength is 1m. That's 343Hz. It's likely to be a room mode or side wall SBIR. You didn't tell us how far the speaker is from the side walls.

More concerning is that dip at 170Hz. It is present in both speakers. That is too high for you to fill with a subwoofer. You should try to diagnose it. The book contains a procedure for diagnosing dips in the frequency response. I would suggest measuring at 30cm L/R of the listening position and see what happens to it. The other possibility is SBIR from the side walls, as already discussed.

 

[janbth]

yup, that 80hz worries me the most. speakers are placed around 25cm from the front wall and yamaha hs7 have rear port. theres an absorber of 15cm between the front wall and the speakers. listening position is around 1.8m from the front wall +-38% of the room.

My guess is that your MLP is close to the null of one or possibly two of the modes in your room. Check out Amroc: https://amcoustics.com/tools/amroc. It's a useful online room mode calculator with 3D visualization of the modes. Note that computed room mode frequencies are never completely exact, so allow for some tolerances.

 

[viktorapo]

Well let's start with what is good.

View attachment 542457

RT60 has been calculated for room volume (49m^3) and application (studio target 200ms). Your RT60 is bang on target. Note this is a single measurement of L+R, it is likely to be accurate from about 1kHz up. Below that is anybody's guess. There is a procedure in the book on how to take a proper RT60 measurement.

View attachment 542460

The first 20ms of the ETC is close to ideal. There is a loud reflection at 16.3ms, corresponding to a path-length difference of about 5.5m. You said that the listening distance is 1.6m, and the speakers are 25cm from the front wall (total 1.85m from the front wall). Room length is 4.7m. So (4.7-1.9) * 2 = 5.6m - that reflection is coming from the rear wall.

View attachment 542461

The Schroder frequency in your room is = 2000 * sqrt (RT60/V); RT60 is 150ms, and room Volume is 49m^3 = 110Hz. So we would expect the freq response above the transition zone (440Hz) to follow your speaker's anechoic response. Here is the published response from spinorama.org:

View attachment 542462

Your measurement looks similar, with the exception of the treble lift. In particular, that step at about 800Hz is present in both measurements. The lack of treble lift can be explained away by your lack of a calibration file and possibly wrong microphone orientation.

As for that 80Hz dip being SBIR: if it was, it isn't coming from the front walls. Speaker to front wall distance is 0.25m. The SBIR cancellation wavelength is 4x this distance, so the wavelength is 1m. That's 343Hz. It's likely to be a room mode or side wall SBIR. You didn't tell us how far the speaker is from the side walls.

More concerning is that dip at 170Hz. It is present in both speakers. That is too high for you to fill with a subwoofer. You should try to diagnose it. The book contains a procedure for diagnosing dips in the frequency response. I would suggest measuring at 30cm L/R of the listening position and see what happens to it. The other possibility is SBIR from the side walls, as already discussed.

Wow thank you so much!!

By doing a dirty math we can "assume":
Room center is: 3.5 m / 2 = 1.75 m from each side wall
Each speaker is placed symmetrically around the center:

• Half speaker spacing = 1.6 / 2 = 0.8 m
• So each speaker sits 0.8 m left/right of center

Therefore speaker from wall: 1.75 − 0.8 = 0.95 m

If this is you, would you buy the "improved" kh310 with dsp or try to fix this null. Im trying to understand on 1-10 how "dirty" these 70-80hz, 170hz and 340hz freqs are.

P.S. printed out the FULL ebook, starting off tonight

 

[Keith_W]

Therefore speaker from wall: 1.75 − 0.8 = 0.95 m

Speaker to side wall = 0.95
SBIR cancellation frequency = 0.95m x 4 = 3.8m
That equals 90Hz.

The problem with speaker placement is that there is no perfect position, only the least compromised positions. This is particularly true for smaller rooms. If you were to push your speakers so close to the wall that you eliminate this SBIR cancellation, you would screw up central imaging by widening your listening triangle. Another option is to position your speakers asymmetrically in the room so that the SBIR frequencies do not coincide. But if you do that, the upper frequencies will also have asymmetric reflections, and it will screw up imaging.

Another option is to get a subwoofer and cross it over at about 100Hz. You will need a bit of DSP to get it to blend in though. It may be best to try to lower that frequency so that you don't have to run the sub so high.

If this is you, would you buy the "improved" kh310 with dsp or try to fix this null. Im trying to understand on 1-10 how "dirty" these 70-80hz, 170hz and 340hz freqs are.

No. Any speaker placed in the same location will have the same problems below the Schroder frequency, assuming the frequency response is the same. The reason you buy a KH310 is because it's not as lumpy at the top end as your Yamaha.

P.S. printed out the FULL ebook, starting off tonight

That eBook is not a complete manual on acoustics, but it will be enough to get you started. You will still need to buy and read an acoustics text like Toole or Everest if you want to fully understand the subject. And BTW I never wrote that book with printing in mind, most of those diagrams rely on colour to make sense.