REW Measurement Issues

[recaro19]

Hello,

I need help with some issues I'm having measuring my room. I just downloaded the latest Beta Version of REW but previous versions did not yield proper results according to the GearSlutz forum members. I've documented everything here on Gearslutz under Studio Building/Acoustic. Thread title "Just Moved in! New Studio Build".

Just moved in! New Studio Build - Gearspace.com

Hello Everyone, Excited to be here as I begin my new journey in this newly rented apartment. Hope to us this post as a great learning experience for not only myself but others who may be in a similar situation. Up until moving into this new space (a small

www.gearslutz.com

Basically, everytime I have done a measurement, the users who have tried assisting have told me that there are some issues with my readings. I'm following Soundman2020 Calibration tutorial for measurements.

https://www.johnlsayers.com/phpBB2/viewtopic.php?f=3&t=21122

Tried to attach the file but i guess it's too big. Here is a link to download:

Microsoft OneDrive

1drv.ms

Gear I'm using:

- MacBook Pro Mid 2015 i7
- Sonarworks XREF 20 Measurement mic
- Komplete Audio 6 Soundcard
- Neuman KH120 reference monitors

Can someone please assist?

 

[John Mulcahy]

Measurements look fine, but your SPL calibration went a bit astray from Aug 20 so the graphs are drawn at a higher SPL than they should be - it doesn't affect the shapes at all so still alright to use them, just ignore the SPL values. To get correct SPL levels you will need to redo the SPL calibration. You are using a mic for your measurements so don't select the "Input device is a C Weighted SPL Meter" box. Make sure the value you type in to REW is the reading from your own SPL meter, not from the REW meter. If you change any gain aong the input path (such as the mic preamp gain) you will need to redo the SPL calibration. Note that your SPL meter should be placed close to where your mic is to get the correct reading.

 

[jtalden]

Just FYI.
There is also a 5 dB, 1500 Hz ripple superimposed on both the L, R speaker measurements that doesn't help the HF appearance. I think this may be a result of mic placement rather than a measurement system problem though.

 

[recaro19]

Measurements look fine, but your SPL calibration went a bit astray from Aug 20 so the graphs are drawn at a higher SPL than they should be - it doesn't affect the shapes at all so still alright to use them, just ignore the SPL values. To get correct SPL levels you will need to redo the SPL calibration. You are using a mic for your measurements so don't select the "Input device is a C Weighted SPL Meter" box. Make sure the value you type in to REW is the reading from your own SPL meter, not from the REW meter. If you change any gain aong the input path (such as the mic preamp gain) you will need to redo the SPL calibration. Note that your SPL meter should be placed close to where your mic is to get the correct reading.

You know what, I think this makes sense. I do recal increasing the volume to get the level up to the proper decibal range. I'll circle back and do a full new reading again. Thanks for verifying.

Also, is the Sonarworks mic okay to use? Where do i place the calibration file as this menu has changed on the newer update. I got a bit confused if i put it in correctly.

 

[recaro19]

Just FYI.
There is also a 5 dB, 1500 Hz ripple superimposed on both the L, R speaker measurements that doesn't help the HF appearance. I think this may be a result of mic placement rather than a measurement system problem though.
View attachment 25396

I'm going to be honest, I have no idea what any of these graphs mean. I was only doing these measurements so i could get them analyzed by the guys at gearslutz. I wanted insight on the room and how to go about treating it.

Do you have any good tutorials for me to read or any quick explanations you can give as to what the graphs mean and how to interpret them?

 

[jtalden]

You have great equipment so improved sound experience will be found through room setup and DSP. The most important measurement chart is the SPL chart. If you improve that it will have the greatest impact.
1. The SPL target is often referred to as a house curve. Different rooms and different preferences result in no single best target. The place to start then is with a browser search for 'house curve audio'. You will find advice and discussions on selecting a house curve. A little experimentation with speaker placement and listening position option can often help a great deal.
2. We can also achieve significant improvement with EQ. The MiniDSP.com website has many helpful hints under 'Application/Digital Room Correction'.
3. Acoustical treatment of the room can have good impact also, but is a difficult subject for a beginner.

I suggest you limit the initial focus on subjects 1 and 2 to start. Your browser is your friend.
Here is link to setup advice that that covers more subjects. acoustic frontiers

 

[recaro19]

Thanks, jtalden!

Some good info here and a little over my head but I'll definitely dig into this a bit more. In response to the order in which you posted:

1) Is the purpose of the SPL graph to tell you how far off you are from a flat sounding room? I assume the idea of the SPL chart is to try and get as flat as a response as possible and as close to 0db across the frequency spectrum? I guess I just want to try and understand what the goals of each graph are when measuring so I can understand them better. Right now I see dips and peaks but don't really understand why or how to fix them.

Also, for the house curve... would getting a graphic EQ in 1/3 octaves be the way to go if I want to apply this curve? Would i apply the curve and leave it like that when producing music? Would I also apply the curve first then do a measurement before treating the room so the room is being treated to the curve?

2) I have Sonarworks Reference 4 and plan to use it but I heard it is best to have treatment for the most optimal results. Apparently, in an untreated bare room like mine, the EQ curve Sonarworks would apply would be too unrealistic. When measuring my room should I just use Sonarworks or is REW better? I don't think Sonarworks gives you waterfall graphs.

3) I've been doing a lot of reading on the acoustic treatement side and seems i will need quite a bit of absorption for the small space i'm in. Bass seems to be the primary issue so will be doing two large superchunk bass traps and 6" panels with roxul safe and sound on as many walls as I can. I'll be addressing the superchunks first and measuring before and after but I want to get the concept of REW down first so ensure i have proper measurements.

Thanks!

 

[jtalden]

I hadn't looked at your thread on gearslutz, but a quick look now suggests you are already getting better help than I can offer. My initial comment was only intended to point out the unusual nature of the high frequency response of your SPL chart as that was probably not related to the calibration issue that John helped you with. It was just something I thought could and should be looked into and was probably relatively easy to improve. I see now that you are intending to apply room treatments. That may be a significant factor in addressing this.

While I am not the best source for detailed advice on the issues you are asking about. I will still offer my basic thoughts regarding your questions in case it is helpful.

The SPL measurement target is to generally approach a chosen house curve that you have selected. A house curve is not flat as it falls off at the higher frequencies and most often rises in the bass range. Large measurement SPL deviations from the target is a significant indicator of sound quality issues. It is not clear cut however as to the underlaying causes of significant deviations and thus the corrective actions that would help address those deviations. The other charts and a very good understanding of measurement methods, analysis and room acoustics is needed for that.

My general sense of good room setup approach is to first follow good practices on speaker positions and listening position. Then follow good practices concerning room treatments. It takes more knowledge and experience than I have to efficiently evaluate the deviations from the room curve target and make effective adjustments to positions and treatments. Most of us casual hobbyists just follow general guidelines as we understand them. The speaker quality, room dimensions, room construction, speaker/LP positions, and room treatments are the basic contributors to the sound quality. Ongoing measurements can help with some of these choices if you have the expertise.

After the basics are addressed then DSP PEQ below 200 Hz is required. Advice on PEQ above 200 Hz is a difficult subject. My current take on this is that if the basics are all carefully addressed as in professional studios then little, or no PEQ is helpful beyond minor shaping to the house curve is needed. It is better to leave other apparent deviations from the curve uncorrected. In more typical rooms for most hobbyists some PEQ above 200 Hz can be very helpful If done correctly. A GEQ is not usually helpful for the bass range. It can be used help to shape to the room curve, but PEQ is the preferred device of these two. Automated EQ correction is very popular and helpful particularly for setups that lack the good basics. I have no opinion/experience with the more sophisticated DSP FIR options such as Dirac, Acourate, et al.

These are the basics you have probably already gathered. Good luck with your effort.

If you are serious in learning more deeply about these subjects, I strongly endorse these 2 books:
Toole, Sound Reproduction, loudspeakers and rooms
Everest & Pohlmann, Master Handbook of Acoustics

 

[recaro19]

jtalden,

Thanks a lot for the in-depth information. Acoustics is definitely an interesting subject. I thought it would have been as simple as buying a room kit and applying the treatment to the walls but onceI dove in I was bombarded with an assortment of theories, practices, and DIY methods that had my head spinning. Now with the room measurement software, and the introduction of House Curves... I'm even more lost! LOL, You seem to be very well educated on the subject.

I really appreciate this information. I'm just looking to get my room sounding as best as possible to allow me to mix my tracks at the highest quality. always second-guessing sounds right now and not hearing things properly. I've never had the opportunity to build a studio the way I want so now that I can, I want to ensure i make the right choices.

I have Sonarworks Reference 4 so once I get treatment, I'll definitely be utilizing it's DSP capabilities to make things sound even better.