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FR vs Waterfall chart for analyzing room measreuments
Old 1 week ago
  #61
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Quote:
Ok so I did 4 new measurements (only on the right speaker for now)because I am still not sure if I should be pointing the microphone at the ceiling or not. When I point it more toward the speaker dead on the acoustic axis the high end gets better. Why is this?
The mic is a pressure sensor. (at least, a proper electret condenser mic is). It detects variations in the air pressure around the spot where the capsule is. That's ALL it does. However, those pressure variations can come from different directions. There are some pressure variations that permeate the entire room, and would be roughly the same in all directions for a large room, but not really like that for a small room. This is simply because of the sound bouncing around randomly inside the room for a while, after it came out of whatever was producing it (a loudspeaker, an instrument, your mouth, etc.). Since the sound bounces around randomly all over, reflecting back and forth between walls, at any give point in the room that sound has the same probability of coming from any direction, or all directions. This is called the "reverberant field" or "diffuse field", and represents the acoustic response of the room itself. Because a true diffuse field or reverberant field is "homogeneous": its the same in all directions. That only happens completely in a very large room: in small rooms, the sound is somewhat diffuse for part of the spectrum, above a frequency that is known as the "Schroeder frequency" or the "critical frequency", and that frequency is different for every room. Fortunately for us, the part of the spectrum below Schroeder is still pretty much the same when measured in any direction, because it is modal: Modes are powerful beasts, with major pressure variations, so they can also be measured pretty much the same with the mic pointing in any direction. However, the measurement will be different at different positions in the room for the low frequency measurements in a small room. In a very large room, it would be the same everywhere: at any point in the room, ad with the mic facing in any direction, you would get the same result. But small rooms are a bit different, so you need to take care when setting things up.

If that was the ONLY sound in the room, then you could point the mic in any direction and get exactly the same result: it would make no difference if you pointed it at the ceiling, or the floor, or a wall, or any old angle that you felt like. But it is NOT the only sound in the room! The speakers themselves are making sound too, which means the are producing their own pressure waves, in addition to the pressure waves produced by the room diffuse field. And while the diffuse field measures the same in all directions, the sound field from the speakers does not: It propagates as a series of pressure waves that leave the speaker and move in one single direction, perpendicular to the face of the speaker. So if you point the mic directly at the speaker, then the mic picks up those waves "head on", and they move the diaphragm from velocity, as well as from pressure. But if you aim the mic at the ceiling, then the waves are now hitting the diaphragm "side on", so there is no velocity component measured: just the pressure component.

Its actually a lot more complicate than that, and the above isn't really 100% accurate, but it does help to get your head around why you are seeing a difference when you point the mic in one direction or another, even though it is an omni mic that supposedly only measures pressure.

The point here is this: if you aim the mic towards the speaker, you are measuring the acoustic response OF THE SPEAKER along with the room. If you point it at the ceiling, then you are measuring the acoustic response OF THE ROOM, not the speaker. Thus, since you are trying to measure what your ROOM is doing, you should be aiming your mic upwards, NOT towards the speaker. In fact, for other complex reasons, it's best to aim the mic upwards at an angle of about 70° from horizontal, not at 90° as you would expect. 90° isn't too bad, but 70° is usually better. (You would only point the mic directly at the speaker if you were interested in seeing the speaker's response all by itself, and if you know how to do time-domain windowing inside REW, to remove the room response... but that's much more complex!).

Quote:
You can see how the high end starts rolling off the more I tilt the mic toward the ceiling.
Exactly. Because with the mic pointing more upwards, it is receiving LESS of the DIRECT sound waves from the speaker, and more of the room sound.

Quote:
Can someone please explain why this happens?
Yes. See above!

Quote:
does anyone actually know the answer ?
Yes. See above!

There's also the issue that dinococcus mentioned: you are using a rather large mic, which has an effect on the wave as it passes by. That's why proper measurement mics are shaped like a very thin pencil, with a slight taper to the body a way back, for the electronics inside and the XLR connector: that is done to minimize the effect that the mic has on the wave it is trying to measure. Your mic is not shaped like that, so it does have a noticeable effect on the wave.

- Stuart -
Old 1 week ago
  #62
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akebrake's Avatar
 

Directivity of Omni???

Quote:
Originally Posted by camomiletea View Post
.. When I point it more toward the speaker dead on the acoustic axis the high end gets better. Why is this?
It's not that complicated.
Note: We talk about Omni-directional microphones now.

When a soundwave hits the microphone membrane "straight on" e.g. "On Axis" or at the Normal* Incidence, a relatively higher pressure will build for frequncies where the ”boundary” (membrane) is bigger than the wavelength. (Treble rise for small mics say 1/2" and smaller)

Manufacturers can compensate more or less for this rise by ”damping” to make the mic Flat On Axis. Like ”free field” calibrated measuring mics.
The larger the membrane the lower start-frequency for that boost.

That means omni mics have some frequency dependant directivity. The smaller the mic membrane, the ”more omni” higher up in frequency so to say. This ”built in EQ” will affect only the highest frequencies.
Example: DPA 4060 5mm (≈1/4”) diameter

Quote:
You can see how the high end starts rolling off the more I tilt the mic toward the ceiling. Can someone please explain why this happens? does anyone actually know the answer ?
For grazing incidence, 90° (sound wave propagates parallell) to the membrane surface and there is no pressure build up. Instead we have cancellations at frequencies where ½ wave length roughly equals the diameter of the membrane. A combfilter pattern will show in the FR plot. Looks like a treble roll off (if smoothed enough).
EDIT: Found a FR of Octava See Pic 2 mt012 Omni (red box) Yellow curve is 90°. Roll off starts at 5kHz

The smaller the mic the less sensitive to direction in the more "useful" frequency range.

Would you mind showing us the supplied FR of your 012 mic?

Best

*PS Geometric "Normal" to a plane (surface) means 90° a direction in right angle to that surface.

EDIT: Hello Stuart! I'm too late this time...
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-dpa4060nogridfreqresp-0-90deg-kopia.jpg   FR vs Waterfall chart for analyzing room measreuments-2185-2_full.jpg  

Last edited by akebrake; 6 days ago at 10:20 PM.. Reason: Added message & FR chart
Old 6 days ago
  #63
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Quote:
Originally Posted by Soundman2020 View Post
The point here is this: if you aim the mic towards the speaker, you are measuring the acoustic response OF THE SPEAKER along with the room. If you point it at the ceiling, then you are measuring the acoustic response OF THE ROOM, not the speaker.
Ok I get this but Dinoccus above said that the high frequency roll off has not to do with the room but the microphone position or the mic itself. So Why are my measurements coming out with a high frequency roll off when the mic is pointed upwards? Also, does it really not pick up any of the speaker when it is in an upright position? Why not point it away from the speaker then?

Also, when I was testing, I found that the low frequency was better when the mic is closer to the speaker. Indeed, the frequency response was much better. is this because the mic picks up more of the speaker and less of the room when the mic is closer? If that is the case, shouldn't we all listen closer to our studio monitors?

Quote:
Originally Posted by Soundman2020 View Post
Exactly. Because with the mic pointing more upwards, it is receiving LESS of the DIRECT sound waves from the speaker, and more of the room sound.
In that case isn't is better to use the waterfall chart to see the "decay" of the sound rather than the frequency response. By asking you this I realize that we are going back to what it was that started this thread.

When I was testing, moving the mic further away or closer to the speaker makes such a huge difference and I couldn't understand how anyone can really tell how much of what the mic hears is

a) the mic FR (or mic placement FR)
b) the speakers FR
c) the room FR?

By changing the position of the mic or moving the mic angle there are such large variations in the frequency response so how do you know?


Quote:
Originally Posted by Soundman2020 View Post
There's also the issue that dinococcus mentioned: you are using a rather large mic, which has an effect on the wave as it passes by. That's why proper measurement mics are shaped like a very thin pencil, with a slight taper to the body a way back, for the electronics inside and the XLR connector: that is done to minimize the effect that the mic has on the wave it is trying to measure. Your mic is not shaped like that, so it does have a noticeable effect on the wave.
ok so you think measurements taken with an omni like mine cannot produce accurate results?
Old 6 days ago
  #64
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Quote:
Originally Posted by akebrake View Post
It's not that complicated.
Note: We talk about Omni-directional microphones now.

When a soundwave hits the microphone membrane "straight on" e.g. "On Axis" or at the Normal* Incidence, a relatively higher pressure will build for frequncies where the ”boundary” (membrane) is bigger than the wavelength. (Treble rise for small mics say 1/2" and smaller)

Manufacturers can compensate more or less for this rise by ”damping” to make the mic Flat On Axis. Like ”free field” calibrated measuring mics.
The larger the membrane the lower start-frequency for that boost.

That means omni mics have some frequency dependant directivity. The smaller the mic membrane, the ”more omni”so to say. This ”built in EQ” will affect only the highest frequencies.
Example: DPA 4060 5mm (≈1/4”) diameter



For grazing incidence, 90° (sound wave propagates parallell) to the membrane surface and there is no pressure build up. Instead we have cancellations at frequencies where ½ wave length roughly equals the diameter of the membrane. A combfilter pattern will show in the FR plot. Looks like a treble roll off (if smoothed enough).

The smaller the mic the less sensitive to direction in the more "useful" frequency range.

Would you mind showing us the supplied FR of your 012 mic?

Best

*PS Geometric "Normal" to a plane (surface) means 90° a direction in right angle to that surface.

EDIT: Hello Stuart! I'm too late this time...
Ok so then from what you are saying, you actually need a measurement microphone to take measurements and not any omni will do? I read that you could take measurements with any omni microphone.
Old 6 days ago
  #65
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The case of the roll off in the high frequency is solved.

if you want beautiful curves, you need to buy a mic. At 7000khz and above, the issue is your body who changes all. So nobody cares at this frequencies if THE SPEAKERS ARE OK.

Put back the desk and the rest of your installation, and show us the ETC.
Old 6 days ago
  #66
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Quote:
Originally Posted by camomiletea View Post
Ok so then from what you are saying, you actually need a measurement microphone to take measurements and not any omni will do? I read that you could take measurements with any omni microphone.
Depends how picky you are.

A measurement with mic position like this would be interesting. mdat pls

To compare with the first measurements (no Krk close)
Attached Images
FR vs Waterfall chart for analyzing room measreuments-post-43.jpg 
Old 6 days ago
  #67
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Quote:
Originally Posted by akebrake View Post
EDIT: Hello Stuart! I'm too late this time...
Yeah, but it was really close! Must have been a few seconds apart, I guess...

Quote:
Ok I get this but Dinoccus above said that the high frequency roll off has not to do with the room but the microphone position or the mic itself.
Right. That's what we are ALL saying! If you read back over our separate posts, we are all telling you the same thing: if you point the mic at the speaker, then you pick up more of the speaker sound, less of the room. If you point it at the ceiling, then you pick up more of the room response, less of the speaker. That's why the response curves look different. When you point it at the speaker, it is picking up the direct sound from the tweeter IN ADDITION TO the room sound. When you point it at the ceiling, it is NOT picking up so much of the direct sound from the tweeter, so the high end seems to be rolled off. It is not actually rolled off at all! I just looks that way because you have deliberately placed the mic such that it reduces the effects of the direct sound from the speaker.

If you want a simple illustration of what's happening, get out a plain old SM58, hook it up to a speaker, and talk into the front of the mic while listening to the speaker. Now rotate the mic so you are talking into the SIDE of the capsule, instead of the front, and listen to the speaker. The overall level has now dropped, and especially the high end has rolled off considerably. Because the sound waves from your mouth are now moving ACROSS the mic diaphragm, parallel to the surface, so they don't cause it ti vibrate. If you talk into the front of the mic, then the sound waves are hitting the diaphragm "head-on", normal to the surface (as Akebrake explained), so all of them are captured. (OK, so this isn't really the same situation as the measurement mic, because the SM58 is cardiod, not omni, but it does illustrate the principle).

Quote:
So Why are my measurements coming out with a high frequency roll off when the mic is pointed upwards?
Because it is not pointing at the speaker, which is generating all the highs! It's only picking up the room sound, without the direct sound form the speaker.

Quote:
Also, does it really not pick up any of the speaker when it is in an upright position?
It still picks up SOME of the speaker sound, yes.... but a LOT less than if it is aimed directly at the speaker.

Quote:
Why not point it away from the speaker then?
... ummmm... that0s exactly what we are telling you to do! Point it up at the ceiling, NOT at the speaker. Or rather, at an angle of about 70° towards the ceiling.

Quote:
Also, when I was testing, I found that the low frequency was better when the mic is closer to the speaker.
One again, that would be because you are measuring the speaker more than the room! The closer you get to the speaker, the more direct sound you are seeing in your data, and the less room sound. But you want to treat your ROOM; not your speaker! So you need the mic far enough away from the speaker that it picks up mostly room sound, and as little speaker sound as possible. If you want to test your speaker without any room effect at all, then take it outside into the back yard, as far away from everything as you can get it, lay it down on its back, with the drivers pointing up at the sky, and set up your mic one meter above the middle of the speaker. That will give you a pretty good indication of how the speaker is performing all by itself, when there's no room around it.

Quote:
the frequency response was much better. is this because the mic picks up more of the speaker and less of the room when the mic is closer?
Correct.

Quote:
If that is the case, shouldn't we all listen closer to our studio monitors?
No. Because each speaker has a minimum listening distance, which is the distance where the waves from the woofer, tweeter, bass reflex port, etc. all combine together smoothly into one single wave front, rather than being heard as several different individual waves if you are too close. The manufacturer will tell you what that distance is for every model he makes, and you should never listen closer than that distance. You should also not listen too far away: manufactures also often tell you what the maximum recommended distance is, but in that case it is not fixed: the maximum distance is also affected by the room. The better the room acoustic response, the greater the maximum distance can be. In a lousy room, you need to be very close to the speaker (but not less than the minimum distance), while in a really good room you can be quite fa away and still hear clearly, without the room coloring the sound.

Quote:
In that case isn't is better to use the waterfall chart to see the "decay" of the sound rather than the frequency response.
Yes! Definitely! I keep on trying to say that all over the forum, everywhere I can, but still there's some folks that don't get it: the frequency response curve is NOT the primary graph that you should be looking at for treating a room: the waterfall, spectrogram, and ETC graphs are far more useful. FR is just an "additional" thing to look at, that gives you more info. A lot of people think that FR is the most important of all, but it absolutely is not. They try to chase a flat line in the FR graph, and when they get close, they think it is wonderful... but that's not the goal.. or rather, it's not the primary goal: it is a secondary goal, after you get the time-domain issues under control. And in fact, if you do a really good job of damping modal resonances, dealing with SBIR, and killing all major early reflections, then you can check back to the FR graph and you'll be surprised to see that it has taken care of itself! It is now a LOT flatter than it was... simply because you corrected the underlying issues with the far more important stuff (reflections, resonances, phase cancellations) that were causing the FR mountains. Fix the underlying issues, and the FR will fix itself mostly.

This is also the reason why I keep on saying, over and over, that it is a really bad idea to use so-called "room correction" hardware or software to "fix" an untreated room, or badly treated room: BAAADDDD idea. You can make the FR flatter, yes, but at the cost of so many other issues. If you first take the time to treat the room properly, ironing out all of the major issues, then you CAN use such software or hardware as the FINAL step in the process, to tweak the room tuning. Because at that stage, EQ adjustments really are operating ONLY on the FR curve, without also affecting phase and time-domain negatively.

Sigh! Don't get me started on the silliness of trying to "correct" the acoustic response of an untreated room with EQ... I can rant about that for days...

Quote:
When I was testing, moving the mic further away or closer to the speaker makes such a huge difference and I couldn't understand how anyone can really tell how much of what the mic hears is
Yes, but by moving the mic you are also looking at a totally different part of the room! You only need to move the mic a small distance to put it in a very different modal situation, with different reflections, different SBIR, different comb filtering, different phase, etc. So you are not really hearing a difference in the SPEAKER: it's just a different acoustic response from the room itself. This is how we optimize room layout. When a studio designer or acoustician is trying to find the best possible geometry for the speakers and mix position, this is exactly what we do: start out with the theoretical best setup, then move the speakers in small increments to see if there is a better spot, then move the mic in small increments to see if there is a better spot. And of course, use your ears too!

Quote:
By changing the position of the mic or moving the mic angle there are such large variations in the frequency response so how do you know?
By not looking too much at the frequency response! As you already figured out, FR is not the main issue: time-domain is. If you look at the waterfall, spectrogram, and ETC graphs as you move the mic to different positions, you'll get a lot more useful info about the best location. Ditto as you move the speakers around. There's a procedure I use for this with my clients, and it takes quite a while to do it properly, but it helps you identify the best locations for the speakers, and the best location for the mix position. You can go through this several times as you add more treatment to the room, since hte treatment can change the room response, so the "best" spot might move a little as you treat.

Quote:
ok so you think measurements taken with an omni like mine cannot produce accurate results?
For rough, initial baseline measurements, it can provide you with some useful information. But if you want to do precision tuning of your room, you will need a proper measurement mic. It all depends on what your goal is here: if you want a room that is pretty good for a hobby studio to have fun and impress your friends, then there's probably no need to get another mic. But if your aim is to have a pro studio, tuned as well as it possibly can be, then yes, you will need that... and other things too. And you'd probably need to hire someone to walk you through the process, or do it for you. It just depends on what your plans are for the studio.


- Stuart -
Old 6 days ago
  #68
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Quote:
Originally Posted by camomiletea View Post
In this one the bass is completely flat up to a certain point but overall I think it is pretty good. Hoping someone else can chime in before I start drawing crazy conclusions. Again the mic pointing up is completely lacking high end. I still don't know what this actually means. Since it is an omni shouldnt it be picking up high frequency upright just as it does pointing at the source?
First of all, you did a pretty good job with your room so far
The on-axis measurements are looking pretty good overall
I suppose you are using the Oktava with a capsule that is not omni-directional? That would explain the fall-off of the high frequencies. The more off-axis the position from the capsule from the sound source is, the more the high frequencies are dropping.
In the end it is most important to get it right in the spot [on-axis] where you are working/mixing

A 150Hz drop [=228cm wavelength] is very common

For future measurements I highly recommend this very affordable measurement mic [works like a charme with REW]:
https://www.minidsp.com/products/aco...urement/umik-1

Some basic knowledge in a nut shell with a nice "peace of mind" factor

http://www.acousticsinsider.com/blog/page/3/

https://www.youtube.com/watch?v=cTnituQu8ig&t=30s

Last edited by TobyToby; 6 days ago at 05:42 AM..
Old 6 days ago
  #69
Gear Addict
 

Quote:
Originally Posted by akebrake View Post
Depends how picky you are.

A measurement with mic position like this would be interesting. mdat pls

To compare with the first measurements (no Krk close)
Here is an mdat with both measurements to compare. I already posted the screenshots but here is the actual file and I included some notes but basically there are 2 measurements for the right speaker and 2 for the left speaker. One is pointing at the ceiling and the other at the spot between the woofer and tweeter like in the photo
Attached Files
File Type: mdat Tuesday11thSept.mdat (11.44 MB, 4 views)
Old 6 days ago
  #70
Gear Addict
 

hi Toby Toby

Quote:
Originally Posted by TobyToby View Post
I suppose you are using the Oktava with a capsule that is not omni-directional? That would explain the fall-off of the high frequencies. The more off-axis the
No siree. I am using the Oktava mk 012 with the omni capsule! The guys in the other posts are saying that there will still be a roll off even though it is an omni. I was quite surprised by this to be honest because I always thought that omnis were.. well, omnidirectional

Quote:
Originally Posted by TobyToby View Post
A 150Hz drop [=228cm wavelength] is very common
Really? How so? by the way I have a 150Hz peak not a 150hz drop, is that what you were trying to say?

Quote:
Originally Posted by TobyToby View Post
For future measurements I highly recommend this very affordable measurement mic [works like a charme with REW]:
https://www.minidsp.com/products/aco...urement/umik-1

Some basic knowledge in a nut shell with a nice "peace of mind" factor

http://www.acousticsinsider.com/blog/page/3/

https://www.youtube.com/watch?v=cTnituQu8ig&t=30s
will check this out thanks!
Old 6 days ago
  #71
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Is the mic stay at the same place in the room when you have measured the left and the right speaker
Or
Did you move the mic between the Left and Right measurements?
Old 6 days ago
  #72
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Quote:
Originally Posted by Soundman2020 View Post
Because it is not pointing at the speaker, which is generating all the highs! It's only picking up the room sound, without the direct sound form the speaker.
Ok I get this but Dinoccus said:

Quote:
Originally Posted by dinococcus View Post
No, for me this deep(I assume he meant Dips) are not an issue. Your lack of high frequency is an issue.

and what you are saying to me is that it is absolutely normal because the mic is pointing at the ceiling. Could you explain this?

Quote:
Originally Posted by Soundman2020 View Post
... ummmm... that0s exactly what we are telling you to do! Point it up at the ceiling, NOT at the speaker. Or rather, at an angle of about 70° towards the ceiling.
No I meant why not point it away from the speaker like towards the back of the room. Should have clarified that further

Quote:
Originally Posted by Soundman2020 View Post
One again, that would be because you are measuring the speaker more than the room! The closer you get to the speaker, the more direct sound you are seeing in your data, and the less room sound.
If we aim the mic upwards to the ceiling to get a better representation of our room and less of the speaker, then why are we not putting the mic even further away from the speaker or behind the speaker? That way there will be even less direct sound.

Quote:
Originally Posted by Soundman2020 View Post
No. Because each speaker has a minimum listening distance, which is the distance where the waves from the woofer, tweeter, bass reflex port, etc. all combine together smoothly into one single wave front, rather than being heard as several different individual waves if you are too close. The manufacturer will tell you what that distance is for every model he makes, and you should never listen closer than that distance. You should also not listen too far away: manufactures also often tell you what the maximum recommended distance is, but in that case it is not fixed: the maximum distance is also affected by the room. The better the room acoustic response, the greater the maximum distance can be. In a lousy room, you need to be very close to the speaker (but not less than the minimum distance), while in a really good room you can be quite fa away and still hear clearly, without the room coloring the sound.
Ok. So at what distance should you place the mic from the speaker when measuring. I don't know what the listening distance is for my Yamaha msp7 is and it doesn't say in the manual. is there a standard distance for this kind of speaker? look at the changes in the frequency response depending on how far away from the speaker I place the microphone. There is a huge difference. If you look at the first three FR charts would you say 70cm listening distance is better than the others? look at how much more even it is!

Quote:
Originally Posted by Soundman2020 View Post
Yes! Definitely! I keep on trying to say that all over the forum, everywhere I can, but still there's some folks that don't get it: the frequency response curve is NOT the primary graph that you should be looking at for treating a room: the waterfall, spectrogram, and ETC graphs are far more useful.
Ok so how do you analyze the waterfall chart. How do I know if my decay times are good or bad? (see pic)

Quote:
Originally Posted by Soundman2020 View Post
....And in fact, if you do a really good job of damping modal resonances, dealing with SBIR, and killing all major early reflections, then you can check back to the FR graph and you'll be surprised to see that it has taken care of itself!
Ok, well I get this but it would be nice to see what I am supposed to be looking for. In the decay times on the waterfall chart, there is some slight variations in the decay time at around 35db. Roughly 115ms to around 173ms. I am not an expert but I think the treatment in the room is doing its job but I still want to learn how to make sense of this before I start drawing conclusions. Should the high end have longer decay times or is the fact that it is even in the high end as in the low end a good thing?[/QUOTE]

Quote:
Originally Posted by Soundman2020 View Post
...then you CAN use such software or hardware as the FINAL step in the process, to tweak the room tuning. Because at that stage, EQ adjustments really are operating ONLY on the FR curve, without also affecting phase and time-domain negatively.
This is making sense! So since my room is treated, can I now make these EQ adjustments. I ask this especially because that area around 150hz bugs me especially since I can hear it when listening to sine tones on my system. I hear the tones get louder across that region and I am almost certain that it will impair my mixes. Can I make EQ adjustments or should I consider more treatment?[/QUOTE]

Quote:
Originally Posted by Soundman2020 View Post
Sigh! Don't get me started on the silliness of trying to "correct" the acoustic response of an untreated room with EQ... I can rant about that for days...
I hear you, I watched a video the other day where the guy said he didn't have enough space for treating the low end so he used EQ to "balance" his room.

Quote:
Originally Posted by Soundman2020 View Post
It all depends on what your goal is here: if you want a room that is pretty good for a hobby studio to have fun and impress your friends, then there's probably no need to get another mic.
I want a room to have fun in but to be able to mix and have a decent idea of what I am listening to. I don't need it to impress anyone or to make money from it. i am not that good
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-a70cm.jpg   FR vs Waterfall chart for analyzing room measreuments-a100cm.jpg   FR vs Waterfall chart for analyzing room measreuments-a130cm.jpg   FR vs Waterfall chart for analyzing room measreuments-adecay.jpg  
Old 6 days ago
  #73
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Quote:
Originally Posted by dinococcus View Post
Is the mic stay at the same place in the room when you have measured the left and the right speaker
Or
Did you move the mic between the Left and Right measurements?
I moved it to where my left ear is when taking left spkr measurements and move it to where my right ear is when I take my right spkr measurements. Should it stay in same place?
Old 6 days ago
  #74
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I wrote the same distance between the mic and the two speakers.

I give up.
Old 6 days ago
  #75
Gear Addict
Nice Space!

Nice Space. IMHO get a sub to flesh out that low end. Your curve looks like it is on its way to being pretty good. Most people don't want a "flat" response and aim for a "target curve". With a bit more energy in the bass it will help to get something that translates.

Anyway how is it sounding to you? Are you feeling the pressure of the bass?
How do "reference" tracks sound? As you would expect or?

Other things I would do, get rid of one set of speakers as I find that acoustically speakers mess with other speakers next to them and get rid of that huge flat surface you have a laptop on.

Floor bounce will always be there. I have heard it said that it may even be an essential part of the acoustic anyway (was it Northward?).

Anyway you have a great space, keep going, keep learning, keep trying, be tenacious. It took me four years of work to be happy with the acoustic in my space!

My target curve has quite a bump in the bass up to 180Hz then flat(ish) to 1kHz then gently rolls off about 2dBs to 20kHz. This is quite typical and like the B&K curve.
Old 6 days ago
  #76
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Quote:
Originally Posted by camomiletea View Post
I moved it to where my left ear is when taking left spkr measurements and move it to where my right ear is when I take my right spkr measurements. Should it stay in same place?
Never move the mic between measurements! Always keep the mic in the exact same spot in the room, even if you change its orientation. As I have said several times already, if you move the mic to a different place in the room, then you are moving it to a different acoustic response. In a small room, the acoustic response varies greatly with your location in the room: moving even a few inches can put you in a very different acoustic situation, which means that you CANNOT compare your REW tests: they were taken at different spots in the room, so it is NOT valid to compare them at all. They are measuring different things. So you need to repeat all of your tests with the mic in one single fixed location. Make absolutely sure that the capsule of your mic is in the exact same spot in the room for every measurement, even if the mic is pointing in different directions.

(There are times when you will need to move the mic around the room for other purposes, yes, and that can be done validly, but for the tests you are doing now, the mic must be exactly in the center of the mix position, always).

I think you probably need to take a careful look at this procedure for using REW, to avoid the types of mistakes you have been making: How to calibrate and use REW to test and tune your room acoustics

- Stuart -
Old 6 days ago
  #77
Gear Addict
 

Quote:
Originally Posted by dinococcus View Post
I wrote the same distance between the mic and the two speakers.

I give up.
Ok but it doesnt really matter because 90% of all the measurements above are ONLY my right speaker anyway. I read somewhere that it is good to position the mic next to each ear. GO EASY ON ME IM STILL LEARNING!
Old 6 days ago
  #78
Gear Addict
 

Quote:
Originally Posted by Soundman2020 View Post
Never move the mic between measurements! Always keep the mic in the exact same spot in the room, even if you change its orientation. As I have said several times already, if you move the mic to a different place in the room, then you are moving it to a different acoustic response. In a small room, the acoustic response varies greatly with your location in the room: moving even a few inches can put you in a very different acoustic situation, which means that you CANNOT compare your REW tests: they were taken at different spots in the room, so it is NOT valid to compare them at all. They are measuring different things. So you need to repeat all of your tests with the mic in one single fixed location. Make absolutely sure that the capsule of your mic is in the exact same spot in the room for every measurement, even if the mic is pointing in different directions.

(There are times when you will need to move the mic around the room for other purposes, yes, and that can be done validly, but for the tests you are doing now, the mic must be exactly in the center of the mix position, always).

I think you probably need to take a careful look at this procedure for using REW, to avoid the types of mistakes you have been making: How to calibrate and use REW to test and tune your room acoustics

- Stuart -
I will take a look thanks but it seems you are very eager to tell me where i am wrong instead of helping me. If i read that introduction(which i will) will you at least answer my questions? They would help me learn over and above what you have linked to.
Old 6 days ago
  #79
Lives for gear
 

Quote:
Originally Posted by Soundman2020 View Post
Never move the mic between measurements! Always keep the mic in the exact same spot in the room, even if you change its orientation. As I have said several times already, if you move the mic to a different place in the room, then you are moving it to a different acoustic response. In a small room, the acoustic response varies greatly with your location in the room: moving even a few inches can put you in a very different acoustic situation, which means that you CANNOT compare your REW tests: they were taken at different spots in the room, so it is NOT valid to compare them at all. They are measuring different things. So you need to repeat all of your tests with the mic in one single fixed location. Make absolutely sure that the capsule of your mic is in the exact same spot in the room for every measurement, even if the mic is pointing in different directions.

(There are times when you will need to move the mic around the room for other purposes, yes, and that can be done validly, but for the tests you are doing now, the mic must be exactly in the center of the mix position, always).

I think you probably need to take a careful look at this procedure for using REW, to avoid the types of mistakes you have been making: How to calibrate and use REW to test and tune your room acoustics

- Stuart -
There is nothing wrong with moving the mic a few inches since we have two ears and they are spaced a few inches apart. Such a slight movement will hardly make a big difference anyway. I use REW like this all the time and many professional acousticans test this way
Old 6 days ago
  #80
Lives for gear
 

Quote:
Ok I get this but Dinoccus said:
Quote:
No, for me this deep(I assume he meant Dips) are not an issue. Your lack of high frequency is an issue.
and what you are saying to me is that it is absolutely normal because the mic is pointing at the ceiling. Could you explain this?
There are TWO issues here that you seem to be confusing. the first one is, as Dinoccus pointed out, that you have a general lack of high end. The SECOND one is that when you point the speaker at the ceiling, you are capturing more room response, less speaker response, and thus the high-end roll-off is even more noticeable. But those are two entirely different things! Not related! 1) You are missing high end. 2) A mic aimed at the speaker artificially inflates the high end, but when aimed at the ceiling it tells the truth... about the ROOM! And that's what you need to know here: how the ROOM is responding.

Your lack of high end is either a speaker problem, or an EQ problem, or a mic problem: it is NOT a room problem. Below I have attached a REW graphs showing all of your original measurements from both speakers, smoothed to one octave. You can clearly, clearly see that there's a major bass boost going on, and a large high-end roll-off starting at around 5 k. There's a drop of ten dB between 5k and 20 k. In other words, 20 k is only half as loud as 5 k. (There's also a lower mid range boost centered around 250 Hz, but that's a different problem).

Now, considering that you are seeing that roll-off for all of your speakers (two different brands and models), it is obviously NOT a speaker problem. It is either an EQ problem (you have EQ applied somewhere in your signal chain, either going out to the speakers or coming back from the mic), or you have a mic problem: the mic is just less sensitive to the high end.

Apart from that, there are ALSO big differences between your two sets of speakers: they each have major dips in the mid range. See the second image: the red line is your Yamaha speakers, the green line is the KRK's. The KRKs have a major dip at around 700 Hz, the Yamaha's have a major dip at around 1100 Hz. Since the speakers themselves do not have those response curves normally, that suggests that it is the setup in your room, or once again it could be EQ... or it could be that you moved the mic and/or speakers between measurements...

Quote:
No I meant why not point it away from the speaker like towards the back of the room.
It's an omni! Pointing it at the back of the room, or the front, would give roughly the same outcome.... The capsule would still be normal to the wave-front from the speaker.

Quote:
If we aim the mic upwards to the ceiling to get a better representation of our room and less of the speaker, then why are we not putting the mic even further away from the speaker or behind the speaker? That way there will be even less direct sound.
No there would not! This is an OMNI mic!!!! Think about it.... We already explained that it is the DIAPHRAGM of the mic that pics up the sound. If the diaphragm is parallel to the ceiling, then it is not affected by the direct sound arriving for the speaker: that sound hits the edge of the diaphragm, and washes over it, running PARALLEL to the surface, and therefor not having much effect. It is at 90° to the approaching wave. But if the diaphragm is at any other angle, then it is no longer 1t 90°, and thus WILL pick up some of the direct sound. It doesn't matter if you tilt the mic forwards or backwards, because it's an omni mic it will still start picking up more of the direct sound, either from the front of the capsule or the back: it is ONLY when the capsule is edge-on to the wave that you get minimum speaker sound, maximum room sound. And that ONLY happens when the mic is facing the ceiling... or rather, tilted at about 70° (for complex reasons...).

Quote:
So at what distance should you place the mic from the speaker when measuring.
At the exact location of the mix position! You should only be making your REW measurements with the mic sitting exactly at the center of the location where your head will be while mixing.

Quote:
I don't know what the listening distance is for my Yamaha MSP7 is and it doesn't say in the manual.
Yep. It's a pretty poor manual, indeed. Not up to the usual standards of Yamaha at all.

Quote:
is there a standard distance for this kind of speaker?
For any given room, there is an optimal setup for both the speakers and the mix position. There is one single "best" location for the speakers, and one single "best" location for the mix position. There might be other "good" locations for them, and there will be PLENTY of "bad" locations for them, but there's only one best. There's a process, or procedure for finding that "best" layout. It starts by placing the speakers and mix position in the the THEORETICAL best location (which isn't always the ACTUAL best location), then doing several tests with REW while moving the speakers closer together and further apart in very small steps, just an inch or so, and doing measurements at each step. Then you look at the results in REW (mostly the time-domain results: and to a lesser extent the frequency response results) to find the smoothest, flattest response. Then with the speakers set up like that, you do the same with the mic: move it forwards and backwards in a series of small steps (just an inch or two each time), and once again you compare the graphs to find the one that has the smoothest response. Then do the speakers again... repeat.... When you have found the best spot like that, do the room treatment to get it even better, then repeat the process again. Eventually, you get to the optimum layout.

Quote:
Ok so how do you analyze the waterfall chart. How do I know if my decay times are good or bad?
The waterfall chart, the Impulse Response graph, the RT60 graph, AND the spectrogram show how the levels change over time, but in different ways. Interpreting those fully is a complex task, but basically you want them to be as smooth as possible. I have also added some graphs from rooms that I have tuned for clients, showing what can be achieved with very careful room design, very careful treatment, and very careful final tuning. There's a set of three FR graphs from one room, all starting with "MRTK". The first one shows the frequency response in the original room (smoothed to 1/24 octave), the second one shows the final frequency response (also smoothed to 1/24 octave) after treatment and tuning, and the third one shows the response at 1/3 octave, but with two different tuning curves applied. One is perfectly flat tuning, the other is after I applied my "house curve", which is similar to the famous B&K curve from nearly 50 years ago, that has stood the test of time rather well! (Blue line is flat tuning, purple is with the house curve).

After that there's a set of curves from a very different room, showing the original frequency response, spectrogram, and waterfall, but only for the lower part of the spectrum up to 500 Hz, followed by similar graphs for the final treated and tuned room. Those graphs all start with the letters "CRFKUS". One again, those give you an idea of what can be achieved with careful work. Of course, those are ideal situations in professionally done rooms: your room probably won't work out like that, but the point is that these graphs represent the ideal that you should be aiming for. It shows what you should be looking for in your graphs. Right now, your situation is similar to the "baseline" graphs for these rooms, or actually a bit better that those were. The goal is to get them better still, more like the "final" graphs, even though it probably won't get as good as those ones.

Quote:
Ok, well I get this but it would be nice to see what I am supposed to be looking for.
See graphs below! And explanation above. But once again, a caveat: your room won't get to be as good as the ones I posted! That's just to show the ideal, best possible situation. Your goal is to just get as close as you can.

Quote:
Should the high end have longer decay times or is the fact that it is even in the high end as in the low end a good thing?
The decay times should be roughly the same across the entire spectrum, with only small variations between adjacent bands. The OVERALL decay time is set by the size of the room. There's a document with the cryptic title "ITU BS.1116-3" that lays out the specifications you should be aiming for, for a critical listening room. Google it, download it, and look at chapters 7 and 8. You can ignore the other chapters, as they are not applicable, but 7 and 8 tell you exactly what you should be aiming for, in terms of room layout, frequency response, time domain response, etc. Caveat: It's very, hard to actually achieve all of those specs! The smaller the room, the harder it is. So don0t get upset if you are still a long way off from those specs even after you have treated your room a lot. You probably won't achieve all of those... but the idea is to get as close as you can. There's another document, called "EBU Tech.3276" that is similar, but has a slightly different set of specs. It might be worth looking at that too. The specs are not exactly the same, but very close.

Quote:
So since my room is treated, can I now make these EQ adjustments.
No, because it's not treated ENOUGH yet. There's still things that need to be improved before you get to the point where you can use EQ.

Quote:
I ask this especially because that area around 150hz bugs me especially since I can hear it when listening to sine tones on my system. I hear the tones get louder across that region
That is very likely the "desk effect". The desk very often produces an acoustic response in that region, which adds a "peak" of maybe 5 dB or so, across a region of maybe half an octave or so. It's better to fix that by "minimizing" the desk, and maybe even tilting it slightly, before you use EQ. If you do use EQ on that, try something around 140 Hz with a fairly broad Q, and a reduction of maybe 3 or 4 dB.

Quote:
I want a room to have fun in but to be able to mix and have a decent idea of what I am listening to. I don't need it to impress anyone or to make money from it. i am not that good
Maybe if your room were better, acoustically, you could be doing better mixes too! Maybe you COULD be "that good"!


- Stuart -
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-camomiletea-rew-fr-20-200-1..1.png   FR vs Waterfall chart for analyzing room measreuments-camomiletea-rew-fr-20-200-1..3-krk.vs.yamaha.png   FR vs Waterfall chart for analyzing room measreuments-mrtk-rew-fr-12..22k-1..24-pre-tuning.png   FR vs Waterfall chart for analyzing room measreuments-mrtk-rew-fr-12..22k-1..24-flat-2.4db-left.jpg   FR vs Waterfall chart for analyzing room measreuments-mrtk-rew-fr-12..22k-1..3-flat-also-b-k-curve-l-r.png  

FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-fr-20..20k-1..24-baseline.png   FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-fr-20..20k-1..24-final.png   FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-sp-20..500-1..48-baseline.png   FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-sp-20..500-1..48-final.png   FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-wf-20..500-1..48-baseline.png  

FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-wf-20..500-1..48-final.png  
Old 6 days ago
  #81
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akebrake's Avatar
 

Octava Omni: On/Off axis

Quote:
Originally Posted by camomiletea View Post
... One is pointing at the ceiling and the other at the spot between the woofer and tweeter like in the photo
Took a quick look at the Tuesday11 sept- mdat. Left speaker only.

Here the difference between Horizontal & Vertical mic. pos.
Also a difference curve. (Both 1/3 Oct smoothed)

The larger the mic membrane the larger the on/ 90°off difference.

These measurements are valid if the mic capsule is reasonable close to the same position in the two measurements. And nothing else is changed.
For convenience I inserted the Octava diagram again.

IMHO It looks like you need a better measurement microphone...

BTW Good measuring mics (for our purpose) are small Omnis with with known FR.

Best
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-hor-vs-vert-1-3-ovly.jpg   FR vs Waterfall chart for analyzing room measreuments-mic-diff-l-hor-ver.jpg   FR vs Waterfall chart for analyzing room measreuments-2185-2_full.jpg  
Old 6 days ago
  #82
Lives for gear
 

Quote:
Originally Posted by attaboy_jhb View Post
There is nothing wrong with moving the mic a few inches since we have two ears and they are spaced a few inches apart. Such a slight movement will hardly make a big difference anyway. I use REW like this all the time and many professional acousticans test this way
Sorry, but that simply is not correct. Such slight movement makes a HUGE difference. You CANNOT validly compare tests taken at different locations. Most people don't seem to realize just what a big difference you get from very small mic moves. Below is a graph showing a set of frequency response measurements I did a while back in a client's room, to demonstrate this exact point. All of the curves are with the mic nominally "at the mix position", but moved left and right over a distance of just four INCHES. That's all. Just four inches, in two-inch steps. You can see the large differences. If you were to place the mic at one of those locations, then design some treatment for the room, then test it with the mic in another location you would NOT be able to say if the treatment had any effect or not. It would be impossible, since you would be measuring a different acoustic response. The same applies for tuning the room: if you were to measure at one location, apply tuning, then measure the result at a different location, you would have no idea what effect your tuning had.

The only reason we move the mic around when tuning a room, is if we want to get an average measurement and tune for that. But even then, we still check the "before and after" in the exact same spots each time, not just in any old spot more or less roughly close to the mix position.

The second graph below shows a different set of tests, with the mic moved forwards and backwards along the room center-line, in steps of 5 cm over a range of +/- 1m. Once again, the huge difference in response is evident.

So no, it is NOT correct to compare REW measurements taken at different locations in the room when you are trying to treat the room, or tune the room. Testing for treatment and tuning should ONLY be done at the mix position, with the mic positioned very carefully and accurately to the same location every time. It is only valid to use different mic positions when you are trying to find the "best" position, based on some criteria, or when you are trying to average over a small area. But you can't use different mic positions once you have found the best layout, and are now deciding on treatment, or on tuning. If I tried to do that when treating and tuning rooms for my clients, I'd end up with useless rooms! The goal of a control room is to have the best possible acoustic response at the mix position, in a small area around that (the "sweet spot"), and secondarily at the client couch. If you also get good response for other locations in the room, then that's great, but the priorities are flat response at the mix position, and as near to flat as possible at the client couch. You cannot achieve that if you are not measuring at the mix position and at the client couch! Sort of like trying to see if it is raining in New York by standing outside in Washington...

- Stuart -
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-crfkus-rew-fr-20-20k-mic-move-compare.png   FR vs Waterfall chart for analyzing room measreuments-rew-fr-sample-walking-mic-2-15-500.png  
Old 4 days ago
  #83
Gear Addict
 

Quote:
Originally Posted by dinococcus View Post
The case of the roll off in the high frequency is solved.

if you want beautiful curves, you need to buy a mic. At 7000khz and above, the issue is your body who changes all. So nobody cares at this frequencies if THE SPEAKERS ARE OK.

Put back the desk and the rest of your installation, and show us the ETC.
Thanks Dinococcus. I will take new measurements but first I am learning a bit more and I will post back when I can level more with you guys.
Old 4 days ago
  #84
Gear Addict
 

Quote:
Originally Posted by Soundman2020 View Post
There are TWO issues here that you seem to be confusing. the first one is, as Dinoccus pointed out, that you have a general lack of high end. The SECOND one is that when you point the speaker at the ceiling, you are capturing more room response, less speaker response, and thus the high-end roll-off is even more noticeable. But those are two entirely different things! Not related! 1) You are missing high end. 2) A mic aimed at the speaker artificially inflates the high end, but when aimed at the ceiling it tells the truth... about the ROOM! And that's what you need to know here: how the ROOM is responding.

Your lack of high end is either a speaker problem, or an EQ problem, or a mic problem: it is NOT a room problem. Below I have attached a REW graphs showing all of your original measurements from both speakers, smoothed to one octave. You can clearly, clearly see that there's a major bass boost going on, and a large high-end roll-off starting at around 5 k. There's a drop of ten dB between 5k and 20 k. In other words, 20 k is only half as loud as 5 k. (There's also a lower mid range boost centered around 250 Hz, but that's a different problem).

Now, considering that you are seeing that roll-off for all of your speakers (two different brands and models), it is obviously NOT a speaker problem. It is either an EQ problem (you have EQ applied somewhere in your signal chain, either going out to the speakers or coming back from the mic), or you have a mic problem: the mic is just less sensitive to the high end.

Apart from that, there are ALSO big differences between your two sets of speakers: they each have major dips in the mid range. See the second image: the red line is your Yamaha speakers, the green line is the KRK's. The KRKs have a major dip at around 700 Hz, the Yamaha's have a major dip at around 1100 Hz. Since the speakers themselves do not have those response curves normally, that suggests that it is the setup in your room, or once again it could be EQ... or it could be that you moved the mic and/or speakers between measurements...

It's an omni! Pointing it at the back of the room, or the front, would give roughly the same outcome.... The capsule would still be normal to the wave-front from the speaker.

No there would not! This is an OMNI mic!!!! Think about it.... We already explained that it is the DIAPHRAGM of the mic that pics up the sound. If the diaphragm is parallel to the ceiling, then it is not affected by the direct sound arriving for the speaker: that sound hits the edge of the diaphragm, and washes over it, running PARALLEL to the surface, and therefor not having much effect. It is at 90° to the approaching wave. But if the diaphragm is at any other angle, then it is no longer 1t 90°, and thus WILL pick up some of the direct sound. It doesn't matter if you tilt the mic forwards or backwards, because it's an omni mic it will still start picking up more of the direct sound, either from the front of the capsule or the back: it is ONLY when the capsule is edge-on to the wave that you get minimum speaker sound, maximum room sound. And that ONLY happens when the mic is facing the ceiling... or rather, tilted at about 70° (for complex reasons...).

At the exact location of the mix position! You should only be making your REW measurements with the mic sitting exactly at the center of the location where your head will be while mixing.

Yep. It's a pretty poor manual, indeed. Not up to the usual standards of Yamaha at all.

For any given room, there is an optimal setup for both the speakers and the mix position. There is one single "best" location for the speakers, and one single "best" location for the mix position. There might be other "good" locations for them, and there will be PLENTY of "bad" locations for them, but there's only one best. There's a process, or procedure for finding that "best" layout. It starts by placing the speakers and mix position in the the THEORETICAL best location (which isn't always the ACTUAL best location), then doing several tests with REW while moving the speakers closer together and further apart in very small steps, just an inch or so, and doing measurements at each step. Then you look at the results in REW (mostly the time-domain results: and to a lesser extent the frequency response results) to find the smoothest, flattest response. Then with the speakers set up like that, you do the same with the mic: move it forwards and backwards in a series of small steps (just an inch or two each time), and once again you compare the graphs to find the one that has the smoothest response. Then do the speakers again... repeat.... When you have found the best spot like that, do the room treatment to get it even better, then repeat the process again. Eventually, you get to the optimum layout.

The waterfall chart, the Impulse Response graph, the RT60 graph, AND the spectrogram show how the levels change over time, but in different ways. Interpreting those fully is a complex task, but basically you want them to be as smooth as possible. I have also added some graphs from rooms that I have tuned for clients, showing what can be achieved with very careful room design, very careful treatment, and very careful final tuning. There's a set of three FR graphs from one room, all starting with "MRTK". The first one shows the frequency response in the original room (smoothed to 1/24 octave), the second one shows the final frequency response (also smoothed to 1/24 octave) after treatment and tuning, and the third one shows the response at 1/3 octave, but with two different tuning curves applied. One is perfectly flat tuning, the other is after I applied my "house curve", which is similar to the famous B&K curve from nearly 50 years ago, that has stood the test of time rather well! (Blue line is flat tuning, purple is with the house curve).

After that there's a set of curves from a very different room, showing the original frequency response, spectrogram, and waterfall, but only for the lower part of the spectrum up to 500 Hz, followed by similar graphs for the final treated and tuned room. Those graphs all start with the letters "CRFKUS". One again, those give you an idea of what can be achieved with careful work. Of course, those are ideal situations in professionally done rooms: your room probably won't work out like that, but the point is that these graphs represent the ideal that you should be aiming for. It shows what you should be looking for in your graphs. Right now, your situation is similar to the "baseline" graphs for these rooms, or actually a bit better that those were. The goal is to get them better still, more like the "final" graphs, even though it probably won't get as good as those ones.

See graphs below! And explanation above. But once again, a caveat: your room won't get to be as good as the ones I posted! That's just to show the ideal, best possible situation. Your goal is to just get as close as you can.

The decay times should be roughly the same across the entire spectrum, with only small variations between adjacent bands. The OVERALL decay time is set by the size of the room. There's a document with the cryptic title "ITU BS.1116-3" that lays out the specifications you should be aiming for, for a critical listening room. Google it, download it, and look at chapters 7 and 8. You can ignore the other chapters, as they are not applicable, but 7 and 8 tell you exactly what you should be aiming for, in terms of room layout, frequency response, time domain response, etc. Caveat: It's very, hard to actually achieve all of those specs! The smaller the room, the harder it is. So don0t get upset if you are still a long way off from those specs even after you have treated your room a lot. You probably won't achieve all of those... but the idea is to get as close as you can. There's another document, called "EBU Tech.3276" that is similar, but has a slightly different set of specs. It might be worth looking at that too. The specs are not exactly the same, but very close.

No, because it's not treated ENOUGH yet. There's still things that need to be improved before you get to the point where you can use EQ.

That is very likely the "desk effect". The desk very often produces an acoustic response in that region, which adds a "peak" of maybe 5 dB or so, across a region of maybe half an octave or so. It's better to fix that by "minimizing" the desk, and maybe even tilting it slightly, before you use EQ. If you do use EQ on that, try something around 140 Hz with a fairly broad Q, and a reduction of maybe 3 or 4 dB.

Maybe if your room were better, acoustically, you could be doing better mixes too! Maybe you COULD be "that good"!


- Stuart -
Ok so it seems the high end issue is the microphone as Dincocuss said. With that out the way I am reading and learning as much as I can from your and other posts and taking more measurements. Regarding the low end, I am pretty sure that the low frequency issue has to do with SBIR and not the desk. The middle of the room has a door (see diagram of my room layout again) and I think the low end was getting colored by this hard surface. I read that low frequency sound waves radiate in all directions which explains why the door, even though it is not directly behind the speaker could cause peaks and dips like this.

Here is the response with the eight speaker more toward the right of the room. The bass looks much better with only slight variations (+-5db) which is an improvement but it leaves me with the question:

If I want to have my speakers in their original location as in the diagram I am going to have to treat the door more somehow. The thing is that I don't really want to use absorption so I wanted to ask you guys if you think a different kind of trap here could work?
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-room.jpg   FR vs Waterfall chart for analyzing room measreuments-thursday12092019.jpg  
Old 4 days ago
  #85
Gear Addict
 

Quote:
Originally Posted by camomiletea View Post
Ok so it seems the high end issue is the microphone as Dincocuss said. With that out the way I am reading and learning as much as I can from your and other posts and taking more measurements. Regarding the low end, I am pretty sure that the low frequency issue has to do with SBIR and not the desk. The middle of the room has a door (see diagram of my room layout again) and I think the low end was getting colored by this hard surface. I read that low frequency sound waves radiate in all directions which explains why the door, even though it is not directly behind the speaker could cause peaks and dips like this.

Here is the response with the speaker more toward the right of the room. The bass looks much better with only slight variations (+-5db) which is an improvement but it leaves me with the question:

If I want to have my speakers in their original location as in the diagram I am going to have to treat the door more somehow. The thing is that I don't really want to use absorption so I wanted to ask you guys if you think a different kind of trap here could work?
You're like a guy who wants his racing car to have 3 wheels and is endlessly asking how he can get the checkered flag without having to use that 4-th wheel.
Old 4 days ago
  #86
Lives for gear
Quote:
Originally Posted by camomiletea View Post

When I was testing, moving the mic further away or closer to the speaker makes such a huge difference and I couldn't understand how anyone can really tell how much of what the mic hears is

a) the mic FR (or mic placement FR)
b) the speakers FR
c) the room FR?

By changing the position of the mic or moving the mic angle there are such large variations in the frequency response so how do you know?

Those are all the telltale signs of a poorly treated/designed control room IMO. Because in real life an engineer will need to move his head around at least a couple of feet N,S,E, and W. So what a well designed control room aims for is a "sweet spot" where both the FR and Time Domain response is linear and consistent. Some designs go to ridiculous extremes to achieve a very large "sweet spot", and those are most often larger rooms with 6 figure (or more) investments. Other designs (like hybrid RFZ for example) will work towards achieving a much smaller "sweet spot", but still something good enough to provide excellent translation of mixes outside the studio as long as the engineer knows where the sweet spot is and has all the gear setup in that "zone".

IMO you need an area of at least 2' (preferably 3' to 4') where you can move the mic back and forth (staying on the center axis of the room, and at average ear height from floor whilst sitting in a chair) and both the FR and time domain response stays essentially the same and is also very linear. That is the goal, and that is also when you know that your treatment plan has been a success. Otherwise you are just chasing a ghost and finding a spot in the room where the graphs in REW look really good, but when you move the mic a little back or forth it all goes to crap.

There are so many folks on this forum (and others) going the DIY route, but cutting out the designer. They arrive at some good looking graphs in REW after stuffing the room full of low density insulation (and feel all proud of that), but never even bother to test outside of that one spot. But in the real world you cannot place your head in a vice while you are mixing, so great results in one spot are essentially worthless if everything drastically changes once you move the mic a foot forward or backwards. From the beginning a good designer is maxing out every square inch of the room's potential, and also the speaker/listener arrangement, with the single goal to arrive at the biggest "sweet spot" possible.
Old 4 days ago
  #87
Gear Addict
 

Quote:
Originally Posted by bert stoltenborg View Post
You're like a guy who wants his racing car to have 3 wheels and is endlessly asking how he can get the checkered flag without having to use that 4-th wheel.
What is that supposed to mean?
Old 4 days ago
  #88
Gear Addict
 

Quote:
Originally Posted by sage691 View Post
Those are all the telltale signs of a poorly treated/designed control room IMO. Because in real life an engineer will need to move his head around at least a couple of feet N,S,E, and W. So what a well designed control room aims for is a "sweet spot" where both the FR and Time Domain response is linear and consistent. Some designs go to ridiculous extremes to achieve a very large "sweet spot", and those are most often larger rooms with 6 figure (or more) investments. Other designs (like hybrid RFZ for example) will work towards achieving a much smaller "sweet spot", but still something good enough to provide excellent translation of mixes outside the studio as long as the engineer knows where the sweet spot is and has all the gear setup in that "zone".

IMO you need an area of at least 2' (preferably 3' to 4') where you can move the mic back and forth (staying on the center axis of the room, and at average ear height from floor whilst sitting in a chair) and both the FR and time domain response stays essentially the same and is also very linear. That is the goal, and that is also when you know that your treatment plan has been a success. Otherwise you are just chasing a ghost and finding a spot in the room where the graphs in REW look really good, but when you move the mic a little back or forth it all goes to crap.

There are so many folks on this forum (and others) going the DIY route, but cutting out the designer. They arrive at some good looking graphs in REW after stuffing the room full of low density insulation (and feel all proud of that), but never even bother to test outside of that one spot. But in the real world you cannot place your head in a vice while you are mixing, so great results in one spot are essentially worthless if everything drastically changes once you move the mic a foot forward or backwards. From the beginning a good designer is maxing out every square inch of the room's potential, and also the speaker/listener arrangement, with the single goal to arrive at the biggest "sweet spot" possible.
Not everyone can hire a designer. I wish i could but i cant.
Old 4 days ago
  #89
Lives for gear
 
Jason Foi's Avatar
 

Quote:
Originally Posted by camomiletea View Post
What is that supposed to mean?
I think it means you cant cut corners and expect to win the race, but i know very little about nascar, and they do use a round track, so...... idk
Old 4 days ago
  #90
Lives for gear
I actually like to use the analogy of a 50 yard dash.

A 6 (or 7) figure CR is like a $3000 pair of the best running shoes out there.

A more humbly designed CR, yet still meeting very high standards, is like a $300 pair of running shoes.

In both of these cases a designer was likely involved from the very beginning.

Then you have the murky DIY CR build category, where most of the knowledge was garnered from the internet, and the build itself was likely done by someone who can barely drive a straight nail with a hammer. In 99.9% of these cases the runner has each foot encased in a 50 pound block of cement, but he doesn't even know it. He completely underestimates the gravity of the situation he is up against -- that being the physics of sound dispersion within a contained space for which the intended purpose is music production/mixing/mastering. Sad but true, especially once you understand the complexity of the subject which IMO is 100X more complicated than anything to do with actual recording, production, or gear !

In cases #1 and #2 , a slightly more talented runner will easily win the race with the $300 pair of running shoes. That $2700 difference in price is no match for the difference in physical abilities/talent between the two runners. But even the most gifted and talented runner in the world would lose the race against a decrepit 100 year old man if his feet are encased in 100 pounds of cement. He has already lost the race before the starting gun even fires, and just falls flat on his face desperately trying to drag those blocks of cement along in a hopelessly futile effort !

All of this can be summed up in a single sentence: You cannot mix what you cannot hear.
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