Login / Register
 
My First Measurement. Am I doing it right?
New Reply
Subscribe
kwow
Thread Starter
#1
4th October 2012
Old 4th October 2012
  #1
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
My First Measurement. Am I doing it right?

Hi Everyone.

I just got done putting in new floor, painting the walls, building sand filled speaker stands, and building frames for 3 superchunks. Before stuffing the superchunks with insulation (right now they are EMPTY), I wanted to take a measurement of the room in a completely untreated state.And since this is the very first set of measurements I ever took, I wanted to make sure that I'm doing this right.





The room is basically 12' x 16'. But as you can see on one of the pictures, the back side of the room has 2 large mirrored closet doors and a little hall way leading to a bathroom.





I took measurements for the right and left speakers separately, but since I use Blue Sky System 2.1, the low end is coming from the sub in both cases and the sub is set to the left side of the room right now (because I haven't build a desk yet where I can put the sub in the center).

Anyway, when you look at the frequency response chart, you'll see that the right and the left speakers are quite different on the higher frequencies. Is this normal? Could this be because of early reflection or something? I do have a 16 space rack and a drum set on the right side of the room.

Also, on the Impulse Response, there's a spike right above 300hz. What could this be? (Could I be overloading something like a mic pre?) and is this ok?

For the waterfall, I set the smoothing to "none" and set the frequency rage from 20hz to 300hz.
For the frequency Response, I used 1/48 Octave Smoothing.

If you could clue me in if I'm doing this right or not, as well as or if the charts looks about right for an untreated room (or not) I'd appreciate it!

Keith
kwow
Thread Starter
#2
6th October 2012
Old 6th October 2012
  #2
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Well, it seems that the discrepancy between the right and left frequency response has to do with the actual high frequency driver or the crossover in one of the speakers. I moved the speaker that was on the right side to the left and took a measurement, it came out pretty similar to the right side.

I guess, I have to send the monitor in for a repair, but meanwhile, I'm going to go ahead and out the insulation in the Superchunk frames.

I still don't know what that bump that I see around 30-40hz on the impulse response chart means. If someone could clue me in, I would appreciate it.

Thanks
Keith
#3
6th October 2012
Old 6th October 2012
  #3
Gear maniac
 
Arqen's Avatar
 
Joined: Jan 2012
Location: Vancouver
Posts: 293

Arqen is offline
Quote:
Originally Posted by kwow View Post
Well, it seems that the discrepancy between the right and left frequency response has to do with the actual high frequency driver or the crossover in one of the speakers. I moved the speaker that was on the right side to the left and took a measurement, it came out pretty similar to the right side.

I guess, I have to send the monitor in for a repair, but meanwhile, I'm going to go ahead and out the insulation in the Superchunk frames.

I still don't know what that bump that I see around 30-40hz on the impulse response chart means. If someone could clue me in, I would appreciate it.

Thanks
Keith
The bump between 30-40 hz is probably due to a resonant room mode. If you know the average dimensions of your room, you can use this Room modes calculator to get an idea of the room modes that would appear in an equivalent volume flat-roofed room.
kwow
Thread Starter
#4
7th October 2012
Old 7th October 2012
  #4
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi Tim

Thank you for responding!
I will look into the resonant room mode that you mentioned.
Is there an easy way (or a formula of some sort) to figure out the average dimensions of a non-flat-roofed room?

Also, I just got done filling the superchunks with insulation, so I'll take another measurement to see if I see any difference (I certainly hope I'll see a difference ... and hear some difference as well).

Thanks again!
Keith
kwow
Thread Starter
#5
7th October 2012
Old 7th October 2012
  #5
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
New Measurement

Ok, so here's the before and after of the frequency Response and impulse response chart.
Blue is before putting the insulation in the superchunks and Red is after.



And here's the waterfall of before



and here's the one from after putting in the insulation.


Next, we have EDT from before


and EDT from after


Now, I'm new to this whole measuring/treatment business so I'm not sure if this is about what I can/should expect from putting in 3 corner superchunks. Is it?

I haven't built any broadband panels yet, so I hear some high-mid's bouncing off the walls still, but the low (or low-mid's) seems tighter/less boomy now.

I have some R30 left so I'm planning on building a short superchunk above the door in the corner as well as stuffing the bottom side of the love seat with the insulation.

However, I'm clueless as to how to deal with the mirrored closet doors and the little hall way that leads to the bathroom in the back of the room.
Any pointers/input would be appreciated!

Keith
#6
7th October 2012
Old 7th October 2012
  #6
Lives for gear
 
Jens Eklund's Avatar
 
Joined: Oct 2009
Location: Stockholm
Posts: 4,615

Jens Eklund is offline
kwow
Thread Starter
#7
8th October 2012
Old 8th October 2012
  #7
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Jens,

Thanks for posting the link.
I actually read that thing that you wrote before I posted the graphs. And I set up the Fuzzmeasure (I'm on a Mac) based on what you wrote and others. In fact, I read it again after you posted the link. Are you pointing me to a specific part of the link? If so, please let me know what part that is. Because with my current meager understanding, this is what I came up with, and I'm a bit lost as to what to make of the graphs or what to do next. That's why I started this thread hoping that someone here could point me in the right direction.

May be I'm missing something in that post that's important, but if so, I don't even know what that is. I've been reading a lot around here for months, and honestly, I'm overwhelmed with information where I don't know what to do next other than building broadband panels.

Again, I would appreciate anyone's input.

Thank you
Keith
#8
8th October 2012
Old 8th October 2012
  #8
Lives for gear
 
Jens Eklund's Avatar
 
Joined: Oct 2009
Location: Stockholm
Posts: 4,615

Jens Eklund is offline
If you want others to be able to help you, the best way is to upload the actual impulse file (exported as wav/aiff) so others can view it the way they want to (in any software). If not; make sure to also include the ETC as this in conjunction with waterfalls (or other types of decay plots) are the most important graphs. EDT or RTxx is of little use when analyzing control room acoustics. If you want an approximation of “decay times”; use the “Topt” tool (in REW, don´t know if anything similar exists in Fuzz).
kwow
Thread Starter
#9
8th October 2012
Old 8th October 2012
  #9
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Jens,

Thank you for your reply, and thanks also for being specific. I'll see if I can find what you're talking about (ETC) in Fuzzmeasure or export the actual impulse file and repost in the next day or so.

Thanks again!
Keith
kwow
Thread Starter
#10
10th October 2012
Old 10th October 2012
  #10
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Update

Jens and others

I put additional bass trap in the back one of the corners above the door + stuffed the bottom of the loveseat with R30.and re-measured today. And as I mentioned before, right now the room only has Superchunks/bass traps and there are no broadband absorbers.

So here are the Impulse response file, Frequency Response chart, Water Fall, and ETC chart.

I hope, I exported the Impulse Response correctly, and the setting for the ETC is OK.

http://soundcloud.com/kwow-1-1/impulse-response-10-10/s-mWKTM







Should I upload the Impulse Response and the ETC chart before I put the basstrap as well?

Any input would be appreciated
#11
10th October 2012
Old 10th October 2012
  #11
Lives for gear
 
Jens Eklund's Avatar
 
Joined: Oct 2009
Location: Stockholm
Posts: 4,615

Jens Eklund is offline
That ETC looks a bit funky … The level makes a sudden drop between 10 and 30 ms right before the direct sound (not normal). How do I download the IR file you´ve posted?
kwow
Thread Starter
#12
11th October 2012
Old 11th October 2012
  #12
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Jens

Sorry about the IR file thing. I just changed the setting of the Soundcloud so now it's downloadable. Just click on the link, and it will go to a new window. And on the top left side of the player, you'll see a arrow icon that's pointing down so just click on that and you should be able to download it.

As far as the sudden level drop between 10 and 30 ms, should I put a silence before the sweep and re-test it? Or that wouldn't help? Or I wonder if this is caused by something in the signal chain.

Keith
kwow
Thread Starter
#13
11th October 2012
Old 11th October 2012
  #13
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Is this any better?

I changed the routing (just used the mixer's mic pre instead of a standalone pre) and re-measured.

Here are the ETC, FR, Water Fall, and the IR file again.







http://soundcloud.com/kwow-1-1/ir-10-10-12/s-Zq03h

I still see a dip in the same time rage on the ETC but it isn't as sudden/drastic as before.
Is this any better?
#14
22nd October 2012
Old 22nd October 2012
  #14
Gear addict
 
Joined: Sep 2011
Posts: 389

akebrake is offline
Hi Keith!

I down loaded the IR file and it looks like you have a lot of low frequency stuff going on ( below 30 Hz). A couple of questions and some suggestions.

1. How long was your sweep? 1 second?
Choose the long sweep duration (10 seconds) and also increase the playback level. Loud, but not distorted. (Use ear plugs) Watch the level meters.
FuzzM sweep settings> Preset: Long sweep 10s , Duration: 10.000 ms

2. Are there ventilation or traffic noise? Take a look at a real time analyzer.
If you have a Hi Pass (lo cut) filter available, switch it in the microphone path. Better?

3. Take several measurements and observe if the lowest frequency levels varies a lot between measurements.
Choose the best shot or average several measurements.

4. Are the drums still in the room during the measurement?
Put them outside of the room during measurements.

5. Take a couple of measurements without the sub also.

Hope this will help to make valid measurements.

Best

Ake
kwow
Thread Starter
#15
23rd October 2012
Old 23rd October 2012
  #15
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi Ake

Thanks for your response/suggestions!

1. Yes, I did use 1 second sweep. I will try 10 seconds.

2. There shouldn't have been any/much ventilation or traffic noise at the time I took these measurements. and I will try the real time analyzer and/or High Pass Filter as you suggested.

3. I will try this as well. Also, hopefully the low's should be at least a bit better since I've added more corner trapping since the last measurement.

4. Yes, the drums are still in the room. I will take them out for the next measurement.

5. Unfortunately, with the speaker system I have, the sub is not an additional thing but it's actually the part of the system (Blue Sky makes them that way). However, I can full back the level of the sub so I will try that.

The mic pre I was using was a bit noisy, and my clean pre is in the shop until later this week or next week. And I'm building a couple of raks right now so I probably won't be able to take another measurement until sometime next week. But I really appreciate your suggestions and input and I will try them and post the results when I do.

Thanks so much!

Keith
#16
23rd October 2012
Old 23rd October 2012
  #16
Gear Guru
 
Glenn Kuras's Avatar
 
Joined: Jul 2005
Location: Atlanta, GA
Posts: 16,210

Glenn Kuras is offline
Hey Kwow,

Things are actually starting to look pretty good and adding more bass trapping would help. For the most part if you can get the frequency between +/-7 db or so on the low end and get the decay times to be as even as possible then you are doing well. How does the room sound in general? Low end seems clear/punchy?
__________________
Glenn Kuras
GIK Acoustics USA
GIK Acoustics Europe
http://www.gikacoustics.de (German Translation)
404 492 8364 (USA)
+44 (0) 20 7558 8976 (Europe)

Built in Slat design (Scattering/Diffusion) on all Bass Traps click here
#17
24th October 2012
Old 24th October 2012
  #17
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,497

DanDan is offline
Improving

Measuring Room Acoustics

For a 2.1 system you could measure 1.1 separately for L and R.
You may as well measure and look at 10Hz up rather than wonder what's down there.
Fuzz presents EDT first which is not helpful in small rooms. I have found T30 to be reasonably similar to Top in REW.
The IR chart and the ETC graph are similar. They show reflections or echoes in the room. The horizontal scale is milliSeconds.
With a piece of string and a calculator you can find the actual reflection associated with each spike.
I think create Minimum Phase copy will move the 0 spike to 0 which makes the time scale a bit more easily readable.
I don't know why the peak of the ETC graph is not of a similar level to the others.
FuzzMeasure really really needs some TLC.

DD
kwow
Thread Starter
#18
24th October 2012
Old 24th October 2012
  #18
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi Glenn!

How does the room sound in general?
Well, compared to before I got rid of the carpet and put in hard floor, not having any bass traps vs. having Superchunks. it's night and day already!

Yes, and low end does seem much more clear & punchy. In fact, since I haven't build any broadband absorbers yet, the mid-hi and highs are still bouncing and a bit bright so the low end almost seem a little small even with the sub.

The Roxul Rockboard 60 that I ordered should be coming in this week or next week so I'll be building may be about 12 panels/cloud, I'm looking forward to hearing things more balanced.

I'll definately keep in mind the +/-7 db thing that you mentioned.

Thanks for your comment!

Keith
#19
24th October 2012
Old 24th October 2012
  #19
Gear Guru
 
Glenn Kuras's Avatar
 
Joined: Jul 2005
Location: Atlanta, GA
Posts: 16,210

Glenn Kuras is offline
Quote:
Originally Posted by kwow View Post
Hi Glenn!

How does the room sound in general?
Well, compared to before I got rid of the carpet and put in hard floor, not having any bass traps vs. having Superchunks. it's night and day already!

Yes, and low end does seem much more clear & punchy. In fact, since I haven't build any broadband absorbers yet, the mid-hi and highs are still bouncing and a bit bright so the low end almost seem a little small even with the sub.

The Roxul Rockboard 60 that I ordered should be coming in this week or next week so I'll be building may be about 12 panels/cloud, I'm looking forward to hearing things more balanced.


I'll definately keep in mind the +/-7 db thing that you mentioned.

Thanks for your comment!

Keith
Then you are getting there. Keep adding traps and enjoy the room
kwow
Thread Starter
#20
26th October 2012
Old 26th October 2012
  #20
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
DanDan,

Oops, I didn't see your response. I'm sorry about that.

I'm not exactly sure what you mean by "For a 2.1 system you could measure 1.1 separately for L and R.".

Do you mean skip the sub altogether? or do you mean going through the sub but only one side/one satellite speaker at a time?

I will set the low to 10Hz next time I measure.

And I will re-read the link that you posted for me.

I just picked up the Roackboard 60 yesterday so I'm going to start building some broadband panels as well.

Thank you!
Keith
#21
26th October 2012
Old 26th October 2012
  #21
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,497

DanDan is offline
One Two One Two

Quote:
or do you mean going through the sub but only one side/one satellite speaker at a time?
Yes. Exactly. This is complicated by the fact that you can move the sub and sat independently. I would prioritise the sub placement to get best bass. You will be creating a reflection free area around the Sats and yourself, in terms of MF and HF

DD
kwow
Thread Starter
#22
27th October 2012
Old 27th October 2012
  #22
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Thanks DanDan!
kwow
Thread Starter
#23
29th October 2012
Old 29th October 2012
  #23
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Update

Few weeks ago, I built a partial Superchunk above the door.



Then I built a movable Superchunk on casters that can fit right under the top piece by the door, or be moved away from the door way.





I also filled the bottom of the couch with some R30.

And today, I took another measurement.
I took you guys' suggestions and made the low frequency 10hz instead of 20hz, removed the drums from the room, and made the sweep 10 seconds instead of 1 second.

I also turned down the sub just a hair, even though at this volume + the sweep being 10 seconds long, the whole floor/room was vibrating with the low frequency sound. (May be I should turn the sub down even more?)

Below are the results.





And here's the IR File.
http://soundcloud.com/kwow-1-1/ir-10-28

I'm currently struggling with the finish on the racks I'm building, but I'll start building some braodband panels soon.

Any comments/suggestions would be appreciated

Keith
#24
29th October 2012
Old 29th October 2012
  #24
Gear addict
 
Joined: Sep 2011
Posts: 389

akebrake is offline
Quote:
Originally Posted by kwow View Post
Few weeks ago, I built a partial Superchunk above the door. ..
Then I built a movable Superchunk on casters that can fit right under the top piece by the door, or be moved away from the door way.

I also filled the bottom of the couch with some R30.

I also turned down the sub just a hair, even though at this volume + the sweep being 10 seconds long, the whole floor/room was vibrating with the low frequency sound. (May be I should turn the sub down even more?)

Below are the results.

And here's the IR File.
http://soundcloud.com/kwow-1-1/ir-10-28

I'm currently struggling with the finish on the racks I'm building, but I'll start building some braodband panels soon.

Any comments/suggestions would be appreciated

Keith
Your new traps looks nice!

Are you going to use this room for tracking and mixing?

The latest measurement looks better and I guess that it's Left speaker with Sub?

There some huge dips in the x-over region so careful placement of sub and satelites are important as DD points out.
At x over you will have 3 sources playing the same "notes" at 3 different positions in the room so speaker and listener position is critical to make the 3 blend nicely in that region.

A deep efficiant ceiling cloud (basstrap) is needed also.

BTW Chris Liscio ( Fuzz M Author) have a couple of YT clips about measuring with FM. He seem to be quite careful with level settings.

Best
kwow
Thread Starter
#25
29th October 2012
Old 29th October 2012
  #25
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi akebrake

Thanks for the compliment for the new traps!

And yes, this room will be used for tracking and mixing. And the measurement was done with the left speaker and the sub.

I was wondering what was causing the huge dips, but x-over point/sub placement I guess is the key, eh? That makes sense. I will definitely try different sub placements and see what happens.

You mention "A deep efficiant ceiling cloud" but by "deep" do you mean the thickness of the cloud panels?

I am planning on building some panels with Rockboard 60s, but I also have a good amount of R30 left. I was wondering if I could use the R30 in the front wall ceiling corners somehow along with the clouds (I say "corners" because the ceiling isn't flat).

I bought 15 panels of 2" x 2' x 4' of the Rockboard. Of course, I will buy more later if I need to. I'm thinking of building mostly 4" thick panels and a few 2" panels.

For starter, I guess I will need to cover the first reflection points, the back wall in front of the mirrors, and the clouds. I also want to build a few panels to surround the vocalist when tracking. I should probably build some clouds above the drums also?

One thing though is that I don't want the room to be too dead. So If anyone has any suggestions on which panel should be how thick and where they should go, etc.
I'd appreciate it (Like: 2" is enough for the clouds above the drums, the makeshift vocal booth, or early reflection point, etc.).

Thanks akebrake (and everyone else) for all the help!

Keith
kwow
Thread Starter
#26
16th November 2012
Old 16th November 2012
  #26
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Broadband Panels (and clouds) Hight?

So I've been building broadband panels, and so far I've build two 2" and four 4" panels (They're all 2' x 4'). I'll be building more, of course.

I'm going to hang two of the 4" panels as clouds, and I have a couple of questions.

My ceiling is a slanted beam ceiling and the highest point is about 11' and the lowest point is at about 9'. The top of the window is at 6' 10" so I want to hang the clouds somewhere above the window. Of course, I'm going to need to try different hight for the clouds (and taking measurements in between) but what would be a good starting point?

I've read some say just leaving the same amount of space behind the clouds as the thickness of the panel, but I've also read some say to mount them as low as possible so I'm confused.


Next question is about where to place the clouds front/back wise. My mixing position is a 6' from the from wall and I have two 2' x 4' panels (and I'm mounting them sideways). Should the center of one of the panels be right above my head? Or is it more important that the clouds are placed above the mixer, etc.?

The last question is about how high to place the other panels on the wall. I'm thinking so that the middle of the panels would be at my ear hight. Would this work?

I'm thinking that the two panels that I'm going to be building for the back of the room will be placed higher since there's a couch near the back wall. I assume this would be ok, but if not, please let me know.

I wanted to ask before I start making holes on the walls and the ceiling

Thanks
Keith
#27
16th November 2012
Old 16th November 2012
  #27
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,497

DanDan is offline
Slope

With a sloped ceiling there is little point in having a thin cloud which would only absorb HF. No need, the HF is directed away from the listen spot by the slope. However it would be great to go at the vertical modes, which will exist despite the slope. So same as it ever was. Big if you want to improve the LF.
DD
#28
16th November 2012
Old 16th November 2012
  #28
Lives for gear
 
Jens Eklund's Avatar
 
Joined: Oct 2009
Location: Stockholm
Posts: 4,615

Jens Eklund is offline
Agreed, assuming the angle of the slope is sufficient to actually redirect the entire reflection from above.
kwow
Thread Starter
#29
16th November 2012
Old 16th November 2012
  #29
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi DD

Thanks for your response!

So you're saying that with the kind of ceiling that I have (with the highest point right above my head, and the low points at the either sides of me) I don't need to have clouds for reflection purpose?

And If I want to put up the clouds to control the low frequencies, then I should put the panels closer to the ceiling (away from me) with some/not a lot of space behind the panels?

I'm sorry, but I don't quite get what you mean by "go at the vertical modes, which will exist despite the slope".

And I assume you're saying 4" thick panels are not thick enough (since you mentioned "thin panels), is this correct?

I'm reading a lot of things and I'm getting a bit confused, so thank you for your help!

Keith
kwow
Thread Starter
#30
16th November 2012
Old 16th November 2012
  #30
Gear nut
 
Joined: Dec 2003
Location: LA, CA
Posts: 80

Thread Starter
kwow is offline
Hi Jens

Thank you for your response!

I just calculated the angle, and the angle at the top (right above my head) is about 156 degrees, and the sides are about 12 degrees each of the triangle.

Is this a sufficient slope?

Thanks
Keith
New Reply Submit Thread to Facebook Facebook  Submit Thread to Twitter Twitter  Submit Thread to LinkedIn LinkedIn  Submit Thread to Google+ Google+ 
 
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Similar Threads
Thread
Thread Starter / Forum
Replies
hey_mavis / Mastering forum
18
Chris Lago / Rap + Hip Hop engineering & production
47
meymia / So much gear, so little time!
10
capkutay / Low End Theory
12

Forum Jump

SEO by vBSEO ©2011, Crawlability, Inc.