My First Measurement

**DozerMayne** · **04-30-09, 06:16 PM**

Attached are my first measurements.
Emu 1820M
2)KRK Rokit RP5's
1)KRK Rokit RP10S Subwoofer
System routed from Emu, through Sub, Crossover 80Hz, to both KRK RP5's
So it goes Emu 1820M Output L/R>Subwoofer Inputs L/R>Outputs L/R on Subwoofer out to>Both KRK RP5's

VeryVery small room.
Length Width=7ft8in x 9ft

Center Triangular Apexed Vaulted Cieling Heights:
8ft5in at Apex
7ft at wall sides(outer edges of apex)

Studio(Sub Under Desk)

Using an ECM8000 with generic .cal file from this site.
My Emu 1820M .cal file
Sampling Rate 44.1K
All measurements @ 512K (11.9 sec)

Here is the Low Frequency Sweep:20Hz-500Hz (Dont mind the sub curve)

Full Range Frequency Sweep:20Hz-20000Hz

Low Sweep Waterfall

Full Range Sweep Waterfall

RT 60

**brucek** · **04-30-09, 06:55 PM**

Note: RT60 is considered meaningless in a room that size.

Note: Waterfalls are usually limited to low frequencies - full range is not usable.

Interesting, you have a very slow decay in your waterfall. Are you using any treatment?

brucek

**Wayne A. Pflughaupt** · **04-30-09, 08:44 PM**

Nice response on those RP5's...

Regards,
Wayne

**DozerMayne** · **04-30-09, 10:57 PM**

Here is one of my photobucket albums.
Just took the pics. I will add descriptions soon, so you can know whats going on.
Just click on the pic to see a bigger size (640x480)
CLICK HERE for Dozer Studio 09 Pics

There is also an older album of an older setup in that same room.

**brucek** · **05-01-09, 06:40 AM**

After looking at all that treatment, I don't understand why your signal is persisting in the room so long. I would think the waterfall would show an almost instant decay - yet it doesn't.

brucek

**DozerMayne** · **05-01-09, 05:35 PM**

Well, I had the ECM 8000 at ear level, pointing toward the ceiling, as seen in the pics.
It was running into my Emu 1820M Preamp. Preamp Gain about halfway.
I know the dip in the low end near 100Hz is because that position is in a trough.
After I have taken care of most of the highend stuff, all I have to do is move my chair back a foot, and see how the low end relates to the rest of the mix. The low end becomes louder as I move back a distance of about 1 foot, toward the corner.
I also use references,known material.

Tweeter to tweeter distance on the Rp5's is 4ft.
I'm using 60degrees, so Mix position for me is 4ft away.

I am going to remeasure. Then, also angle the Monitors out a little, and move back a foot.
So tweeter distance will still be roughly 4ft, but measureing/mixing distance will be 5ft apex.
Which will narrow the stereo image a little. But not much. And measure again.
Look for which position is the best.

I thought there was something up with the waterfall diagram myself. 600ms and barely any decay.

Updated Sig
Myspace quality is 96kbps .mp3
SO I have another player on the left with 320kbps tracks.

The first song that plays "Good Love" from the myspace player is really just a Hook I did for someone.
And also used for promoting a video tutorial I sell on Smooth Autotuned Vocals.

**Wayne A. Pflughaupt** · **05-01-09, 06:56 PM**

Quote:

brucek wrote:

After looking at all that treatment, I don't understand why your signal is persisting in the room so long. I would think the waterfall would show an almost instant decay - yet it doesn't.

brucek

Are you basing that on what is showing above 100 Hz? Below 100 Hz it looks fine to me...

Regards,
Wayne

**Wayne A. Pflughaupt** · **05-01-09, 06:58 PM**

Quote:

DozerMayne wrote:

Well, I had the ECM 8000 at ear level, pointing toward the ceiling, as seen in the pics.

Are you using our calibration file, or is your mic custom calibrated?

Regards,
Wayne

**brucek** · **05-01-09, 07:55 PM**

Quote:

Are you basing that on what is showing above 100 Hz? Below 100 Hz it looks fine to me...

I don't see how you can feel it's fine?

He is using a 600msec time range, so each slice is 20msec. See how closely spaced the first half of the slices are? The signal doesn't hardly decay at all for about the first 15 slices =~ 300msec.

It's really quite bad. Did you look at the photos he referenced. He has a room full of damping on the walls. The signal should drop like a rock - yet it doesn't...

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Name: 500119secwaterfall.jpg
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Size: 60.7 KB

brucek

**Wayne A. Pflughaupt** · **05-01-09, 08:31 PM**

Yeah, it's definitely peculiar the way the signal "hangs" so long, then drops like a brick. But it seems to have completely "rang out" by 400 ms or so (except for the 60 cycle noise). My thinking, ultimately it's really not any worse than most of the other stuff we see posted, especially considering the really high signal level he's using. (I wouldn't mind seeing what it looks like with a 3 or 400 ms window).

Quote:

He has a room full of damping on the walls. The signal should drop like a rock - yet it doesn't...

We might get Brian to weigh in, but AFAIK treatments like that have little-to-no effect on bass signal decay. (I'm ignoring the <100 Hz readings since waterfalls aren't supposed to be used for them...)

Thoughts?

Regards,
Wayne

**DozerMayne** · **05-01-09, 11:50 PM**

Quote:

Wayne A. Pflughaupt wrote:

Are you using our calibration file, or is your mic custom calibrated?

Regards,
Wayne

Im using the calibration file I got from here.
The mic is just a regular ECM 8000 I got from zzound.com
Brand new.

I really have no low frequency treatment.
I was going to be making some homemade panels with Owens 703 corning,
and maybe some corner bass traps.

Most of the foam was just mainly for getting a good vocal room. To get no reverb/room with the vocals.
The room had a lot of ringing and slapback.
Clap your hands, and it would riiiinnnnnggg.

As Ive said, I use alot of different reference material. If you know what I mean.
For those who don't..
I listen to Commercial Albums that I believe are mixed well, in my room.
And use that sound as a reference.

I will just be glad when I move and get a larger room.

I got military business this weekend, so Monday I will do some other measurements.

**robbo266317** · **05-02-09, 12:57 AM**

Out of interest, what are the walls, floor and ceiling made from?

**JohnM** · **05-02-09, 02:32 PM**

That initial flat period is a consequence of the window types used for the waterfall. In the Analysis Settings change the Spectral Decay Left window type to Hann.

**brucek** · **05-02-09, 02:43 PM**

Quote:

consequence of the window types used for the waterfall.

I was assuming he hadn't changed the default window. Even with a Hamming window, I don't think you could get a waterfall that decayed like that, unless it was the room causing it............

brucek

**JohnM** · **05-03-09, 05:47 AM**

Quote:

brucek wrote:

Even with a Hamming window, I don't think you could get a waterfall that decayed like that, unless it was the room causing it............

That effect occurs when using a Tukey 0.25 window for the left spectral decay, which was the default in the software and is made more evident by the zero time of the response being set further back in V4.11 (rather than at the peak as it was in earlier versions). It is caused by the 75% of the window that is flat, and is more obvious on wider measurement bandwidths as that in turn results in narrower peaks. The response doesn't start to decay until the tapered part of the window starts to overlap the peak.

**brucek** · **05-03-09, 07:30 AM**

Quote:

when using a Tukey 0.25 window for the left spectral decay, which was the default in the software

Ah OK, I thought Hann was the left window default for waterfall. That explains it then. I have always used Hann as the left window. Maybe we need a set defaults to original button in the next version...

brucek

**DozerMayne** · **05-03-09, 07:11 PM**

I changed the Spectral Decay Left to Hann. Not much change.
I am going to do some more measurements.

Lets not forget that the bottom of my walls, up to about 2 feet, all around, there is no treatment.
The walls are made of drywall board, and insulation inside. Nothing spectacular.
There is a large window on the wall that this picture is facing, right above the backing of the chair. But its covered with a thick blanket, and foam.

Also, though there is a camo blanket in this pic, its super thin. Prevents slapback though, from that area.
So where the entrance is to the room,
there is the little area that can be thought of as a very very very, short hallway. No what Im saying??

There is a door on the other side.

And here it is as if you were coming into the room.

Im guessing that for sure the entrance way could be a big deal.

**DozerMayne** · **05-03-09, 11:51 PM**

Allright, I got it.
Dont know what the deal was, didn't really change anything. Must have been a quark.

I took new measurements. From different positions.
QUESTION: Which position(mix,mid, or corner/far) do you suggest I work from/use as reference for acoustical treatment?
I would rather work from mix position and just find a way to get rid of the
big dip in the lowend around 100hz. Or I could just move back a little to mid or corner, and rematch the sub to the RP5's at that position

Attached far below is a .zip file with all screenshots, and .mdat (measurement data) files.

Here are my Analysis Settings.

Here are the Spectral snapshots. (1/3 smoothing)"Positions" can be derived from photos in posts above.
500Hz sweep and 20khz 23.9second sweeps

Two from "Mix Position". 500Hz sweep and 20khz sweep

Two "Midway" between "Mix Position" and "Corner" 500Hz sweep and 20khz sweep

Two from the "Corner/Far"(behind mix position) 500Hz sweep and 20khz sweep

Here are the Waterfall snapshots. NOTE: 400ms

Two from "Mix Position". 500Hz sweep and 20khz sweep

Two "Midway" between "Mix Position" and "Corner" 500Hz sweep and 20khz sweep

Two from the "Corner/Far"(behind mix position) 500Hz sweep and 20khz sweep[/COLOR][/B]

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