Room Response

[Chili]

I finished building Studio Cubito in my garage, packed it full of junk and moved in. See this thread:

https://homerecording.com/bbs/showthread.php?t=279814

I was fortunate enough to borrow the company's Bruel and Kjaer sound meter and took some measurements of the room's response. Now I need help interpreting the results.

This is a small cube-shaped room, hence the name, dimensions are 9Wx11Lx10H. Sound source is a wav file of Pink Noise played through my DAW at levels near 65db, based on the meter. I use Event ALP5's which have a bandwidth of ~50hz - 20khz, set as near fields and the mic was in the sitting position.

The measurement spectrum is 11hz - 5khz and charted as dB re 20uPa. I loaded the data in Excel and charted the results. Then I charted a subset for 11hz - 500hz.

i see the peaks and valleys, but don't know if they are of concern or not. I know I don't have any bass response, are the speakers too limiting to be a subjective test? For my size room, I believe the trouble spots are around 240hz and 500hz.

Anyways, here are the screenshots. I can email the excel spreadsheet if any is interested.

Thanks for any thoughts.

11hz - 500hz


11hz - 5khz

 

[pandamonk]

Your bass response looks pretty decent to me, ±6dB from 100-500Hz. This is decent considering your speakers vary ±3dB.

With such small woofers, you'd expect it to tail off below 100Hz, although the specs claim only -3dB at 53Hz.

"I believe the trouble spots are around 240hz and 500hz", if that is the case then the bass traps have completely tamed the beast, bringing it within ±4dB.

Looking at the 11Hz-5kHz graph, it seems that the bass and low mids (to around 2.5kHz) are slightly enhanced. If these were pulled back ~6-10dB that'd bring everything above 100Hz within ~±6dB, although you'd lose a lot at 50-100Hz.

What do the experts think of using EQ to flatten the freq response after installing decent acoustic treatment? If so, I'd pull back 100Hz-2.5kHz by ~6-10dB, leaving the rest. This might not be a great idea though, because movement of just 1" can completely change the freq response. If you repeat the test a few times for a larger area around the mixing position, this will give you a much more accurate freq response for the room and you will have a better idea of whether you can EQ.

 

[Chili]

Thanks for taking the time, Pandamonk. I do need to take measurements in different areas; within a 1 ft radius of optimal sitting position, I think. Then maybe differernt points in the room.

Glad to see someone thinks the room is halfway decent.

Anyone else have some ideas???

Thanks!

 

[CIRO]

Panda it´right about the response above 100hz, Chili,seems fine at first look; altough a high resolution software like Room EQ Wizard (free) probably will shows some nulls that are hidden with the pink noise.
I´m sure you can improve the the bass below 100hz changing monitors and mix position.It will vary a lot from each room, you know, but things like putting speakers near the front wall possibly will improve this lows.
Another thing is avoiding the "50%" (mix position lenght, height speakers floor/ceiling...).
A "side effect" will be (probably) the increase of bass decay times in the sub lows (something that only thick treatment in the corners - like 6" panels or superchunks will solve).It´s the "price"...

This Plus lots of placements and measurements... (try the REW,it´s great).
*How many traps you have in the room and where?

Ciro

 

[Ethan Winer]

I was fortunate enough to borrow the company's Bruel and Kjaer sound meter and took some measurements of the room's response.

That looks like one-third octave resolution, which is not adequate for measuring the bass response in a home-sized room. You need much higher resolution to see the true extent of the peaks and nulls. You also need a way to see time-based problems such as modal ringing. These are the programs I suggest:

ETF, Windows, $150
FuzzMeasure, Mac, $150
Room EQ Wizard, Windows and Linux, Freeware

This article explains how I use ETF, but the principles apply to all such programs.

--Ethan

 

[Chili]

Thanks Ciro and Ethan. Good info from both. I read most of the article, but will come back to it tonight for further digesting.

Guess I need to figure out how to get the B&K to yield a higher resolution than 1/3 octave results. It's an expensive instrument, it should be capable....