Speaker/Room calibration

Bruce B · Feb 22, 2012

In the next few weeks, I will attempt to calibrate my speakers to my room. I will post graphs before and after as well as tell you what was done to (try) correct any deficiencies. As most of you know, when we put speakers in a room, sometimes we get the dealer to set them up... sometimes not. After a few months, after they've broken in, we're on our own. So instead of hiring Bob Hodas again or flying the designer to my room, I will attempt to do this myself.. with your help.

My speakers, Evolution Acoustics MM3, have a vast amount of flexibility as far as settings you can adjust. The settings as they stand now, are flat. They sound great but I've always wondered if I can get that last 1-2% out of them.

The equipment I will be using is:

Room EQ Wizard
Smaart v.7

Earthworks M50

M-Audio Pro Track via USB

Toshiba Tecra Business Laptop (modified)

For adjustments, I will mainly be using what is available on the back of the speakers. If I need more, I also have 2 analog parametic equalizers, the Crane Song IBIS and the Meyer Sound Lab CP-10.
I will also try a couple of digital EQ's that I have, the Sony Oxford and the Algorithmix.

Wish me luck!

jazdoc · Feb 22, 2012

Bruce,

Thanks for sharing this (hopefully not too long) journey. I suspect most of us who follow along vicariously will learn a great deal.

treitz3 · Feb 22, 2012

Hello, Bruce. Will you be using the Cardas method or maybe the Sumiko setup to first place your speakers or are you going to let the numbers decide where to place them as you go?

Bruce B · Feb 22, 2012

treitz3 said:
Hello, Bruce. Will you be using the Cardas method or maybe the Sumiko setup to first place your speakers or are you going to let the numbers decide where to place them as you go?

Because of size/weight of speakers and dimensions of the room, I have about 8" fore/aft and 12" side to side movement. Don't know if that will make any difference but I can sure try. The speakers are on Wave Kinetics 2NS footers, so I can slide them fairly easily. The room is 13' wide.

There is an initial setup guide on the EA website.

Short wall Placement

NorthStar · Feb 22, 2012

Bruce, good luck! :b

rbbert · Feb 22, 2012

That appears to be very similar to the "Cardas method". How long is your room, and the height? The speakers appear to be large for the room?

c1ferrari · Feb 22, 2012

That's exciting, Bruce ;-)
I'm thinking of exploring Smaart as well.

Bruce B · Feb 22, 2012

rbbert said:
That appears to be very similar to the "Cardas method". How long is your room, and the height? The speakers appear to be large for the room?

the measurements are 13' x 22' x 10.5'

Almost 1/3rd of the cubic volume is bass trapping

NorthStar · Feb 22, 2012

Those are very decent (more than decent) dimensions. ... Even for a Home Theater room.

Bruce B · Feb 22, 2012

NorthStar said:
... Even for a Home Theater room.

Even for a basement!

rbbert · Feb 22, 2012

Almost identical to my listening room (166" x 274" with a slanting ceiling averaging 132"), so I'll be following your journey with great interest.

NorthStar · Feb 22, 2012

Bruce B said:
Even for a basement!

Well, the length is within 5% of the height's multiple (X2 = the only onion; oil in the ointment).

* http://www.silcom.com/~aludwig/Room_acoustics.html
* http://www.linkwitzlab.com/rooms.htm
* http://www.ethanwiner.com/acoustics.html :b

* http://www.tmlaboratories.com/RoomDimensionsCalculator.html

P.S. My older room was 13.5' by 23.5' by 8.0'.
So, I'll be watching you. ...Except for the ceiling (height). :b

Soundproof · Feb 22, 2012

Definitely a thread to watch! Looking forward to following Bruce's investigation!

Bruce B · Feb 22, 2012

NorthStar said:
Well, the length is within 5% of the height's multiple (X2 = the only onion; oil in the ointment).
...Except for the ceiling (height). :b

Well the ceiling height is actually 2 levels. There is a center section that is 10.5', but there is a perimeter soffit, that serves as a bass trap, that is just over 8'. The center section is broken up with diffusors and the ceiling surface is 2" 703 covered with fabric.

NorthStar · Feb 22, 2012

WoW! Ok, you win! :b

Bruce B · Feb 24, 2012

First, the easy part. REW wants me to do a calibration of the soundcard via analog loopback (M-Audio Pro Track USB)

jazdoc · Feb 24, 2012

Bruce,

Could I ask a big favor...could you try and use English to explain for the 'technically challenged' audiophiles what the graphs are used for and what the data means to you. Thanks in advance!

Bruce B · Feb 24, 2012

jazdoc said:
Bruce,

Could I ask a big favor...could you try and use English to explain for the 'technically challenged' audiophiles what the graphs are used for and what the data means to you. Thanks in advance!

For any good engineer, you need to make sure the test equipment itself is within normal limits (WNL). This was the first part in making sure what I measured was actually happening. In the above graph, lets say the line dipped down -6dB at 100Hz. Well instead of thinking that is a room problem when I did the actual measurement, the software would take that into consideration and correct for that. The calibration file that you save in the program would say the "M-audio Pro Track" does not accurately track the signal and the software has to correct (raise the graph +6dB at 100Hz) for that deficiency.

Now, if I wanted to be anal, I could purchase the calibration file of the microphone that I'm using from Earthworks. Every measurement microphone they sell, they calibrate and have the freq. plot and such available, for a price!. You would then load in the calibration file for the microphone too and the software would correct for any variance of that particular microphone.

I don't think REW software does this, but some software even adjusts for elevation, humidity and temperature, all factors on the speed of sound. So the top green line in that graph above should be as straight across 0dB as possible.... especially in the audible band of 20Hz to 20k. Here you can see the test equipment in the chain is down maybe 0.1dB at 20Hz. If you want to measure below that, the calibration file would compensate for that downward slope.

Bruce B · Feb 27, 2012

Now this has been a pain in the arse...

Seems the M-Audio Fast Track Pro does not have enough gain for the Earthworks Mic. I'm just using USB bus power now, so I'm assuming that you need the AC/DC adapter to give it enough gain.
So.. I ended up using my Radio Shack digital SPL meter. Guess that's "good enough" for a down and dirty shot to see if this thing works.

There are several adjustments on the back of the speakers.

Bass Filter - regulates how much low freq. is sent to the woofers. Settings are 50 - 100 - 150Hz. Mine set at 100Hz

Bass Level - the loudness level of the bass. Settings are Off to 0 to +6dB. Mine set at 0 (Neutral)

Bass Quality - ?? Tight - Neutral - Full, Mine set at Neutral

Bass Extension - this is how low you want your speakers to go. Settings are 0 - 1- 2 octaves. Mine set at 2

Rumble Filter - can be used when playing vinyl. Factory default is Off.

Now the first graph is the initial sweep.

Though the first graph shows a nice bass extension from 20Hz all the way down to 4.5Hz? at -10dB. Don't know if I needed all that bass or not. I'm sure the Bass Pig would be proud!

I started playing around with some of the settings and the only thing I changed is Bass Extension. I turned it down to 1.5 This is shown in the second graph.

As you can see in the second image, the null at 40Hz and peak at 75Hz are less obtrusive.

The experts can chime in anytime now?? HELP!

theguesswho · Feb 27, 2012

hi Bruce, That looks like a great response! With bass extension down below the stated 10hz that the factory posts! I am jealous. My system barely manages 16hz. Your system goes down to the level of the rotary woofer!
I do have a few questions
1) can you post a picture of the controls on the back of the speakers, so we can see what is adjustable.
2) did you originally have the system tuned when the were originally set up?
3)Do you think you can eek out the last 1-3% with the controls?
4)What is your goal?
THanks,
Wendell

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