Room measurements

mep · Mar 30, 2013

So I downloaded the room measurement app that Steve is high on-Analyzer is the name. I used track four from the Stereophile test disc #2 and here is the screen shot of my room response:

You can see some pretty big suck outs at 57.75 Hz and 145.8 Hz. Any recommendations on which way to move my main speakers in the room to try and counter these suck outs?

KeithR · Mar 30, 2013

That is a pretty significant rising top end- do you have first reflection treatment?

microstrip · Mar 30, 2013

Nice rainbow. IMHO only a magician can help you just looking at this single measurement you are showing us.

Steve Williams · Mar 30, 2013

what don't you understand Francisco

BTW, I do agree that this program does not replace those that you have mentioned. This app also provides a spectrograph and FFT

amirm · Mar 30, 2013

The high frequency response at 1/6 octave smoothing should be very smooth. What is there doesn't make much sense. Did you use an external measurement mic or that of the phone?

JackD201 · Mar 31, 2013

-41.8 dBFS?

mep · Mar 31, 2013

amirm said:
The high frequency response at 1/6 octave smoothing should be very smooth. What is there doesn't make much sense. Did you use an external measurement mic or that of the phone?

I just used the iphone microphone Amir. Steve said it's just dandy. I don't know whether to believe the graph or my ears with regards to the measurements. I think my room sounds great. Frantz has been on me for awhile to spend a couple hundred bucks to buy some measurement gear and spend the rest of my life learning how to use some free software program that is guaranteed to drive you nuts. Steve told me all I needed was $14.99 and Iphone and I could be an instant measurement genius.

Seriously, there was a pretty big suck out in the mid-upper bass which I already tamed quite a bit before the snapshot above was taken. I moved one sub (I moved both inititally, but only the left sub made a difference) and adjusted both of the crossover points higher.

mep · Mar 31, 2013

JackD201 said:
-41.8 dBFS?

Too high Jack? Does it matter? The pink noise was recorded at -20dB.

Steve Williams · Mar 31, 2013

Steve said it's just dandy.

well I did say it outperformed my Phonic PAA2 but I also said it doesn't replace any of the other apps that have been mentioned earlier

mep · Mar 31, 2013

Steve Williams said:
well I did say it outperformed my Phonic PAA2 but I also said it doesn't replace any of the other apps that have been mentioned earlier

Steve-For $14.99, who's complaining? I just don't know how good or accurate this program really is-specially when used with the Iphone microphone.

DonH50 · Mar 31, 2013

I would expect the peak around 80 - 100 Hz would make the sound a little boomy. If you like it as-is, the best advice I have is to delete the app and just listen. If you want to piddle, just move things around (mains and subs, plus listening position if you can) and see what helps. Ethan's site has some nice write-ups on room modes and such that might help identify if the peaks and valleys in the low frequencies are room modes.

dallasjustice · Mar 31, 2013

Does the app try to compensate/calibrate for the inaccurate iphone mic? Its not that expensive to get a legitimate mic, ADC and software.

Especially if you are going to rely on the results to make changes to a system that costs far more than $15 dolla.

Steve Williams · Mar 31, 2013

dallasjustice said:
Does the app try to compensate/calibrate for the inaccurate iphone mic? Its not that expensive to get a legitimate mic, ADC and software.

Especially if you are going to rely on the results to make changes to a system that costs lt more than $15 dolla.

as I said, it is every bit as good as my $279 Phonic PAA2

mep · Mar 31, 2013

dallasjustice said:
Does the app try to compensate/calibrate for the inaccurate iphone mic? Its not that expensive to get a legitimate mic, ADC and software.

Especially if you are going to rely on the results to make changes to a system that costs far more than $15 dolla.

I have no idea if there is any compensation going on.

dallasjustice · Mar 31, 2013

How do you know that? I very much doubt the mic in an iphone is as accurate as the paa.

Steve Williams said:
as I said, it is every bit as good as my $279 Phonic PAA2

rockitman · Mar 31, 2013

dallasjustice said:
How do you know that? I very much doubt the mic in an iphone is as accurate as the paa.

The software was designed to be calibrated to the iPhone mic. I'm am not saying the iphone mic is the best one to use, there are other outboard solutions.

amirm · Mar 31, 2013

mep said:
I have no idea if there is any compensation going on.

Their web site does not say. What it does say and repeatedly so is to use an external calibrated mic. I would think that it has some amount of calibration but if the response of the mic say, has nothing above 15 Khz, then there is nothing calibration can do.

There is now a very cheap solution for PC/Mac measurement in the from of UMM-6 USB mic. It is $80 and is plug and play. You would need a few minutes of investment with Room EQ Wizard to use it but then you get a wealth of reliable data.

Portable solutions like you have are good for quick field measurement when you don't know to bring the real gear. But for proper analysis, you want to use an ominidirectional mic. Oh, talking about omnidirectional, that could be the problem with the use of the iPhone mic. Likely if you point it differently you would get entirely different high frequency response.

mep · Mar 31, 2013

I just don't know how much to believe in this app.

FrantzM · Mar 31, 2013

rockitman said:
The software was designed to be calibrated to the iPhone mic. I'm am not saying the iphone mic is the best one to use, there are other outboard solutions.

REW (free) + an USB Soundcard with phantom power such as the M-Audio or the Tascam US-122MkII (75 to 140) + a calibrated behringer ECM-8000 (80) combo is the real deal. It will not take more than a few hours to get result with and improve many systems.

Happy Easter people!

rockitman · Mar 31, 2013

Here is one screen shot off the iPhone running -20dB pink noise uncorrelated. Speakers Wilson X-2.2 and MIT MA-X SHD speaker cables. It is my opinion that your speaker cables will also be big factor on the frequency RTA plot in addition to the room/speakers. I bass trap in the front corners behind the speakers, diffusion on the center soundstage area and full frequency trap behind the seating position in addition to diffusion. I also have 1st reflection points trapped for mids/highs on the side.

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