The proper way to measure speaker frequency response

[Natural Sound]

This posting was sparked by something Doc B wrote in "The Fix" forum. I'm at a point where I'd like to invest in a measurement microphone to "tune" my room." I did a little searching on the web but the more I read the more confused I get.

First of all I don't really want to spend a ton of money. I'm looking for a good "bang for the buck" option that will get the job done well without breaking the bank. Is the Behringer ECM8000 still a decent entry level measuring microphone or should I be looking at something else?

The other thing I'm interested in is software. Should I go with a PC based software or iOS?

And finally what are some of the cost effective mic to computer interface options that I should be looking at?

Thanks in advance.

 

[Clark B.]

I've used a few different systems but have come back around to the Dayton Omnimic system.  Good enough and pretty inexpensive.  It has done well enough for me to get a ballpark idea of a system's FR and to then fine tune by ear from there. 

I like to try multiple room positions, including off axis response.  It can really help with tuning subs to a system especially. 

Oh, as a quick note, you definitely need to test one channel at the time.  You'd be surprised how many anomolies can come from running the measurement in stereo!

Clark

 

[galyons]

I bought a calibrated mic that plugs into Android and IOS.  Dayton Audio iMM-6...Very inexpensive, about $16. I am using Audio Tools for Android as the app.  There is an apple based app, as well. 

The mike is pretty accurate. A buddy, sound technician, brought over his NTI Acoustilyzer AL1 with calibrated mic and the results with my cheapy system were within about +/-0.5dB from 60h to 13.5Khz.  The high and low tails showed about 1-1.5dB variation, but my speakers don't have much going on in the extremes.  So not bad for a home measurement system that costs 1.5% of his pro unit.

The pro unit is a small hand held, (we used a tripod), had a tiny monochrome display.  My buddy really liked the big, full color display on my tablet and thought the apps tools were quite good.  So there you go!

Here is the link from Parts Express:
http://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-iphone-ipad-tablet-and-android--390-810

I am still learning to use the app tools, but can't imagine I need more power or precision than what I am getting.

Cheers,
Geary

 

[Natural Sound]

I've used a few different systems but have come back around to the Dayton Omnimic system.  Good enough and pretty inexpensive.  It has done well enough for me to get a ballpark idea of a system's FR and to then fine tune by ear from there. 

I like to try multiple room positions, including off axis response.  It can really help with tuning subs to a system especially. 

Oh, as a quick note, you definitely need to test one channel at the time.  You'd be surprised how many anomolies can come from running the measurement in stereo!

Clark

Great tips Clark, thanks. The omnimic looks pretty nice for the price. Parts express is even throwing in a mic stand plus free shiping. The only issue I have is that it's windows based. I have a bunch of computers but none of them do Windows.

 

[Natural Sound]

I bought a calibrated mic that plugs into Android and IOS.  Dayton Audio iMM-6...Very inexpensive, about $16. I am using Audio Tools for Android as the app.  There is an apple based app, as well. 

The mike is pretty accurate. A buddy, sound technician, brought over his NTI Acoustilyzer AL1 with calibrated mic and the results with my cheapy system were within about +/-0.5dB from 60h to 13.5Khz.  The high and low tails showed about 1-1.5dB variation, but my speakers don't have much going on in the extremes.  So not bad for a home measurement system that costs 1.5% of his pro unit.

The pro unit is a small hand held, (we used a tripod), had a tiny monochrome display.  My buddy really liked the big, full color display on my tablet and thought the apps tools were quite good.  So there you go!

Here is the link from Parts Express:
http://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-iphone-ipad-tablet-and-android--390-810

I am still learning to use the app tools, but can't imagine I need more power or precision than what I am getting.

Cheers,
Geary

Wow, that sounds too good to be true. But I'll definitely look into this a bit closer. Thanks!

 

[Reap]

I used to compete in car stereo. Not the boom boom but the sound quality. And I've lived in 2 different states while doing so and the one thing I know is that all the high end car stereo shops have Real Time Analyzers (RTAs).  And all of the setup discs have a track for pink noise. So if you can get your hands on these you can do wonders for your environment.  Just set the mic at the approximate location of where your head will be for normal listening and run the pink noise track. But don't think that what you see on the graph will indicate when a system sounds good because it will not. What it will do however is point out the mechanical problems you are dealing with. And, you also do not want the system to be ultimately flat, you should end up with what we call a listening sound curve.

The setup disc will also have tracks to check polarity, or phasing of the speakers.  Stuff like this should be corrected first. Critically important too is the crossover network. But that is a discussion too deep for this media. Slopes, crossover points, and component selection can all fill up a book. I know you may be aware of all of this but not being inside your head I can only assume you do not.

http://en.wikipedia.org/wiki/Real-time_analyzer

http://www.virtins.com/img/VTRTA-168System.gif

Judging by the pic it looks like there is now software for the pc. But you will still need the mic.

 

[Balle Clorin]

I use the REW software, it is free and excellent. The Beringer 8000 mic I use is supposed to be very poor quality nowdays, do a google on it and find something better.  Oh, REW also does speaker impedence measuremnet ,and I also can use it for distortion measurement on my amps...

 

[Tubejack]

I also use REW, coupled with the relatively affordable mini-DSP boards and their calibrated mic.  Their software couples nicely with REW.

http://www.minidsp.com/products/acoustic-measurement/umik-1

 

[2wo]

I have one of those, can't say I have messed with it much. The nice thing about this one is it is a USB device. You don't need a mike preamp or a phantom power source...John 

 

[johnsonad]

I'm happy with the Omni Mic from Dayton. It's easy to set up and use and does what I need other than phase work.

 

[Paul Joppa]

The biggest problem with cheap mics for this application is in the top octave or two - such mics are usuall not flat, more than a little directional, and (most important!) variable from sample to sample.

This is very important if you are a speaker maker developing a new tweeter.

For typical audiophile use, it's not important - you mostly want to see that things are reasonable flat through the midrange, and to move your speaker around the room modes, and maybe to check that the crossovers are phased correctly. Flat to 5kHz or above is just dandy for these purposes.

 

[Natural Sound]

Well it looks like a toss up between the Dayton Omni Mic and a Mic/REW combo. The iPad option was very tempting but I've pretty much ruled it out as an option at this time.

Tubejack, the Mic you linked to is USB so it shouldn't require a mini-DSP board. Am I missing something? http://www.minidsp.com/applications/acoustic-measurements/loudspeaker-measurements

Paul, my goal is to learn about how speaker placement, room treatments and "The Fix" affect the sound from my listening chair. I don't plan on using this setup to design speakers. I just want the ones I have (Orca's and Subs) to sound the best they can in my listening space.

So here is the delema. Should I buy a $75 Mic like Tubejack recommends and use the free REW software package? Or is the $300 Dayton Omni Mic and software bundle that much better and/or easier to use?

 

[2wo]

The USB Mic is just that, plugs right into your computer. Download the free REW and you are good to go for $75...John

 

[Natural Sound]

Well I finally got around to using my new Dayton OmniMic. As suspected I have a 12dB hump @ 75Hz in my left channel to sort out. Pulling the left channel Orca away from the wall helps tremendously. However once its performing well the speaker is too far out into the room. I'm looking into different locations but ran out of time last night.

I originally thought that maybe I had a problem with my subs. But I switched the subs off and the problem remains. I'm learning a lot in the process but I have a long way to go.

 

[Doc B]

Move the speaker a foot at a time in different directions. You may find another null point that isn't necessarily out in the room.