[marsx]

Hi,

I got a measurement mic, Dayton ECM-6.  It came with a graph of it's reponse and then, the company offers a service on their website.  Type in your mic's serial number and you can download a calibration.txt file.  The calbration.txt file is 7 pages long and here is a sample starting with 20 Hz: 

"*1000Hz   -39.9

20.00   4.0
20.55   3.7
21.11   3.5
21.69   3.3
22.29   3.0
22.90   2.8
23.53   2.6
24.18   2.3
24.84   2.1
25.52   1.8
26.22   1.6
26.94   1.4
27.68   1.2.
 
It goes all the way up to 20,000 hz.

My questions are as follows: 

1) What does *1000Hz   -39.9 at the top mean?
2) What do all the numbers mean next to the frequencies on the left?
3) It is in a text file; can it be used with some of the software out there available that helps you tune your room; such as Room EQ Wizard?  Can you import the data or is this not really a calibration file?
4)  Any recommendations on what is the best free and low priced room tuning/calibrating software that would work with a mic like this one, which uses XLR connection into an audio preamp with +48v Phantom power.
5)  Where do you place the mic, besides the place where you listen.  Do you put it in different parts of the room?  Does it help you decide what kind of room treatments you need.  And, if you can't afford or achieve the treatment you need in a home small room.  Do you recommend an EQ unit, between the mixer and the speakers, but that doesn't go to tape (or hard drive). 
6) Also, do you know of any names of different room tuning software that is either freeware like REW and others, or is no more expense than about $150.  Will any of them read a text calibration file like the one I gave a sample of and described at the beginning of this post?

I know it's a low end mic, but it's all I can afford right now.  I would appreciate any help or guidance, since I'm totally new to room treatment.  The only thing I've done so far is built 4" thick bass traps using Corning rigid fiberglass, 2" of 705 FRK in the front and then 2" of regular 705 in the back for 4" thick in wood frames I made and put up 2" auralex foam on the ceiling above where I sit and above both sets of speakers I use.  All the noise is out of the room, with the computer in a room next door, with the cables coming through a small whole in the wall. 

I do have some stuff ready to treat the room if I need it.  I have a couple of boxes of 2" Auralex foam wedgies and I also built some honeycombed frames to house a lot of NASA type memory foam that's is four inches thick that I had from some bed toppers.  I put the foam into honeycombed wood frames in pieces no larger than 1' x 1' because the foam is so malleable.  I know this foam has never been acoustically tested.  But I had it so I thought, who knows maybe I might need it and I might use it and it will work.  Of the memory foam, I have two 3' x 2' frames filled with 4" thick foam, as well as two 2' x 2' and two 2' x 1'. framed in wood and honeycombed so that no piece of the foam is bigger than 1' x 1' because it is so malleable.  The floor is covered with industrial carpet and the ceiling is drywall.  The walls have several layers of alternating drywall and soundboard.  The room itself is which is rougly 13' x 11' with the 13' walls parallel and the 11' walls half parallel for five feet and then one wall angles off by about 15-120 degrees. 

That's all I can think of to tell you.  If anyone can offer advice or links to good sites to help me learn about room tuning and mic measurement and what good software is available as freeware, like REW, or that is not too expensive, (under $150); I would be indebted. 

Thanks.

Sincrely,

Wade
aka marsx

[Nuance]

1)  I wouldn't worry about it - they know what they're doing at Dayton.  The numbers are just corrections.
2)  I assume they are the frequencies and how much they were adjusted for, but again, its nothing to worry about.
3)  Yes, you should be able to load the calibration file.  With REW you can just rename it "Dayton.cal" and it should load just fine.
4)  REW is the best I've used compared to anything "cheap."  Just use REW.
5)  It depends on what you're measuring and what the manufacturer specified.  They may have designed the mic to be used solely in horizontal or vertical position; you'd have to find that out.  Generally, though, if measuring bass (15-200Hz or so), the mic can be positioned either straight up or straight ahead, pointing dead center between the speakers.  The mic needs to be placed at ear level at your listening position.  If you want to measure above 200Hz, measure one speaker at a time and point the mic directly at each speaker's tweeter.  Again, the mic needs to be at ear level at the listening position.  You can then use REW to average the left and right speaker's response.  You can also put the mic in different parts of the room to measure multiple seating locations, and then average them all together.  Measurements can give you an idea where to place treatments, as they'll show you which frequencies are ringing and where the peaks and nulls are.  But I highly recommend using a parametric EQ below the crossover point.  Combine that with bass traps and you'll get a flat response and reduce ringing dramatically.  For EQ below 100Hz I use the Behringer 1124p and love it. 
6)  YMMV, but I wouldn't bother.  In my opinion nothing in that price range will best REW. 

For what its worth, foam doesn't absorb as well as particle/rock board or OC703/704.  They are denser and absorb much better IMO.  You can find them here:
http://www.atsacoustics.com/cat--Fiberglass-and-Mineral-Wool-Batts-and-Boards--106.html

Home Theater Shack has a great REW tutorial if you're interested.  Check it out.