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Interpreting REW results?

Discussion in 'Room Acoustics / Isolation / Treatment' started by JohnTodd, Mar 25, 2013.

  1. JohnTodd

    JohnTodd Well-Known Member

    Hi! I used Room EQ Wizard V5 and now I don't know how to even begin interpreting the results.

    I did a "Save All" on the data. Should I just forward it here for a knowledgeable people here to analyze? I'm definitley more of an artist than engineer; but I want to compensate for my room's deficiencies by putting a master EQ on the mixdown bus. Best I can do for now, but proper studio treatment will be here in the next five years.

    Here's the details:
    REW v5 software;
    Standard bedroom studio, smallish room, sheetrock, paint, bedroom furniture.
    MXL990 condenser mic (flattest response mic I have)
    Altec Lansing home theatre w/sub for monitoring.
    PreSonus FP10 for I/O.
    Mic placed at the mix position facing the speakers, sub to the right and below, resting on computer. Sub is de-coupled from computer case with a washcloth!


    Well, this sounds challenging! If anyone can make something useful from all this I'll be in awe!
    Thanks!
    -Johntodd duh
     
  2. JohnTodd

    JohnTodd Well-Known Member

    Here is the file. I'm still having trouble wrapping my head around it.

    https://www.dropbox.com/s/w08nsa1kgv18mzy/RoomTests.mdat

    Thanks!
     
  3. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    I took a look and it doesn't look like a good measurement. Measuring speaker and room response isn't as easy as you'd think so don't feel bad.

    You need a reference mic to make a proper measurement because it's not only (purportedly) flat but omnidirectional. The cardioid pattern and response of the MXL990 makes it unsuitable for measurement. Behringer's ECM8000 is about $50 which would get you started. The dbx mic is about $100 and there are other options. If you want to be more accurate you can get them calibrated.

    Aside from that, eq may help improve the accuracy of the speakers themselves but you can't really eq the room response without causing more problems than you solve.
     
  4. McMurphy

    McMurphy Guest

    Why run the software to begin with? It's only going to depress you. You like paying for depression? Everybody wants you to buy something and you bit by bit by bit. All 24 or more. One bit at a time.

    I thought you knew all calibration microphones were omni-directional electret's like DPA all the way down to RadioShack $20 tie tack microphones which are flatter than that MXL. Many low-cost analyzers all use low cost similar Taiwanese capsules. It's only needed for a frequency response plot and not for recording. So distortion is not an issue or, a factor. In fact it doesn't even need to be balanced output microphones.

    McMurphy
     
  5. JohnTodd

    JohnTodd Well-Known Member

    OK, I'll can this project until I obtain the proper mic.

    Basiclly the results I've given are so skewed as to be worthless, right?
     
  6. McMurphy

    McMurphy Guest

    I can't even decode that file? It's some kind of obscure suffix?

    I don't figure results should be completely skewed because of that microphone? It's just not a calibration reference microphone. And it is directional but then so is our hearing when you think about it. And some folks actually have fairly well calibrated hearing in spite of the fact that they're hearing is not omnidirectional LOL. But the microphone should be. Though I don't think you're data should be completely useless? It still supplying some data with a microphone that is not exactly flat. And the aberrations from off axis response on large diaphragm condenser microphones is rather brutal. So that could definitely skew you up so to speak.

    I'm curious why you find this measurement necessary? Are you having monitoring or recording problems? Are you using active or passive monitors? How are your mixes going? Is this just out of curiosity? I've never really found these measurements to be all that relevant when it comes to the monitoring in the room. Unless you're looking for problem areas? Most likely?

    McMurphy
     
  7. JohnTodd

    JohnTodd Well-Known Member

    Gotta have this software. Dont know why I didnt think of this before:

    https://www.dropbox.com/s/52sztww18pq3lzu/ROOMEQwizardinstallv5.exe
     
  8. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

    Although REW can measure THD, so not adding distortion with the mic can be useful.
     
  9. JohnTodd

    JohnTodd Well-Known Member

    @ McMurphy: Gotta have the software to read the file. Sorry.
    -Johntodd
     
  10. McMurphy

    McMurphy Guest

    Not being familiar with that software, I did not know it was capable of reading distortion. By the way thanks for the links to the software. Looking forward to checking it out myself. There are plenty of reasonably priced calibration microphones but if you want the good ones, DPA, Larson Davis, Earth Works, can be used both for calibration purposes and truly excellent recordings. I have a couple of old B&K's, with Larson Davis capsules. You might be able to find some of those used?

    McMurphy
     
  11. MadMax

    MadMax Well-Known Member

    The Behringer ECM 8000 is 60 bucks from Sweetwater.... Behringer: MEASUREMENT CONDENSER MICROPHONE ECM8000

    Plenty fine/accurate for what you're doing.

    We don't have the sticky here, but Ethan's got one, GIK's got one, and there are a couple of "primers" over at GS, John L Sayers and Studio Tips that pretty much will guide you step by step on how to use REW to get accurate and meaningful test results.

    You should end up with waterfall plots that show the amount of energy and decay for a given frequency range.

    Since LF energy is the most difficult to get squared away, you want to be sure that you mainly concentrate there first, then move upward in the spectrum. Generally, most folks measure from 20Hz up to about 600-800Hz, then from there up to 6-8kHz, then from 6kHz on up... then look at the overall response curves as a whole.

    This is NOT a rule, a suggested range spread or anything else... just an observation I've made, and you should look over your room's response and make the judgement call based upon your own findings.

    I will say this though... the narrower the frequency range, the more accurate your observations... with the caveat, that looking too narrowly MAY give you a false impression of how good, or how bad your existing situation may be.

    So, dig around for those primers, get the ECM8000, test, re-test, make adjustments, re-test again, and understand that your speakers, their placement, your listening position, speaker frequency response and your rooms' frequency response all interact with each other in strange and sometimes seemingly unpredictable ways.

    Depending upon all the specifics, you might move something as little as a couple of inches and see HUGE changes, or you might move things as much as a foot and not see any appreciable change... such is the nature of the beast.

    One thing I will encourage you to do, or anyone else for that matter, is to take your time and do things as accurately and methodically as you can.
     
  12. gullfo

    gullfo Active Member

    :) but if you felt compelled to have a calibrated mic, they're starting at about $75... Cross·Spectrum - Calibrated Dayton Audio EMM-6 Microphones for Sale Cross·Spectrum - Calibrated Behringer ECM8000 Microphones for Sale and the owner is pretty active on HT forums with lot's of info on different models...
     
  13. DanDan

    DanDan Active Member

    Even cheaper Glenn, what a bargain. Dayton Audio EMM-6 Electret Measurement Microphone Allows For Accurate Acoustic Measurements At A Fraction Of The Price 390-801
    The UMIK-1 is an interesting new contender, USB, Calbrated including SPL, recognised and integrated into REW.
    DD
     
  14. Hallo all. I'm new to this forum and dont know if this is the right place.... I have made measurements with REW 5 Beta and are looking for help to analyzing the data. And if possible to get input on possible treatments. I just upload the files here if anybody would like to have a look, also the exported reading files for import to REW if anyone would do me the favour... ;-)

    Is the readings ok or is this a hopeless room? ;-)

    Regards
    Kjetil
     

    Attached Files:

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