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suggest best mic for room treatment calibration.

Discussion in 'Microphones' started by vaibhav dewangan, May 11, 2015.

  1. vaibhav dewangan

    vaibhav dewangan Active Member

    please suggest best mic for room treatment calibration.
     
  2. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    There is none that I know of.. measurment mics mesure frequencies, they can't account for standing wave and reverb control.
    Also, no mics are 100% flat so you need a software that calibrate itself to the mic.
    Exemple : http://www.ikmultimedia.com/products/arc/
    This is good to calibrate speakers but not room treatment (well not entirely)

    The best way to calibrate treatment is by calculations taking materials in count. I have no knowledge of how to do this but there is a few sites that offer calculators.

    The real question is ; are you building a mastering room that needs to be perfect ?
    If it's for recording, the room don't have to be perfect.. it just need to sound good with the instruments you want to record and this can be done by ears for the most part.

    You should state want you want to do and the room dimensions. some here have more experience in that area ;)
     
  3. Matt

    Matt Active Member

    From what I have read, dbx has one around $100 or so which is very similar to more expensive ones. I think I read that in Ethan's book...
     
  4. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    http://www.amazon.com/dp/B000HT4RSA/?tag=recording.org-20

    This is more mic than most people would probably ever need for this purpose. An earthworks isn't a bad choice, and B&K also a well known reliable brand.

    A radio shack meter and a copy of the freeware REW is all you need for room tuning / speaker calibration, in most general cases.
     
    pcrecord likes this.
  5. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    I have this behringer mic.. it's good to tune speakers on a live venue but not room treatments.

    A db meter is indeed a greater tool for this ! ;)
     
  6. bouldersound

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

    I'd go for the Behringer mic and REW over an SPL meter of comparable cost (and I have both). Unlike a crude spectrum analyzer or an even cruder SPL meter REW is time sensitive and can help distinguish between the natural response of the speakers and the room effects.
     
  7. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    The problem with the Ecm8000 is that it isn't flat and out of 1000 mics none are Equal. May be the prototype was, but along the production chain some are good some are not.
    ecm8000_curve.gif
    Now, may I remind you that we are not talking about speaker calibration but room treatment!
    A calibration mic won't help to reduce flutter echo and bad reverb, only frequencies (if the mic, pre and software are calibrated together)
    This is why I do believe it's not a perfect choice.. Yes it can help but not all the way..

    I say it again, if it's a recording room, record in it first. Deal with the problems you hear when you listen to the recording not what you hear in the room when standing in it.. ;)
     
    Kurt Foster likes this.
  8. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    A test mic is a test mic. You use it to collect data so you can calibrate your audio system, and tune your room.

    In general you set up your system and basic treatment. Then you test using a test mic, either purpose built or an spl meter. The mic and audio equipments (interface) non-linear response, is compensated for within the testing program via a pre made preset, or via a setup procedure, specifically for this purpose.

    So now you have test data that is testing your room and system, and your testing equipment has been compensated for.

    It's at this point you analyze the data, and then add whatever treatment you need and can afford. The last step is to then use any sort of electronic 'speaker room correction' type things.
     
  9. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    K, I agree that the test mic has it's value. I just wanted to point out that it is not perfect and hard to apply in small home studio. I don't know any software that can account for the mic, the preamp and the monitors frequency response. What if you have a standing wave peak at 30hz and your monitors don't reproduce audio below 40hz ? It all stands on a lot of assumptions.

    Anyway the OP hasn't return and never said if it was a mastering room or a recording room that he wanted to threat and to me they are not to be addressed the same way.
     
  10. Kurt Foster

    Kurt Foster Distinguished Member

    shooting a room can reveal shortcomings. usually RTA's come with a calibrated mic. shoot the room with pink noise and look at the readout / display to get an idea where the problems lie. good bass trapping is necessary in a tracking room as well as adequate mid high absorption, don't over do the high absorbers. diffusion is also good to address issues while not sucking the life out of the room.

    i agree.
     
  11. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    True, the OP hasn't returned. Lol we don't even know if it's a tracking or mix room!?

    Marco, you might wanna check out REW. As part of the setup process, you 'calibrate' your test system. Aka- test mic, and interface. You do this via the instructions and after 20 min or so, the software has made a 'fingerprint' of the frequency response of your mic, and interface. When you do your tests, is figures this information in, so your test equipment is pseudo flat, for testing purposes.

    This leaves your room and speakers as variables. Using the time slice function of a testing software, you can effectively 'gate out' the room for testing purposes. Doing this gives you an effect similar to anechoic testing, where your messing the response of the speakers themselves.

    Once you know of your speakers that were advertised as flat, are doing in the real world. You use this, As you test your rooms actual response, you can see where defincies lie in both places. This is only in the case of a listening room.

    Recording rooms, I've never heard a scientific test for 'sounds bitchin' lol
     
    pcrecord likes this.
  12. pcrecord

    pcrecord Don't you want the best recording like I do ? Well-Known Member

    I might give it a shot... ;)
     
    kmetal likes this.
  13. DonnyThompson

    DonnyThompson Distinguished Member

    @pcrecord @Boswell @kmetal .... or anyone else who can answer....

    So then, what is the best mic to use for control room treatment, or in conjunction with REW? I've had the REW prog on my PC for about a year now, but I've not yet gotten around to getting a decent test mic. All of my room treatments thus far have been put up based on dimensions, materials, and an RT60 app on my iPad... yeah, I know... not exactly a perfect scenario... although I am getting mixes that seem to translate " okay " - but, not nearly with the same degree of accuracy as I had back when I had my commercial studio.

    Years ago, back when I was having my real control room built, I knew very little about acoustics, ( I knew just enough to be dangerous LOL) so I hired a pro acoustician - who had experience with treating control rooms, recording spaces, small theaters, conference rooms, etc. - to come in and test my space for mixing purposes, as opposed to me just throwing up random types of treatment on the walls... we ended up installing a variety of traps, BB absorbers and diffusers... One of the diffusers was actually mounted directly above my position at the console, with two 2x4 clouds, each suspended on either side of the diffuser. (BTW, I never did have any 1" auralex anywhere in that room, nor was it ever suggested or even discussed)

    I remember that he used an Earthworks Omni Mic for the analysis, and then he brought in a Neumann Dummy Head afterwards to check for the best mixing position in the room, which, as it turned out, ended up being fairly close to dead-center in the space ( it was a pretty big room, 18 x 20 with a canted ceiling starting at 10' and ending at 12', so it wasn't an issue with having the console and monitoring in the middle of the room).

    I have no idea what analyzing software/program he used, though. I can say that after treatment, it turned out to be one of the best control rooms I'd ever mixed in. The mixes that I turned out of that studio were very accurate, and translated extremely well to outside playback systems. It gained a reputation in the area as being a great space to mix in. There were even a few times when some of my competitors (we were on good terms with each other) would rent out my control room to check their mixes, and even to mix their own projects from time to time. (We had a good relationship between the three of us - we would warn each other about deadbeat clients, people who wrote bad checks, and we even occasionally rented or borrowed gear from each other ).

    Anyhooooo....

    So, understanding that I'm likely not ever going to get the same results as I had then with where I am now, what would be the suggested "best" mic to use to analyze the current room I'm in for mixing purposes?

    Do I need to use an actual dedicated "test" omni mic, like the Earthworks Omni that everyone seems to recommend?

    Or, is it possible to substitute that with a high quality condenser - like say a 414, or a U89, set for Omni? Or would there be too much coloration inherent in those mics?
     
  14. Boswell

    Boswell Moderator Distinguished Member

    The best I've ever used have been the Earthworks M23 and M30. I was surprised how the calibration process cleaned up when using a standard measurement microphone rather than a good audio mic.

    A tip I was given but have never had the opportunity to put into effect is to hire one of the professional measurement mics for a day and do your calibration runs with it and an SDC side by side. If you subsequenly make small changes to the gear or the room, you can (in theory) duplicate the test using just the SDC at a later date without having to hire the measurement mic again.
     
  15. DonnyThompson

    DonnyThompson Distinguished Member

    That's a god tip, Bos. I only wish I had a decent set of SD condensers. I sold a pair of KM's several years ago, after scaling down to a home studio. I'm set just fine in the LD category, though - LOL - which is why I was inquiring as to their possible use for the application. But it sounds like - if I want accurate results - that I need to rent ( or buy) an EW.

    Can you use the EW M23 for any other applications? I've personally never used one in any studio I've worked in, but I'd assume that as an omni mic, it might be good for apps other than just testing, like perhaps as room/ambient mics?... or no?
     
  16. Boswell

    Boswell Moderator Distinguished Member

    The same guy who gave me the side-by-side tip also said that the internal design of most LDCs rules them out of calibration work, even when set to omni. I know mics like the AKG C414 have well above average off-axis characteristics, so they could be OK for this sort of job, but without doing the side-by-side check I wouldn't like to guess.

    The other side of a good calibration mic is that it can make a dog's dinner of working as a full-range SDC. Apart from low sensitivity and the internal noise due to the very small diaphragm, this could be because the amplitude and phase characteristics are set up for flatness when in a sinewave sound field, and wide-spectrum sounds do not get fully differentiated. Again, it's not an area I have investigated in any detail.
     
  17. DonnyThompson

    DonnyThompson Distinguished Member

    @kmetal @pcrecord @audiokid


    I always learn new things from you, Bos. You're a wealth of knowledge, an absolute asset to RO, and to the whole audio recording field as well.

    Thanks for taking the time to explain the above, and for clearing that up for me... or for anyone else here who may have been wondering he same thing(s). :)
     
  18. bouldersound

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

    If the problems you're having are in the lower frequencies almost any measurement mic will do. Even the cheap mics are pretty flat in the mids and lows, and the nulls are often very deep. When you're looking for 40dB nulls it doesn't matter if the mic response varies a couple of dB. That's actually the primary intended market for REW, home theater guys setting up their subwoofers, even though it can do so much more.
     
  19. DonnyThompson

    DonnyThompson Distinguished Member

    I'm not even sure if my monitors ( Alesis Monitor One Passives) even reproduce down that far, Boulder... LOL. Maybe they do, but if so, I'd think it probably wouldn't be pushing all that much at that low of a range.

    My primary concern(s) would likely be those that are fairly common to most home rooms: 80/100/200/400 (or thereabouts)... I currently have bass traps ( Roxul) in all 4 corners - floor to ceiling, Two 3' x 5' x 4" BB's on opposing walls, and a Hemholtz on the wall behind me. An OC 703 2' x 4' x 3" cloud rounds that out, suspended 4 inches down from the ceiling, directly above my mixing position.

    I'm not sure if I even have any serious issues at this point, but I'd like to analyze the room and check, just to be sure, or, to be able to find out what existing problems may be present, so that I can take corrective measures.
     
  20. bouldersound

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

    40dB, not 40Hz.
     

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