Using Waves PAZ Plug to Set Room?

Discussion in 'Mastering' started by Gary Gidak, Dec 17, 2002.

  1. Gary Gidak

    Gary Gidak Member

    Hey Guys,

    I just had an sudden brainstorm and I'm looking for opinions as to whether or not it will work.

    If I were to obtain a pink noise generator, or a recording of pink noise (if there is such a thing), I'm thinking I could use this in conjunction with the PAZ plug to set my control room acoustics to a flat frequency response.

    Here's my proposed approach:

    1. Play pink noise through my monitors at the normal listening level for mastering.

    2. Input this audio into a channel, with the PAZ plug installed, using a microphone placed at the listening position my ears normally occupy.

    3. Adjust the EQ of my monitors (effecting only the pink noise output) to obtain a flat fequency response as measured with the PAZ.

    I think it would work, but I would have to take into consideration the frequency response characteristics of the microphone I use. So, I'm guessing I would set my monitor EQ to closely resemble that of the microphone as listed in the mic's spec. sheet. This is also assuming I could obtain a recording of some pink noise - is there such an animal? Am I dreaming here? Have I lost my mind? What do you folks think?
     
  2. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    Sure you can do this, taking into account the things that you mentioned. The microphone is going to be the tricky part but you can give it a shot. This should help identify some problem areas but I wouldn't jump right to the eq to fix it. See if you can't do some stuff in the room first. Also most room tuners start off with an analyzer and then put on music that they really know and finish tweeking from there. You'll probably find that after you've made it "flat" your going to want to undo some of this cause it's not going to sound natural. Music that you know will really be the test on the curve you come up with.
     
  3. Gary Gidak

    Gary Gidak Member

    Thanks, Michael. I know it will be a challenge, and I also know there's no way in hell I'll get it perfect, but I figure it will get me a lot closer than where I am now. I appreciate you taking the time to reply.
     
  4. e-cue

    e-cue Active Member

    Interesting thread. When you say "2. Input this audio into a channel, with the PAZ plug installed, using a microphone placed at the listening position my ears normally occupy." Don't you mean "using microphones"? Unless you are mastering in mono right? The room tuning thing has always intrigued me, but anytime I ask people about tuning rooms, I get the ole "re construct it" response. This doesn't help someone that has a portable rig that has done sessions, tracking AND mixing, in every environment from tour buses, to hotel rooms, to studio lounges, to backstage of an outdoor festival gig and beyond.
     
  5. Michael Fossenkemper

    Michael Fossenkemper Distinguished past mastering moderator Well-Known Member

    No, you can use 1 mic and mute one speaker and measure it, then mute the other. Using one mic also helps finding modes.
     
  6. Bob Olhsson

    Bob Olhsson Distinguished Member

    I wouldn't assume that it'll get you closer than you are now. Equalization can solve speaker problems but not room problems. Measurements really need to isolate the speaker from the room or else you will by trying to counteract room colorations by adding both speaker and measurement microphone colorations. The problem with this is that our ears have no problem separating the sound of a speaker from that of a room.

    A lot of us in the recording business really learned this lesson the hard way during the 1970s.
     
  7. Interesting thread... Thanks all for your thoughts.

    This is my first post to the board, though I have been at this for a few years now. I have been planning on attempting the same PAZ trick myself.

    I am also considering running frequency sweeps out of PT and through one channel (lets say "Left") of a stereo PAZ plug. I am curious to see what happens when I take the mic signal and run it into the right channel. I hoping to see any mode buildup as a difference between the two graphs.

    Of course, like it has been mentioned, you can't differentiate the variables in the mic and speaker from those in the room. I am wondering if anyone has thoughts about whether it would make more sense to use the mic out of a sound level meter I own, or a decent omni condenser mic (AKG C4000 or CAD E-200) with a known frequency response.

    Thanks again! I look forward to gleaning more wisdom from the audio wizards who inhabit this board!

    - robert hartwig
     
  8. audiowkstation

    audiowkstation Active Member

    You wrote...

    I am wondering if anyone has thoughts about whether it would make more sense to use the mic out of a sound level meter I own, or a decent omni condenser mic (AKG C4000 or CAD E-200) with a known frequency response.
    RE:
    Use the known and the SLM and compare! You got to try and see what works better in your situations dude!!!

    Do not know until you "Know" from trial.
     
  9. anonymous

    anonymous Guests

    Be careful with a spectrum analyzer and equalizer. First thing, you need to be aware that the spectrum analyzer (waves PAZ) is simply estimating the spectrum, and it can be quite wrong (or rather misleading). You'll notice this a fair amount when adjusting FFT parameters on spectrum analyzing tools.

    Second, PAZ doesn't give you tons of resolution in terms of frequency...I think it uses very few FFT's in order to stay light on the CPU load. Don't expect to resolve sharp nulls from this tool (unless there's other parameters to set for # of FFTs and windows...it's been a while since I played with PAZ).

    Listen to Bob Ohlsson's advice...you can't fix a room problem with EQ, only some speaker problems. You can compensate for speakers being too close to a wall or corner by trimming the bass, but don't expect to EQ out a 80hz hole at the mix position.

    At the same time, you should realize that you can build acoustic sweeteners for your room based on the information that your spectrum analyzer gives you. If you find an 80 hz hole (pretty common problem from what I've seen), you can build helmhoz type traps for it, or other forms of bass traps. These are not as costly as rebuilding, and produce much better results than trying to EQ out room problems.

    Cheers, and good luck.

    Kris
     
  10. Thanks, guys. I should have mentioned that I don't have any intention of trying to "fix" the room with EQ, but am more interested in using the data to help fine tune acoustic treatment placement.

    I know the resolution of the PAZ is limited, but it's more accessible than a TEF or other more sophisticated analyzer. I'm also curious to compare the PAZ against the readings on the SPL meter to see how closely they correlate.
     
  11. themidiroom

    themidiroom Active Member

    I use a Behringer digital EQ that has an RTA built into it. They sell a calibrated mic that goes with it. I also generate sine tones and take measurements with my handy Radio Shack sound meter to narrow in on specific frequencies.


    themidiroom
     

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