When taking Sub frequency readings do I just run the subs?

Discussion in 'Archived Threads 2001-2004' started by Steve Morgan, Nov 17, 2001.

  1. Steve Morgan

    Steve Morgan Second Unit

    Joined:
    Nov 10, 1999
    Messages:
    328
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Farm in Kansas
    Real Name:
    Steve
    I am hooking up my BFD and am taking my readings with the B&K Ref 30 tone generator and the RS spl meter.do I just have the sub that I am reading on or can I leave the mains on to?
    ------------------
     
  2. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Trophy Points:
    0
    It is a lot easier to understand what is going on if you disconnect your mains temporarily when first adjusting the sub with the EQ. After you have more comfort using the EQ you can go back and slightly retweak with the mains on. The problem with running the mains at the same time is that there will be peaks and valleys from the mains which obscure the subwoofer's response curve. That makes it tough to see where the parametric is having its effect - like fine tuning an instrument while a bunch of people are yelling. Ultimately, you do want to take into account the output of the mains, but start simple.
    I very strongly suggest a program like ETF (www.etfacoustic.com) or SpectraPlus (www.spectraplus.com) for doing this type of work. Yes, it some cash, but ETF will do hours of work in seconds and let you concentrate more time with trying for better results instead of tedious, slow measurements.
    ------------------
    Guy Kuo
    Ovation Software, The Calibration Tool Source
     
  3. Wayne A. Pflughaupt

    Moderator

    Joined:
    Aug 5, 1999
    Messages:
    6,207
    Likes Received:
    55
    Trophy Points:
    9,110
    Location:
    Katy, TX
    Real Name:
    Wayne
    For the way your system is configured (mono sub send split to two subs) take the readings with each sub individually, with the mains off. After both subs have been equalized, you can turn on the mains. Then you will need to blend them with the mains, that is, turning them both up or down. At that point it might be necessary to tweak the EQ in the crossover region for a proper blend, but that usually isn’t needed.
    Regards,
    Wayne A. Pflughaupt
    ------------------
    My Equipment List
     
  4. Steve Morgan

    Steve Morgan Second Unit

    Joined:
    Nov 10, 1999
    Messages:
    328
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Farm in Kansas
    Real Name:
    Steve
    Guy I don't have a laptop or a mich.I don't mind spending the $ but how do I get the mich or RS spl meter to the listening position with my computer in another room.I guess it would take a 20ft. cable. If you can tell me how I will purchase this software.
    Thanks Steve
    ------------------
     
  5. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Trophy Points:
    0
    I dragged my PC to the video room. A bit of work, but much cheaper than getting another machine. I have a laptop, but it is a Mac and the programs only run on PC's.
    ------------------
    Guy Kuo
    Ovation Software, The Calibration Tool Source
     
  6. LeungNing Chu

    LeungNing Chu Auditioning

    Joined:
    Nov 16, 2001
    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    0
    Guy,
    I used ETF5 to get a low frequency plot of my room response, but after the burst signal, the plotted graph is always changing. I cannot get a constant pattern to see the peaks and lows. Is there any special timing parameter I need to use or procedure I need to follow?
    L. N. Chu
     
  7. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Trophy Points:
    0
    I used the default timing windows. Did you first do the loop back tests to make sure there aren't any oddities with your sound card's inputs and outputs? I found a big problem with my card's sound mixer and had to disable it to get a clean result during loop back.
    The mic must also be mounted, not handheld, to get consistent readings. Hand motion of the mic would throw things off.
    ------------------
    Guy Kuo
    Ovation Software, The Calibration Tool Source
     
  8. John Morris

    John Morris Guest

    Steve: I did things a bit differently than others who posted here. I run my fronts at full plus LFE and my 4 surrounds at small so I decided to EQ for room effect only. So, I Spectraplus calibrated with all speakers driven, including subwoofer, and then used the graph to EQ my subwoofer output. This mostly involved reducing my subs output from 40-55Hz. I figured that in modes where I would have my sub active (movies), I would want to EQ for what I would hear and not what each speakers would output. Since then, I've added a multichannel SACD player. NOW, EQing with all channels driven is even more important... IMO.
    ------------------
    Take Care,
    merc
    ----------------
    [​IMG]
    God Bless America!!!
     
  9. LeungNing Chu

    LeungNing Chu Auditioning

    Joined:
    Nov 16, 2001
    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    0
    Guy, Thanks for the info.

    My soundcard Maudio 24/96 runs the loopback test pretty well. I may need a tripod for my RS SPL meter.

    L. N. Chu
     
  10. BruceD

    BruceD Screenwriter

    Joined:
    Apr 12, 1999
    Messages:
    1,220
    Likes Received:
    0
    Trophy Points:
    0
    If you don't have the ETF5 (what I use and prefer) or SpectraPlus, then just using an RS SPL meter and various source signals is possible. You could probably use a low-loss RCA cable from the ETF calibrated mic preamp to your PC and from your PC to your amp (for
     

Share This Page