Testing frequency response

Discussion in 'Archived Threads 2001-2004' started by Mike__D, Apr 18, 2002.

  1. Mike__D

    Mike__D Supporting Actor

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    Hi all,

    I'm interested in testing the frequency response of my speakers in my room. I've done some searches, and have received little bits of info, but I'd like to know step by step on how to do this correctly.

    From what I know, I need to buy, or create a CD with sine waves? On one of my searches, I found a link to download a tone generator for the pc. I assume I record the sounds to a CD-R? Then playing the sounds through each speaker, I measure the SPL with my radio shack meter from different spots in my room? Then plug these values into a spreadsheet found on the web (forget the site, but I can search for it).

    Now the bigger question, what do I do with this data? I guess my main goal, is to make my system sound as best as it possibly can in my particular room. Do I need equipment such as an equalizer or what not to adjust for weaknesses in my system? Also, I believe I limited to what I can do since my receiver has no pre outs (Onkyo 595).

    Thanks in advance!

    Mike D.

    P.S. I'm not sure if I posted this in the correct forum...
     
  2. Steve_Ma

    Steve_Ma Second Unit

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    I used the Stryke disk. http://www.stryke.com
    * I first re-calibrated my setup as I normally would, with test tones and the SPL meter.
    * I then tossed in the Stryke disk and used the level set tone to set the volume level near a comfortable range. I used 75db. I think you really need to be higher than 65db to be sure you won't contaminate results with ambient noise.
    * Next, I started playing the test tones all the way up from 10hz up to over 1000hz, recording each SPL reading (from the listening spot) for each tone.
    * I then plugged my raw SPL data into the excel file which can be found here: http://www.snapbug.ws/bfd.htm
    This will plot your response and tell you what is happening in your room.
    I found this most valuable for setting the sub in relation to the mains. It also helped me experiment with different x-overs and connections to get the best bass response. I never even bothered with measurements around the rest of the room, as my main concern was optimizing for 2ch listening from the sweet spot. Whether or not you need an EQ depends on your budget and your room. My sense is that pretty much anyone can realize a benefit from EQ'ing their sub, provided they know what they are doing. For me, money is tight, and my odd a#$ room actually gave a reasonably good response, so I'm not going to worry about it right now. When $ allows, I'll get the BFD.
    NOTE: If using the stryke disk, BE VERY CAREFUL when playing test tones in the upper frequencies. These tones can easilly destroy tweeters. I almost learned that the hard way.
    Hope this helped.
    --Steve
    EDIT: Here is a link to a post I started regarding sine vs warble tones, as they relate to this type of experiment. Pretty deep waters technically, but informative and interesting.
    http://www.hometheaterforum.com/htfo...threadid=62243
     
  3. syeo

    syeo Agent

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    which stryke disc? the basszone vol 1?

    thanks
     
  4. Steve_Ma

    Steve_Ma Second Unit

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    That's the one I used. I don't know if the other 2 are for sale yet.

    --Steve
     

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