Calibration Question

Discussion in 'Speakers' started by CliffA, Apr 29, 2003.

  1. CliffA

    CliffA Auditioning

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    I just got my speakers, and I want to calibrate them with my Ovation Avia disk. I have two questions.

    First, how do I calibrate the rear surround channels (it's a 7.1 setup). The Avia disk only has calibration tracks for 5 speakers.

    Second, I've downloaded the correction table for the Radio Shack sound pressure meter. But the Avia tones are "pink noise", not just a single frequency. How to I apply the correction to the Radio Shack meter?

    Thanks for your advice!
     
  2. Edward J M

    Edward J M Cinematographer

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    Calibrate your five surround to 85 dB with Avia at Master Volume 00. Then leave the Master Volume at 00 and run the AVR internal test tones. Bring the rear surrounds up to the same level as the rest of the speakers.

    For example, on my 3803, the internal test tones generate 81 dB at Master Volume 00, after calibration with Avia to 85 dB. So I set my rear surrounds to 81 dB on the internal test tones.

    While opinions differ on this, the RS meter is "about" 2 dB low on the typical subwoofer pink noise. A note of caution: Since Avia is true DD 5.1, the surround speaker in question will also contribute significant SPL to the sub test tone for that channel. The test tone is NOT discrete. If you don't believe me, run the sub test tone for a given channel and power off the sub - I get as much as 82 dB contribution from the surround speaker in question and I use an 80 Hz high pass! Bottom line with Avia and sub calibration - the surround speaker masks the true sub level and this can result in a "weak" sub calibration for HT.

    For sub calibration, I ditch Avia and go straight back to the internal test tones because they ARE discrete. In my case, since my speaks are at 81 dB at Master Volume 00 (after Avia calibration) with the internal test tones, I calibrate the sub to 84-85 dB, which is 3-4 dB hot. Works very well for me, your results may vary.

    Regards,

    Ed
     
  3. CliffA

    CliffA Auditioning

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    Thanks very much for your advise. Your method for calibrating the rear speakers should work for me. (The other thing I thought of doing was temporarily connecting the rear surround speakers to the side surround outputs of the amp, running the Avia side surround tracks, noting the trim level, setting the trim level for the rear surround channels to that same level, then reconnecting the speakers properly.)

    I may have a harder time with the subwoofer though. My receiver is a new HK7200. I doesn't generate test tones for the subwoofer. They recommend using an external tone source. Is there a better disc to use for calibrating the sub than Avia (Video Essentials, maybe?)
     
  4. Edward J M

    Edward J M Cinematographer

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    I like the "test tone method" better than disconnecting and moving the rear surrounds, since room acoustics, location, and distance will come into play. The rear surround "test tone method" is really infallible, because you don't touch any other settings. Just switch to the internal tones after calibrating the five speakers with Avia, and note the SPL for all 5 speakers (they should all be almost exactly the same, just not 85 dB) and then set the rear surrounds to the exact same level.

    What I suggest for Avia and the sub is to power down the sub and run the sub tone for the left main, center, right main, right surround, and left surround. Note the average volume level that each surround speaker contributes to the sub tone. If one of the channels stands out as contributing much more or much less, then I would discard it and select a channel that is more representative of the middle ground and calibrate the sub off that channel. You might also want to go a bit on the "hot" side with Avia for the sub level, with the knowledge that the surround speaker in question is definitely contibuting to the volume of the sub tone.

    Alternatively, you could disconnect the surround speaker in question and simply run the sub test tone for that channel with just the sub powered up and calibrate it that way, knowing the surround speaker in question is obviously not contributing anything to the volume of the sub test tone if it is disconnected.

    Ed
     

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