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bass and treble adjustments

Discussion in 'Home Theater Projects' started by allan espinoza, Dec 24, 2004.

  1. allan espinoza

    allan espinoza Stunt Coordinator

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    do making any of the above adjustments change spl readings? Do you turn any of them up or is it best to just leave it at 0? Does turning up the bass on the receiver change the bass on the subwoofer if all speakers are set to small? thanks
     
  2. Wayne A. Pflughaupt

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    Wayne
    The SPL meter’s reading reflects the “hottest” frequency in the room. Bass frequencies are typically overall at higher levels than treble, so yes changing the bass setting can alter SPL readings.

    How the tone controls are adjusted (if at all) is determined by the response of your specific speakers, the size of the room, etc. So it’s impossible for anyone who hasn’t actually heard your system to tell you how to set them.

    Typically the subwoofer level is not changed by the tone controls.

    Regards,
    Wayne A. Pflughaupt
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    Wayne is correct - but the bass-level control is the total-volume of bass, while the tone knobs shift emphasis on some frequencies without changing signal strength.

    They are similar adjustments - but a bit different.

    Most of us leave the tone-controls at the neutral position. They are really too-course to do much good.

    But .. if you find that they make a difference in your enjoyment, go ahead and adjust them. Here is what I suggest you do:

    Simple Technique

    - Use music to adjust the tone controls, not a movie.

    - Once you have a pleasing sound, use the SPL meter to re-adjust your levels on your speakers.

    - Set your subwoofer to 50-75% of it's max volume on the sub, then use your bass-level on the receiver to get the subwoofer to produce about 10-15 db higher volume than your speakers.

    Listen to the system for about a week to get used to it.

    Complex Technique

    (This is basically a poor-mans RTA real-time-analysis).

    - Level adjust your speakers with the tone-controls at neutral position. Record these settings in case you want to revert.

    - Get a test-tone CD like the Stryker Bass CD and with the SPL meter fixed at one spot, chart the volume as the CD plays different frequencies. Example: chart the volume at 40hz, 80hz, 120hz, 200hz... on up.

    - Looking at the chart, decide if you need more treble or bass to try and get all the volumes as flat as possible. Make the adjustment and create a new chart.

    - Repeat the chart step after every adjustment.

    In a perfect world, you would get a chart that shows the identical volume for all frequencies. In real-life this will never happen, but the chart does show you where your problems are. This is often better than adjusting things by ear.

    Note: If the room-response is really horrible, consider getting a multi-band equalizer. This gives you better control over things.

    Hope this helps.
     
  4. allan espinoza

    allan espinoza Stunt Coordinator

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    thanks for both inputs, they did help.
     
  5. Allan Jayne

    Allan Jayne Cinematographer

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    The bass control on the receiver or amp. may affect the sound level from the subwoofer depending on where in the audio signal path the subwoofer feed taps off (before or after the tone controls).

    If the subwoofer is fed using the amp's speaker outputs (and the other speakers daisy chained from the subwoofer) then the amp's bass control will definitely affect the subwoofer output.

    If the amount of low frequency energy in the signal going to the subwoofer is increased, the subwoofer's output will also increase.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     

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