Sub v Speaker and Room question (long)

Discussion in 'Archived Threads 2001-2004' started by Steve_D, Jun 28, 2001.

  1. Steve_D

    Steve_D Second Unit

    Nov 28, 1999
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    Last night I hooked up my new Paradigm Studio 40's which replaced some Paradigm Mini's. I was blown away by the bass these things put out. But, this leads me to a problem, let me explain.
    I have always run small all around with all bass directed to my 14" Citation 7.4 sub powered by a Marantz MA700 monobloc. For experimental purposes, I first measured my room at the listening position in stereo mode using step down test signals, C weighting on a Radio Shack SPL meter. Should I use A weighting on pure test tones? Anyway here's the measurements in db from reference 1) Large no sub 2) Small with Sub with "best" blend calibration and placement, 80HZ fixed Denon AVR1700 bass management.
    Hz 1 2
    100 -5 -4
    95 -2.5 -2
    90 -7 -2
    85 -6 -3
    80 -3 0
    75 -2 +.5
    70 -5 -1.5
    65 -3 -3
    60 -4 -7
    55 -6 -8
    50 -6 -8
    45 -3 -8
    40 0 -6
    35 +4 -1
    30 -2 -3
    25 Gone -4
    20 LOL -8
    If you look in the 65 - 100 HZ region, the sub/small looks smoother. 60-40 The Paradigms on large look smoother. 40-30 about even depending on preference and under 30 the sub small again.
    Opinions please:
    1) Active crossover with L/C/R speakers set to large? FYI, the center speaker is a matching Studio 40 and my surrounds for now are Paradigm Micros.
    2) Bass EQ on sub? Isn't this "cheating" Any recommendations?
    3) How do I set my receiver so that stereo listening is L/R only and Dolby Digital is small with sub? Or how about running the front 3 in large and using the sub for LFE only using the LFE out instead of the sub out? But if I do this can I still set my surrounds to small? Isn't that supposedly a "bad" thing to do, set some speakers to large and others to small?
    4) Replace the sub (it does real well close miked from 25-80 HZ) with an SVS 16 or 20?
    5) Room treatments?
    Any help, ideas, suggestions appreciated. The room is L shaped, the HT portion 17x13 and the other part of the L about about 7x10, with 8 foot ceiling on a carpeted basement floor. A picture sans the Studio 40's can be found here"
    Just imagine the mini's directly replacd my Studio 40's. BTW, I have Marantz mono-blocs coming to power the front 3 channels if that helps.
  2. Richard Greene

    Richard Greene Stunt Coordinator

    Mar 5, 2001
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    The best frequency response I've ever measured in a home listening room was approximately +/- 6dB from 25Hz. on up.
    The test tone I use is a slow sine wave sweep from 20Hz. to 20,000 Hz. available on many test CDs. For subwoofers, the Stryke Audio BassZone test CD has slowest bass frequency sweep I know of. A slow sweep will excite room resonances and room noises (wall and floor resonances, pictures rattling, etc.) that are not excited by warble tones and pink noise. Your frequency response deviations are not likely to be less than +/- 6dB even with eqyualization to reduce the SPL of standing waves.
    If you use an inexpensive Rat Shack sound meter, you'll have to adjust readings, especially below 50Hz., to eliminate the C-curve weighting (assume the meter follows the C-curve unless you are able to compare your RS meter to a higher quality meter for more precise adjustments).
    Ignore treble readings above 2kHz. because the RS meter has a high frequency peak at around 5kHz. followed by a roll-off above 10kHz.
    Adjustments to C-curve weighting frequency response to convert to a U-curve (unweighted) frequency response are:
    Add 6.2dB at 20Hz.
    Add 4.4dB at 25Hz.
    Add 3.0dB at 31.5Hz.
    Add 2.0dB at 40Hz.
    Add 1.3dB at 50Hz.
    Add 0.8dB at 63Hz.
    Add 0.5dB at 80Hz.
  3. Steve_D

    Steve_D Second Unit

    Nov 28, 1999
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    thanks Kevin,
    I was aware of the RS SPL corrections, but did put out uncorrected numbers. I usually just assume an "average" +1.5 db for low freq sub adjustments when using VE for 5.1.
    Also, the +-6db experience is really useful, I've been trying my hardest to adhere to the +-3 db. Taken in context of 6 db, and the freq adjustments to the RS SPL meter, my readings aren't too bad actually. It sounds like you would leave well enough alone and just do the best I can.
    My test tone CD actually has separate 30 second tracks at 10 HZ intervals from 200-100, and at 5 HZ intervals from 100-15. It also has a ton of other sweeps, pink noise, etc....A total of like 70 tracks.
    Now, still looking for advice on connections and settings, probably large/no sub for 2 channel and small all around with sub for movies.

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