Playing with sub combinations

Discussion in 'Speakers' started by Richard_M, Sep 10, 2003.

  1. Richard_M

    Richard_M Second Unit

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    I have been having a play with my sub combinations.

    Current equipment is 2x M&K V125, 1x M&K 5000, and 1x oddball sub.

    This time I decided to do some experimenting with different combinations, and the (current) final combination is I have each M&K V125 off each main speaker, mains set to small 80hz xover,(amazing how much material is still output below the Xover) I have the oddball sub up front, & the 5000 at the rear at right angles, My problem at the moment is there is not much room to move things around, hench why the 2x large subs are at each end of the room. I have disconnected my BFD for these results, using a notebook, ETF5, and a Behringer cal mic these are the in room results at the listening position. ETF5 was calibrated to 80dB. (I don't know how to post graphs here so will just put up the data)

    Freq SPL

    10.2591.06
    10.9994.64
    11.7296.85
    12.4598.39
    13.1899.52
    13.92100.37
    14.65101.02
    15.38101.48
    16.11101.77
    16.85101.90
    17.58101.87
    18.31101.67
    19.04101.31
    19.78100.83
    20.51100.28
    21.2499.81
    21.9799.59
    22.7199.71
    23.44100.12
    24.17100.69
    24.90101.26
    25.63101.74
    26.37102.07
    27.10102.22
    27.83102.19
    28.56101.96
    29.30101.55
    30.03100.99
    30.76100.33
    31.4999.67
    32.2399.14
    32.9698.88
    33.6998.94
    34.4299.24
    35.1699.67
    35.89100.11
    36.62100.46
    37.35100.69
    38.09100.77
    38.82100.70
    39.55100.48
    40.28100.13
    41.0299.67
    41.7599.14
    42.4898.61
    43.2198.17
    43.9597.90
    44.6897.87
    45.4198.05
    46.1498.38
    46.8898.75
    47.6199.07
    48.3499.29
    49.0799.36
    49.8099.27
    50.5498.98
    51.2798.48
    52.0097.78
    52.7396.86
    53.4795.70
    54.2094.30
    54.9392.63
    55.6690.71
    56.4088.54
    57.1386.22
    57.8683.96
    58.5982.13
    59.3380.95
    60.0680.30
    60.7979.88
    61.5279.52
    62.2679.25
    62.9979.18
    63.7279.39
    64.4579.82
    65.1980.33
    65.9280.83
    66.6581.29
    67.3881.76
    68.1282.29
    68.8582.91
    69.5883.60
    70.3184.30
    71.0484.93
    71.7885.42
    72.5185.72
    73.2485.82
    73.9785.71
    74.7185.39
    75.4484.92
    76.1784.38
    76.9083.91
    77.6483.67
    78.3783.74
    79.1084.06
    79.8384.48
    80.5784.86
    81.3085.12
    82.0385.24
    82.7685.25
    83.5085.22
    84.2385.26
    84.9685.46
    85.6985.85
    86.4386.37
    87.1686.91
    87.8987.38
    88.6287.70
    89.3687.82
    90.0987.72
    90.8287.37
    91.5586.76
    92.2985.88
    93.0284.74
    93.7583.36
    94.4881.82
    95.2180.33
    95.9579.20
    96.6878.62
    97.4178.47
    98.1478.43
    98.8878.20
    99.6177.61
    100.3476.56

    The sharp drop from 50-64 hz is a room problem. These results are with subs and main speakers only i.e amp set to stereo mode.

    My question is, is it worth pulling the high spl down from 20hz up using the BFD, and if so how much should I reduce it and to what frequency?

    Richard
     
  2. Richard_M

    Richard_M Second Unit

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    Been listening to this for a week now and have got used to it, still would like to reduce some of the 20+ dB gain though.

    BTW both large subs were each calibrated to 85db using spl meter then both coupled I reduced to 85dB using the SW control on the amp.

    Richard
     
  3. Greg_R

    Greg_R Screenwriter

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    Greg
    No, move the subs so you get a response with a few peaks. Reduce these peaks with the BFD. Reducing the SPL of the majority of your audio spectrum to fix a large null is not an advisable solution.

    EQs are meant to tame peaks, not fix nulls.
     
  4. Richard_M

    Richard_M Second Unit

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    Thanks for the reply Greg,

    At this time I don't have much movement available for relocating the subs.

    I think where I am getting very confused with the levels is(now don't ask me where I dreamed this theory up) if the calibrated level of ETF5 was 80dB then the bass response should be as close to 80dB across the spectrum.

    So in my case because the room null only drops to around 80dB this should not be a problem due to it being around the calibrated level, but the room gain above 80dB requires it to be lowered to around 80dB. I think this stems from using an SPL meter to level all the speakers, to say 85dB so in theory the subs output should be around the same across the lower spectrum.

    But I'm not sure if this is what is required or not, and reading your reply Greg I don't think this is what you had in mind either.

    I have ordered a book that BruceD has recommended to other forum members "Master Handbook of Acoustics by F. Alton Everest", so I might be able to understand things a bit better.

    Richard
     
  5. Richard_M

    Richard_M Second Unit

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    Its okay guys I have now figured out where I went wrong, I check out tagmclaren web site as per Stephen Dodds recommendation in another thread (thanks Steve), and this puts everything in perspective.

    I have rounded up the loose Kangaroos in the top paddock, and I am now on the right tram. (I hope).

    If there are any other nuf nuf's out there that need clarification on ETF5 and analysing the results check out Tagmclaren

    Richard
     

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