Preliminary Brahma15 Results

Discussion in 'Archived Threads 2001-2004' started by Mike Lazalier, May 6, 2002.

  1. Mike Lazalier

    Mike Lazalier Auditioning

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    I had a dual ported 160 liter (5.75 ft^3) Tempest sub tuned to 19 Hz driven by a NHT SA-3 amplifier, but I felt that I needed a little more excursion (rather than a second Tempest - considering WAF) to faithfully reproduce the lowest frequencies with authority. So, I replaced the Tempest with a 15" Brahma driver from Adire Audio. The results are impressive. I tested the new setup from 20 Hz to 70 Hz (the primary frequency region I assign to the sub - 20 Hz was the lowest freq. on the disk; I assure you, it will plummit far below this) The test was done with a benchmark of 100 dB @ 60Hz. So, the measurements are nowhere near the limits of the sub. These are uncorrected values taken with the infamous Radio Shack meter. I realize that many of you frown upon simply replacing the driver in an existing enclosure, but I was more than a little bit curious. And, for me, it seems to have worked. I believe the setup will suffice:
    For comparison, I included the old Tempest numbers (thus the need of a benchmark)
    FREQ Brahma Tempest
    20 94 87
    21 94 87
    22 94 88
    23 94 88
    24 94 89
    25 94 89
    26 9489
    27 9690
    28 9791
    29 9892
    30 9994
    31 10096
    32 10197
    33 10298
    34 10499
    35 106100
    36 107100
    37 108100
    38 109102
    39 109102
    40 108101
    41 107101
    42 106100
    43 10499
    44 10398
    45 10298
    46 10098
    47 9998
    48 9999
    49 99100
    50 100102
    51 102102
    52 103102
    53 103101
    54 102100
    55 101100
    56 101100
    57 100100
    58 100100
    59 100100
    60 100100
    61 99100
    62 9999
    63 9998
    64 9997
    65 9595
    66 9899
    67 9698
    68 9698
    69 9597
    70 9597
    I realize the nasty hump at 39 Hz (I believe it to be a primary room mode or summation of a few given its neverending presence), but from what I have read, the BFD (my next HT purchase) can handle this with ease.
    Mike
     
  2. James W. Johnson

    James W. Johnson Screenwriter

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    Looks good , what is the vas ,fs and spl on the Brahma you used?
     
  3. Cam S

    Cam S Screenwriter

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    I was under the impression that the Brahma need way more power than the Shiva and the Tempest, much like the BP 03 series subs???
     
  4. Leon Shing

    Leon Shing Extra

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    I felt the same way comparing my shiva to my brahma sealed.

    the shiva moved alot more air. I had about 600watts each for each driver at 4ohms. The brahma was much less efficient. I guess porting did the trick.
     
  5. Mark Seaton

    Mark Seaton Supporting Actor

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    Mark Seaton
    Hey guys,

    Note that Mike qualified these responses:

     
  6. Mike Lazalier

    Mike Lazalier Auditioning

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    Mark,
    You are correct. I did need to boost the amplifier about 10-15% in order to reach the specified level. I just attributed this to the fact of the decreased sensitivity of the Brahma (87dB/W/m as opposed to 89 of that of the Tempest). The need for power is there, but from all data that I have collected it is not substantially more.
    As for the slightly, yet mismatched, peaks around 50-54Hz, they are hard to explain. The sub is back in its old footprints (that it left in the carpet), and I measured from the exact location that I have done many times before. The results of the Tempest were easily duplicated and so are the results of the Brahma. This test was not done just once but several times each yielding the exact same results. The setup of the room and mic remains the same. The only difference is the driver. (In)Accuracy of the meter? maybe.
    The power issue is one that I thought that I would have problems overcoming - that is, before I installed it. I read that the driver needed an immense amount of power to produce any sound at all. I found that this was not my case, if only for ported enclosures. The NHT SA-3 amplifier that I'm using has no trouble pushing the series-wired vc's (about 3.5 Ohm) with just a minute twist of the amp's gain knob (now set at about 50% up from about 40-45%).
    I did notice the increased stiffness Brahma's suspension. The Tempest's cone is easily manipulated, and the Brahma's is not.
    Mike
     
  7. Patrick Sun

    Patrick Sun Moderator
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    Hmm...I do have a current Tempest sub that's in a 6 ft^2 sono-enclosure... [​IMG]
     
  8. Cam S

    Cam S Screenwriter

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    How much power does that NHT amp have, something like 300 watts? Anyone have pics of this beast???
     
  9. Mike Lazalier

    Mike Lazalier Auditioning

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    Why is it that the Brahma is considered to be a "car sub"?

    The results that I have gotten show, to me, that it has the low end extension that we all crave without the need for "cabin gain."

    Mike
     

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