Preliminary Brahma15 Results (1 Viewer)

[Mike Lazalier]

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

 

[James W. Johnson]

Looks good , what is the vas ,fs and spl on the Brahma you used?

 

[Cam S]

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???

 

[Leon Shing]

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.

 

[Mark Seaton]

Hey guys,

Note that Mike qualified these responses:

The test was done with a benchmark of 100 dB @ 60Hz.

This basically would suggest that additional power was provided to produce 100dB @ 60Hz. What is interesting is that it appears the sub or mic might be in a somewhat different location explaining the slightly enhanced peaks in the midband with the Brahma.

 

[Mike Lazalier]

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

 

[Patrick Sun]

Hmm...I do have a current Tempest sub that's in a 6 ft^2 sono-enclosure...

 

[Cam S]

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

 

[Mike Lazalier]

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