Nousaine Numbers on "The Sub"

Kevin P · « **on:** 30 Sep 2003, 08:38 pm »

Hot off the press. Here are the basic measurements from Tom Nousaine on our new sub. There were no surprises in that the unit performed pretty much as we have measured in-house.

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Bass Limits: The dynamic capabilities of the subwoofer were evaluated with the unit Corner loaded in a 7600 ft3 room @ 2 meters with 6.5 cycle tone bursts at 1/3 octave centers with 10% distortion limit. (Add 2.5 dB from 25-62 Hz and 4.0 dB from 16-62 Hz averages for comparison in a smaller 2136 ft3 room.)

Because I’ve used this method and this room for all the subwoofers tested by me for Stereo Review and Sound & Vision for the past seven years direct benchmark comparisons can be made by examination of past issues. For comparative purposes with other published data remember I use 2 meters as a standard measurement microphone distance which yields SPL figures that are 6 dB less than data obtained at 1 meter.

Average SPL 25-62 Hz:    111.3 dB
Average SPL 16-62 Hz:    103 dB
Bass Extension:       16 Hz @ 70 dB SPL
Maximum Output:    115.2 dB SPL @ 32 Hz
Bandwidth Uniformity   97%

SPL @ 1/3 Octave Frequencies:
16 Hz = 70 dB SPL
20 Hz = 93 dB
25 Hz = 104.8 dB
32 Hz = 115.2 dB
40 Hz = 113.1 dB
50 Hz = 111.9 dB
62 Hz = 111.4 dB

This system has excellent output. Both output and extension put the unit in the top quartile of subwoofers without regard to cost. The subwoofer will deliver more than 111 dB SPL @ 2 meters at any frequency above 25 Hz although maximum output falls by 40 dB per octave below that frequency. The system maximum SPL is limited by suspension noise over most of its bandwidth although this may have also been a function of amplifier clipping. At high SPL there also seems to be an audible leak or some other “shoooshing” noise emanating from the cabinet that can be heard when standing close to the subwoofer.

The 97% Bandwidth Uniformity (Average SPL 25-62 Hz / Maximum SPL @ any frequency) is remarkable and also places the unit in the top decade. This figure has been added to my test results recently to avoid giving an unfair advantage to subwoofers with very high output at the upper part of bandwidth (50-62 Hz) but limited capability at lower frequencies. In this particular case the maximum SPL delivered occurs at 32 Hz which is remarkable all by itself.

Other Data:
Footprint: 2.3 square feet
Gross Volume: 4.1 cubic feet

Test Equipment:
MLSSA Acoustical Measurement System with 800-mHz PC
Earthworks M30 measurement microphone
Earthworks Lab 1 microphone preamplifier
Legacy High Current preamplifier
Fluke 45 Multimeter
Marantz CD-63 CD player
Audio Control 3050a Sound Level Meter

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A couple notes about the "shooshing" noise at high SPL.

The shoosing noise we have tried to address by sealing the plate amp better. The only time it becomes audible is when you play test tones at VERY high SPL and you stand near the subwoofer. We are working to address it just the same and we expect to solve this problem so that it is a non-issue even under extreme use.

doug s. · « **Reply #1 on:** 30 Sep 2003, 11:21 pm »

hi kevin,

this is commendable performance for a small box!

i'd be curious to see how a "real" subwoofer does (yust kidding here!) - one that uses a big box, & doesn't try to cheat the laws of physics. somehow, i doubt the specs of your sub would compare favorably w/a larger vmps, even tho ya prewiously posted nothing would touch yer sub for anywhere near the price. how about *half* the price - that's not near yer subs' price!

of course, amp & x-over need to be supplied w/the purely passive vmps... and, of course, the above is mere speculation on my part - i'm only basing my opinions on subjective comparisons of my subs, w/other subs (rel, hsu velodyne) in different enwironments...

regards,

doug s.

Tyson · « **Reply #2 on:** 30 Sep 2003, 11:32 pm »

Kevin, congrats on some very impressive #'s, especially for a sealed subwoofer - those #'s are better than a LOT of Brick and Mortar subs (and many of those are ported!). Nice work.

jackman · « **Reply #3 on:** 30 Sep 2003, 11:35 pm »

Posted: Wed Oct 01, 2003 12:21 am Post subject:

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Quote

hi kevin,

this is commendable performance for a small box! i'd be curious to see how a "real" subwoofer does (yust kidding here!) - one that uses a big box, & doesn't try to cheat the laws of physics. somehow, i doubt the specs of your sub would compare favorably w/a larger vmps, even tho ya prewiously posted nothing would touch yer sub for anywhere near the price. how about *half* the price - that's not near yer subs' price! of course, amp & x-over need to be supplied w/the purely passive vmps... and, of course, the above is mere speculation on my part - i'm only basing my opinions on subjective comparisons of my subs, w/other subs (rel, hsu velodyne) in different enwironments...

What the hell is this all about? It's completely unfair. To say the VMPS is "HALF" the price of this sub and then point out that your estimate was without an amp or crossover. What the hell is that?

I like VMPS subs but some people don't have that kind of room. I know one thing, they are designed well and use decent looking drivers, but NOTHING like the one in this sub. Does it mean this sub is better? I don't know, but at least Kevin is posting specifications. Where are Brian's spec's for the VMPS sub? I would be shocked if it bested this one for the money. That Tumult (I think that's the driver) is a total monster. In a large, well built, sealed box, I doubt the VMPS sub would be able to compete. That's just my guess based on the driver and amp used in this speaker.

Great work Kevin.

Anyway, just my ten,

Jman

Kevin P · « **Reply #4 on:** 1 Oct 2003, 12:16 am »

Thanks guys.... not my work though. Wiggins & Hyre are the brains.

Doug: Looking at the VMPS unit I'd just say that it is comparing apples with oranges. Our goal was small with lots of usable low distortion output where it is most used in the frequency range. Also keeping cost in line was important and using a musical low Q sealed enclosure. In those respects I think we have a fine product.

If you want a large subwoofer Adire has many designs that are available for free for use with their drivers. In addition to giving you all the specs for the drivers they include a FREE copy of LSPCad so that you can model any of them. I know of no other comany that gives you more technical information and tools if you know how to use them. If I were to build a large sub I think I'd go with a couple Maelstroms in a large sealed box. Better yet a IB (really large box) with two Maelstroms would only set you back $600 and you could use your amplfication of choice.

Tyson: Thanks.... once again... Dan & Dave deserve the credit.

jackman: Don't let doug get you stirred up.

doug s. · « **Reply #5 on:** 1 Oct 2003, 02:54 am »

hey jackman, chill! of *course* it's unfair to tink the vmps is half the price of kevin's new sub - which is why i pointed it out myself, & included the smiley face!

i was yust poking fun at kevin, who earlier stated his sub would be far better than any sub anywhere near its price.

i seriously *do* tink that kevin's sub has commendable performance from such a small sealed box. and, i'm certain the driver used is *far* better a driver than what vmps uses. but, the products have to be compared as a whole. i tink it's certainly easier (and a lot less expensive) to achieve quality bass w/o bending the laws of physics, which is why vmps can achieve fantastic results w/less expensive drivers, cuz they use bigger boxes, & slot-loaded passive radiators.

re: specs, vmps' published specs aren't too shoddy, if not as detailed as what kevin or tom nousaine does. (i *would* like to see tom test the vmps, tho, fwiw...):

"Frequency Response: +0, -3dB, 17Hz to 250 Hz
THD: 0.5% 20Hz to 250 Hz with 1W drive
Sensitivity: 92 dB/1W/1m
Maximum undistorted output: at least 115dB/1m SPL at 20Hz for 2.5% THD"

even their smallest sub has decent specs, for those space-challenged, & these would likely work better in a smaller room than the big ones anyways:

"Frequency Response: +0, -3dB, 28Hz to 600hz (standard version) -3dB 24 Hz with Megawoofer option
THD: .5% max 28Hz to 600Hz with 1W drive
Sensitivity: 90dB/1W/1m
Maximum undistorted output: 112dB/1m for 5% THD"

kevin, thanks for the info about the adire stuff. it has been a while since i checked, but last time, they dint have any large-box multi-driver designs. there is no doubt in my mind that multiple large drivers of the quality shown here, in a well-constructed 8cu.ft.+ cabinet, would provide fantastic bass.

regards,

doug s.

Tyson · « **Reply #6 on:** 1 Oct 2003, 04:22 am »

Well, if ya wanna play that way, just throw the tempest in a 24" cube w/dual 18" PR's from Stryke, w/ a bridged Crown K2 amp, and we'll see who has the most output

Kevin P · « **Reply #7 on:** 1 Oct 2003, 04:46 am »

doug:

Having a larger box allows you to come up with cheaper bass... no doubt. You can get by with using several cheaper drivers and efficiency goes up the larger the box (in general) hence the need for less amplification. The laws of physics are not being cheated though. We are using them to our full benefit. The main tradeoff made for the small box is that you just need more power to achieve the same response. Power is cheap though so we think it is a good tradeoff up to a certain point. It would be difficult to get smaller than we are at this point simply because the driver is too large to fit in a smaller box. If we had more power though we could extend our frequency response to get more low-end response. We are not really EQing our response at this point (except the bass boost) so down the road if we design a more powerful amp with some parametric EQ capability we could choose to EQ the response downward further. I think it would be more for the sake of playing the spec game though as I see very little need for the output down that low. It is fun to sweep low frequency signals and vibrate the house but it doesn't add much to the musical event.

What we have is headroom and VERY low distortion output for any reasonable playing level.

In terms of using PRs or ported enclosures.... I think I've outlined before that I have a subjective preference for sealed enclosures based upon their simplicity of design and the ease with which you can design a musical sub. I also think that there is a lot of support for my view in the industry. Many of those (not all) products that are considered most musical are of the sealed variety.

As for the spec's... there isn't a spec on any subwoofer made that is meaningful until you place it in context of how it was measured. That is why we paid for the Nousaine testing because he applies a standardized test to the product that has been used against most subs in the industry. Those measurements mean something because they are performed in the same manner on every unit tested without prejudice.

One other feature of the Adire driver that is getting glossed over is the XBL^2 motor. It has more advantages than just low distortion and monster excursion (output). The Le is extraordinary low in comparison to the typical under hung/overhung motor design and that can translate to better transient performance. The other huge benefit is that these drivers exhibit much less power compression than the typical driver. That means that as you apply more power the effiency doesn't change downward as drastically as it does in a traditional direct radiator. Efficiency of drivers is usually measured at 1W of power. Try putting 20W into a driver and you will see the measured efficiency plummet. The XBL motors efficiency remains much closer to the 1W rating than other motor designs as you increase power. In a sub this is very important because these drivers, even the most efficient of them, require large amounts of power to displace the volume of air needed to reproduce these frequencies.

Of course neither of these attributes show up in our specs nor the Nousaine numbers. The problem is that the spec's are not a total picture of everything that is going on in the system. They are just a snapshot of certain aspects of performance... not the complete show.

MaxCast · « **Reply #8 on:** 1 Oct 2003, 11:42 am »

Good job Kevin, Dan and Mr. Hyre!!!!

Have fun at the show.

Doug, let it rest.

doug s. · « **Reply #9 on:** 1 Oct 2003, 12:02 pm »

hey max, if i can find out how to get better performance at a reasonable price, why should i "let it rest"? kevin's info has been most informative & helpful, imo, & i'm not sure it wooda happened if i was "resting"... isn't that what these forums are for?

doug s.

rosconey · « **Reply #10 on:** 1 Oct 2003, 01:02 pm »

i do love my vmps large

but the thing is big. also brian doesnt design his drivers with 800lb magnets he has a different school of thought on that.

this sub loooks very good on paper

and with a proven driver

its going to be tough to beat

DeanSheen · « **Reply #11 on:** 4 Dec 2003, 09:45 pm »

Ohh man, drool. Now how much can I get for my Rava............

IanATC · « **Reply #12 on:** 2 Jan 2004, 10:18 am »

Undistorted output 16-20hz at 103db from a sealed box!!! neener neener to all you ported sub owners that can't accomplish this!

One of these days, I will build a 1.5" thick box strong enough to house such a monster.

BTW: I don't think any British sub can do this under $8,000 USD. Maybe not even then.

Kevin P · « **Reply #13 on:** 2 Jan 2004, 08:45 pm »

If you stretch the box size a little and use some EQ & more power you can get even more undistorted output in that range.

You should see Adire's newest gadget. Has the volume displacement (66L) capability of more than 12 Tumults. The version we are going to have at CES is capable of 121db at 20HZ WITHOUT room gain. Flat anechoic response to 6 Hz. The CES version is just the tip of the iceburg too.... The technology can be scaled to give up around 450L of displacement to satisfy even the sickest LF freaks.

IanATC · « **Reply #14 on:** 3 Jan 2004, 02:20 am »

I saw that monster! THE PARTHANON...

It kind of resembles an Adamantium deep-sea reel made for Thor...

Or a secret weapon, used to stun troops at 50 yards or evacuate the air from a room.

It looks like it could be harnessed to shatter rocks for strip mining, or perhaps induce enough shake to drop the west coast into the ocean.

I really, really want to hear that in a system, or at least get a review when it's implemented properly.

It pretty much makes all other subs run for mommy. It is the ultimate manly-man he-man rig sub. It will make the Wilson XS seem like a Bose acoustimass bass module.

Jack Gilvey · « **Reply #15 on:** 5 Jan 2004, 11:58 am »

Quote

If you stretch the box size a little and use some EQ & more power you can get even more undistorted output in that range.

This implies that the limitation in this instance is available wattage, not Vd. Fair?

Kevin P · « **Reply #16 on:** 5 Jan 2004, 05:23 pm »

Jack: Yes... if we had another 1000W we could pick up a couple more db across the bottom.