Subwoofer Tests - Fall 2007

**mojomike** · **10-22-07, 07:50 AM**

Quote:

chengbin wrote:

Does the Gotham have EQ boost? It has the same FR as the f113.

Pretty much any sealed sub which can show a flat anechoic response is using EQ.

**ISLAND1000** · **10-22-07, 08:50 AM**

Linkwitz showed a long time ago that any sealed system has an FR that drops at a predictable 6db rate. Using an EQ to flatten or even GAIN spL as the frequency drops is an easy electronic fix.
What's wrong with EQing a system to gain lower end, the distortion remains low even below 20Hz with the LMS.
If it's OK to use the BFD to adjust (EQ) for room anomolies or an active crossover or a Zobel, it should be good enough to EQ a subs lower end. It's the future for subs. Subs should be getting smaller not bigger.

**ISLAND1000** · **10-22-07, 08:57 AM**

Quote:

Ilkka wrote:

http://www.formula1.com/
http://www.ferrariworld.com/FWorld/fw/index.jsp

Her???

Illka I apaologize. I thought I was being cute not crazy. Congratulations to Kimi! I saw a few short clips of the race, he did an awesome job.

ps I hope your day after drunk is not too bad and hope you'll be feeling better soon.

**Ricci** · **10-22-07, 09:10 AM**

The 13W7 looks decent in about 240L tuned to 15hz with a 6" port. This seems to be about the lowest that you can tune it and still get decent port area.

**DevilDriver** · **10-22-07, 10:16 AM**

Quote:

noah katz wrote:

"If a driver is designed to work best in a small sealed enclosure, that typically means it has a very low Qts, which means it won't work well in a large ported design, as the low end will be way too peaky."

A driver optimized for sealed has a higher Q for two reasons:

1) High Mms (which raises Q) will be needed to get a reasonably low Fc

2) Being a single-mass system, it will be overdamped with low Q; vented systems need extra damping to control the second mass (port air/PR)

Yes, but you can use a driver with a surprisingly low Q in a sealed enclosure with very impressive results. How do you overcome the need to add mass to drop Fs? Increase BL and drop Qes/Qts which will make your target Qtc achievable in a slightly smaller enclosure.

**mojomike** · **10-22-07, 10:37 AM**

Quote:

ISLAND1000 wrote:

Linkwitz showed a long time ago that any sealed system has an FR that drops at a predictable 6db rate. Using an EQ to flatten or even GAIN spL as the frequency drops is an easy electronic fix.
What's wrong with EQing a system to gain lower end, the distortion remains low even below 20Hz with the LMS.
If it's OK to use the BFD to adjust (EQ) for room anomolies or an active crossover or a Zobel, it should be good enough to EQ a subs lower end. It's the future for subs. Subs should be getting smaller not bigger.

Your right. There is nothing wrong with that. It's been done successfully for years. Velodyne, Paradigm, JL, SVS(SB12-Plus), etc., etc. It will usually call for more power and drivers with longer excursions to do it without winding up with very limited output down deep.

**Ilkka** · **10-22-07, 07:16 PM**

Quote:

chengbin wrote:

IIkka, do you mind putting the f113 driver in a large enclosure such as the size of a PB13U and test it? Thanks. I'm sure the result will be very interesting.

That might be possible but not probable. At the moment I can't do any testing due to cold weather (and it's likely that it won't be better any time soon). Also I'm not sure how JL Audio would like about that...

Maybe some day I will test the car version of the 13W7 in a ported box. So many woofers, so little time.

**Ilkka** · **10-22-07, 07:20 PM**

Quote:

chengbin wrote:

Is there any EQ boost on the F113? I don't think so, but I'm not 100% sure.

It definitely has. No way it could have such flat and well extended frequency response without some serious low frequency boost(s). Oh wait, you haven't seen the FR yet.

Well I can tell you that the -6 dB frequency is ~18 Hz. It doesn't have a natural 12 dB/oct. slope though.

**Ilkka** · **10-22-07, 07:21 PM**

Quote:

ISLAND1000 wrote:

Linkwitz showed a long time ago that any sealed system has an FR that drops at a predictable 6db rate.

Small correction. The rate is 12 dB/octave.

Dipole is 6 dB/octave.

**Ilkka** · **10-22-07, 07:47 PM**

I noticed that I haven't posted any teasers yet.

Well here we go. A few frequency responses that I really like (for small/mid-sized rooms). Can you guess which ones they are (they contain a very subtle hint)?

Neither of them has any 'external' EQ.

**chengbin** · **10-22-07, 08:08 PM**

SVS PB13 sealed? None of the subs you tested had such "flat" response.

**Ilkka** · **10-22-07, 08:19 PM**

Quote:

chengbin wrote:

SVS PB13 sealed? None of the subs you tested had such "flat" response.

Those two graphs represent a FR of two separate subwoofers. The other one is commercial, the other is DIY.

**Sonnie** · **10-22-07, 08:20 PM**

PB13 15Hz tune and PB13 20Hz tune.

**chengbin** · **10-22-07, 08:23 PM**

Oh, now I have to look at the DIYs.
No, I haven't found that sub with that FR graph like that. The closest one I found is DIY Chorus XP3 clone.
BTW to sonnie, if you haven't read the AVTalk's GP FR graph, I'll tell you right now SVS PB13 20Hz tune will stay rule flat till 19 to 20Hz. 15Hz tune is not as flat down low, but it's definitely not a -6dB @ 20Hz. The sealed tune looks more like the second graph, because the sealed PB13's -3dB point is 22Hz.

**Ilkka** · **10-22-07, 08:25 PM**

Quote:

Sonnie wrote:

PB13 15Hz tune and PB13 20Hz tune.

Sorry, Sonnie. No win.

**Sonnie** · **10-22-07, 08:33 PM**

Hmmm... HSU VTF-3

**chengbin** · **10-22-07, 08:33 PM**

Is it the PB13 sealed or DIY Chorus XP3 clone for any of the graph?

HSU VTF-3 looks close.

**Ilkka** · **10-22-07, 08:40 PM**

Guys,

These are from my newest round of testing. So no HSUs or XP3 clones...

You can't find these frequency responses from my previous results. You just have to use your wits to figure them out.

**Sonnie** · **10-22-07, 08:41 PM**

The comment "(for small/mid-sized rooms)" kind of got me thinking something not so terribly powerful, but still decent.

**chengbin** · **10-22-07, 08:43 PM**

thanks for that hint.

**Ilkka** · **10-22-07, 08:44 PM**

Quote:

Sonnie wrote:

The comment "(for small/mid-sized rooms)" kind of got me thinking something not so terribly powerful, but still decent.

Actually I meant the shape of those frequency responses. Slightly tilting down so there is room for some room gain down low.

That should narrow them down pretty well, if you have done your homework.

**Sonnie** · **10-22-07, 08:44 PM**

BK Extreme

**chengbin** · **10-22-07, 08:47 PM**

Gradient Evidence MKII
DIY: DIY CSS SDX15 sealed 100L

If I'm not right, here's some hint for the rest of you guessing. Is it not the JL, or the Velodyne, or the Yamaha for sure. They are not flat enough or does not have flat upper bass capabilities. If memory serves, JL's upper limit is 111Hz, and Velodyne's FR graph wasn't flat, and Yamaha, I doubt it. I'm not too sure of other subs. DIY it has to be the SDX15 sealed. The other ones are too powerful.

**mojomike** · **10-22-07, 08:51 PM**

The blue one looks a lot like the sealed 13Ultra.

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