JL Audio 13w7 in prowedge box

[tpaxadpom]

Has anyone tried JL Audio 13W7 in the prowedge JL Audio (sealed) box for HT application?
I have 12W7 ProWedge in the car for some years and have been always impressed with the way it sounds. I can get a good deal on 13w7 in the pro wedge box and thought about using it at home. I wonder how different would it be from their fathom line assuming I get a comparable amp and room equalization (not sure if I can rely on Audyssey).

[WmAx]

Forget the sealed box. That is an utter waste of the driver's capabilities. If you use this driver in a 4.5 ft^3 enclosure with a folded slot vent that is 4.25" x 12" and 51" in length, you will have incredible output level, with minimal port compression. You can also use two high excursion 15" PRs if the added cost is not issue. In an average size room, you would yield well over 120dB in the 20-25 Hz range. It would yield a -3db at 20Hz and -6db at 17Hz. 1st port resonance would be at about 107Hz; no issue if you cross at 80Hz or below using a 4th order crossover. Note: with this driver and it's unusual output abilities - you should design the cabinet to be 2-3x more densely braced as compared to the average subwoofer. I recommend cabinet grade hardwood ply as opposed to MDF for construction; the ply is considerably stiffer/stronger. You can not reduce the port cross section area I have suggested above; if you do, it will result in appreciable port compression(loss of SPL around the port tuning frequency). An amplifier delivering a minimum of 1000 watts at the driver's nominal load impedance should be used.

-Chris

[tpaxadpom]

Chris,

thanks a lot for the design ideas. I was thinking more of using this sub in original ProWedge box. I don't have any cabinet design skills but I do know some people that could help. Though I know that once I build a first sub I'll be doing this for the rest of my life (it would be my new hobby). So I'm trying to stay away from the cabinet design piece. Also the real estate could be an issue with 4.5^3 ft.
I'm not looking for 120dB at 20-25Hz. In fact I'm not looking for high SPL at all. I like the quality that W7 offer. I haven't heard this sort of quality in HT setups. Being a 2 channel guy (I have dedicated room for music) I haven't heard many full range speakers/subs that would offer similar low end quality. I wouldn't buy another Parasound JC-1 just to drive this sub but I would be interested to know what would be a good amplifier candidate to pair with this sub.

Another concern that I've got is wether dynamating the insight of the box would help with shielding problems. I have CRT RPTV monitor that I don't want to be affected by this humonguos magnet. One would be to place the sub in the opposite side of the room behind the couch.

Thanks in advance.

[Geoff St. Germain]

I disagree that a sealed design is an "utter waste of the driver's capabilities". The Fathom uses a tweaked 13W7 (13HT7?) in a sealed enclosure and tests as one of the best commercial subwoofers out there. It totally depends on a person's goals.

[eyekode]

WmAx wrote:

Forget the sealed box. That is an utter waste of the driver's capabilities. If you use this driver in a 4.5 ft^3 enclosure with a folded slot vent that is 4.25" x 12" and 51" in length, you will have incredible output level, with minimal port compression.

Woah, that would be a 4.5 ft^3 enclosure with a 1.5+ cubic foot port (not counting the port walls!). Another way to put it is the port volume would increase the total volume of the cabinet by 33%. Also, even crossed at 80Hz the ~100Hz first port resonance can be excited. Much like blowing air over a bottle excites the first port resonance regardless of the frequency you blow over the bottle.

[WmAx]

eyekode wrote:

Woah, that would be a 4.5 ft^3 enclosure with a 1.5+ cubic foot port (not counting the port walls!). Another way to put it is the port volume would increase the total volume of the cabinet by 33%. Also, even crossed at 80Hz the ~100Hz first port resonance can be excited. Much like blowing air over a bottle excites the first port resonance regardless of the frequency you blow over the bottle.

With a 4th order L-R crossover set at 80Hz, the signal would be reduced by about -20db by 107Hz. This is simply not enough to matter. In addition, if it is still a worry, you need only add a notch filter at the resonant frequency to completely abolish it, or use a steeper crossover, or use both.

As a side note, I do find it interesting that some are so worried about a port resonance that is substantially attenuated on a subwoofer such as in the use I suggested above, when it is so common to build ported midbass hi-fi speakers that place the port resonance, with no attenuation of signal, right into the passband.

-Chris

[avaserfi]

Perhaps the real question here is should one limit them self to using such a high quality, low distortion, driver in a sealed enclosure. If one's goal is to build a high quality, small subwoofer then the JL 13W7 is a good option, but far superior results as compared to a sealed enclosure could be had using a properly designed vented enclosure.

WinISD modeling:

Green: 4.5 cubic foot enclosure with a 4.25x12x63" port
Yellow: Ideal, sealed, 4 cubic foot enclosure
Blue: More typical, sealed, 1.5 cubic foot enclosure

There is a significant amount of output loss by using even the larger sealed enclosure with an F3 of 34Hz as compared to one at 20Hz in the ported enclosure (F3 in the smaller enclosure is about 38Hz). One could perhaps make the argument for parametric equalization of the lower octaves with the sealed enclosure to achieve a lower reaching linear response, but this would result in increased distortion along with loss of overall output.

It is also important to note that while the Fathom series subwoofers are low distortion for a sealed subwoofer it is extremely likely that this distortion would be far lessened by using a properly designed ported enclosure.

As far as the sealed sounds better than a ported subwoofer that is simple lack of knowledge. With proper use of a quality equalizer one can tailor virtually any response with a sufficiently linear subwoofer such as the ported example above.

The only reason I could see someone building a sealed enclosure with such a superb driver is if they must utilize minimal floor space otherwise the drivers true capabilities are not being used.

[WmAx]

Geoff St. Germain wrote:

I disagree that a sealed design is an "utter waste of the driver's capabilities". The Fathom uses a tweaked 13W7 (13HT7?) in a sealed enclosure and tests as one of the best commercial subwoofers out there. It totally depends on a person's goals.

Your reply does not appear to apply to my post. I recommend you re-examine the quote you chose to high lite and how/why your following statement is not applicable.

-Chris

[Ricci]

Well I'm going to agree with Geoff here. The 13W7 is a great driver for sealed or ported apps. Sealed is hardly a waste of the drivers capabilities. I for one would not build the 4.5ft slot ported enclosure mentioned. In that size enclosure, just PR it. The slot port mentioned will tune to approx. 23hz which is quite high for HT with a driver of this caliber. Also the port resonance at 107hz could be a problem that I'm not confident will be addressed totally by the bends in the port, and definitely not by an 80hz low-pass. What if a 100hz LP is needed to match better with smallish main speakers?

If you can go with a bigger enclosure 7.5ft tuned to 17hz looks way better. You can either use a heavily flared 6" port, or use a 3.25" x 12" x 42.75" slot for a bit more port area. The port air speed isn't too bad until over 1000watts.

[mayhem13]

Since size matters to the OP, Passives would be the way to go on this baby. Dual opposing 15's at 4.6 hz 1050 grams each would come very close to ported output without the threat of compression, reduced box size for about $100 for the PR's from acoustic elegance. If SQ is what he's looking for-give it to him.