Box 2242H

[DJHades]

I have just acquired 3 2242H's and 1 2242 HPL.
What would be a good box for these subs. I am just
getting into speaker design and building. I built two of the
boxes designed by Drew Daniels. They were OK. Were
these designed to be used with four together? The enclosure
recomendation by JBL has a smaller box design. I don't understand how many ports and what size I am supposed to use.
Is it 1 eight inch port or 4 four inch ports or is it 6 four inch ports?
Is there something better than both of the above?

[boputnam]

Go here and Search on 2242H: http://www.jblpro.com/search_22.htm

Then, mouse around and you'll find this for the 4645C:

At least this is one iteration that certainly works! BBPro should be able to assist with port dimensions.

[4313B]

As Bo has pointed out the 2242 has replaced the 2245 in the 4645 series subwoofer. It has also replaced the 2245 in the consumer Synthesis S1S subwoofer. The tuning for the 2245 was 30 Hz and the tuning for the 2242 is 25 Hz.

The 4645C is going into theaters worldwide at an alarming rate and for good reason. It is a very versitile transducer. I've used it in as small as 2.5 cubic foot sealed enclosures all the way up to the 8.0 cubic foot ported 4645C-sized enclosures.

I have to admit that I still think the 2245 is king for typical home subwoofer use. At very low to low power levels the 2245 has resolution the 2242 can't touch. Beyond that it's all 2242! Massive power handling, serious efficiency, minimal power compression, extremely low distortion, and excellent transient response.

I think I detailed elsewhere on the forum how to modify a 5234A/5235 to provide the proper EQ (if EQ is desired) for the 2242/4645C.

Fun transducer!

[TimG]

I would recommend using a single 8" port rather than 4 4" ports because you will be less likely to have audible port noise with a larger port. However, larger diameter ports have to be longer for the same tuning frequency, so they won't always fit in the box. Giskard has also recommended a pair of 6" ports in the past. This size would be a more reasonable length than a single 8" port for a low tuning frequency. If you model the vented box in Unibox http://www.danbbs.dk/~ko/ubdwnld.htm you can look at the port velocity under the vented box design to determine how big of a port you need depending on how much power you have available and how low you want to tune the box.

Flared ports can also help reduce chuffing sounds for smaller ports, but I haven't seen them available in larger than 4" sizes. Although I don't know where to find them, I have heard rumors that some company offers 6" flared ports.

[4313B]

"I would recommend using a single 8" port rather than 4 4" ports because you will be less likely to have audible port noise with a larger port. However, larger diameter ports have to be longer for the same tuning frequency, so they won't always fit in the box. Giskard has also recommended a pair of 6" ports in the past. This size would be a more reasonable length than a single 8" port for a low tuning frequency."

This becomes even more important if you use boost at the tuning frequency I've personally not had issues with the dual 6's but that's just me and the levels I operate at. JBL has migrated from the distributed ports to the single sewer pipe as well.

[Alex Lancaster]

Giskard:

As long as the total area and length are the same, for a reasonable 4" to 8" diameters, let´s say, does it make a significant difference?

Alex.

[neriks]

DJHades,

I'm using four 2242's in my listening room. The enclosures hosting the 2242's have a volume of approximately 700 liters ...

[Daniel B]

Hades,

I couldn’t agree more with what Bo and Giskard have just posted. I noticed you went with one of Mr. Daniels' designs. Here's a photo of him sitting on what looks to be a box very similar to the 4645. The 18 at his right knee looks like a 2245 to me too.



As always, your primary application should dictate what drivers you use.

dB

[TimG]

I wonder what he is using to prevent the magnets of those subwoofers from distorting his TV?

[DJHades]

Thank you for your help. Where can I purchase a copy of BBpro?

[boputnam]

Our second favorite well (after JBL Pro...) - Parts Express!!

Parts Express: Bass Box Pro - Link

They also have it packaged with "X-Over 3 Pro" for a bit more - (use the pull-down chooser on the Linked window).

There's also freeware WinISD - Link which I've had great luck with, and have corroborated it's findings with BBPro, both at home, and with the help of "Others" here on the Forum. As Robh will tell, there are some nifty things BBPro does (in helping optimize Fb...) that I've not been able to replicate in WinISD, but think I ultimately could with more mousing around...

[DJHades]

Thanks Bo. One more question. I was playing with WinISD using the T/S paramaters of the 2242H and the 8 cu. ft size of the 4645C tuned to 25hz. Using one 8 inch port, WinISD calculates a port that is 20.70 inches long. Is that correct? I am purchasing BBpro but just ordered and it will arrive in the mail as opposed to downloading it.

[Robh3606]

Hello DJ

Tried 8cuFt. tuned to 25 hz vent length is 20.18 in BBP. Little shorter, tuning frequency for your vent length is 24.77Hz in BBP. What's .23Hz between friends?? I would say thats real close. Good you ordered it that way the manual is nice. You get the crossover program too??

Hey Bo

Beat you to it

Rob

[4313B]

If I'm not mistaken the ID on that port is ~ 6".
You would do better to simply calculate the necessary port diameter to keep the end of the duct ~ 4 to 6" away from the rear panel of the enclosure.
An 8" ID port would have too long a duct to fit into the 17.75" depth of the enclosure.

BTW - Here is the 4645C Technical Manual - right click, Save Target As...

[boputnam]

Originally posted by Giskard
You would do better to simply calculate the necessary port diameter to keep the end of the duct ~ 4 to 6" away from the rear panel of the enclosure.

And that calc is quite easy in BBPro. You can set Fb to 25Hz (or whatever) and then iterate the port diameter until your result is as Giskard describes (for a straight duct).

Alternatively, if you already own plenty 4-in duct, you can use a right-angle bend to achieve the proper length, while not encroaching on any cabinet side/bottom. I did that in a recent project of a modified L65 (using the LE14A) and the results were excellent (thanks to Robh, Giskard and the rest... )