2235 subwoofer

[Figge]

hoho!

ok as many of u know i´ve been having some problems with one of my 2235:s, distortion at 600Hz...i have now bought a new one so the old is lying around.

also as some of u know i have a buddie with a little home studio i have hooked up with a pair of 4301B:s wich he loves! however he complains sometimes about the deepest bass performance! (the really deep)

so i thought: lets build a sub outof my 2235! GREAT idéa he said! how do we go about this?


any suggestions? box size? could it work out?

[Figge]

i´ve been searching for a while on this and came up with just about nothing?? strange i remember some thread like this a while ago.

[Robh3606]

Just do a clone of the B380 you would need a BX-63 but the schematic is available if you wanted to build one. You could also just put it in a reflex box as unassisted they can do very nicely in about 5 cu. Ft. Take a look at the Audio DIY article too for the 2245 sub. They will cover the same bandwidth as a 2235 but with more output.

http://www.lansingheritage.org/html/jbl/specs/home-speakers/1983-b380-b460.htm


http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm

Have Fun

Rob:)

[Figge]

tnx rob! i found the thread!

how about this one?

the #8
http://www.jblpro.com/pub/manuals/enclgde.pdf

the only thing i dont really get is the ports..."vent area 25,1"??
"equivalent duct tube (2)4.0" what the heck does that mean?:)

2*4" tubes that are 11" long?

[Robh3606]

Not sure on the area. The area of the openings? A calculation will answer that one but yes 2 4" ports 11" long will do nicely'

Rob:)

[Figge]

i guess such a box loaded with my 2235 will add some low-end to those 4301B:s....?

how low can i expect it to go? (with room gain)

[Robh3606]

Here is a Win Isd plot to give you an idea. Depends on the room I get solid low end into the upper 20's with a pair is the same size enclosure and similar tunning.




Rob:)

[Zilch]

You don't HAVE to have the BX63(A) specifically for B380's to sound good; it does somewhat enhance the very low end though.

Curves and construction info for B380 are in the "New Lows" article, near the end....

[johnaec]

Originally posted by Figge
the only thing i dont really get is the ports..."vent area 25,1"??
"equivalent duct tube (2)4.0" what the heck does that mean?:)

2*4" tubes that are 11" long? It's saying that you need a 25.1 square inch port that's 11" long to tune the box to 30 hz. Two 4" diameter ports is roughly equal to 25.1 sq. in. , and you are correct - both need to be 11" long. This would also equate to a single port roughly 5" x 5" square, also with a length of 11".

John

[Figge]

Where can i find the bx-63 schematic?

[Robh3606]

Do a search for BX-63 Schematic, there is at least onther thread out there



http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=610&highlight=bx63+schematic


Rob:)

[korgroenewoud]

Hi,

If you are really intersted in a 2235 subwoofer, I have a b380. It is build like the original. It sounds superb. Really deep bass.

[Figge]

well box is allmost finished with bracings and damping material...just waiting for the 3 holes in the baffle!

any sugesstions on a Xover frequency?

the 4301:s i guess goes down to about 45hz should we make the 2235 to take over from 45-50 and down?

how can i make a simple but working lowpass for that...guess the filter should sitt before the amp that will drive the woofer?

[Zilch]

BX63 low pass is 63 Hz. BX63A is adjustable from 63 - 125 Hz.

For starters, I'd probably do a quick passive lowpass on the subwoof itself, aiming for around 60 Hz. Somebody else gonna have to tell you how to do that, tho.

My local booming car audio guy knows, heh, heh....

Ideally, you ultimately do a full two-way, off-loading the bass from the 4301B's, which become satellite mains.

I just run my B380's off the subwoof output of my preamp through 6260 amp.

We want pics, of course....

[Chas]

Hey Figge,

My experience has shown that it is contingent on the H/P filter charactersitics and room modes. Fourth order (24dB/octave) low pass at about 60 Hz and first order (6dB/octave) high pass at 100 Hz works for me here. Maybe you can experiment?
:cheers:

[4313B]

True.

Another experiment might be to stuff the ports of the 4301B's which will roll them off earlier and more gradually. Add in the sub(s) as needed.

Here's another link:

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=610

[Figge]

some great idéas!

giskard whats your guess on the rollof on the stuffed 4301:s?

[Figge]

does anyone know how to do a passive 60hz filter?


and ofcourse there will be pictures of our handywork....

[4313B]

"does anyone know how to do a passive 60hz filter?"

Well, from past posts I thought that might be obvious, but since you ask point-blank, yes. :p

"giskard whats your guess on the rollof on the stuffed 4301:s?"

I can't remember off-hand. I do recall using a pair of L-19's with a single B380 eons ago and it worked well enough but I can't remember where the crossovers were set.

[Figge]

well tell me how!dammit!....:)

some simple will do. right?

[4313B]

Yes, there are simpler filters than the BX63.

[Zilch]

Giskard and me are thinkin' different approaches. I'm suggesting you put the appropriate size inductor in series with the subwoof for an inelegant quick-and-dirty starting point.

See, for example, how 4435 does it with 18 mH inductor here:

http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4435LR.pdf

I don't know why the 4 parallel 62-ohm resistors are there, attenuation, perhaps.

Giskard can tell ya, probably, tho. Heh, heh. :nutz:

[Figge]

Originally posted by Zilch
inelegant quick-and-dirty starting point.

thats exactly the way we do it...improve afterwards!!

btw how the heck do i get a mono signal to the sub-amp from a stereo mixer?

[4313B]

Originally posted by Figge
giskard whats your guess on the rollof on the stuffed 4301:s? Ok, the L19 had the ubiquitous bump between 50 and 100 Hz and plugging the vent basically flattened out the bump, probably a good thing with the addition of a sub. :p

Can you post the port/duct configuration of your 4301 along with the gross internal dimensions please? Millimeters is fine. :)

[Figge]

hi G!

i´ll do my best to look up that info! isnt it available in the library somewhere?

otherwise i´ll do some meashuring next time im over there, hmm.... probably tomorrow.

[Robh3606]

Look here:

http://www.jblpro.com/pub/obsolete/4301.pdf

Rob:)

[4313B]

Originally posted by Robh3606
Look here:

http://www.jblpro.com/pub/obsolete/4301.pdf

Rob:) I submitted the color version of that pdf for the Library in January. :)

If you don't feel like posting the port diameter and duct length I can get it from somewhere else eventually. Not a problem :)

[Guido]

Originally posted by Giskard
I submitted the color version of that pdf for the Library in January. :)

Don!
I think Giskard submitted a lot of interesting material which is not online at the moment. Is it a problem of bandwidth, copyrights or just your limited time?

[4313B]

Originally posted by Giskard
If you don't feel like posting the port diameter and duct length I can get it from somewhere else eventually. Not a problem :) Thanks Bo! I thought it was out there somewhere. :p

2-in diameter (straight)
5-1/4-in long from face of baffle

[Figge]

ok here is the damn thing:)

sounds really good! we first tried it without xover and played ZZ-Top "sharp dressed man" and hell the kick drum was spectacular!!

[Figge]

and "the terminal" this one i like!:)