WinISD vs Published Data re: 2213H

[clmrt]

I might be getting my hands on some 4312A's with bad cabinets, missing a grille and possibly a bad woofer. Thinking about cabinets, I can either DIY, have someone DIFM, or buy used nekkid cabs on Ebay.

Seeing as how empty cabinets go for about a billion bucks these days, I was thinking of these -

http://www.madisound.com/cgi-bin/index.cgi?cart_id=%Êrt_id%%&pid=1443

They are pretty close to the same dims as the originals. Now, thinking about tuning the 2213 for the cabinet, WinISD says 15 cuft....shrink it down to a reasonable 1.75 and you have to tune it to about 36hz for a decent size port, but now you have a 5db boost at 70 hz.


My point is, on the 4312A spec sheet -

http://www.jblpro.com/pub/obsolete/4312a.pdf

...there is no such boost apparent.

Why not?

PS -

Going sealed seems practical. Opinions?

[Robh3606]

"Why not?"

Who knows??? It's sure there though. It was in my L100's that's for sure. And it's in the 4311 brochure as well.

Rob:)

[Zilch]

BB6P says tune 2213H in 1.75 cuft to 30 Hz with heavy damping and one 3" port 7.75" long. (black)

Heavy damping mitigates the hump a bit to 2.89 dB max at 67.54 Hz, but it's there, and quite broad.

Closed box with heavy damping seems to work nicely, yes. (red)

It's thermally limited in the closed box, though, dropping from 75W at 50 Hz to just 10W at 30 Hz.

I'd go ported, with the port in from the rear to accommodate the heavy damping conveniently.

UNLESS I was gonna high-pass them at, like 60 Hz, for use with a sub, in which case the closed-box approach would be the better option, looks like....

[clmrt]

Thanks - :bouncy:

[spkrman57]

I am thinking a sealed design might be interesting for use with my 300B amps. At only 7 watts/chnl they would not stress the driver and might sound decent depending on how the 300B SET design interacts with the 2213!

Ron





BB6P says tune 2213H in 1.75 cuft to 30 Hz with heavy damping and one 3" port 7.75" long. (black)

Heavy damping mitigates the hump a bit to 2.89 dB max at 67.54 Hz, but it's there, and quite broad.

Closed box with heavy damping seems to work nicely, yes. (red)

It's thermally limited in the closed box, though, dropping from 75W at 50 Hz to just 10W at 30 Hz.

I'd go ported, with the port in from the rear to accommodate the heavy damping conveniently.

UNLESS I was gonna high-pass them at, like 60 Hz, for use with a sub, in which case the closed-box approach would be the better option, looks like....

[4313B]

It's thermally limited in the closed box, though, dropping from 75W at 50 Hz to just 10W at 30 Hz.I think you mean mechanically limited.

[Zilch]

Yup.

[Zilch]

Which leads to contemplation of L100's et.al. used this way, i.e., closed port, with sub, and the appropriate HP slope and frequency?

:hmm:

[Them what have and like 'em, anyways.... :p ]

[4313B]

I spent about an hour explaining all this. No one responded so I yanked all the posts. I do that alot. Besides, it's all explained in BB6P and they got paid for the explanation.


Yup.The graph you actually want to show in your post #7 and the reason for my post #6 in response to your post #3

It's thermally limited in the closed box, though, dropping from 75W at 50 Hz to just 10W at 30 Hz.would be:

It's an important point to make. And my explanation went through how the L212 would never have worked according to the model. We all know for a fact that it actually did and that's were the practical experience comes in. My explanation also pointed out that the model is only as good as the data entered. BB6P suggests that it's best to go conservative. Once practical experience is garnered one can push things a bit, especially with conservatively rated, robust transducers like JBL's.

[4313B]

Which leads to contemplation of L100's et.al. used this way, i.e., closed port, with sub, and the appropriate HP slope and frequency?

:hmm:

[Them what have and like 'em, anyways.... :p ]You don't necessarily need a HP on the satellites. Run sealed they are falling at 12 dB/octave usually starting at a decent frequency that allows for inclusion of subs. At most you may want to use a passive line level high pass like that which is used in the BX63 or BX63A. Get fancy and charge couple (bias) it like JBL did in later versions of the DX-1. I've posted this quite a few times.

[Robh3606]

I responded. I thought it was great, saved it too. I took my post out so it didn't interupt the flow. I wish you left them up there those posts were excellent and well thought out.


Rob:)

[clmrt]

Me too - I about passed out reading them.


:thmbsup:

[Ian Mackenzie]

Yeah well I've been off line all week and missed all this completely.:(

Just because Zilch reacts to all of your posts and visa versa does not mean to say the rest of us more techncially literate members don't read an appreciate what you have to say...that is until they are deleted.:screwy:

[johnaec]

I read all the posts too and was going to comment, especially about the flat group delay! I was actually planning on reviewing them in more detail later. :(

John

[Zilch]

I spent about an hour explaining all this. No one responded so I yanked all the posts.Please put it back up. There's obviously more interest than you presume; more members are getting into the technical aspects of how this all works. Dueling sims is FUN stuff!

The intricacies of BB6P are hard to fathom, sometimes, and any insight is appreciated. I never saw that "Track Excursion" checkbox before, for example. Turns out it's better than even my initial analysis showed.

Left coast is 3 hours behind, of course.

[And we sleep late, too.... :p ]