4344 Active Project

[ayaboh]

Hi Guys.

I have been working on a 4344 project for a while, and done some real engineering and 3D modeling for this project. The idea is to make a fully active speaker system based on Hypex UcD modules (http://www.hypex.nl), but be able to start out with a passive network and add amps and stuff later. The cabs have enough internal space to put all the network components, amps, powers, and transformers inside. The compartment for the electronics is part of the internal sub-structure, and can be accessed trough a door in the back panel.

I have constructed a sub-structure as a back-bone for the cabinets, and used a lot of bracings for the baffle and back plate. This should make the cabinet much stiffness and more stable than the original JBL.

The cabinets are deeper than the original 4344s due to the volume occupied by the amp/filter box, sub-struc and bracing, but the net volume is probably close to the original.

Some preliminary data:

Dimensions = 1050 x 635 x 410 mm (hwd)
Sub assy weight = 12,5 kg (fiber board with density 0,685 g/cm^3)
Braces weight = 3,25 kg (pine wood with approx density 0,25 g/cm^3)
Driver weight total = 23,5kg
Total weight = 81,55 kg

Total internal volume = 210,6 L
Dog box volume = 15,4 L
Filter box volume = 13,8 L
Sub assembly volume = 18,26 L
Bracing volume = 9,23 L
Net internal volume =153,91 L
Volume occupied by drivers and horn (except 2123) = 7,5 L (+-0,1 L)
Net internal volume with drivers in place = 146,41 L

Duct dia = 100 mm id

Parts used:
2235H, 2123H, 2420J with H-91 and Coral AL-603, 2405H

Take a look at the pictures and give me some feed-back on the design, construction, and baffle layout. The production drawings will be made later when I have necessary data for all the smaller parts.

I need some help with the duct length. I guess some of you guys out there know how to calculate this based on the given data.

You can find pics of the 3D-model in 1600x1200 here: http://www.designcut.com/4344

[johnaec]

'Looks very nice! Are the cabinet sides double-thickness? (Solid!). Are you allowing for some kind of amp ventilation?

Also - what program are you using for 3D modeling? ('Always interested...)

John

[Robh3606]

Hello ayaboh

Hey that look real nice!! I see you have the net volume figured. You can get WinIsd to try on your own.

http://www.linearteam.dk/default.aspx?pageid=winisd

The 2235 driver is preloaded. It is very easy to use and is shareware.

Will post duct length latter on but really where do you want to tune them?? Cabinet tuning will determine duct length. Do you want clasic flatest response or extended bass. I have my DIY 4344's cabinet tuned at 30hz, Attached is a quick look using WinIsd port lengths look to be 11.34 inches. Didn't check your internal depth to see it you have enough clearence. Figure you want about 3" or so behind them.

Rob

[Earl K]

- Beautiful Drawings !

- I'd redo the bracing in the woofer area.
- It's too close to the woofers magnet for my liking.
- From the looks of your pics , the bracing is blocking the magnets rear air vent. That's not a good situation .
- I'd like to see, 3" or 4" of clearance between that vent and any bracing immediately behind it .

[matsj]

That looks really good .

I just got a question . How did you get the speakers in the CAD program ? I got my Cad program yesterday ( solid works ) and i´m not so good at the program.

regards mats

[ayaboh]

'Looks very nice! Are the cabinet sides double-thickness? (Solid!). Are you allowing for some kind of amp ventilation?

Also - what program are you using for 3D modeling? ('Always interested...)
John

The sides are 25 mm plywood. They may look thicker because of the 45 deg end cuts. The UdC amp modules I plan to use are dgital and produce very little heat, and a small heat sink at the back door should be enough.

The modeling has been done in Autodesk Inventor.

[ayaboh]

Hello ayaboh

Will post duct length latter on but really where do you want to tune them?? Cabinet tuning will determine duct length. Do you want clasic flatest response or extended bass. I have my DIY 4344's cabinet tuned at 30hz, Attached is a quick look using WinIsd port lengths look to be 11.34 inches. Didn't check your internal depth to see it you have enough clearence. Figure you want about 3" or so behind them.

Rob

I want a flat response.

I have 16 inches of free space for the duct, so a length of 11.34 is a bit to much if it's necessary with 3 inches of space between the duct end and rear wall. Is it better to increase the diameter of the duct?

[ayaboh]

- Beautiful Drawings !

- I'd redo the bracing in the woofer area.
- It's too close to the woofers magnet for my liking.
- From the looks of your pics , the bracing is blocking the magnets rear air vent. That's not a good situation .
- I'd like to see, 3" or 4" of clearance between that vent and any bracing immediately behind it .

Hi Earl.
Are you taking about the pole vent outlet, or is it that the bracing is to close to the magnet? I think the clearence is 2 inches, but I have to check my drawings to be sure.

[ayaboh]

That looks really good .

I just got a question . How did you get the speakers in the CAD program ? I got my Cad program yesterday ( solid works ) and i´m not so good at the program.

regards mats

Hi Mats.

The models of the drivers are made from scratch.

[Robh3606]

I want a flat response.

I have 16 inches of free space for the duct, so a length of 11.34 is a bit to much if it's necessary with 3 inches of space between the duct end and rear wall. Is it better to increase the diameter of the duct?

Then you should download WinIsd. The tuning is off a couple of Hz so go higher to give you flat however you will loose a little extension down low. As far as the port you need to change the tuning, go to a single, or smaller ID to shorten the length on the ports. You can also angle them a bit with a partial elbow to keep the length as is.

Rob

[Mr. Widget]

The models of the drivers are made from scratch.

Cool project! I like heavily braced designs too. Instead of 25mm plywood, I think you would find a slight improvement with 13mm MDF covered in 13mm birch ply. The bass will be slightly tighter with slightly less box loss.

If you don't mind, I'd love iges files of your drivers... I have been too lazy to build such nice examples.


Widget

[cvengr]

Nice job, ayaboh.

[matsj]

Is it possible to get a file on the 2235, it´s similar to my 2226 and the 2405 ?

Mr.Widget what drivers do you have on cad ?

Is here someone who have 2245,2446, 2450, 2382 on Cad files ?

regards mats

[4313B]

Please post an impedance curve of the finished system as well as a near-field response graph of the LF transducer. I'd recommend you build a single prototype and test it.

[ayaboh]

Please post an impedance curve of the finished system as well as a near-field response graph of the LF transducer. I'd recommend you build a single prototype and test it.

Sorry, I don't have the equipment for that. Is this necessary because of the internal bracing/sub struc or the increased volume? If this throws the impedance and response for the 2235 way off, it will be much easier to copy the original 4344 cabs instead.