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View Full Version : Sub enclosure Mdf , Cardboard ? Pvc ?



gerard
03-26-2005, 02:08 PM
I have seen some conversation about building sub enclosure .
(like 2123 in 434x)

For an Le5 and le8 T Can I use an Mdf sub enclosure for my project or should I use cardboard ?

Is there a sound difference at the end or is it easy to use cardboard or similar ?


Thank's for answer .

gerard

Robh3606
03-26-2005, 06:12 PM
Use what is easier for you to use. I have done both but now use the round concrete tubes. Have had good results with both.

Rob:)

hector.murray
03-27-2005, 12:40 AM
For an LE5 you can use the cover from a stack of CDs, the 100 CD stack variety. You'll come up with length of 4 1/4 to 4 3/8. Pop a hole in the top for wires, line it with fiberglass or carpet and epoxy to the baffle.
The pic below was taken before I padded the enclosure.

gerard
03-27-2005, 12:47 AM
thank you hector , But...

This Cd pack does not seem so rigid , can't wa have some bad resonance with ?

regards

gerard

MJC
03-27-2005, 07:42 AM
When I was building my L212s I had to make a sub enclosure for the LE5-9. Originally I was going to buy a sonotube, but could not find any with a small enough diameter. So I took a piece of cheap, 1/8" paneling, the kind that has a printed face, and soaked it in water.
I had already cut it to the width needed to give me the length of the enclosure, and long enough to bend around a 1/2" thick mdf circle. The circle would act as the end of the enclosure.
I let the panel strip soak long enough until the printed face separated from the paneling. Then it was just a matter of bending it around two circles, using gorrilla glue, and clamps and small finish nails. The edge of one circle had the glue on it. The other circle was used at the "open" end of the tube just to hold the shape until it dried.

duaneage
03-27-2005, 07:55 AM
I have used tupperware bowls. Cut out the lid to the baffle hole diameter, fasten it to the baffle. RTV the bowl to the lid, stuff with polyester and your done.

Target sells these disposable microwave reheating containers, perfect for mid enclosures and they make several sizes.

johnaec
03-27-2005, 08:10 AM
I agree with gerard - aren't soft plastic enclosures exactly what you don't want? I can easily see substantial LF driver interaction really flexing these...

John

R Beardsley
03-27-2005, 12:16 PM
An appropriate tupperware bowl makes a GREAT mold for fiberlass which is available at any auto parts store. if you use the spun matt instead of the cloth, it will conform to any shape you can imagine when it gets "wetted out". Cardboard tubing reinforced with fiberglass cloth is really easy too. It is also really fun to get your hands all sticky along with everything you touch - not to mention that nice "scratchy felling" you get when the fiberglass works it's way into your shirt.

hector.murray
03-27-2005, 06:18 PM
Once you epoxy the open end to the baffle, it is quite rigid. after you pad it down with either fiberglass or carpet, I don't think there would be any particular issues, but I'm not the expert in this area. Worked for me, Although I understand that I might have cut the open end at an angle so the rear end isn't parallel with the baffle.

John
03-27-2005, 06:32 PM
Well it is obvious that alot of you guys were fans of the TV Show Home Improvement:applaud:

hector.murray
03-27-2005, 08:55 PM
An appropriate tupperware bowl makes a GREAT mold for fiberlass which is available at any auto parts store
I think I'll do a variation of this. Since I have my enclosures in place now, I'll take some of the fiberglass cloth strips, soak them in resin and wrap them around the sub enclosures already in place. Then I'll use some tiger hair mat mix to cover the top and tie it all in together.
( the tiger hair I have on hand, the cloth strips I don't - but the small kits are like what - $10 ?)

duaneage
03-27-2005, 09:14 PM
I see my tupperware idea is not all that well received. :p

Well I doubted it too but to be sure i removed the midrange, played music through the woofer and felt the plastic bowl through the midrange hole. Some vibration was felt but not much. After the polyester was put back I reinstalled the mid and used a voltmeter on the midrange to check for microphoning with the woofer playing sine tones and the midrange only hooked to my meter. I found almost no effect on the midrange, the fill material did it's job and damped what was left of the vibration right out.

Test your midrange enclosures, removes the guesswork. You can spray automotive undercoating on the bowls if you are concerned about it.

rek50
03-28-2005, 06:54 AM
I don't know if they have a Home Depot store in Casablanca, but I've found some nice heavy-duty cardboard tubes in the carpet section. They're FREE.

gerard
03-28-2005, 07:36 AM
Hi rek50.


No there is no Home depot in casablanca , I would be happy if there was some ...
In fact in Morocco most of the people do not make any DIY so if you need something you better find it on the moon . But apart from that we got camels ..
May be I can make a sub enclosure with a camel bone ?

No joke : this is why it is easy for me to make it with MDF ...
gerard

boputnam
03-28-2005, 08:23 AM
You guys need to SEARCH - there is quite a bit on this out here!!

Try this Acoustic Isolation chamber for LE5-series thread.

These things are quite specifically engineered. They need be constructed of rigid material, airtight, stuffed with batting, and are best when the rear of the chamber is not parallel with the front of the baffle.

Read on...

To quote Giskard (August 2003):


JBL has always specified a subenclosure volume of ~ 80 cubic inches for the LE5.
The ratio of the inside diameter of the subenclosure and it's depth is usually roughly equivalent to the "Golden" ratio:
(SQRT(5)+1)/2 or ~ 1.62 : 1 : 0.62

The inside diameter of the tube is often 5.3125"
On some models they purposely tilted the closed end of the subenclosure so it wasn't parallel with the baffle.

The 3.5 mH inductor having 7.5 ohms of DCR is set to smooth out the impedance peak of the LE5x in this sealed volume.

Don Mascali
03-28-2005, 08:29 AM
A piece of PVC pipe with the glued on cap is ridgid and the cap is concave on the inside so there are no parallel surfaces to resonate. You can get PVC in large sizes to match drivers (Even 10" or 12") but unless you can get a piece on a construction site you have to buy 10' or 20' sections. Schedule 40 pipe is the best, DWV will work but is thinner.

gerard
03-28-2005, 08:56 AM
M Bobutnam .

please take a look at this drawing , the sun enclosure is made of mdf and end is parrallel to the baffle .and I will work on this drawing because it is the only one I have !

I have to make the same speakers and ready to start building the baffle but I am lot for the sub ????

Can I go to mdf ? Mdf no parrallel to the baffle ? Pvc ? :banghead:
forget the other stuff , where I live no way to get it !

thank's for help .

gerard


http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=3762&stc=1

boputnam
03-28-2005, 09:22 AM
Hey, gerard... :wave:

- No problem with MDF.
- Try to get the optimum internal volume. 80 in3 (1311 cm3) and follow the "Golden Rule".
- Try for a small angle of the back wall (rear) of the subenclosure.
- Make sure airtight.
- Stuff with fiberglass batting.

You might find the "sono tube" around some construction site - they use these for concrete forms. :dont-know:

But, MDF will be fine, too - just more work!

Don has a good idea, too.

A piece of PVC pipe with the glued on cap is ridgid and the cap is concave on the inside so there are no parallel surfaces for reflections. My edit... ;)

gerard
03-28-2005, 09:54 AM
Hi Boputnam

thank you for your input .:applaud:
I believe i'll go for Mdf as I have to build the whole speaker !

regards

Gerard