compact box for 15" JBL E140 bass

[pp-guitars]

Should anyone have some plans for a compact cabinet?
I have a speaker lying around, which I could use for demos for my bassguitars!
BR
Peder
PP-guitars

[bea]

Hello Peder,

plans like this are always welcome.
Maybe we get some life to the cabinet (and amp) building sections of the forum...

[potomac]

Yes Peder, I'm going to build a small box for my bass amp, maybe your plan could help me, too.

[pp-guitars]

Yes if someone could come up with a cabinet plan! I got some directions years ago, but lost them, and I remember seeing plans on JBL's site, but apparently, they are not there anymore....I think I'll try to contact JBL directly, and see what happens!
....done....hold your breath!

[bea]

Anyway: any plan can be valid only for the speakers the box is designed for. This is especially true for vented designs. So the Thiele Small parameters of the speaker are needed for a thorough design.

Last Year i did a design for a 15" Eminence Kappalite speaker - compact and lightweight, about 70 l vented. I am using LSPCAD for this purpose (and sometimes WINISD).

So it would be important knowing tuning frequencies fo those speakers in order to give others the possibility to adapt those plans for their own needs.

BTW: in the Electro Voice also published some interesting designs for speaker enclosures. They are still floating around in the net. The discussion on the TL806 (12") is attached.

[irgendwer]

Hi Peder!

I found some Thiele/Small Parameters for that speaker on the net:
http://www.usspeaker.com/jbl%20e140-1.htm

I think the easiest way would be to put it into a closed enclosure of maybe 50x50x50cm?
Any other suggestions?

Regards, Max

[bea]

Last year i built three compact cabinets which are cubes or nearly cubes.

A strict cube has the disadvantage of strong resonances caused by the geometry. This can be handled, and it urgently needs be handled - by damping of the central part of the volume. It is, however, easier to handle if at least one dimension deviates from a strict cube. Surface resonances are also more pronounced than in non cubic enlosures, simply because the resonances of all surfaces coincide or nearly do so.

Anyway, the design procedure is different: You start with a given speaker and an estimate for the volume of the box. This needs to be fine tuned to a fairly high Q of the high pass the enclosure acts as. In practice of guitar and bass cabinets, a small peak of 1-3 dB above the corner frequency of the system leads to a good sound, corresponding to a Q of about 1.0 to 1.1. To achieve this, some iterations through volume /tuning frequency are required. Not all available speakars work well under these conditions!

The aspect ratios of the design will be determined after this step.

[pp-guitars]

Whauu! seems like a joke to build guitars instead of speaker enclosures...BEA your title in the forum should be "boxbauer"
b.t.w got an answer from JBL, but the only thing they had was this http://www.jblpro.com/catalog/support/g ... &doctype=3 ,which could be what I'm looking for....what do you think BEA ?
Grüss
The amateurboxbuilder

[bea]

There are others here, and with more competence in electronics and speaker building.

[irgendwer]

There's a plan for you speaker in the file:
proposal 6

That one has 4 cubic feet, that's about 2*28=132l, and even the dimensions of the bass refelex port are given:
2 ports, each about 10cm (4") of diameter and length of 16.5 cm (6,5").

So you could start your build right away.

Regards, Max

[pp-guitars]

Thanks everybody I appreciate your help
Grüss
Peder

[12stringbassman]

@Max:
4 Cubic-Füße sind 113 Maß (Liter)

[irgendwer]

Sakra di, verrechnet.

Ja, ein Cubic-Fuss sind 28l.

Gruss, Max