2x15 JBL E130 Cabinet

[David Root]

I am changing out a mid 60s Fender/Sunn knockoff 2x15 bass cabinet from D140Fs to E130s. I say "knockoff" because it does not have the divider plate in it that the Fender cab had, no logo and the input jack is located differently than the originals, and is cheaply built. It is however a period not modern knockoff as the D140Fs are period correct w/ S/Ns <20000. It has castors on it which I desperately need, it is a heavy mofo w/the E130s.

I have been looking at JBL old cab design info. I am not a speaker cab expert so I'm looking for some seasoned advice here as to how to modify this old cab to suit the E130s.

This cab is closed back, with a rectangular port about 6"x4" and no tuning tube on it. Never had one, the port is covered with a piece of fiberglas insulation which looks original.

Is the E130 amenable to a Dumble style oval open back, or should it stay closed back and ported? If so, I believe the cab should be ported for the volume, which is 6 cu.ft.

I have an old JBL Pro Enclosure guide which lists a single spkr cab for the E130 at 3 cu. ft. and 12 sq. ins. port area, tuned for 40Hz, so 6 cu. ft. at 24 sq in for two spkrs seems to make sense to my simplistic non-Thiele mind....

I would think it would make more sense to tune the E130 a bit higher for guitar, but that is uninformed speculation on my part.

Can any spkr/cabinet gurus point me in the right direction? All my cabs except one are open back and I kinda like that. I also like old Altec Alnicos too.

[Structo]

I'm not sure of the interior volume but somebody here scaled this picture to figure out the port dimensions.
I haven't tried it so I'm not sure how accurate it is.

The other picture is of a Redplate cab (I think) with dual ports.
Notice the divider in the middle.

Another thing I would like to consider is building a dual TL806 with two EVM 12L's .

[David Root]

Thanx Tom, that helps. The Redplate cab is interesting. I can see it has a central sealing baffle so that would account for the dual ports.

I just scaled the ports off my two Avatar oval back cabs. One is their large 1x12, 16x20x10" (1.85 cu. ft.) internally and the other their standard 2x12, 19.5x27x10" (3.0 cu. ft) internally. The oval cutout areas scale approximately to the front baffle area, so I think I can either:-

1) Scale that up to my 2x15 cab which is 24x34x13 (6.1 cu. ft.) internally, which makes the oval cutout 24.5" long and 8.25" wide with 16" straight side length.
OR
2) Put in the cental sealing baffle and two smaller dual ports the same size as in my Avatar 1x12, since that cab is half the volume of my 2x15 cab, 3.0 vs 6.1 cu. ft.

It would be less work to do 1), but might 2) sound better?

Then again, all the JBL designs are for ported closed back application.

The bass forums all say NOT to use open back cabs for bass guitar but for regular guitar it seems to be OK.

If that is a Redplate cab, perhaps Heistl would be kind enough to comment.

[Bill Moore]

Dave, I've got a JBL drawing for a 5.75 cu ft cabinet for K130/K140 drivers, both showing 2 ports 4 3/8" diameter x 5" long, between the drivers. I don't have it scanned, or I would send the drawing.

[David Root]

Thanx Bill, I will have to look up the differences between the E130 and the K130.