A friend of mine has a single E140 and I would like to help him make use of it somehow at home.
So, I'm asking if anyone could suggest what to do with it.
BR
Roland
A friend of mine has a single E140 and I would like to help him make use of it somehow at home.
So, I'm asking if anyone could suggest what to do with it.
BR
Roland
Does your friend play electric bass? -grumpy
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
No, he doesn't play guitar. He found it in a container. It had been thrown away because the dust cap had been dented, go figure!
How deep would the sub be able to go, if used with a passive radiator on opposite side?
I think he's got another cheapo 15" lying around, which might do for now.
Would a 2 to 2.5 cu ft box be enogh?
BR
Roland
Ah, perhaps then have it reconed as an (almost) 2235 and build a real sub... ala B380.
I'm not sure my friend would see the point of replacing a working cone to another that almost looks the same. He doesn't know the first thing about Fs or any of the implications that different T/S values create.
I therefore think it'll have to be done with what he's got.
BR
Roland
Maybe use 1" MDF, build a 20" cube. Mass weight the PR to resonate at 30hz or so. Adjust weight as needed to suit sound taste. He'll need to make a simple low pass or drive it with an active x-over and amp.
Part of the fun of that type of project is the nearly no cost involved. The real audio guru's around here will probably laugh at this design....but whatever....it's not for them is it?
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
different strokes I liked 'em quite a bit doubled up in a well ported cab... not for all...I never liked them much even for bass guitar, because of the lack of low end...he should sell it and start with something else, even if it is not JBL...just MHO.
styles of playing and there was no low B string (or precious few) back then. 2nd point
is a good one ... even after playing with it and some power tools for awhile
Originally Posted by soundboy
That's the beauty and the utility of a passive radiator cabinet. The low end can be tuned quite easily by adding or taking away mass weighting.
Will it be ruler flat down to DC? Probably not.
Did Pangea ask for some suggestions for his friend's new found toy? I think he did.
There's nothing worse than being talked into doing nothing. Let him play and experiment....it's not like he's gonna burn his house down fer cryin' out loud....he found the discarded E140 in a dumpster....the cost would be FREE.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
scottyj
Used them both, yup, years ago. Know the difference, too..The 140's WERE punchy for the bass guitar....but...the Fs is 40hz....not the F3....in any kind of alignment that would give even half way decent bass, with the qts of...what is it .21??? It just has no low end, or floor shake..and that's what bass is all about in a sub, I think..I am a celestion 12 fan, so the 130's did nothing for me except for clean stuff...and they are great for that.
I wasn't trying to do anything but save him some time...if he was looking for bass, free in a dumpster, or not....there isn't much there...
I think the best I got at the time was about 4.5 cu ft with a pair of them, tuned to 45 hz or something....clean, punchy, clear....and no bass.
The E155's were another story....and a bigger box to carry...and they weren't free in a dumpster, either...
Many thanks for your thoughts and suggestions.
I think I will recommend to him, that we build a sub with a PR on the opposite side.
However I'm not familiar with the use of PR, so I could do with some help tuning it.
Does added weight lower the tuning?
How much weight would be reasonable for a 30Hz tuning, roughly speaking?
If all works well, it will even make him see the light and become a JBL fan...
BR
Roland
Yes....more mass will lower the resonant freq of the PR...and that will depend on the natural resonant freq of the PR to start with.
At the tuning freq of the PR, the active driver...E140 in this case...will have virtually no cone movement as the PR is resonating. It's the same concept as the tuning freq of a port in that the port is making the bass at it's resonant frequency. If you want to tune the PR lower....simply add a bit more weight....such as fender washers....we're talking grams or ounces here. The stiffer the PR the more weight it'll take.
A simple way to make a PR is to use a cheap stamped frame speaker and pry the magnet assembly off while retaining the cone and spider assembly intact for linearity of movement. Or....blown Peavey Black Widow or Scorpion 15" baskets with the cone assembly intact make a great passive radiator to build on....and they're cast aluminum. You can hot glue a hardboard disc with a threaded bolt through the center to the inside of the voice coil former to add or take away mass with fender washers. Your mass weights should be where the voice coil is to keep the weight centered.
You'll also need some sort of sinewave generator to zero in on your tuning freq. Download 'WinISD' to get the included tone generator. It's a freeware program.
www.linearteam.dk
On top of all this....the E140 has a sensitivity of 100dB, 1w/1m....so it won't take much power to drive you out of the room.
Good luck and have fun.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
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