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Repairing JBL E140...or not...

K

kootenay mellie

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Feb 3, 2015
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#1
Hi all
New to forum but have gleaned lotsa info over the years. Good stuff. Came into 2 E140's a few years ago so I got dimensions etc for JBL Cabaret 4625 and built a couple cabs. Just took them to a gig for the first time (nothing crazy - community hall) paired with my G-K 700RB-ll. Near the end I noticed one of them frapping a bit so checked out next day and with cab on its back and gentle pressure on the cone, there is an obvious rubbing sound. Frick. I guess first question - is that amp too much for those speakers - ran both speakers from separate 1/4 inch jacks on GK and from my reading ability figured that would be 350 watts if fully cranked. Which it was no where near. Thought speakers were rated 400 watts? Could be the speakers old (but in great shape) and something let go or over excursion? Recone time? Looks like kits are about a 100. (slightly more in Canada...) Thanks
 
#2
Funny, I ran that same rig for years, only in a 215 cab, with no problems at all. If you liked what you were hearing, then I would definitely get it reconed. One of my all time fave JBL 15's, next to the K140. Unless you are turning a lot of knobs all the way to the right, you should not have any problems using the GK.
 
#3
Not sure if those are 200 watts each or not. The important thing is that, like all great speakers from that era, they've probably been played extensively. So, unless they've been re-coned in recent years, they're worn out and will not take much volume. Great speakers when re-coned, and I would re-build in a heart beat. As is always the case, let your ears guide you in usages. both amp and speakers. Mismatching is not fatal. In fact, one of my favorite rigs is a newer Kustom 500 watt head through a 1970 Kustom cab with 2 JBL D140F's. An obvious mismatch, 500 vs. maybe 200, but they sound great.
 
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#5
I don't mean to be a wet blanket, but I've had a hard time liking a JBL E140s sound in any cabinet for bass guitar, and a Caberet box especially.

And yes I played an E140 Cabaret box with bass for a while.

I still have that Caberet box, with a JBL 2226 in it now, and a JBL 2441 mounted on a McCauley short pattern hi-frequency horn. Sitting on top of a RCF 18" powered Bandpass Sub, it makes a fine drum monitor.
 
#6
Thanks for the replies. Getting mixed messages re power handling ability. Thinking they should handle the go as knobs don't make it to twelve o'clock. These actually hung in a small town arena as bass cabs and probably never saw much power a spa was small. They are like mint. Can't picture a 215 jnewmark, you must have had to use a forklift.
Update - just pulled it out of cab and when shook, you can hear a ringing jingling as if a thin metal piece was loose. Dust cap is tight but I carefully removed back plate and can see old foam pieces which probably covered vent hole at one time. Can't tell what is loose. Worst case scenario is surgically remove dust cap and see what's shaking. Something has come loose. Not sure what.
 
#9
This is a driver I am intimately familiar with...

The 200 watt rating is what's refered to as the "continuous" or "thermal" rating, and the 400 watts is the program rating. What needs to be remembered here is that when this driver was designed, there was not a lot of low end extension encountered (or even desired), and since power was expensive, the focus was as much on efficiency as it was on acoustic performance. The giveaway is the short winding height on the voice coil relative to the magentic gap, and also with this class of driver, the magnetic gap tolerances are very, very tight (more on this later). This means that the Xmax is quite small and can EASILY be exceeded at low frequencies. this is a driver that benefits greatly from a steep high pass filter in the mid 30's. Other than the above limitations, it's a really nice sounding driver with a fairly open (and low distortion) low mid to midrange character. It's also well engineered and manufactured.

Now for the hard part... there are a ton of aftermarket recone kits out there, the majority are terrible or worse. Because of the very tight tolerances, and the "buck" formed magnetic field, this type of driver benefits from using the original factory parts. There are also a few really good aftermarket kits available, if your recone tech is a real pro, he will probably know which ones might be suitable as an option (they won't use the crappy ones because they don't want to get stuck doing it again under warranty.

IMO, the best success is using about 200 watts per driver maximum, and a high pass filter set at ~35 - 40Hz (Fdeck is a good choice IMO) and use reasonable, common sense. Or, sell them to somebody who is looking for something like this and move onto a more robust part.
 
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#10
kootenay mellie said:
Thanks for the replies. Getting mixed messages re power handling ability. Thinking they should handle the go as knobs don't make it to twelve o'clock. These actually hung in a small town arena as bass cabs and probably never saw much power a spa was small. They are like mint. Can't picture a 215 jnewmark, you must have had to use a forklift.
Update - just pulled it out of cab and when shook, you can hear a ringing jingling as if a thin metal piece was loose. Dust cap is tight but I carefully removed back plate and can see old foam pieces which probably covered vent hole at one time. Can't tell what is loose. Worst case scenario is surgically remove dust cap and see what's shaking. Something has come loose. Not sure what.
Click to expand...

Actually, back in the day, 215 cabs loaded with JBL E or K 140's were pretty common, along with Peavey 215 cabs loaded with similar drivers. They were not all that bad to move around, until you got to a flight of stairs ! Casters were a must, of course, but, if you had a hatchback vehicle, it was just a matter of roll and tip into the back. I drove around with one in a Plymouth Horizon for years !
 
#11
Haha - our son had an '84 Horizon back in the day - you are probably familiar with the song Horizon by the Arrogant Worms then - if not, you should be.
Thanks agedhorse for the info - lotsa related reading off your info and forays into previous threads and Fdeck info. I wouldn't disagree those drivers were (and still are) good for what existed back then but lots of tech improvements since then. Not convinced its a recone yet as I want to determine what is loose under the dust cap and hampering the throw. I have in the past, thought about the GK biamped feature on the 700-RB and wondering if I should pair it with a GK cabinet - as far as what that looks like - totally different discussion.
 
#12
Probably something else that should be mentioned is the tone of these old JBL MI drivers, especially the K140, which had a very sweet, top end. The only 15 that I have used that even gets close to that sweet tone is the Faital PR400. The E140 has a more harsher tone to my ears, but still a nice top end.
 
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#13
E-140s are killer drivers. I own several of them. I don't believe that any GK amp is capable of destroying them unless you are doing something wrong. On the other hand I could easily blow up any GK driver with a number of different amplifiers.
Does your amp have an impedance matching switch? If so, make sure that you do not overload the output.
A heads up in case you were not aware ..JBL drivers are reverse polarity, in other words, you have to apply a positive bias (instantaneous DC voltage) to the NEGATIVE terminal on the driver to generate forward (or outward cone excursion) of the driver and visa-versa. It is very important to make sure that all of the drivers are in phase when using multiple drivers otherwise you will destroy the one that is wired wrong ..this goes for all multiple driver scenarios.
I do not recommend moving JBL driver cones with your hands as there is only a couple of 1/thousands of an inch tolerance in the field gap for the voice coil windings and they will interfere so it will scrape.
Hope this helps!
 
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#14
kootenay mellie said:
Thinking they should handle the go as knobs don't make it to twelve o'clock....

I carefully removed back plate ....
Click to expand...

Thinking that the position of a knob as anything to do with how much power an amplifier is capable of delivering would be incorrect.

The back plates of JBL drivers are not removable. If you have you may well have destroyed the driver.
 
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#17
Thanks badass. I would agree on the durability of these - I will double check the polarity point - I believe I ran across that when building these a few years ago but will double check that I didn't screw up - no impedance switch that I can see on the 700RB-ll. That was why I floated the question about the amp - driven into two 8 ohm speakers - thought somebody might have a definitive idea of output - as I mentioned the spec says 320 watts but perhaps that's a bit much for those JBL's. Of course I realize the numbers on a pot are not indicative of output wattage - just wanted to illustrate that it wasn't cranked to eleven while playing Proud Mary to a bunch of seniors when the issue started. Actually the back 4 inch aluminum name plate is removable (held on by a dab of glue) and merely exposes the throat and lets you look at the backside of the dustcap (now that the foam filter has deteriorated ) It has no bearing on the operation of the driver.
 
#18
If I had the time, I could tell you for sure but I'm looking at a set of 4 black 2225H's and they have wire mesh screen the grey ones should be the same but they are in cabs. I have a set of E 140-8's and they are all black too but I have one brand new one in the box and I'm sure it's grey. I have not looked at the back of any of these in a long time and I can't remember if they have the slotted labels with the blown out foam or the mesh. the newer ones possibly had black pressed fiber filters instead of the foam. but I know my set of K 140-16's have blown out foam.

The wattage rating is 400 watts continuous program and 200 watts continuous sine wave for the 2225's and the E 140's the K 140's are rated at 300 watts continuous program but those are only ratings that they need to give so you have some idea of what you are dealing with. They can take many times the rated power. I have done it too. I used to have a K 151-8 rated for 300 watts and it handled 800 watts continuous R.M.S. 20-20,00o kHz (and that is way underrated) driven to clipping and the driver's motor didn't even get warm.
 
#20
You will not be able to salvage it if you do. I have seen drivers with them missing. For me, that would be a real pain trying to tell what it is apart from several other sets of JBL 15's. Apparently, the glue that hold the foil plates on is so strong that you can't peel it off without it getting mangled!
 

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