2214H question

[Boss96]

I hope I'm not beating a dead horse but like I posted previously I find it hard to believe I am bottoming out these woofers with my 100wpc receiver. At this point I have my EQ set to flat, the only EQ I am using now is the loudness compensation on the receiver and that's it. Even so, at about 1/2 volume with the right music I still hear the voice coils hit the magnet occasionally. Is this normal for this woofer?
I removed both of them and looked at the spider assembly, it looks like the spider is a little bit sunken in when looking parallel to the magnet. I would guess perhaps a little less than 1/8". Both look the same. I am guessing the surrounds have been replaced at some point, they are attached behind the cone like they are supposed to be. It's just hard to believe they can't handle the power or have such a limited suspension travel.
Any thoughts?
Thanks,
Bob

[Zilch]

Originally posted by Boss96
It's just hard to believe they can't handle the power or have such a limited suspension travel.
Any thoughts?

The wrong surrounds, perhaps? Take 'em in and have them checked....

[Mr. Widget]

Originally posted by Boss96
...I am bottoming out these woofers with my 100wpc receiver. ... I am using now is the loudness compensation on the receiver...at about 1/2 volume ...I still hear the voice coils hit the magnet occasionally.

100 watts is plenty.

Loudness compensation can add a significant amount of extra bass energy.

Most receivers are designed so that they are putting out full power between 12:00 and 1:00 on the rotation. 12:00 being "half way" is actually very near the maximum and by adding a loudness contour you may actually be clipping your amp.

Without a subsonic filter it is relatively easy to exceed Xmax (bottoming) with a woofer if you are asking it to reproduce frequencies below the tuned frequency of the cabinet.

Widget

[Boss96]

Originally posted by Mr. Widget
100 watts is plenty.

Loudness compensation can add a significant amount of extra bass energy.

Most receivers are designed so that they are putting out full power between 12:00 and 1:00 on the rotation. 12:00 being "half way" is actually very near the maximum and by adding a loudness contour you may actually be clipping your amp.

Without a subsonic filter it is relatively easy to exceed Xmax (bottoming) with a woofer if you are asking it to reproduce frequencies below the tuned frequency of the cabinet.

Widget

Thanks for the quick replies Widget, I understand the amp may be clipping but how could that cause the cone to bottom out? I realize the loudness contour can drive the amp to clipping even sooner at low frequencies but even so, clipping should not matter "mechanically" as far as the woofer is concerned. I had some other woofers (12") before and they simply did not bottom out regardless of the volume on the same amp. The sound would distort, naturally, but that was it. And these were much cheaper woofers with stamped frames, smaller voice coils, and similar surrounds.
Frustrating..
Bob
Oh, forgot to mention, as far as subsonics go, on this relatively new receiver, I do not have a subsonic filter and I'm not using a turntable anyway. But, I did use my EQ to reduce (from flat) signals below 45hz and they would still bottom out. Seems to be in the 60hz range. I would think the box it tuned in the 30-40hz range which should greatly reduce the cone excursion in that range and even help a little up to the 60hz range.

[Robh3606]

When amps clip strange stuff happens. The amp helps control the woofers cone motion. When you clip this all goes out the window you loose that control and can have what amounts to DC pulses mixed in. Needles to say it is not a good thing. Does it happens with the loudness switch off???

Rob

[Boss96]

I'll try it without the loudness comp. but I suppose it will not happen as easily. The only thing about that is they just don't sound good without at least some bass added no matter where I sit or place the speakers. I realize that for some people tone controls are a no-no, but that seems to require a perfect room, placement, and perfect source material.
I will say that these speakers generally sound very good with just the loudness comp, something that is "new" to me compared to other speakers I have had. But with no bass added at all they just are too "thin" to me.
On monday I'm going to see if there are any local JBL dealers in town and bring one for them to see. Maybe sometime in the past they were reconed or repaired incorrectly.
Bob

[Alex Lancaster]

Boss:

Try plugging the port with a sock, if it still does it, Your amp is crazy.

[Boss96]

A sock?? I guess I could try that one but would'nt that negate the tuning of the port and the "limiting" of the cone excursion at the tuned frequency and therefore make the problem worse?
Hmm,
Bob

[Robh3606]

Could you post a picture of one of the woofers??

Rob

[Boss96]

Originally posted by Robh3606
Could you post a picture of one of the woofers??

Rob

Sorry, no camera, will have to borrow one and post it when I can.
Bob

[DavidF]

Do both woofers seem to be the same with this problem?

If so, can you try another amp? You should not use the loudness equalization circuit under high power use with any amp. This will likely cause problems on both the amp side and the speaker side. The 2214s can take a lot of clean power and tempt you to keep upping the power. This may be pushing the amp to current levels where it is not linear, especially with the low end signal boosted.

If not, does the surround on the offender appear concentric, that is it bunched up on one side and seem stretched on the opposite side? Perhaps a sloppy surround repair job.

Do you have the enclosures out in the room or near a wall? You will pick up some mid-bass oomph with them near the wall.

Overall, a lack of bass may be somewhat of an illusion. The L100T has a generally flat response that may SEEM lacking compared to another system with bass emphasis.

If all else fails, take them to a local JBL service center and ask them to run a series of test tones through them to verify the problem is in the speaker(s).

David F

[Boss96]

Surrounds look even, I have done surrounds on speakers myself a few times and know how they can get messed up. Both speakers do the same thing also.
I have another amp at work I can try that has the same power rating I think ( a big Yamaha), I also have a small Hafler power amp I could try with the preamp outs from the current receiver but it is only 60 wpc so it may not be a valid test.
Speakers are against the wall about 6" away from the port.
You guys have me really wondering about the amp though...
Bob

[Zilch]

Few "dealers" are gonna be able to tell if there's anything wrong with the drivers, or if so, what.

You want your nearest JBL Pro Service Center, found from the JBL Pro website, if you want them "checked out."

[Zilch]

Wimpy bass and bottoming out. Donald mentions similar in his LE14A thread. Never bottomed out 2214H's in 4425's, tho I've run them pretty hard on occasion....

What are the symptoms of partial demagnetization? Does the voice coil run away because there's no damping?

I'm not sayin' that's what's going on here; merely asking the question that someone having experience with it might know....

[scott fitlin]

What I have always been told about a woofer with a weak alnico magnet, is that when power is applied to the woofer it will just move forward, and stay leaning forward. Rather than pushing outwards and quickly pulling back!

But, in my experience, some vintage woofers just dont handle very low frequency very well! It is driver dependent, and I had such an experience. We used to use the JBL E-155-8 as the 18,s here, and in the `70,s it was fine! As we moved into the 80,s and the bass in music got heavier, the E155,s would sometimes make a popping sound with a recording with a deep strong bass note. This was the reason for us switching to the 2240H. Now the 2240,s didnt have as much upper bass attack as the 155,s, but the bass was deeper sounding . But, you can pound the 2240,s and they dont bottom, like the E-155,s did! I mean, with some recordings in the 80,s that had a very punchy midbass, but little deep bass, you could push the amps driving the E155,s into clip with no audible problems, but a recording that had deep bass could make the woofers pop easily!

We found it to be more frequency dependent than anything else!