2214 speaker pop

[pathfindermwd]

I had posted awhile back about my L100t's which I had recently purchased, popping at high bass levels. I had received some advice to recone them, which I was hesitant to do because of the cost. I finally did get the recone done with genuine JBL cones, and while I can tell the bass is much tighter and punchier, they will still pop at higher volume/bass levels/sources. I am a little disappointed, am even more baffled. Though I really like the sound and have little doubt about the quality of these speakers, this popping has me really scratching my head. None of my other speakers has ever done this. CF100's, CF150's, and cheaper ones still.

I had hoped that reconing them would be the solution, thinking that and old suspension might be the problem. A few of my friends own these speakers and they report that they will also pop if driven (too) hard. A friend suggests that other speakers will just distort, while these will instead pop. Seems reasonable.

I was hoping someone here might be able to add something more to this, and my general knowledge.

The enclosures are original L100T's, with T3 crossovers, powered by a NAD C375BEE/150w/channel

[Don C]

What signal source is in use when you hear the pop? A turntable?

[Robh3606]

Turn it down a couple of dB if it happens with all sources.

Rob

[pathfindermwd]

What signal source is in use when you hear the pop? A turntable?

No, any source. CD player, computer. This is an over-extension popping. Like when you hook up a 9v battery polarity check and a cone pops in and out to its limit.

[pathfindermwd]

Turn it down a couple of dB if it happens with all sources.

Rob

Hi, thanks Rob, I know, it's what I am forced to do, I just don't understand why the suspensions aren't holding them back from doing this.

[edgewound]

Check to see if the port tubes are still in place.

If they are, you can experiment with tuning the box to a leakage-damped port by stuffing some breathable open-cell foam in the port or some dacron fiber fill. This can prevent the cone from unloading below the tuning frequency of the enclosure...

Or...the spiders have torn loose from the voice coil former.

[pathfindermwd]

Check to see if the port tubes are still in place.

If they are, you can experiment with tuning the box to a leakage-damped port by stuffing some breathable open-cell foam in the port or some dacron fiber fill. This can prevent the cone from unloading below the tuning frequency of the enclosure...

Or...the spiders have torn loose from the voice coil former.

Thanks Edgewound. I checked the spider and it's fine both to the frame and the voicecoil. The original tubes are in place. I will have try the stuffing to see if it helps. Thanks for the the advise.

[Don Mascali]

Perhaps we are talking about the need for a high pass filter?

[DavidF]

I had posted awhile back about my L100t's which I had recently purchased, popping at high bass levels. I had received some advice to recone them, which I was hesitant to do because of the cost. I finally did get the recone done with genuine JBL cones, and while I can tell the bass is much tighter and punchier, they will still pop at higher volume/bass levels/sources. I am a little disappointed, am even more baffled. Though I really like the sound and have little doubt about the quality of these speakers, this popping has me really scratching my head. None of my other speakers has ever done this. CF100's, CF150's, and cheaper ones still.

I had hoped that reconing them would be the solution, thinking that and old suspension might be the problem. A few of my friends own these speakers and they report that they will also pop if driven (too) hard. A friend suggests that other speakers will just distort, while these will instead pop. Seems reasonable.

I was hoping someone here might be able to add something more to this, and my general knowledge.

The enclosures are original L100T's, with T3 crossovers, powered by a NAD C375BEE/150w/channel

Is the "pop" sporadic or more of a machine gun rattle?
What is the woofer doing when the pop occurs? Is there considerable visable motion with the cone? Does the woofer shift in or out and seem to hang in that position?
Has the crossover been altered from original spec, that you are aware of?
Can you swap out amps to check on the power side to confirm the problem is the speaker?
Me thinks the NAD is behaving badly under this load for some reason.

[pathfindermwd]

Is the "pop" sporadic or more of a machine gun rattle?
What is the woofer doing when the pop occurs? Is there considerable visable motion with the cone? Does the woofer shift in or out and seem to hang in that position?
Has the crossover been altered from original spec, that you are aware of?
Can you swap out amps to check on the power side to confirm the problem is the speaker?
Me thinks the NAD is behaving badly under this load for some reason.

Thank you for your reply David. Hmm, well It could be the amp, but a friends L100t does this as well on his own amp. When it pops I see the cone come out to a maximum level, so this leads me to believe that it is an elctronic sound, like when you use a 9v battery for a polarity check, and you get a pop or click. The crossovers came out of a L100s I also bought. The crossover wires to the speakers do not look original as the positive for the woofer is yellow and the negative blue. Whoever had the "S' had also switched the connectors on the tweeter itself. I caught theis one day and checked it against the "T" tweeters, the positive and negative spades on the tweeters were opposite! And you could see that the glue was messy suggesting that there had been some tampering. The "S" had always sounded terrible and we now think this is why. The "T" however sound great with the crossover, much less bright. Edgewound had hit upon something which I think has solved this problem, and I will reply to that in the following post.

[pathfindermwd]

Check to see if the port tubes are still in place.

If they are, you can experiment with tuning the box to a leakage-damped port by stuffing some breathable open-cell foam in the port or some dacron fiber fill. This can prevent the cone from unloading below the tuning frequency of the enclosure...

Or...the spiders have torn loose from the voice coil former.

Edgewound, I am glad you mentioned unloading. Is the ventpole screen/filter part of the restrictive system? Mine was completely deteriorated, just being foam. So I made one of my own from some aluminum screen and thin foam and glued them together to the back of the vent hole. I used the screen just to support the foam, and made sure the foam was very breathable. Hard to believe but I think the problem has been solved! I cranked them up and got no popping! It may have affected the outright output at higher levels, but if it stops the popping, I'm happy.

[robertbartsch]

...get the amp checked since it could be dumping DC into the outputs

[DavidF]

...get the amp checked since it could be dumping DC into the outputs

Agree. The description of the cone maxing at limits of suspension is a telling symptom. I am no electronics guru but this sounds like a problem strictly with the amp. Is this an 15 year or so old solid state? It seems a coindence that your friends system does the same thing. Is he using an older model as well?

If you have a digital mutlimeter you should check for DC at the speaker terminals. No input or speaker connection, amp on, set meter to DC mVolts, probes to each of the speaker terminals on one channel at a time. A reading of more than 50mV is a concern. More than 100 mV a problem.

[Chris Brown]

I've only had this happen a few times with my JBLs.

About 7 years ago I was using my L150's as mains in my home theater, watching Apollo 13 on Laserdisc (PCM audio track with NO dynamic range compression) during the Saturn 5 launch scene. Woofers popped a few times but you could tell the Pioneer SX-1050 I was using at the time was struggling via the faceplate lights dimming...

2nd time was when I had a loose connection on a cable I was using between my preamp and Yamaha P2201 amp, I touched it while the amp was on and it must have shorted for a second. The woofer did more than pop, what came out of my L100T's sounded like someone pushing a bookshelf (with books) down a staircase.

I have not had any issues during "normal" usage while supplying the speakers with good clean power, and I run the speakers pretty hard. My EQ settings are hardly flat, and I regularly measure as high as 133dBC with my meter.

[pathfindermwd]

ok so I finally dug out an old amp, some old JVC receiver. Same thing, it pops. On the JVC I noticed that in loud mode the woofer movement is wild, talk about good vibrations...or err not so good. Given the inability of the JVC to control woofer excursion and the inevitable woofer popping, I think this might have something to do with an under-powered amp.

The NAD on the other hand is maybe a year old. I have not done a DC volt test on it because I am not sure how it is done. How can I test only one channel at a time with the positive and negative on the volt meter (I am going to feel stupid)? But I am kinda leary at the notion of it being a problem with the amp, my CF150's are the "B" channel and they never pop with the same power on the same music, even at 98db sensitivity (and that's brutal output for them). And they used to be switched around, so it shouldn't be that. Why is the notion that popping can occur not being readily acknowledged? Under what conditions is what I feel I am chasing, so I can perhaps address it.

The addition of the foam filter to the vented pole piece has greatly helped, I mean I really have to get toward abuse for it to pop now. I lean towards it being under-powering, though I know this cant be the whole story. These 2214's are kind of an interesting breed because they have a very deep cone. Is this design contributing to this? Does it cause some kind of instability at high excursion?

The ramblings of a mad-man!