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daversa
08-05-2013, 08:53 PM
Hi all,

I recently came across a really clean pair of JBL 4406's on craigslist and it seems like I'm having issues with the tweeters. They sound fine on most music, but with movie dialogue and orchestral pieces I notice a pretty bad fuzz/crackle on the high-end of both speakers. I'm hoping to get a little input on the situation before I go buying new parts.

The tweeters aren't completely blown, it just seems like certain frequencies cause a bad resonance.

If someone could walk me through a troubleshooting process I would really appreciate it!

Thanks,
Dave

Edit: one other note, this rattle is imperceptible at very low volumes.

BMWCCA
08-06-2013, 08:54 AM
Both sides the same and it doesn't happen with any other source? I'd say it's not the speakers.

Or:

If these are the non-A versions, perhaps the L-pads could use some cleaning or at least work them full cycle a few times, without a signal through them, and try again. :dont-know:

daversa
08-06-2013, 09:35 AM
Both sides the same and it doesn't happen with any other source? I'd say it's not the speakers.

Or:

If these are the non-A versions, perhaps the L-pads could use some cleaning or at least work them full cycle a few times, without a signal through them, and try again. :dont-know:

Thanks for the help! Unfortunately it happens on multiple sources. I've tried working the l-pads quite a few times but it didn't seem to help. I'll try cleaning them tonight to see if that helps. Is it possible that a tweeter could partially fail like this? I always thought it was an all or nothing sort of thing.

hjames
08-06-2013, 09:47 AM
Thanks for the help! Unfortunately it happens on multiple sources. I've tried working the l-pads quite a few times but it didn't seem to help. I'll try cleaning them tonight to see if that helps. Is it possible that a tweeter could partially fail like this? I always thought it was an all or nothing sort of thing.

Phil's idea is spot on -
You may have tried with different sources,
but what about trying with a different amplifier?
replace all parts in the chain EXCEPT the speakers and see if the problem goes away.

grumpy
08-06-2013, 10:10 AM
failing the quite reasonable electronics-string-substitution line of thought...
might be "crap in the gap", but repairs along those lines
can prove semi-destructive, so eliminating all other likely culprits
first is a healthy path. Ensuring -all- internal connections are solid is another,
usually simple check.

daversa
08-06-2013, 10:12 AM
Phil's idea is spot on -
You may have tried with different sources,
but what about trying with a different amplifier?
replace all parts in the chain EXCEPT the speakers and see if the problem goes away.

Yeah, I tried the speakers on a completely separate amplifier and input source that normally drives some ADS l300's (that sound great) and it was still happening. It's definitely the speakers.

rdgrimes
08-06-2013, 11:47 AM
My solution would be to grab a 035ti off eBay and see if that fixes one of the speakers. I wouldn't rule out tired crossovers either, but a different tweeter will help you do so. In any case, one can never have too many 035ti sitting around. ;)

daversa
08-06-2013, 11:59 AM
My solution would be to grab a 035ti off eBay and see if that fixes one of the speakers. I wouldn't rule out tired crossovers either, but a different tweeter will help you do so. In any case, one can never have too many 035ti sitting around. ;)

If I don't have any luck cleaning the l-pads I'll probably go this route :). What's the consensus on the Chinese replicas? Also, I noticed there's some people selling the diaphragm only—is that worth pursuing?

Jonis
08-06-2013, 01:23 PM
I recently had a similar problem with L20t's but only on one. Distorted, crackling sound. I changed components with the good one until I narrowed it down to the crossover. Waited for a crossover to come up on eBay and now all is good.:)

daversa
08-06-2013, 01:48 PM
I recently had a similar problem with L20t's but only on one. Distorted, crackling sound. I changed components with the good one until I narrowed it down to the crossover. Waited for a crossover to come up on eBay and now all is good.:)

Ah, wish I had one good one to do the same! :)

rdgrimes
08-06-2013, 02:47 PM
Its probably safe to say that some previous owner has abused these in one way or another. But I think the easiest way to troubleshoot will be with a tweeter. If it fixes the speaker then the crossover is OK. You could also try removing the tweeter and direct connecting to an amp at LOW power, see if you can duplicate the issue using sine waves or HF sweeps.

daversa
08-06-2013, 03:59 PM
Its probably safe to say that some previous owner has abused these in one way or another. But I think the easiest way to troubleshoot will be with a tweeter. If it fixes the speaker then the crossover is OK. You could also try removing the tweeter and direct connecting to an amp at LOW power, see if you can duplicate the issue using sine waves or HF sweeps.

Since this only happens at normal listening volumes (not outrageously loud or anything) is it safe to power it up that loud without a crossover?

macaroonie
08-06-2013, 05:03 PM
Free download from LCH , the tone generator lets you create a very slow sweep across the audio spectrum. Either burn a disc that you can use in a CD player or if you can run from your computer you can nudge the frequency till you nail the resonance. This will let you get a better idea where its coming from. If its definatly the tweet remove it from the cab and run it direct wth the tone and continue your investigations. No bass of any merit will be present in the signal so you are OK
03 series tweets mostly have a foam damping pad behind the diaphragm. These are known to rot and can have debris in places you don't want it.
To get in at the foam remove the inner for retaining screws and the faceplate should pull away from the magnet. There are postings on this subject in the event that it sticks. I think someone used a hair drier to warm the magnet , thereby releasing the 'stick '.

Good luck

BMWCCA
08-06-2013, 05:53 PM
All the talk of swapping out tweeters has me compelled to offer my normal caution when working with the 035Ti that the terminals and the wire connecting them to the diaphragm are extremely fragile. If you even slightly bend the terminals when removing the Faston connectors you can (likely will) sever the wire on the diaphragm or break its connection to the terminal. You can also pull the terminal right out of the plastic housing since they appear to only be glued in-place.

All of this is possibly repairable if you need to and if you are very careful with soldering tools, but paying attention to the experience of others before attempting disassembly is far more satisfying than squeaking out a repair after screwing one up.

No need to ask me how I learned this. :o:

Again, the cheapest way to acquire spare 035Tis is to buy some donor speakers such as L60T. Even a pair of L20Ts can cost less than a pair of 035Tis, though I would consider it heartlessly cruel to part out a working pair.
:hmm:

daversa
08-06-2013, 06:03 PM
All the talk of swapping out tweeters has me compelled to offer my normal caution when working with the 035Ti that the terminals and the wire connecting them to the diaphragm are extremely fragile. If you even slightly bend the terminals when removing the Faston connectors you can (likely will) sever the wire on the diaphragm or break its connection to the terminal. You can also pull the terminal right out of the plastic housing since they appear to only be glued in-place.

All of this is possibly repairable if you need to and if you are very careful with soldering tools, but paying attention to the experience of others before attempting disassembly is far more satisfying than squeaking out a repair after screwing one up.

No need to ask me how I learned this. :o:

Again, the cheapest way to acquire spare 035Tis is to buy some donor speakers such as L60T. Even a pair of L20Ts can cost less than a pair of 035Tis, though I would consider it heartlessly cruel to part out a working pair.
:hmm:

Thanks for the heads-up, I really appreciate it! If I take out the tweeter to test it independently do you think I should just clip the wire instead of trying to pull it off the terminal?

rdgrimes
08-06-2013, 09:25 PM
Since this only happens at normal listening volumes (not outrageously loud or anything) is it safe to power it up that loud without a crossover?

the key is to not feed it anything below its crossover point, hence the suggestion to use sine waves and/or HF sweep tones. There are more than a few free downloads of DVD ISO and assorted other test tones around. I've found that sweep tones usually make it easier to identify issues that are confined to a narrow freq range. But sine wave tones will get you there too, just find the one that triggers it. I'll wager it's somewhere between 5K and 10K.

daversa
08-06-2013, 10:44 PM
the key is to not feed it anything below its crossover point, hence the suggestion to use sine waves and/or HF sweep tones. There are more than a few free downloads of DVD ISO and assorted other test tones around. I've found that sweep tones usually make it easier to identify issues that are confined to a narrow freq range. But sine wave tones will get you there too, just find the one that triggers it. I'll wager it's somewhere between 5K and 10K.


So I got home tonight and tried using some DeoxIt in the L-pads but that didn't really seem to do anything. So I went ahead and pulled one tweeter to test it. It's funny, with a sine wav generator I didn't hear any obviously terrible frequencies, just slight rattles every now and then around 2.1khz and 5khz. But I came up this monstrosity using a Klipsch horn and it sounds way better than the other speaker now. :D
59677

So now that I know the tweeter is the issue I guess I'll try taking it apart and seeing if there is anything obvious I can fix. If anyone could point me to a good 035ti teardown guide I'd appreciate it. Most likely I think I'll end up having to buy new tweeters.

daversa
08-07-2013, 12:07 AM
So I took the tweeters apart and there was probably an 1/8" of foam attached to the bottom of the tweeter dome. Crazy! Also, some of the coils had popped off. I cleaned and fixed everything up and the speakers sound 100x better but I'm still hearing rattles on choral pieces. This song is particularly bad Johann Sebastian Bach – Mass in B Minor - Christe eleison (Duetto) (spotify:track:18T9SdV1C6jWa9Qe6qAntR).

Anyway, I think I'll keep an eye out for new tweeters, but this is at least bearable in the meantime. Thanks for everyone's help!

4343
08-07-2013, 02:11 AM
So I took the tweeters apart and there was probably an 1/8" of foam attached to the bottom of the tweeter dome. Crazy! Also, some of the coils had popped off. I cleaned and fixed everything up and the speakers sound 100x better but I'm still hearing rattles on choral pieces. This song is particularly bad Johann Sebastian Bach – Mass in B Minor - Christe eleison (Duetto) (spotify:track:18T9SdV1C6jWa9Qe6qAntR).

Anyway, I think I'll keep an eye out for new tweeters, but this is at least bearable in the meantime. Thanks for everyone's help!

The foam is probably rotten if it's sticking to the dome. Best to clean it all out and find some new foam. Having the voice coil come apart is never a good sign. As long as you carefully glue it back it should be OK as a trainer, 'cause you know your "new" tweeters off the 'bay will also need foam replacement...

daversa
08-07-2013, 12:03 PM
The foam is probably rotten if it's sticking to the dome. Best to clean it all out and find some new foam. Having the voice coil come apart is never a good sign. As long as you carefully glue it back it should be OK as a trainer, 'cause you know your "new" tweeters off the 'bay will also need foam replacement...

I looked around and I didn't see an obvious "go-to" foam to buy. Do you have any recommendations? Also, do you know if the 035tia or 052ti's have the same foam issue?

4313B
08-07-2013, 02:19 PM
I drove some L65's and L220's with an h/k set like that for a few years.