JBL L60 tweeters crackling

[ripa_porcorum]

Hello,

I've recently acquired a pair of old-but-gorgeous JBL L 60 floor-standers (these, not the older, more common, L 60 T).

At low volumes, they sound amazing (to my fairly uneducated ears, at least). But when I turn the volume up, I hear a bunch of crackling and popping sounds coming from the tweeters.

I've been using a tone generator to send signals at specific frequencies to the speakers. Per the specs, the crossover between the mid and the tweeter should be at 2.5 kHz. And, indeed, any tone I send above 2.5 kHz sounds great. But if I send a tone around 500 Hz, the tweeters rattle like crazy, even at fairly modest volumes.

Any ideas as to what I should make of this? I'm wondering if the tweeters should never be seeing those low frequencies at all, and they're only getting through because there's a problem with the crossover. But it seems rather surprising that this should happen on both speakers.

Pointers or suggestions as to what else I should be investigating would be very much appreciated!

 

[Integralista]

Hi ripa, just to be shure, your amp is in good condition? If speakers show both the same behaviour, there can be also something with your amp. Try other amp, if the problem with speakers will repeat and let us know.

 

[Gray]

I've been using a tone generator to send signals at specific frequencies to the speakers.

Presumably after you'd heard cracky and popping on music?

if I send a tone around 500 Hz, the tweeters rattle like crazy, even at fairly modest volumes.

Hopefully you haven't been sending tones at excessively high volume and / or for prolonged periods 🤨

Obviously you've checked that all of the mounting screws are tightened 🤔......

 

[ripa_porcorum]

Thanks both for your help!

Hi ripa, just to be shure, your amp is in good condition? If speakers show both the same behaviour, there can be also something with your amp. Try other amp, if the problem with speakers will repeat and let us know.

As far as I can tell the amp is in good condition, and works properly with other speakers. Unfortunately I don't have another handy for a comparison; I'll see if I can track one down.

Presumably after you'd heard cracky and popping on music?

Hopefully you haven't been sending tones at excessively high volume and / or for prolonged periods 🤨

Yes, after I'd been wondering why the nice piece of Satie I'd been listening to to enjoy my new speakers had sounded crackly when I turned the volume up. And just for long/loud enough to hear the tweeters sounding unhappy, so hopefully no bad side effects.

Obviously you've checked that all of the mounting screws are tightened 🤔......

👍

 

[ripa_porcorum]

As far as I can tell the amp is in good condition, and works properly with other speakers. Unfortunately I don't have another handy for a comparison; I'll see if I can track one down.

Actually, I remembered we had an old mini system in storage, so I dug it out and wired it up to these speakers. And sure enough... the tweeters are still crackling, in just the same way.

 

[nopiano]

And, indeed, any tone I send above 2.5 kHz sounds great. But if I send a tone around 500 Hz, the tweeters rattle like crazy, even at fairly modest volumes.

The tweeters shouldn’t receive any electrical signal below the crossover frequency. That’s what the crossover does. It stops the tweeters being blown by lower frequencies they cannot cope with.

Tweeters don’t rattle, unless someone took the fastening screws out. They might buzz or tizz, but rattling is something else.

As Gray cautions, go easy on the test tones or you’ll completely destroy the tweeters in a trice.

More cautious investigation needed. Where exactly is this noise coming from? Are you sure it’s not from the woofers/mid-range drivers!

Welcome to the forum! 🙂

 

[Gray]

....I'm a bit concerned about the previous owner - what he might have done / known.

 

[ripa_porcorum]

The tweeters shouldn’t receive any electrical signal below the crossover frequency. That’s what the crossover does. It stops the tweeters being blown by lower frequencies they cannot cope with.

That's what I've understood, but it's not a sharp cutoff, right? There's some reduction of power as a function of frequency, so conceivably a strong enough signal at lower frequencies could still cause the tweeter to do... something. (Sorry, I'm new to this, and I'm learning as I go!)

But this was my initial thought — if the crossover should be blocking low frequencies from the tweeter, and if the tweeter makes noises when I feed the speaker low frequencies, does that mean the crossover is broken? (On both speakers?! 🤔)

Tweeters don’t rattle, unless someone took the fastening screws out. They might buzz or tizz, but rattling is something else.

Understood — my bad vocabulary!

As Gray cautions, go easy on the test tones or you’ll completely destroy the tweeters in a trice.

Did I mention the “learning” bit? I appreciate the advice!! 😊

More cautious investigation needed. Where exactly is this noise coming from? Are you sure it’s not from the woofers!

So in an attempt to address this, and to avoid tripping over my bad descriptions, I made a recording — find it on YouTube. From my phone, so apologies for the woeful quality. For the first 25 seconds or so, I held the phone right in front of the tweeter. You'll hear the succession of “clicks” — that's what's bothering me. After that, I held it for a few seconds each in front of the other two drivers. No clicks to be heard.

Welcome to the forum! 🙂

Thank you! It's great to see a bunch of folks already providing useful suggestions and correcting my misapprehensions & bad ideas! Hope I can contribute back at some point.

 

[nopiano]

So in an attempt to address this, and to avoid tripping over my bad descriptions, I made a recording — find it on YouTube. From my phone, so apologies for the woeful quality. For the first 25 seconds or so, I held the phone right in front of the tweeter. You'll hear the succession of “clicks” — that's what's bothering me. After that, I held it for a few seconds each in front of the other two drivers. No clicks to be heard.

Ok, thanks for that. I listened. What is the source: CD, LP, something else?

Yes, I hear the distortion, which sounds a bit like mistracking from a record. It’s very clear from the tonal balance when you move away from the tweeter at about 30 seconds, then a few seconds later to the bass unit.

 

[twinkletoes]

That's what I've understood, but it's not a sharp cutoff, right? There's some reduction of power as a function of frequency, so conceivably a strong enough signal at lower frequencies could still cause the tweeter to do... something. (Sorry, I'm new to this, and I'm learning as I go!)

But this was my initial thought — if the crossover should be blocking low frequencies from the tweeter, and if the tweeter makes noises when I feed the speaker low frequencies, does that mean the crossover is broken? (On both speakers?! 🤔)


Understood — my bad vocabulary!


Did I mention the “learning” bit? I appreciate the advice!! 😊


So in an attempt to address this, and to avoid tripping over my bad descriptions, I made a recording — find it on YouTube. From my phone, so apologies for the woeful quality. For the first 25 seconds or so, I held the phone right in front of the tweeter. You'll hear the succession of “clicks” — that's what's bothering me. After that, I held it for a few seconds each in front of the other two drivers. No clicks to be heard.


Thank you! It's great to see a bunch of folks already providing useful suggestions and correcting my misapprehensions & bad ideas! Hope I can contribute back at some point.

This is all getting a bit complicated

Quite simply they have been over driven at some point or if they are bi wirable maybe have been wired up wrong at some point, I did this in my youth and trashed the tweeters and main drivers, sounded like Rice krispies, they would still make sound and sounded "nice" but they would tick and pop at idle and sound bit rough on top and down low .

I'd say source a new tweeter and check the other drivers for signs of over drive.

 

[ripa_porcorum]

Thanks both for your thoughts!

Ok, thanks for that. I listened. What is the source: CD, LP, something else?

In that case, S/PDIF coming from my laptop. I hear the same effect with Airplay streaming from my phone, though.

Quite simply they have been over driven at some point or if they are bi wirable maybe have been wired up wrong at some point,

Ugh. That's obviously not what I wanted to hear, but thank you nonetheless!

 

[Jasonovich]

Hello,

I've recently acquired a pair of old-but-gorgeous JBL L 60 floor-standers (these, not the older, more common, L 60 T).

At low volumes, they sound amazing (to my fairly uneducated ears, at least). But when I turn the volume up, I hear a bunch of crackling and popping sounds coming from the tweeters.

I've been using a tone generator to send signals at specific frequencies to the speakers. Per the specs, the crossover between the mid and the tweeter should be at 2.5 kHz. And, indeed, any tone I send above 2.5 kHz sounds great. But if I send a tone around 500 Hz, the tweeters rattle like crazy, even at fairly modest volumes.

Any ideas as to what I should make of this? I'm wondering if the tweeters should never be seeing those low frequencies at all, and they're only getting through because there's a problem with the crossover. But it seems rather surprising that this should happen on both speakers.

Pointers or suggestions as to what else checked should be investigating would be very much appreciated!

Daft or perhaps an obvious question, have you checked the JBLs tweeter frequency range?
Perhaps the manual will indicate the best operational frequency for the tweeters?

 

[ripa_porcorum]

Daft or perhaps an obvious question, have you checked the JBLs tweeter frequency range?
Perhaps the manual will indicate the best operational frequency for the tweeters?

The manual says the crossover is at 2.5 kHz, which I assume is appropriate for the tweeters. The tweeters themselves are JBL 050 Ti, but I've not yet found any more information about them.

 

[Gray]

The tweeters themselves are JBL 050 Ti, but I've not yet found any more information about them.

The only information you need is whether you can buy a couple of new ones.

I reckon there are 3 possibilities with that previous owner:

1) He was one of those strange people that see no harm in using tone controls - set to maximum.

2) He was using an underpowered amp - and running it into clipping, causing overheated voicecoils....and the result you've inherited.

3) He enjoyed listening to test tones as much as you do 😉

Contact JBL, Harman or whoever currently owns them about tweeter availability.
Just ensure you reconnect with the correct polarity.
They might have different sized tags for + and - (in which case you can't go wrong).

 

[ripa_porcorum]

Thank you all! Not the ideal outcome from my point of view, but I really appreciate your help in getting here!

 

[nopiano]

Hang on a minute….!

I think you/we have headed rather hastily a long way down the ‘replace the tweeter’ route without eliminating all the possibilities.

In your initial post you said a 500Hz signal makes the tweeters rattle. We have narrowed that down to crackling per your recording. And you’re certain the distortion is from the tweeters only, yes?

Ok, so how does 500Hz get to the tweeters? As you surmised in the OP the crossovers must be letting something through. Sure, a crossover is not a ‘brick wall’ filter, but 500Hz is more than two octaves below the crossover frequency. At 500Hz the spec says the mid-range driver should be functioning. (as it crosses to mid from bass at 125Hz).

I’m therefore wondering if the crossovers are way out of spec, which isn’t a total surprise on 30 year old speakers. Or the mid drivers are crackling.

If the former, than any new tweeters will soon get destroyed too. If the latter, then new tweeters won’t fix anything.

Do you have a Hi-Fi store you can try them in?

Unfortunately I couldn’t find a manual for your L60 in the link you provided in post #13 . The point being the biwire terminals might allow for more specific driver testing. How many binding posts are fitted because a 3-way would typically have six, a pair for each driver? That is, tri-wired!

 

[Gray]

Hang on a minute….!

I think you/we have headed rather hastily a long way down the ‘replace the tweeter’ route without eliminating all the possibilities.

In your initial post you said a 500Hz signal makes the tweeters rattle. We have narrowed that down to crackling per your recording. And you’re certain the distortion is from the tweeters only, yes?

Ok, so how does 500Hz get to the tweeters? As you surmised in the OP the crossovers must be letting something through. Sure, a crossover is not a ‘brick wall’ filter, but 500Hz is more than two octaves below the crossover frequency. At 500Hz the spec says the mid-range driver should be functioning. (as it crosses to mid from bass at 125Hz).

I’m therefore wondering if the crossovers are way out of spec, which isn’t a total surprise on 30 year old speakers. Or the mid drivers are crackling.

If the former, than any new tweeters will soon get destroyed too. If the latter, then new tweeters won’t fix anything.

Do you have a Hi-Fi store you can try them in?

Unfortunately I couldn’t find a manual for your L60 in the link you provided in post #13 . The point being the biwire terminals might allow for more specific driver testing. How many binding posts are fitted because a 3-way would typically have six, a pair for each driver? That is, tri-wired!

I could be wrong, but on his music it did sound like a little crackle from the tweeter (which I think he said is also present from a mini system he's tried).

Not sure what's generating the '500Hz' tone - have to wonder how pure that might be 🤔

 

[ripa_porcorum]

Hang on a minute….!

I think you/we have headed rather hastily a long way down the ‘replace the tweeter’ route without eliminating all the possibilities.

In your initial post you said a 500Hz signal makes the tweeters rattle. We have narrowed that down to crackling per your recording. And you’re certain the distortion is from the tweeters only, yes?

As certain as I can be. See the recording above; I can replicate the same results any time I hear a crackle.

Do you have a Hi-Fi store you can try them in?

There are some local shops, but they're pretty focused on selling gear that is substantially outside my budget (at least, based on their websites). I'll drop them a line and ask if they can help, but I imagine they have better (or more lucrative!) things to do than worry about my 25+ year old speakers!

Unfortunately I couldn’t find a manual for your L60 in the link you provided in post #13 . The point being the biwire terminals might allow for more specific driver testing. How many binding posts are fitted because a 3-way would typically have six, a pair for each driver? That is, tri-wired!

Sorry for that. Hopefully these links work better:

Instruction manual: https://user.fm/files/v2-679d0972cd98ff878649f70770a6436f/L Series Instruction Manual.pdf
Technical manual: https://user.fm/files/v2-c21e055693b1adde8e4d7dc928ddaf42/L60 Service Manual.PDF

The speakers have four binding posts. If I only connect my source to the high-frequency inputs, I hear the crackling. If I connect it to the low frequency inputs, no crackle.

I could be wrong, but on his music it did sound like a little crackle from the tweeter (which I think he said is also present from a mini system he's tried).

Not sure what's generating the '500Hz' tone - have to wonder how pure that might be 🤔

I used https://apps.apple.com/us/app/tone-generator-audio-sound-hz/id1206449238, running both on a laptop (connected by S/PDIF) and a phone (connected by Airplay). You're right, of course; I can't vouch for how pure the output is.

Thanks again to everybody for your help & suggestions — much appreciated!

 

[nopiano]

The speakers have four binding posts. If I only connect my source to the high-frequency inputs, I hear the crackling. If I connect it to the low frequency inputs, no crackle.

Ok, that was the key point, I think. I’d still be concerned the LF might still reach any new tweeters, which could then become an expensive replacement.

The only other possibility with a direct PC connection is that some other unwanted noise is reaching the speakers, but that’s impossible to know for sure. The app looks pretty nifty!

 

[My2Cents]

"The speakers have four binding posts. If I only connect my source to the high-frequency inputs, I hear the crackling. If I connect it to the low frequency inputs, no crackle."

This makes me think that you don't have any bridging bars connecting the 2 red terminals and the 2 black terminals?
If bridging bars are in place then it shouldn't make any difference whether you use the HF or LF inputs.
Unless the crossover is screwed.

Tweeter for JBL L5, L7, L60, L80, 4410, 4412, Others, T-035Tia | eBay

Also replaces the 037Ti and 052Ti. The instructions and Youtube video made things very easy to follow. I now have a fully functional 2002 Toyota Avalon subwoofer! No more sound only in the front, now I can enjoy the whole JBL experience!

www.ebay.co.uk

 

[ripa_porcorum]

This makes me think that you don't have any bridging bars connecting the 2 red terminals and the 2 black terminals?

Well, I didn't when I was running that experiment, because I took them out. 😄 Totally worthwhile checking, but I am comfortable with how that works.

Thanks again to everybody for their help & suggestions!