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View Full Version : Good substitute for JBL 033 Tweeters?



kingmetal
07-06-2009, 12:00 PM
A few months ago I found a pair of JBL L40s (two way version) out by the dumpster at my old apartment that are in remarkably good shape. I moved into my new house the last month, finally hooked the speakers up and immediately noticed that the high-end on them sounded harsh to me. It's enough for me to know that something is wrong, but it's not too drastic - I immediately started looking for replacement drivers and I'm finding that replacements for the JBL 033s that should be in this cabinet (I say 'should' because I don't know of these drivers really are 033s!) are hard to find and expensive, as are the 052ti which seems to be officially recognized as the 033 replacement. I've heard rumors that the 052ti is just an Audax tweeter that was rebranded as a JBL and it looks like those are available for a reasonable price - and I've heard even further murmurings that the Morel MDT 33 is a spiritual successor to the 033 (or at least that people have swapped them into their L40s with good success). I'm on a pretty tight budget for this project so I'm not looking to spend much over $50 per tweeter but I'd like to get these speakers back to as close to original spec as I can within reason - can anyone make a good recommendation for tweeter replacements for JBL 033s that aren't terribly expensive?

I'm pretty green when it comes to all this, so no suggestion / advice will offend my intelligence. Thank you for your time!

Fred Sanford
07-06-2009, 02:44 PM
A few months ago I found a pair of JBL L40s (two way version) out by the dumpster at my old apartment that are in remarkably good shape. I moved into my new house the last month, finally hooked the speakers up and immediately noticed that the high-end on them sounded harsh to me. It's enough for me to know that something is wrong, but it's not too drastic - I immediately started looking for replacement drivers and I'm finding that replacements for the JBL 033s that should be in this cabinet (I say 'should' because I don't know of these drivers really are 033s!) are hard to find and expensive, as are the 052ti which seems to be officially recognized as the 033 replacement. I've heard rumors that the 052ti is just an Audax tweeter that was rebranded as a JBL and it looks like those are available for a reasonable price - and I've heard even further murmurings that the Morel MDT 33 is a spiritual successor to the 033 (or at least that people have swapped them into their L40s with good success). I'm on a pretty tight budget for this project so I'm not looking to spend much over $50 per tweeter but I'd like to get these speakers back to as close to original spec as I can within reason - can anyone make a good recommendation for tweeter replacements for JBL 033s that aren't terribly expensive?

I'm pretty green when it comes to all this, so no suggestion / advice will offend my intelligence. Thank you for your time!

Are you thinking that the 033s are damaged? Do the two tweeters sound the same, or is one cabinet souding different than the other? I have 4 speakers here with 033s, and like them so much that I use them as my recording monitors. There is a thread here somewhere on adjusting the 033s, I'll see if I can dig it up to link you to it.

Pretty sure the L40 is the lowest crossover frequency I've ever seen for the 033s (1800Hz), so it's possible these tweeters have lived a hard life. Keep that in mind, though, when looking for replacements- that's a low x-over point for a dome tweeter.

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L40%20ts.pdf

je

Fred Sanford
07-06-2009, 02:46 PM
http://www.audioheritage.org/vbulletin/showthread.php?t=4777

je

kingmetal
07-06-2009, 02:54 PM
Are you thinking that the 033s are damaged? Do the two tweeters sound the same, or is one cabinet souding different than the other? I have 4 speakers here with 033s, and like them so much that I use them as my recording monitors. There is a thread here somewhere on adjusting the 033s, I'll see if I can dig it up to link you to it.

Pretty sure the L40 is the lowest crossover frequency I've ever seen for the 033s (1800Hz), so it's possible these tweeters have lived a hard life. Keep that in mind, though, when looking for replacements- that's a low x-over point for a dome tweeter.

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L40%20ts.pdf

je

Thanks for the reply and the helpful thread link - they both sound the same as far as I can tell, very harsh in the high end and vocals sound like they have just a hint of what might be distortion. They really just sound like they were mistreated over the years (I did find them at a dumpster after all!). I've heard that the L40s have an exceptionally low C/O point and for this reason they are extremely sensitive to loud program, which I suspect was the undoing of the poor 033s in my L40s (assuming that they are 033s!). I will do some more critical listening tonight and make sure that both speakers sound the same and that it's not my amp or anything simple like that.

I've heard fantastic things about the 033s but I really don't think I'd be able to buy another set - are there repair kits available and is it particularly difficult to undertake?

rdgrimes
07-06-2009, 03:39 PM
Thanks for the reply and the helpful thread link - they both sound the same as far as I can tell, very harsh in the high end and vocals sound like they have just a hint of what might be distortion. They really just sound like they were mistreated over the years (I did find them at a dumpster after all!). I've heard that the L40s have an exceptionally low C/O point and for this reason they are extremely sensitive to loud program, which I suspect was the undoing of the poor 033s in my L40s (assuming that they are 033s!). I will do some more critical listening tonight and make sure that both speakers sound the same and that it's not my amp or anything simple like that.

I've heard fantastic things about the 033s but I really don't think I'd be able to buy another set - are there repair kits available and is it particularly difficult to undertake?
I'd blame the XO for what you're hearing. I'd much rather see them XO at 3500 than at 1800. :blink: You can pop them out and check them with an ohm meter to see if they are in spec.

kingmetal
07-06-2009, 04:55 PM
I'd blame the XO for what you're hearing. I'd much rather see them XO at 3500 than at 1800. :blink: You can pop them out and check them with an ohm meter to see if they are in spec.

You know that's actually a good point - 1800 would be pushing more mid-range through those tweeters than my ears are probably used to. Could be a little of both I suppose!

Anyone have any comments on the XO for the L40s and liking / disliking them?

rdgrimes
07-06-2009, 05:41 PM
You know that's actually a good point - 1800 would be pushing more mid-range through those tweeters than my ears are probably used to. Could be a little of both I suppose!

Anyone have any comments on the XO for the L40s and liking / disliking them?
I can't speak directly to the 033, but the 066 is pretty similar. The 066 really starts to crap out below 3500Hz, and even at 3000 you can hear some strain with high power and high volume. Keep in mind I'm hitting them with 350W plus. Many of the small 2-way consumer JBL's use XO points that are way too low, but it's a trade off for the woofs which can't handle mid range either. The problem is that this is exactly the range that effects vocals and instruments the most. And it's why we have 3-way speakers.

The L46 is the best of the small 2-ways. It has an XO at 3000. At best, your L40 will not do well at high volume. If you want to play with these, XO and parts for L46 are cheap and easy to find and might swap in with a minimum of difficulty.

Fred Sanford
07-06-2009, 07:22 PM
I can't speak directly to the 033, but the 066 is pretty similar. The 066 really starts to crap out below 3500Hz, and even at 3000 you can hear some strain with high power and high volume. Keep in mind I'm hitting them with 350W plus. Many of the small 2-way consumer JBL's use XO points that are way too low, but it's a trade off for the woofs which can't handle mid range either. The problem is that this is exactly the range that effects vocals and instruments the most. And it's why we have 3-way speakers.

The L46 is the best of the small 2-ways. It has an XO at 3000. At best, your L40 will not do well at high volume. If you want to play with these, XO and parts for L46 are cheap and easy to find and might swap in with a minimum of difficulty.

The 034 in the L46 might be more readily available, but it's not as good-sounding a tweeter (in my opinion, owning 4 x 033s and 8 x 034s). The 034s, though, will likely be a drop-in replacement if you just want to test, I took the 034s out of my 4401s to put 033s in.

Got any pics of the cabs, so we can see if they're even 033s you have in hand? If you remove them, there should be a stamped model # on the magnet.

je

duaneage
07-08-2009, 12:08 AM
FWIW a tweeter should be crossed over 3 times as high as it's resonant frequency, the minimum is twice as high. Running anywhere near the resonant frequency results in the diaphragm moving way too much, the tweeter's output will be greater but not in a good way. Ultimately they will be damaged by the signal and their power capability is greatly reduced.

Most domes crossed around 3500 to 4500 hz depending on the system and what midrange was used. Think 4 uf with .2 mh of coil across it and 1.2 to 2.4 ohms of resistance with 20 ohms across as well.

kingmetal
07-08-2009, 11:36 AM
Thanks for the replies everybody - I spent a few hours listening to the speakers last night and ran a signal generator through them (2k - 10k sweep and then a sweep from 2k down to 200hz) and I'm beginning to suspect that my ears are fooling me a bit - I could detect no distortion in the tweeters and I think they are actually operating properly. I think the strange cross-over point, coupled with the fact that the speakers are two-way and quite old all tricked me into hearing a problem that may never have existed - although I can't say that I'm thrilled with how these things sound. I'd like to pull the tweeters and see if they are in fact 033s - there is a little damage on the front of the speaker that leads me to believe someone did try to swap the tweeters at one point, but it could just be random damage.

I'm currently lacking an ohm meter, so besides a signal generator is there a better way to objectively tell if my tweeters are working properly?