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caddisgeek
09-24-2009, 09:44 PM
Hi all. Iíve been a lurker here for a while but now it is time for me to start posting.

About 6 months ago I acquired a pair of large JBLís from a guy selling his late fathers hi-fi gear. The speakers are loaded with LE15B woofers, 375 compression drivers with short horns and lenses, 075 bullet tweeters, LX5 and N7000 crossovers. The cabs are c37 (not sure if they are originals or home made. All the red wax seals are still in place.

I really like these speakers, and have no intention of parting them out (the reason I got them so cheaply is that he knew they were going to a good home so, it would be very disrespectful to pull them apart and make a profit (I know how much these are worth, my wife however does not!).

So does anyone have suggestions on how to get the best out of these speakers? Should I get the 375ís/075ís serviced, replace the crossovers, internal wiring, damping/bracing? Iím open to any suggestions, and looking forward to your replies

Cheers
Steve

hjames
09-25-2009, 07:57 AM
What's prompting you to consider an upgrade or refurb?
Is there something about the sound that you like or don't like?
People's tastes vary so much its hard to just give a blanket response to a wide-open question like that.
Plus, every tweak begets another tweak ... how technical are you?


Hi all. I’ve been a lurker here for a while but now it is time for me to start posting.

About 6 months ago I acquired a pair of large JBL’s from a guy selling his late fathers hi-fi gear. The speakers are loaded with LE15B woofers, 375 compression drivers with short horns and lenses, 075 bullet tweeters, LX5 and N7000 crossovers. The cabs are c37 (not sure if they are originals or home made. All the red wax seals are still in place.

I really like these speakers, and have no intention of parting them out (the reason I got them so cheaply is that he knew they were going to a good home so, it would be very disrespectful to pull them apart and make a profit (I know how much these are worth, my wife however does not!).

So does anyone have suggestions on how to get the best out of these speakers? Should I get the 375’s/075’s serviced, replace the crossovers, internal wiring, damping/bracing? I’m open to any suggestions, and looking forward to your replies

Cheers
Steve

Mr. Widget
09-25-2009, 09:23 AM
Hi all. I’ve been a lurker here for a while but now it is time for me to start posting.

About 6 months ago I acquired a pair of large JBL’s from a guy selling his late fathers hi-fi gear. Welcome and congratulations.

If the 375 drivers have been babied, they may be fine... If they have seen a lot of use, the diaphragms will be worn out and they will not sound as they should.

I am not a fan of those woofers or tweeters so I am not the one to ask about them, but as you have undoubtedly noticed, there are many here who cherish them.

Beyond that I'll echo Heather's comments above.


Widget

dwight8
09-26-2009, 04:18 AM
got any pixs?

caddisgeek
09-26-2009, 09:43 PM
Like I said I really like these speakers, my main criticism is a lack of "sparkle" in the high end (compared to the EMITS in my Infinity RSb's) for want of a better term.

They also lack the sound stage of my Infinities

But like a lot of people into audio, I like to tinker and tweak, to get the most out of my gear.

I'll post some pic's later

hjames
09-27-2009, 07:09 AM
About 6 months ago I acquired a pair of large JBL’s from a guy selling his late fathers hi-fi gear. The speakers are loaded with LE15B woofers, 375 compression drivers with short horns and lenses, 075 bullet tweeters, LX5 and N7000 crossovers. The cabs are c37 (not sure if they are originals or home made. All the red wax seals are still in place.

I really like these speakers, and have no intention of parting them out (the reason I got them so cheaply is that he knew they were going to a good home so, it would be very disrespectful to pull them apart and make a profit (I know how much these are worth, my wife however does not!).

So does anyone have suggestions on how to get the best out of these speakers? Should I get the 375’s/075’s serviced, replace the crossovers, internal wiring, damping/bracing? I’m open to any suggestions, and looking forward to your replies

Cheers
Steve

Like I said I really like these speakers, my main criticism is a lack of "sparkle" in the high end (compared to the EMITS in my Infinity RSb's) for want of a better term.

They also lack the sound stage of my Infinities

But like a lot of people into audio, I like to tinker and tweak, to get the most out of my gear.

I'll post some pic's later

Consider swapping a pair of slot tweeters (077 - or the pro version 2405) in place of the 075 bullet tweeters. That should extend your high end and get you some sizzle/sparkle.

BMWCCA
09-27-2009, 07:42 AM
Consider swapping a pair of slot tweeters (077 - or the pro version 2405) in place of the 075 bullet tweeters. That should extend your high end and get you some sizzle/sparkle.Will they really? I thought they all shared the same diaphragms? (http://www.audioheritage.org/vbulletin/showthread.php?t=6368) I always found the 075 to be pretty "sparkly" on it's own. Did we ever determine if what Steve has is working properly, or if the crossovers needed a rebuild, or if the L-pads were shot, or even set properly? Any of those can account for a drop in 075 output. 075/076/077 should all extend beyond what any of us can hear, if they're working properly. Or maybe Steve's ears (and brain) have been conditioned over the years by those EMIT ribbons? :dont-know

Mr. Widget
09-27-2009, 10:12 AM
Will they really? I thought they all shared the same diaphragms? There are three distinct diaphragms for the 075/2402, 076/2403, 077/2405.

To my ears the 077 has more sparkle and the 075 has more zing... not sure if my attempt at using words to describe sounds will work for others...

Beyond that, due to the high frequencies that these devices reproduce, their electro mechanical tolerances need to be quite tight. Poor assembly/reassembly or excessive wear have enormous effect on their performance. i.e. old tweeters will unlikely sound as good as new ones. A proper rebuild should always be seriously considered if you are serious about the sound.


Widget

BMWCCA
09-27-2009, 10:20 AM
To my ears the 077 has more sparkle and the 075 has more zing... not sure if my attempt at using words to describe sounds will work for others...

Correct, of course, as the link in my last post to your explanation clearly indicates! I should have said all three can use the same diaphragms. So then would a reasonable option for Steve be to update his 075s by replacing their current 075 diaphragms with the "sparkling" ones for the 077 to get more of what he's looking for? Is that a better/cheaper path then just buying a pair of 2405s? This assumes the N7000s are working as designed.

toddalin
09-27-2009, 11:08 AM
Correct, of course, as the link in my last post to your explanation clearly indicates! I should have said all three can use the same diaphragms. So then would a reasonable option for Steve be to update his 075s by replacing their current 075 diaphragms with the "sparkling" ones for the 077 to get more of what he's looking for? Is that a better/cheaper path then just buying a pair of 2405s? This assumes the N7000s are working as designed.

We've been through this.

While there are some who say that the 077 diaphram will fit (and work) in an 075, there are many (including some LHF members and Orange County Speaker) who have encountered a fit interference where the phase plug meets the diaphram around its perimeter. I made this work by making my own shims that would alleviate any such interference.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/shim1.jpg
http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/Concrete_Rocks/Shim2.jpg

I tested the "bastard" and documented it all here, but these data were subsequently removed from the Forum and you will have to go elsewhere to find these data. The results showed that this did extend the HF of the 075, and produced a flatter curve over 8 kHZ.

In my subsequent testing, I came up with the elastomeric filter for use on the 075. The filter extended the high frequency such that with the 077 diaphram, I could get the 075 to play higher and smoother than the 077 (above 10 kHz) with greater dispersion than a standard 075 (though not to the extent of the 077).

Toward the end of the run JBL did produce some 2402s that used the 2405 diaphrams (2402-5), but these seem to be few and far between no one seems to know if the phase plugs vary from the standard 075 fare. Someone on this forum showed he had some of these at the time.

caddisgeek
09-27-2009, 03:56 PM
Did we ever determine if what Steve has is working properly, or if the crossovers needed a rebuild, or if the L-pads were shot, or even set properly?

Or maybe Steve's ears (and brain) have been conditioned over the years by those EMIT ribbons? :dont-know


When I got the speakersm the crossovers needed a shot of de-oxit to get one of the tweeters working. (btw what does the control on the N7000 do?)

As for the EMIT's, I've had the JBL's longer than the Infinites, so when I started running the RSb's, that swhen I started noticing deficiencies in the JBL's (even though I like them better than the Infinites)

Heres a pic

roads31
09-28-2009, 10:25 AM
Hi Steve,

My experience with old JBL systems is that they crossovers need to be rebuilt. What I have done and strongly suggest is that you shelve the originals and build a replacement with quality components. You don't need to go over the top and buy $30 caps for a vast improvement. There are several threads here about components, if you've tinkered before you may have already come across caps you like.

Enjoy

caddisgeek
09-29-2009, 04:18 AM
Hi Roads, thanks for your reply. That's one thing I've been thinking of (I've considered selling the crossovers to fund building new ones)

Main problem is my lack of ability to read a schematic, and I understand that some parts are unavailable

Cheers
Steve

Beowulf57
09-29-2009, 06:32 AM
When I got the speakersm the crossovers needed a shot of de-oxit to get one of the tweeters working. (btw what does the control on the N7000 do?)

HF level control.