What Am I Missing ??

[saeman]

Since joining all you JBL nuts on the forum I have read thread after thread on crossovers - rebuilding them, modifying them, aged components, etc. To my knowledge the x-overs in all of my JBL's are original and have not been repaired or updated. My Sovereigns have been with me since new in 1974 and although I have had the LE15A's reconed, the LX5's and N7000's are original. I play the hell out of them and to me they sound great (maybe my hearing is screwed). My question is "WHAT AM I MISSING" by not updating/rebuilding the x-overs. If there is a benefit I want to proceed. I understand that caps go south with age but what about coils and the other misc parts. Bigger question is where can I get the properly rated components to facilitate a meaningful rebuild (certainly not Radio Shack). Your help and opinions would be appreciated. Thanx - Rick

[4313B]

where can I get the properly rated components to facilitate a meaningful rebuild

www.partsconnexion.com

www.solen.ca

www.partsexpress.com

www.gr-research.com

www.percyaudio.com

www.soniccraft.com

www.madisound.com

Requested by Zilch - 5-way binding posts as used in the JBL Ti Series

http://www.northcreekmusic.com/ACCESSORIES.html

[saeman]

Giskard - Thanks for the list of parts sources. You have obviously been at this for a while. What parts are candidates for renewal in the x-overs? Elecrolytic caps are, as I understand, but how about the coils and other parts. Some of the JBL X-overs I have seen have their parts potted with some kind of thick wax looking stuff. What is done with that? (removed/replaced). Should pots be replaced or can they just be cleaned. I have schematics for a few of my x-overs and I know there are others available. Does a guy make a list of "like" components from the schematic and then just cut and replace or do you upsize certain components. To some of you I'm sure that this is not rocket science, having done it many times, but I need an idea of where to start. How about a pair of NIB pro x-overs. Never used but still 20-30 years old. Should I consider ungrading their internals prior to using them? Thanx Guys - Rick

[4313B]

I'm pretty much a wholesale rebuild kind of guy Rick. Many of today's better components won't fit in those cans anyway. One probably shouldn't go stuffing two air core inductors in them no matter how small the inductors might be.

Put the originals in a box somewhere for whatever reason and build new networks. I wouldn't go hacking up original N7000's or LX5's, especially while people on eBay are still willing to pay big bucks for the silly things (I'll be blunt - I consider anything over $20 for them "big bucks". The cans are cool in a retro kind of way but that's about it.).


Biased N7000 filter using all Solen parts (Just an example, use whatever brand you want).
Add a battery, two 3.0 Mohm resistors, input and output connectors, and an L-Pad.

[boputnam]

Put the originals in a box somewhere for whatever reason

Welcome to MY shop...!!

[Mr. Widget]

I play the hell out of them and to me they sound great... "WHAT AM I MISSING" ...

If they sound great why mess with them? It leads to hours of fun, satisfaction, the occasional disappointment , and eventually complete insanity where you find yourself seeking out those platinum diaphragmed mid and high frequency compression drivers blessed by the Dalai Lama which are only available every third leap year.

Don't do it!

Widget

[Zilch]

I'd also build completely new ones, but LX5 used a tapped inductor for attenuation:

http://www.jblproservice.com/pdf/Net...matics/LX5.pdf

SO, I'd need an equivalent circuit schematic to build.

Thus, already departing from the originals, I'd be considering what changes might be made to improve the system, like, is 500 Hz REALLY the optimum crossover frequency for L/M there? Maybe I'd try 3110 instead, at 800 Hz? What's your mid, LE85 or 375?

N7000, I'd just change out the L-pads and put 0.01 uF Theta bypass caps across both 1.5 uF's and see if I liked them any better. Soon's you drill out the rivets to open them up, their resale value goes down, tho.

http://www.jblproservice.com/pdf/Net...tics/N7000.pdf

Or, similarly, build anew. They're cheap....

[saeman]

Thanx for the input. I'm getting closer to understanding what I'm up against to accomplish upgrades. I considered a change on x-over freq between the low and mid but am of the opinion that the components will not support an 800 hz. x-over. Years ago, about 1980 while listening to Sultans Of Swing on two pairs of Sovereigns (one S8R and one S7R), with the house shaking and the outside walls bulging I suddenly lost the high end on one of the S7R's. They were about one year beyond their 5 year factory warranty but JBL repaired the LE85 anyway. Their description of the Problem was "Voice Coil Shattered". They probably didn't know that I pushed them too hard, didn't have enough headroom on the amp and clipped/squarewaved the diaphragm into oblivion. The reason they repaired the driver is that they were having no end of problems with the LE85 when crossed over at 500 on top of the LE15A. I had several conversations with technical on the subject (pre Northridge when they were on Casitas Ave. in LA). The S7R was great until you cranked up the volume. Since the LE15A didn't offer much above 500Hz. they picked the LX5, but the LE85 didn't handle the power well from the 500-800 portion of the signal and they lost a ton of drivers from those customers who were high volume nuts. To my understanding, they honored all the repairs. They did not have the problem in the L200 with it's x-over at 1200. They led me to believe that the 136A/LE85 used in the L300 grew out of these problems. Didn't mean to write a book but wanted to let you know that I have thought about a higher x-over point but if I do there will be a likely hole above 500 using the LE15A. Rick

I'd also build completely new ones, but LX5 used a tapped inductor for attenuation:

http://www.jblproservice.com/pdf/Net...matics/LX5.pdf

SO, I'd need an equivalent circuit schematic to build.

Thus, already departing from the originals, I'd be considering what changes might be made to improve the system, like, is 500 Hz REALLY the optimum crossover frequency for L/M there? Maybe I'd try 3110 instead, at 800 Hz? What's your mid, LE85 or 375?

N7000, I'd just change out the L-pads and put 0.01 uF Theta bypass caps across both 1.5 uF's and see if I liked them any better. Soon's you drill out the rivets to open them up, their resale value goes down, tho.

http://www.jblproservice.com/pdf/Net...tics/N7000.pdf

Or, similarly, build anew. They're cheap....

[Zilch]

You're saying LE 85, so I assume we're talking S7. I'd say you're losing more by the H91 not playin' down there than you would by crossing LE15A at 800 Hz.

Plus, H91 at 500 Hz just sound BAD, in my opinion.

[And I've plenty of them here I don't play for that reason, among others....]

L200's used LE15B for higher mid response, and 1200 Hz crossover frequency, but blew LE85's anyway until the LX16 crossovers received a mandatory upgrage to LX16-A. L200B moved it back down to 800 Hz with 136A woof, and added HF boost for a marginally acceptable two-way.

Even there, H91 doesn't do very well. That's why H92 is preferred for 800 Hz, and used in L300, instead.

The LE15 brochure in the Library says 600 Hz max recommended, but the 2215 data sheet says they're within 3 dB out to 1200 Hz:

[saeman]

I've never sweep tested an LE15A so can not personally vouch for JBL's statement that "it doesn't produce much above 500 Hz. I have heard others claim that the LE15A will go higher. Would be nice to have the long H92 horn but the Sovereign/Olympus cabinets are not deep enough to allow it. They is what they is, I guess.

You're saying LE 85, so I assume we're talking S7. I'd say you're losing more by the H91 not playin' down there than you would by crossing LE15A at 800 Hz.

Plus, H91 at 500 Hz just sound BAD, in my opinion.

[And I've plenty of them here I don't play for that reason, among others....]

L200's used LE15B, of course for higher mid response, but THEY blew LE85's until the LX16 crossovers received a mandatory upgrage to LX16-A. L200B moved it back down to 800 Hz with 136A woof.

The LE15 brochure in the Library says 600 Hz max, but the 2215 data sheet says they're within 3 dB out to 1200 Hz:

[Zilch]

I've never sweep tested an LE15A so can not personally vouch for JBL's statement that "it doesn't produce much above 500 Hz.

I'm challenging that, of course. They said whatever fit their current product offerings at the time, is what.

LE14A they said was good to 1500 Hz concurrently. It wasn't, but they were using it that way in product....

Would be nice to have the long H92 horn but the Sovereign/Olympus cabinets are not deep enough to allow it.

Oh, it'll FIT, all right, so long as you don't mind the big ol' hole in the back with the LE85 stickin' out....

[saeman]

I'd like to agree with you and think the LE15A will produce higher. I have a pair of tall towers that I built to as a test bed to test the S7R/S8R systems, up off the floor in a taller cabinet. I liked the results but the cabs are currently empty. I have the necessary components to put them back together but will have to skunk up 3110's or LX13 to try the 800 Hz. x-over. Even though I don't own S7R's anymore (my Sovs are S8R) I would like to see if there's a noticeable difference. Maybe I can get someone with the necessary equipment to help me determine if the LE15A's fall off before 800. We'll see. As Mr. Widget suggested, I think for now I'll leave the S8R's alone. Sounds like I might be just pissin up a rope. I'll find another system to experiment with x-over upgrades. An earlier question that I asked was - I have a NIB pair of 3107's and will be putting them into my 4350 restorations. Is there any merit in upgrading their components before using them, given they are 20+ years old?? Rick

I'm challenging that, of course. They said whatever fit their current product offerings at the time, is what.

LE14A they said was good to 1500 Hz concurrently.

[Zilch]

An earlier question that I asked was - I have a NIB pair of 3107's and will be putting them into my 4350 restorations. Is there any merit in upgrading their components before using them, given they are 20+ years old?? Rick

I have a couple of those here, too, which I recently used for some testing. The only upgrade I'd consider is to add bypass capacitors to them, but only after I got it all working, to see if they made a difference.

NIB, the L-Pads are likely to be just fine....

[Steve Gonzales]

If they sound great why mess with them? It leads to hours of fun, satisfaction, the occasional disappointment , and eventually complete insanity where you find yourself seeking out those platinum diaphragmed mid and high frequency compression drivers blessed by the Dalai Lama which are only available every third leap year.

Don't do it!

Widget

Here here!!!!.

[saeman]

That's a fairly bold statement. From the info contributed by you and others on my inquiries I've come to several conclusions - 1. There's nothing cut and dry in my thought to update my crossovers. 2. Instead of trying to modify the LX5's and N7000's in my Sovs (and destroy the value they might have by opening them up) I will proceed with the thought of building new x-overs from new components. After doing this I will be able to make an A/B comparison to see "What I'm Missing" if anything. 3. I will pick another pair of x-overs, with the help of someone more knowledgable than I am on the subject, and play around with them to see if parts change outs will make a difference. I think in the future I'll refrain from asking these types of questions on the forum, where I understood that information was freely and willingly shared, for the sake of not offending anyone.

Evidently you didn't pay much attention when you
I went ahead and deleted it for you. It was obviously a waste of my time as usual.