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saeman
05-05-2005, 08:26 PM
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
05-06-2005, 05:27 AM
where can I get the properly rated components to facilitate a meaningful rebuild

www.partsconnexion.com (http://www.partsconnexion.com/)

www.solen.ca (http://www.solen.ca/)

www.partsexpress.com (http://www.partsexpress.com/)

www.gr-research.com (http://www.gr-research.com/)

www.percyaudio.com (http://www.percyaudio.com/)

www.soniccraft.com (http://www.soniccraft.com/)

www.madisound.com (http://www.madisound.com/)

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

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

saeman
05-06-2005, 05:58 AM
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
05-06-2005, 06:54 AM
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
05-06-2005, 07:47 AM
Put the originals in a box somewhere for whatever reason Welcome to MY shop...!! :banghead:

Mr. Widget
05-06-2005, 09:42 AM
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!:bs:

Widget

Zilch
05-06-2005, 10:10 AM
I'd also build completely new ones, but LX5 used a tapped inductor for attenuation:

http://www.jblproservice.com/pdf/Network%20Schematics/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/Network%20Schematics/N7000.pdf

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

saeman
05-06-2005, 03:12 PM
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. http://audioheritage.org/vbulletin/images/smilies/banghead.gif Rick




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

http://www.jblproservice.com/pdf/Network%20Schematics/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/Network%20Schematics/N7000.pdf

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

Zilch
05-06-2005, 03:41 PM
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
05-06-2005, 04:07 PM
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. http://audioheritage.org/vbulletin/images/smilies/smile.gif




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
05-06-2005, 04:15 PM
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.... :p


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.... :D

saeman
05-06-2005, 04:30 PM
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. :p

Zilch
05-06-2005, 04:36 PM
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?? RickI 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
05-06-2005, 08:35 PM
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!:bs:

Widget Here here!!!!. :applaud:

saeman
05-06-2005, 09:13 PM
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.

johnaec
05-06-2005, 09:14 PM
Naw, *I* grabbed 'em ALL! :DThanks! I was gonna' grab them myself for a collection of links I someday hope to get posted here. I'll have to get them from you.

Giskard - some might not appreciate what you post, but others here definitely like to see the info! Please leave the stuff up if it's good... :o:

John

Zilch
05-06-2005, 09:30 PM
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.There's lotsa other options to consider, as well, like N200B for two-way, or N333 equivalents if you're gonna use a tweeter, too.

If you find LE15A will play up to 1 kHz, a whole bunch more alternatives open up. I've never tried to see how far I could push LE15A, but I have a freshly refoamed one here I could pop in a B380 to try, maybe.... :p

There's "Hours of fun, satisfaction, the occasional disappointment , and eventually complete insanity" to be had here. It jus' don't GET no better! :bouncy:

4313B
05-07-2005, 03:32 AM
Please leave the stuff up if it's good...The moderators restored it as per your request. I added Zilch's requested link.

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??At the very least install bypass capacitors as per every other JBL network since the L110A. I'd use the 4355 network unless you're starting a museum. I recently went to the trouble of redoing an equivalent network (no tapped autotransformers) for it. The schematic is around here somewhere.

***

Here they are:

Here's the stock 3155 (http://www.jblproservice.com/pdf/Network%20Schematics/3155%20Network.pdf) schematic for reference. Absurdly cheap and effective filter to build for what the system is.

4313B
05-07-2005, 03:33 AM
New simplified equivalent circuit for 375/376/2440/2441 compression driver in JBL 4355 Studio Monitor.

Two things

- the DCR's of the coils should be as low as possible - in other words you can use the best coils you can find without fear of jacking up the passband.

- the resistors should probably be ganged. I figured you could calculate the power ratings of the resistors easily enough so I didn't bother.

*****

Circuit is looking for a 16 ohm L-Pad between it and the driver.

4313B
05-07-2005, 03:35 AM
New simplified equivalent circuit for 077/2405 ring radiator in JBL 4355 Studio Monitor.

This high pass is extremely tight! I'd go as tight as possible on tolerances.

*****

Circuit is looking for an 8 ohm L-Pad between it and the driver.

saeman
05-07-2005, 08:19 AM
To all of you guys who have piped up in response to my inquiries - Thanks but please be aware that you may have to nurse me through some of this stuff as it's all new to me. Please know that before you offer to help as I don't want to be a thorn in anyone's side. Remember, this is supposed to be fun. The idea of custom x-overs is new to me. I've been just a plug and play JBL'er and never given any thought to the electronics inside. If you guys decide to power your amps using a nuclear power plant let me know, I built them, ran them and fixed them for 20 years. If you need some metal fab work done let me know, I have a mill, lathe and 3 welders and there's not much that I can't build. If you need to know about mixed gas technical scuba diving, let me know as diving is a passion of mine right next to vintage audio. If you need your car washed, waxed or oil changed, come see me. That's what I do to support my family. I'm not an expert at speaker enclosure design but I can build one like you're never seen. I can take a pile of parts and a schematic and solder like a big dog - but that's where my electronic talents end. I do know the difference between a coil and a cap but circuit design is not my bag. http://audioheritage.org/vbulletin/images/smilies/bouncy.gif

4313B
05-07-2005, 08:34 AM
If you guys decide to power your amps using a nuclear power plant let me know, I built them, ran them and fixed them for 20 years.I'm interested in a personal sized power plant of the nuclear variety, something I can wheel around in the back yard or take camping if desired.

saeman
05-07-2005, 08:40 AM
I knew that would come back on me !!! When you get your license from the Nuclear Regulatory Commission to handle nuclear fuels/materials, let me know and we'll get started. "On every bus, there rides at least one bozo". I'll take the seat today. http://audioheritage.org/vbulletin/images/smilies/smile.gif




I'm interested in a personal sized power plant of the nuclear variety, something I can wheel around in the back yard or take camping if desired.

4313B
05-07-2005, 08:46 AM
Personal Pan Pizza -> Personal Data Assistant -> Personal Power Plant (Nuclear)

Seems like a natural progression to me... :dont-know

johnaec
05-07-2005, 08:48 AM
Being technically minded, in the past I often thought a small reactor in a closed system to power cars would be a great answer to the energy crisis. Of course, you'd have to encase it in something that would survive a train wreck...

John

4313B
05-07-2005, 08:51 AM
Being cartoon minded, how much nuclear material are we talking to replace the 9V battery in a biased network? If it blows how big will the mushroom cloud be? 6" high? 12" high?

johnaec
05-07-2005, 09:04 AM
If it blows how big will the mushroom cloud be? 6" high? 12" high?:applaud: :dont-know :crying: :bomb:

John

Earl K
05-07-2005, 09:23 AM
Hmmmm,

One goes away, a train derails / is then re"tracked" / and no-one knows how many were taken to hospitals :o: .

- Rick , as Giskard said early on its' worth ones' time just to rebuild from the ground up ( at least one channels worth ) a passive crossover setup / at least to see if one has been robbed of lost resolution for years & years worth of HiFi listening . ( Okay those are now my own words ) .

- The cost of this voyage for a DIY discovery is miniscule ( as Giskard obviously was spending some of his time documenting for you ) when stacked against the expensive "off-the-shelf" Solution of the Month that the magazines are littered with .

- Now, I don't care nearly as much as say, a guy like Giskard that you make this discovery / so I'm not going to waste a lot of evangelical breath on the topic to see if I can change your inertia. I will eventually provide some search links &/or links to the topics I'm about to mention ..

- Some specific areas that have increased sonic resolution in my own listening situation ; ( in order of my opinion on their efficacy or return on "satisfaction" investment)

(i) DC Biasing Capacitors ( Charge-Coupling )
(ii) "Trans-Capping" / or Bi-Passing Caps with different or better types.
(iii) Inductor Swaps to the "better" types vs the laminar/ferrite core types that are sometimes found in JBL crossovers. ( I have little to no hands-on experience doing this inductor swap thing since I've always owned Solen Air-Core types.


Actually if forced to choose only one to implement , I would have a hard time choosing between (i) or (ii), since these topologies both bring me a lot of sonic enjoyment/improvement to the table.


:cheers: