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Thread: How to open N8000?

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    How to open N8000?

    I am in this writing moment the newest member on the site and also quite a novice. My question; - is there anybody out there who knows how to dismantle a JBL xover filtre N-8000? I have a pair of old L200's that have been up-graded with original JBL components to 3-way speakers, now including the 077 prism and H91 horn. The filter that was added was the N8000. The old LX16 is still there. Now I would like to maybe change some of the internal components in the filter but it seems that it is somehow "glued" or "melted" together. Is this the case and can I open it somehow?

    Thanks
    Erik

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    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by Stavne View Post
    I am in this writing moment the newest member on the site and also quite a novice. My question; - is there anybody out there who knows how to dismantle a JBL xover filtre N-8000? I have a pair of old L200's that have been up-graded with original JBL components to 3-way speakers, now including the 077 prism and H91 horn. The filter that was added was the N8000. The old LX16 is still there. Now I would like to maybe change some of the internal components in the filter but it seems that it is somehow "glued" or "melted" together. Is this the case and can I open it somehow?

    Thanks
    Erik
    I swapped my 4320 components into an L200 cabinet then later upgraded it as you have. The original crossover was in a metal casing that had a faceplate rivetted on.
    Frankly, I built my own crossover from a design 4313B posted here a year or two back. But at one point i did want to open the original crossover, so, I drilled out the rivets, put the unit on the stove in a pan partly full over water and heated the water to boiling. But before it actually got to boiling I was able to lift the face plate and attached circuit out of the "can". Once I did get it open it, it was full of what seemed to be beeswax.
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    beeswax in the N8000..

    Thanks HJAMES - I was afraid it was going to be something like you mentioned. I do not think it's worth the effort to open it.

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    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by Stavne View Post
    Thanks HJAMES - I was afraid it was going to be something like you mentioned. I do not think it's worth the effort to open it.
    Okay, but remember, beeswax is much easier to deal with than the epoxy based potting compound many manufacturers used to encase their circuits.
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    I disassembled two N7000s for the cases and neither the caps nor the chokes are "potted" but mearly held in place with "foam rubber" or whatever you call that beigish colored open cell spongy stuff.

    But why ruin a good crossover unless you are after the case? The only difference between the N7000 and N8000 is that the N7000 uses 0.6 mH chokes wheras the N8000 uses 0.3 mH. (I used 0.5 mH with my 075 tweeters.) You can certainly put better caps and chokes in and add by-pass caps to make a better crossover all for less than you could sell the N8000s for (or keep them for whatever comes along).

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

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    Administrator Robh3606's Avatar
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    But why ruin a good crossover unless you are after the case?
    It's so much easier to just build up a pair from the schematic.

    Rob

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    Why opening the N8000 !

    I'm glad that I posted the question on this site. I have been a regular reader for a long time, but never posted anything. The original idea of opening the filtre was basically to see if any of the +30 year old components could be changed with positive results. The sound seems a little bit "boxed in" and not quite so dynamic and detailed as I could wish for. But now, it seems that I may be better off building new ones and just keep the old N8000 for resale purposes. If I want to sell the speakers at some point, is it then better to have the original N8000 instead of potentially better sounding "no name" filtres? Thanks for all your comments. Erik.

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    Heather [Senorita member] hjames's Avatar
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    Well, if you've already converted your L200s to 3-ways, I wouldn't worry about the resale value dropping due to putting new 3-way crossovers in them. Besides, I doubt there's much demand for the old canned crossovers with dried out caps (30+ years old, right?)
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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by hjames View Post
    Besides, I doubt there's much demand for the old canned crossovers with dried out caps (30+ years old, right?)
    Sure there is.

    It's the "Bigger Fool" theory in action....

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    Administrator Robh3606's Avatar
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    Sure there is.

    It's the "Bigger fool" theory in action....
    Or how about the guy who want's a system to be completely vintage and correct as JBL would have provided it???

    Different strokes for different folks.

    Rob

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    I'm not sure I understand the irony of all this! - maybe I just dont understand the technical issues good enough. I just bought my L200 and the former owner upgraded these many many years ago. I the late 70's, I believe there was a common understanding that the L200 needed upgrading and JBL officially specified the upgrade-data as an N8000 with the 077. This is what he did. But now many years after, I was just wondering if it could be a good idea to change the caps in the filtre. This is when I encountered the problem of opening it. Some of you the mention that I may just as well build a new xover. Then I ask if it's better, re-sale wise, to keep in the original. Thanks for your comments. Erik

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    Quote Originally Posted by Stavne View Post
    I'm glad that I posted the question on this site. I have been a regular reader for a long time, but never posted anything. The original idea of opening the filtre was basically to see if any of the +30 year old components could be changed with positive results. The sound seems a little bit "boxed in" and not quite so dynamic and detailed as I could wish for. But now, it seems that I may be better off building new ones and just keep the old N8000 for resale purposes. If I want to sell the speakers at some point, is it then better to have the original N8000 instead of potentially better sounding "no name" filtres? Thanks for all your comments. Erik.
    Keep the original crossovers original for resale purposes and build new networks for your personal use. Use polypropylene capacitors and air core inductors but remember that the air core inductors will interact if placed too close together (the old iron cores in those canned filters weren't supposed to interact with each other).

    The people that buy this stuff for collectibility probably prefer it all to be as pristine as possible/practical.

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    Thanks, I will pass on the message to a friend of mine who will help me with this. I'm not very competent in the electronics. Since I will now build e new filtre, I'm curious on one thing. Should I make a "copy" of the N8000 but with new components and can I use the schematics for the 3106 as listed somewhere on this website? The schematics that was included in this thread was for a set-up with the 136A and not my LE15B and I take it, cannot be used. Also when looking at the 3106 on this link ( http://www.jblproservice.com/navigat...chematics.html ) it seems that the cross-over frequency is 7 khz - I thought that was the original spec for the N7000 and not the N8000, or am I just misunderstanding this? Thanks for all help. Erik

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    Quote Originally Posted by hjames View Post
    Well, if you've already converted your L200s to 3-ways, I wouldn't worry about the resale value dropping due to putting new 3-way crossovers in them. Besides, I doubt there's much demand for the old canned crossovers with dried out caps (30+ years old, right?)
    The caps in the N7000/N8000 are not the typical JBL cardboard cylinders filled with ???, but are the typical long, thin, sealed caps with a lead on each end. These do not appear to be subject to drying and deterioration like the cardboard tubes.

    Mine are now serving duty on our garden railroad as "spike filters" in a 555 timing circuit that was previously subject to glitching when a train would pass over the buried wires. They work great in this function too!

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