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Thread: My "New" 4345 Clones

  1. #31
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by boputnam View Post
    I didn't even get to them!

    Anyway, have fun! Now I must go find some panties...
    All those spring-loaded terminal posts made me wonder how many 3145's died so these could live on stuck in the Masonite?

    Like any good 43XX owner, I'll get these up and running with what I've got and then I'll fiddle with it for the next ten years.

  2. #32
    Administrator Robh3606's Avatar
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    Well too see what you have as far as the networks all you have to do is compare them to the 4345 schematic for the 2122 crossover and 4313B's equivalents for the 2421 and 2405.

    Don't let the CC intimidate you it is very simple to convert them so they match the schematics. Simple rule of thumb is for a 10uf to change over to a CC network you would double the value to 20uf and add another 20uf cap so you would end up with 2 20uf caps.

    Going the other way if you saw 2 caps of equal value you would half the value of one to get the non CC network value.

    I don't know what he used but it easy to find out. I will attach a schematic for the 4345. The 2122 chould be the same but with double the number of caps and 4 times the value. The equivalent 2121 and 2405 networks were developed because the tapped inductors are no longer available so same premise.

    Don't forget to throw the biamp switch looking at the schematic.

    Rob
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  3. #33
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Robh3606 View Post
    Well too see what you have as far as the networks all you have to do is compare them to the 4345 schematic for the 2122 crossover and 4313B's equivalents for the 2421 and 2405.
    Thanks. Another member pointed me to this link which is color-reversed version of 4313B's 3145 CC schematic used for these networks, and seems to follow what I have:
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  4. #34
    Administrator Robh3606's Avatar
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    Could you please post the link.

    Thanks Rob
    "I could be arguing in my spare time"

  5. #35
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Robh3606 View Post
    Could you please post the link.
    How about a link to a link? I ran across the original in black with white print earlier today and now can't find it. Heather has put many of the 4345 links together here: http://www.audioheritage.org/vbullet...d.php?p=171841
    but even she seems to have lost the link to the original from "4313B" which she reversed for legibility as you see it here. I'm sure I'll stumble upon it again.

  6. #36
    Administrator Robh3606's Avatar
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    They do match that schematic?? Good then you know the voltage drivers are correct.

    The lost link.

    http://audioheritage.org/vbulletin/s...?t=1388&page=9

    Rob
    "I could be arguing in my spare time"

  7. #37
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Robh3606 View Post
    They do match that schematic?? Good then you know the voltage drivers are correct.

    The lost link.
    Thanks, that got me close enough in the thread to this post I'd been looking for: http://audioheritage.org/vbulletin/s...&postcount=124
    Maybe Heather can add it to her thread as an edit.

    I'll go over mine piece by piece in a bit and see if I can confirm it is what I was told it was! I hate jigsaw puzzles. Give me a good old mechanical problem any day. A Rube Goldberg mousetrap makes more sense to me than an electrical schematic. I have a hard enough time following them for my cars.

  8. #38
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    Quote Originally Posted by BMWCCA View Post
    Thanks, that got me close enough in the thread to this post I'd been looking for: http://audioheritage.org/vbulletin/s...&postcount=124
    Maybe Heather can add it to her thread as an edit.

    I'll go over mine piece by piece in a bit and see if I can confirm it is what I was told it was! I hate jigsaw puzzles. Give me a good old mechanical problem any day. A Rube Goldberg mousetrap makes more sense to me than an electrical schematic. I have a hard enough time following them for my cars.
    Thanks for the heads up - very odd - thats already part of my last post in the 4345 reference Thread (see post #5) - where I posted the reverse-color version of G's schematic (white on black prints lousy on every laserwriter I ever used!)

    http://audioheritage.org/vbulletin/s...25&postcount=5
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  9. #39
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by hjames View Post
    Thanks for the heads up - very odd - thats already part of my last post in the 4345 reference Thread (see post #5) - where I posted the reverse-color version of G's schematic.
    You sure did! I guess I never made it past the earlier post in the thread where your said:
    (I can't find the original thread I saved it from, at the moment, but I'll post the link when I find it)
    I've been searching too much stuff recently and it's all beginning to look alike! Your compilation thread was very helpful, had I just scrolled to the end my question would have been answered. Maybe you'd consider deleting the reference to not finding the original thread for the next idiot like me who gives up early.

  10. #40
    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by Robh3606 View Post
    Good then you know the voltage drives are correct.
    True...?
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  11. #41
    Senior Member BMWCCA's Avatar
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    To the best of my ability to determine, the only differences in the circuitry are (and I'm only reading what's on the components):

    In the Mid-bass section:
    The 39-ohm MILLS 64057 on the schematic are replaced by Dayton Audio Grade 40-ohm 10-watt

    In the HF section:
    The (2) 18-ohm MILLS on the schematic are replaced with (2) 20-ohm MILLS. It also looks like there should be another 20-ohm just before the output that doesn't seem to be there. Possibly a change made for the 435Be driver used previously?? Or a change to accommodate the current 16-ohm 2425J instead of the older 2421B?? Or lost in the shuffle? I have no idea.

    In the UHF section:
    7-ohm MILLS MRA12F's are used instead of the two 6.8-ohm MILLS 62753's on the schematic.

    Caps are all Solen. And, of course, there is no passive LF section since these are bi-amp only and require an external active crossover, hence the posting in this thread!

    Any thoughts? :dont-know

  12. #42
    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by BMWCCA View Post
    ...
    In the HF section:
    ...It also looks like there should be another 20-ohm just before the output that doesn't seem to be there. Possibly a change ... to accommodate the current 16-ohm 2425J instead of the older 2421B??
    Uh, no.
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  13. #43
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by boputnam View Post
    Uh, no.
    Well, oddly enough that last 20-ohm resistor doesn't seem to be in any of the three designs that our ex-member built, at least according to the photos here: http://www.audiokarma.org/forums/sho...45#post1494601

    I find it hard to believe I found something so obvious, missing. Must be some reason for it, maybe an earlier or later change in the network schematic? Easy enough to add if need be. I'm sure there are some here who created the design who could comment on it, if they wouldn't mind. I see a schematic. I see one resistor missing. I see the same resistor missing in two other versions built by the same guy. So, should I just run one between the HF output terminals and see what it does? I'm sure there was a somewhat more scientific approach to the original design!

    Here's a link to a huge photo that might be of some help if someone wanted to delve into this a bit deeper: http://i203.photobucket.com/albums/a...5/IMGP7564.jpg (click on the image to enlarge it even further).

    I'd certainly appreciate the help and opinions of you who actually understand this stuff. Last time I looked there wasn't a word limit on posts here!

    Thanks.

  14. #44
    Administrator Robh3606's Avatar
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    I find it hard to believe I found something so obvious, missing. Must be some reason for it, maybe an earlier or later change in the network schematic?
    You don't need it if you are using 8 ohm drivers.

    http://www.audioheritage.org/vbullet...light=4345+ohm


    Rob
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  15. #45
    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by BMWCCA View Post
    Last time I looked there wasn't a word limit on posts here!
    I was only pointing out the fact that the network design allowed for the swap (2425J or 2421B) you were concerned about - it was annotated right on the schematic. So, there were no words needed.

    Quote Originally Posted by Robh3606 View Post
    You don't need it if you are using 8 ohm drivers.
    Which is part of what concerns me...

    Quote Originally Posted by BMWCCA View Post
    Well, oddly enough that last 20-ohm resistor doesn't seem to be in any of the three designs that our ex-member built...
    Which is the other part that concerns me.

    You bought these with that driver compliment. Apparently, no-one along the way noticed the importance of that last resistor in the HF signal path? The frequency response of these will be unbalanced, without it.

    So, back to a point I tried to make a couple days ago, these speakers are likely not performing to spec, thus their recurring sale. You have a real treasure in your hands that will take some work you may not have anticipated.

    We know there is nothing whatsoever wrong with those cabinets.
    We know there is nothing whatsoever wrong with that transducer compliment.

    The trouble lies with those networks.

    For starters, you should complete a very thorough and diligent tracing of the signal paths of those networks, for each band pass - and by that I mean make sure the signal goes where it is supposed to go and the (nearly) right components are there, end-to-end. Obviously these came from a network amateur who may have missed a few key points - we know he thought it immaterial to deviate from the exact component specs.

    There are many here who can help with this, and we all want these to fulfill your expectations. They can be wonderful...

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