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Thread: The JBL 4345 Club

  1. #16
    Senior Member Ian Mackenzie's Avatar
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    I have edited post #8 because apparently (although I have not seen evidence as yet) some from within the masses were a bit put out by the change of thinking that sparked this thread.

    This thread is just a focal point for those who are deeply passionate about a particular subject and that is the purpose of this thread. To share and to enjoy experiences about this loudspeaker and to discuss how best to attain maximim listening pleasure.

    If you think you are as deeply passionate as the owners and users of the 4345 you are welcome to post here.

    Similarly, if you are very passionate about what you have ie a 250ti, a 4333 or an L100 you might want to get together for a good chin wag

    Please do not be offended, this is not a private meeting room.

    If you do have concerns send me a pm.

    At this point I have only had positive feedback

  2. #17
    Senior Member saeman's Avatar
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    Yo Down Under: Your post #8 was fine the way it was. I can't see how it could have offended anyone. A little Aussie humor now and then helps take the edge off. See Ya - Rick

  3. #18
    Senior Member Ian Mackenzie's Avatar
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    Yes exactly,

    However trans continental cultures and mindsets often get these scewed up.

    I saw a great movie last night The Worlds Fastest Indian. Aside from the immense Utah Salt flats the story was facinating and will ring true for many.

    http://www.imdb.com/title/tt0412080/

  4. #19
    Senior Member Ian Mackenzie's Avatar
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    While I don't want to be seen as leading anything here perhaps we need to list a few initiatives and take on board what members globally might be interested in seeing arranged.

    This might take quite a while to action but a list of what would add value is useful. We can work out the how , who and when over a forum beer.
    I am sure there are other items so please elaborate.

    Product Profile

    There is not as yet a product profile in the Library of the 4345
    An account of this model and how it came about would be quite interesting.

    Owners manual

    I don't think there is one but l am sure we could work on something and perhaps use something along the lines of the 4344Mk11 OM as a template/guide for the contents.

    This could be quite a job to work on and would make a great project.

    Photo Gallery.

    I have some images on my HD. I'll bet others have some as well aside from your own set up. We need to do something with this.

    Members Systems.

    This could be part of the photo gallery but that would not allow discussion and questions. Members stuff like Bo's has been talked about from time to time but what is out there is fragmented.

    Maintenance and upgrades

    Part of the manual. A while ago I did some stuff on the 4344. Some of it applies but there needs to be a revised focus on vintage 4345's.

    Building a 4345

    Cad drawings. I know we have some basic drawings but there is a need for some proper drawings. I recall Rick and someone else has done something. We need to update where we are at here.

    Serial number registry

  5. #20
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    over a forum beer
    only 1 ?!

  6. #21
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by hapy._.face
    only 1 ?!
    When I first joined my local audio club..The Melboune Audio Club I was asked if I would like to attend Sunday School with the Lad's.

    Wanting to fit in so I turned up and was the odd man out without an Esky( a beer cooler that holds a slab of Fosters).

  7. #22
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    Quote Originally Posted by Ian Mackenzie
    When I first joined my local audio club..The Melboune Audio Club I was asked if I would like to attend Sunday School with the Lad's.

    Wanting to fit in so I turned up and was the odd man out without an Esky( a beer cooler that holds a slab of Fosters).
    What's 'odd' about that? How else were you supposed to keep your beer cool?

  8. #23
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    Quote Originally Posted by Ian Mackenzie
    While I don't want to be seen as leading anything here perhaps we need to list a few initiatives and take on board what members globally might be interested in seeing arranged.

    This might take quite a while to action but a list of what would add value is useful. We can work out the how , who and when over a forum beer.
    I am sure there are other items so please elaborate.

    Product Profile

    There is not as yet a product profile in the Library of the 4345
    An account of this model and how it came about would be quite interesting.

    Owners manual

    I don't think there is one but l am sure we could work on something and perhaps use something along the lines of the 4344Mk11 OM as a template/guide for the contents.

    This could be quite a job to work on and would make a great project.

    Photo Gallery.

    I have some images on my HD. I'll bet others have some as well aside from your own set up. We need to do something with this.

    Members Systems.

    This could be part of the photo gallery but that would not allow discussion and questions. Members stuff like Bo's has been talked about from time to time but what is out there is fragmented.

    Maintenance and upgrades

    Part of the manual. A while ago I did some stuff on the 4344. Some of it applies but there needs to be a revised focus on vintage 4345's.

    Building a 4345

    Cad drawings. I know we have some basic drawings but there is a need for some proper drawings. I recall Rick and someone else has done something. We need to update where we are at here.
    How about a serial number registry specific to 4345's, too? It might prove interesting.

  9. #24
    Senior Member Ian Mackenzie's Avatar
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    Good idea!

  10. #25
    Senior Member Ducatista47's Avatar
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    Serial #s

    My babies are #12511 and #12555 They are a matched pair, left and right.

    4345 #12555
    2421B......#11604
    2405...no name plate!
    2308 Lens...#79778

    4345 #12511
    2421B......#12770
    2405........#121990
    2308 Lens...#79791

    2245H's and 2122H's are not original.

    It will be interesting after a public post like this to see if they show up on eBay in Singapore or Nigeria.

    Clark in Peoria
    Information is not Knowledge; Knowledge is not Wisdom
    Too many audiophiles listen with their eyes instead of their ears


  11. #26
    Senior Member Ian Mackenzie's Avatar
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    Good stuff.

  12. #27
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    You Guys are Amazing

    I can't belive all the interest in this 30 year old system. It was never very successful during its life time primarily due to its size. Most people would get something smaller. It also had a reputation for less than detailed bass, which I have always thought was due to the enclosure not being quite large enough. I haven't thought about these things in years but since I have received a few requests for comments - here goes.

    The system was and probably still is a stellar performer if you like the inherent sound of the traditional big JBL 4-ways. There is good news and bad news in the basic design. Good in that they are dynamic as hell and never get confused with intermodulation products of any type. They don't take much power to run and can swallow up a really big amp should you wish to do so. The weak areas of that type of design are several. First, there is a large time off-set between the 10" driver and the HL92 horn. This shows up in both the on-axis response, the directivity pattern and the homogeneity of the driver blending. The second problem is the use of a passive crossover between the top of the woofer and the bottom of the 10". Passive crossovers set to frequencies below about 500 Hz react badly with the motional impedance of the woofer/box combination and give substantial gain around 100 Hz. Gain out of a passive system is generally a bad thing. In the case of the High Pass, we have to work the passive network through a really large motional impedance peak resulting from the 10" fundamental resonance in the sub enclosure. This means that the actual voltage drive that occurs at the terminals of the 10" is less than ideal. There was the added complexity that the Marketing folks of that time required switchable bi-amp capabilities in which the incorrect setting of the switch was not allowed to hurt anything. These little things all add up to additional insertion loss for the woofer and loss of damping control. Now all of this sounds pertty bleak, but as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway.

    My sonic memory of the big 4 ways, the last of which was the 4344MkII, is that they are effortless, dynamic, pretty low in coloration and really "alive". They are a little vague by today's standards in terms of precise imaging and although they are very low in intermodulation effects, they are not as detailed as really good lesser way designs. There is no simple answer to any of this and no one design statement that is best. Everything is a series of compromises, and the 4345 has a very good set of complimentary compromises.

    I noticed a comment earlier in this string regarding the 2122H. It is a really good voice transducer. It always has been and always will be. Things just sound really natural through it. Another one that might be slightly better is the 2123. It is a little less smooth but perhaps a little more realistic on voice. Either are really good for that critical range from a few hundred Hz to about 1500 Hz.

    I imagine you guys have talked about and tried lots of things to get the most out of the system. I will mention a few things that I would do if I had a pair at home for my primary system.

    • Get rid of the bi-amp switch. Hardwire it in which ever mode you want it. The switch is not that great.
    • If you can work out bi-amping do so. The difference in the 2245H and 2122H will be amazing. The crossover will have to be non standard. Neither driver is flat around crossover so the voltage drives will need to be adjusted to get proper acoustic bandpasses.
    • The network components should be updated and this isn't easy. All the capacitors should be polypropylene and you would want to use air core inductors where ever possible. I believe the 4345 used some tapped iron cores. Those are hard to replace with aircores because the surrounding network topology would have to change and all of the values have to be re-engineered. I would suggest leaving them alone unless you are really good at this stuff.
    • If you can swing it, go to a biased network. The difference is unbelievable.
    • The ring radiator hates passive networks. A major improvement in the upper range would be to drive the 2405 from its own little amp. You only need 3 or 4 v rms. The 2405 does 110 dB for 2.83v. It is padded way down in the system. There is little real power at those frequencies anyway. You only need to know the voltage output of the amp, power is irrelevant. The 2405 is about 12 ohms and won't draw much current. I would use some little chip amp with a 2ond or 3rd order low level highpass in front of it. Take off the passive network to the ring and just feed it straight. Make sure the amp doesn't make a DC thump on turn on or turn off. That will fatigue the diaphragm. The amp will also have to have really low noise characteristics as any hiss will be really loud directly into the ring. I used to use an old Marantz 1030 integrated amp to run my rings. I could separate out the power amp section and the tweeters always sounded really good.
    • The L-pads aren't so hot either, particularly after all of these years. Once you have your preferred balance, it is fairly easy to measure each leg of the L-pad and replace it with fixed resistors.
    • I notice from many of the pictures that the system is elevated on blocks. It is very good to get the 2245 up off of the floor to minimize midbass fatness.
    For resale reasons, you should be very careful about doing as much of this as possible reversibly.

    Before closing I should comment briefly about the 250 - 4345 comparison. Simply put, I prefer a 250. I like the bass quality of the LE14 woofer. Alway have and always will. The 2245 when used as a dedicated sub is one of the best sounding woofers ever. It has an amazing blend of speed, pitch and punch. So does the 14" but the 18" is better. Unfortunately the 18" dislike for passive networks hurts it more than the 14" is hurt by a passive network. I think the mid and high range on the 250 is smoother and much more open however the 4345 wins by a bunch in terms of effortless dynamic sound. I have made all of the above changes to 250 systems (except for separate amp on UHF) and the improvement is huge. I have not done so on the 4345 but I suspect that that system will benefit from theses changes more than a 250 would. If both systems were tweaked out to about the same level, I suspect it would be very hard to come up with a clear overall winner, but I think I might lean towards the 4345 as having the greater potential.

    Thank you all for the interest in my work. I must admit I have been blessed with a really nice profession that has treated me well for a very long time. Remember that sound and music enjoyment are very personal things and that what makes you happy may or may not please others. Screw them. If you are happy and no one is geting hurt then go for it. No loudspeaker system even approaches real life so there is plenty of room for interpretation.

  13. #28
    Senior Seņor boputnam's Avatar
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    Thanks, Greg, for taking the time for such a generous and enlightening post.
    bo

    "Indeed, not!!"

  14. #29
    Senior Member Ian Mackenzie's Avatar
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    Greg,

    Thankyou for providing such a thorough and thoughtful post with your busy schedule.

    Many thanks from Lansing Heritage Forums.

    Ian

  15. #30
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by gtimbers
    No loudspeaker system even approaches real life so there is plenty of room for interpretation.
    That is some mighty sage advice!

    Ditto what Bo said!
    Thanks,


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