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Thread: Discussion Thread JBL 4343 to 4344 upgrade

  1. #196
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by Giskard
    Looks much better than the stock 4344. Very nice!
    Well when you are done with the crossovers he is in for a real treat.

    I listened to the Carol's last night on TV and it would be difficult to imagine anying more impressive than a 4344 using the Giskard's crossover design.....it just didn't sound like loudspeaker at all.

    There is discussion elsewhere on the virtues of overly expensive Westlakes in reference to the 4343.

    If you take your 4343's to the next level (as discussed in these pages) you can be content that without spending a real lot of money they will give anything else a serious run for their money....and you will have the true JBL sound!

    On that note I am inspired by Rick's handy work and I plan to build a 4344 in 2006 using the Giskard crossover and enclosures using a special acoustic grade ply with lead laminate to ensure minimal sound transmission.

    Ian

  2. #197
    Senior Member Ian Mackenzie's Avatar
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    I am sure once you are making them you will enjoy it!

  3. #198
    Senior Member Ian Mackenzie's Avatar
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    Update:

    http://www.audioheritage.org/vbullet...7&page=1&pp=15

    Incidentally,

    Something most of you propably have skipped over, the inception of the 4343-4344 thread was of Porschedman, (Ed) who asked me over 12 month ago to build some new crossovers for his 4343's that he had updated to 4344 driver specs.

    Ed has yet to install the new crossovers and write an detailed review which I would expect sometime in Feb -April 2006 pending Ed's schedule.

    The reason I bring this up is the "project" is still in a state of flux and if with the arrival of the now new "DIY Forum everything gets chopped up and the whole continuity of the project will be lost.

    I should also point out that prior to publication of the 4343 -4344 upgrade project there was such contentious resistance to the idea by Super Moderator Robert Hamel that the project was nearly dropped.

    Robert, fearing members might not hear the difference would therefore have post-project concerns over there being a lack of value for money for the effort and the outlay involved. This reaction served and prompted me into investigating and proving the updates even more rigorously.

    What eventuated was quite revealing.

    My approach is simple. Take nothing for granted and assume nothing when it comes to this business..

    Old ears and attitudes are deaf ears in this business.

    But if you are the cautious type you may want to wait for Ed's reviews and then make up your own mind.

    Collectively however, if you follow and read carefully all the steps in the 4343 upgrade stages common sense prevails and there is justification and satisfaction to behold by every 4343 owner. Even the most passive changes like enclosure height adjustments and positioning can be the difference b/ n love and hate with these systems.

    Change is often good and refreshes our sensory perceptions. Even Ed was surprised after some hounding by me at the overall improvement reverting back to full 4343 passive crossover mode made with his Passlabs X Series 250 power amplifier over using the Ashly active crossover in bi amp mode. The point being if the expertise and reasoning behind this was not pointed out in the way it was Ed would never have made the change and been the non the wiser. This is a key behaviour in attaining the ultimate in audio sound reproduction. Don't let sticks in the mud stop you from progressing, walk over them if you have to.

    It is interesting to note that JBL also resisted the innovation and introduction of the L250 designed by Greg Timbers for some time and it was then latter upgraded to the 250Ti and remains one of the best JBL systems of all time.

  4. #199
    Senior Member Ian Mackenzie's Avatar
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    I have been getting a string of pm's nagging me about that discrete active 4343-4344-4345 active crossover and that the details are scattered all over the place.

    Its taken a while (over 12 months) to perfect it, numerous iterations, adjustments and component choices apart from getting all the bugs out hence the odd post here and there to let you know its still alive.

    I am not proposing to publish a how to article or the final design.

    If you think you are competent enough to design and make it please go to the Mox thread on diyaudio.com and have a go at it from scratch otherwise all genuinely interested parties please pm me (again with your email address) so I can put you on a mailing list.

    best regards

    Ian

  5. #200
    Senior Member porschedpm's Avatar
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    Installing the External Crossovers in the 4343

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  6. #201
    Senior Member porschedpm's Avatar
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    Installing the External Crossovers in the 4343 (continued)

    • Remove LF and MF drivers.
    • Remove Upper Baffle. Disconnect HF and UHF drivers. Pull MF wires out of MF box.
    • Label all wires. Recommend taping off or placing shrink tubing over these abandoned wire ends to avoid any future mishaps. Coil up the old wires and secure with a tie wrap
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    • Prepare your 5-3/8" x 6.5" wood or plexiglass panels to replace the rear input teminal plates by drilling a 1-3/16” hole for the male Speakon connector and pilot holes for the screws. Alternatively you could leave the rear input terminal plate in place and drill a 1-3/16” hole in the speaker cabinet for the Speakon connector. I opted to replace the plate so that the speaker could be returned to stock condition and to retain the value of the speaker.
    • Remove rear input terminal plate. Route it out of the way and in a place that will be rattle free. I wedged it into the upper left hand corner of the speaker and covered it with fiberglass.
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    • Install your wood or plexiglass panels which replace the rear input terminal plates. If your panel is less than 3/8” thick, you can re-use the original bolts. Regardless if you use the original bolts or not, you will need new nuts as the nuts on the original rear input terminal plate were pressed into the fiberboard and cannot be removed.
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    • Install front-to-rear brace. My brace ties the top of the rear center 1x4 upright brace to the front baffle. Where it ties into the front baffle it is offset to the left approximately 1” from center to provide clearance for the lower center baffle bolt and avoid interfering with the stock L-Pads. I made very sure before gluing and screwing that this bracing would not interfere with the L-pads. I’m sure there are other and maybe better ways to provide additional bracing in the 4343 cabinet so I won’t go into more detail here other than I did cover the new braces in fiberglass.
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  7. #202
    Senior Member porschedpm's Avatar
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    Installing the External Crossovers in the 4343 (continued)

    • Install Speakon connector in your wood or plexiglass panel.
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    • Route MF leads into the MF Box. Seal the hole.
    • Reinstall drivers.
    • Connect crossovers.
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Size:  64.2 KB Downloadable test tones can be found at:
    · http://www.ronelmm.com/tones/
    · http://www.nch.com.au/tonegen/#101
    • Play some music, and make sure all drivers are operating properly.

  8. #203
    Senior Member gerard's Avatar
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    Giskard's crossover design 4343

    Hello

    Please forgive me but , where can I find the Giskard's crossover design drawing for the 4343 .

    This thread is very nice but whre is the crossover design ?

    Gerard

  9. #204
    Senior Member Ian Mackenzie's Avatar
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    The original schematic is below however the upgrade for the 4343 to the factory 4344 used the 3145 network. Since then the tapped inductors are NLA and Giskard/GT re designed the HF and UHF filters for an equivalent design and more recently a simplified "new equivalent".

    These schematics have been posted so often elsewhere I didn't re post them earlier in the thread.

    Here are some other links and aside from that you can also charge couple if you wish.

    http://www.audioheritage.org/vbullet...&postcount=169
    http://www.audioheritage.org/vbullet...&postcount=170
    http://www.audioheritage.org/vbullet...&postcount=173
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  10. #205
    Senior Member gerard's Avatar
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    Thank's a lot Ian

    Now it's better to understand , the threads on 43xx are so large , you get lost sometimes .....

    Gerard

  11. #206
    Senior Member Ian Mackenzie's Avatar
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    While Ed is waiting for the delivery of an active crossover I disgress to offer some commentary.

    One of the themes that we are pushed in this upgrade series is that the sum of a number of key updates will lead to overall improvement in listening pleasure.

    I recently had the opportunity to evaluate an improved compression driver and while it was obvious there were real improvements in transparency I also felt that the system had taken a step back as certain colourations had surfaced in the presentation.

    By chance I also accepted the opportunity to trial a different AV Processor that uses a Shark processor. All my previous observations were based on a quality DVD player that had a built in decoder. The new processor is subjectively better and the above mentioned colourations have vanished.

    This has also given rise to a final assessment of the active crossover before being shipped as my previous evaluations were based on assumptions using the original source. Things like component choices in key areas require careful consideration to ensure the signal path remains absolutely pure.

    In order to do this and be absolutely certain of the results Ed will get I had to completely re build the passive crossovers to the exact specification that was delivered to Ed recently.

    As you can appreciate nothing is left to chance with Hi End audio particularly when you have JBL loudspeakers!

    Ian

  12. #207
    Senior Member porschedpm's Avatar
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    Below is a link to Greg Timbers' observations regarding the 4345 and some suggested improvements that could be made to the 4345's. Many of these suggestions could also be applied to the 4343/4344's.

    http://www.audioheritage.org/vbullet...5&postcount=27

  13. #208
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    Quote Originally Posted by porschedpm
    Many of these suggestions could also be applied to the 4343/4344's.
    Definitely. We've gone over them quite a few times. Now that Greg has put them all down himself, I wonder if we will still have to continue to go over them. I notice after David took the time to write about the 4430... oh nevermind.

  14. #209
    Senior Member Ian Mackenzie's Avatar
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    Its the how, not how many.

    Yes I agree you have been talking about charge - coupling for years now.....But how many have actually built their own.......

    What is apparent is the reluctance of some members to modify these grand vintage monitors because of the difficulty as stated in the link above in making these modifications and that of not being able to re sell them in original vintage condition unless these changes are carefully implemented.

    That is quite understandable.

    The extent to which a particular owner decides to make these changes is entirely at their discretion. The might leave it for a while and then come and ask you about it because they are ready.

    My understanding is the "How" as decribed in Ed's project offers minimal invasive impact of non reversable change while taking up many of the benefits of these modifications. (please refer to previous posts in this thread).

    Unfortunately our "new" owners will not always be aware of these threads and the details of the modifications therin and what they mean.

    This was another reason for opening the club thread. Its brings members together and enables a focal point of a micro forum community of owners. From there they can gather and share information efficiently while also communicating to the wider forum.

    As the forums grow in size an complexity we all need to adopt smarter ways of managing our valuable information.

    Perhap you can arrange for some of these updates to be copied as a pdr in a reference update area or a sticky?


    Ian Mackenzie
    Melbourne Australia

  15. #210
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    On the subject of "minimal invasive impact of non reversable change while taking up many of the benefits of these modifications." Please realize I've already done several 250Ti's that are completely reversable and Bo and I have already discussed minimal impact to stock 4345's. I believe the subject of minimal impact to stock systems has been a fundamental theme I've mentioned pretty consistently over the last five years. The painful fact is, most people who would like 4345's will need to build them themselves.

    As the forums grow in size an complexity we all need to adopt smarter ways of managing our valuable information.

    Yes, I'm working on that.

    Thanks Ian.

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