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Thread: jbl 4344 refurbishment

  1. #1
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    jbl 4344 refurbishment

    Dear Forum Members,
    this is my first post. I am in Sydney Australia.

    I recently got a pair of 4344. they are stock. Amazing! I like them very much. I have to turn the EQ up to max otherwise treble is pretty dull, but they have heaps of life and really fill a room. I use them with a tube amp.

    All good. Very happy to stay where I am however cogniscent that capacitors are a bit old and probably casue of need to turn EQ up (also is the EQ on 4344 what is called "L pads"?)

    I note the thousands of posts on this forum and the wealth of information that must surely be contained within.

    However i do have overarching questions and I was wondering if someone who has walked this path before me might help.

    The 15 and 10" drivers have been re-done I think. rubber around them is supple and cones are intact etc.

    As i see it, first thing to do is to replace capacitors. My questions in this regard are:
    1. is this a good idea to replace capacitors? I presume it is and at a minimum I am looking to do this. just in case has anybody got a parts list for this?
    2. has anyone out there put a charged crossover into the 4344 with any success? if so what did you think of that specific upgrades utility? was it worth it?
    3. anybody want to tell me there is something else i should be doing?

    Mine is the original 4344 and driver list is as follows:
    Unit For low-pass: 2235H
    For inside low-pass: 2122H
    For mid-high ranges: Horn type (2421B+2308)
    For high regions: Horn type (2405)

  2. #2
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    Hi and welcome to LH, good too see classic JBL'S in Australia. You have a great set of monitors there, as far as the upgrade on the Capacitor's i would definately do this i did this to my Everest's and i'm 100% happy and glad i did it. Maybe do research on what type would suit your ears.

    There is a wealth of Knowledge here and the guys are very helpful. Congrats on the perchase.

  3. #3
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    Cool

    Quote Originally Posted by mr_gray View Post
    Dear Forum Members,
    this is my first post. I am in Sydney Australia.

    I recently got a pair of 4344. they are stock. Amazing! I like them very much. I have to turn the EQ up to max otherwise treble is pretty dull, but they have heaps of life and really fill a room. I use them with a tube amp.

    All good. Very happy to stay where I am however cogniscent that capacitors are a bit old and probably casue of need to turn EQ up (also is the EQ on 4344 what is called "L pads"?)

    I note the thousands of posts on this forum and the wealth of information that must surely be contained within.

    However i do have overarching questions and I was wondering if someone who has walked this path before me might help.

    The 15 and 10" drivers have been re-done I think. rubber around them is supple and cones are intact etc.

    As i see it, first thing to do is to replace capacitors. My questions in this regard are:
    1. is this a good idea to replace capacitors? I presume it is and at a minimum I am looking to do this. just in case has anybody got a parts list for this?
    2. has anyone out there put a charged crossover into the 4344 with any success? if so what did you think of that specific upgrades utility? was it worth it?
    3. anybody want to tell me there is something else i should be doing?

    Mine is the original 4344 and driver list is as follows:
    Unit For low-pass: 2235H
    For inside low-pass: 2122H
    For mid-high ranges: Horn type (2421B+2308)
    For high regions: Horn type (2405)

    Hello


    I have done on my 4345 with similar path.

    Order is value for money.

    1. lift speaker 6inch from floor
    2. replace l-pads (200$)
    3. charge coupled crossover - more realistic and natural sound overall (500$)
    4. replace 2421b+2308 with 2450+2311 and 2451sl diaphragm for smooth and well mixed upper range. (800$)
    5. multi-amping with full discrete active crossover (first watt B4 or Bryston 10B) for tight bass and clear mid bass. (2000$)

    order in sound-wise are 4-5-3-1-(2)

    Now my 4345 is best sounding speaker in the world~~

    Sorry for bad english

  4. #4
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    OK since i already have the speakers up a bit I have decided to now do the following:
    1. going to open them up and remove the switch (external or internal crossover switch)
    2. replace capacitors

    I figure this will be plenty for now.

    Why do people replace L-pads by the way? And the l-pads being the EQ knobs? is that right. i muyst admit i do not understand how replacing the knobs helps but hopefully somebody will come and tell me.

    I plan to take photos of the 4344 as i open them so i can log the work on here. for all the posts etc i never found clear photos of the 4344 3144 network with a clear listing of what needs to be replaced so maybe that is something i can contribute to the forum.

    one more thing - what capacitors to use? any recommendations? i've been looking and the range is vast. i'm sorted on use of propylene but then note there are dozens of brands to choose from and a price range from a dollar per to in order to 500 per.

    cheers

  5. #5
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    Quote Originally Posted by mr_gray View Post
    OK since i already have the speakers up a bit I have decided to now do the following:
    1. going to open them up and remove the switch (external or internal crossover switch)
    2. replace capacitors

    cheers
    The switch is definitely worth bypassing. I personally wouldn't bother with the capacitors, if I were spending money I would build charge coupled networks and call it a day. IME you benefit just as much with inductor upgrades as well as capacitors.

    Quote Originally Posted by mr_gray View Post
    Why do people replace L-pads by the way? And the l-pads being the EQ knobs? is that right. i muyst admit i do not understand how replacing the knobs helps but hopefully somebody will come and tell me.
    cheers
    Because they wear out over time and it can audibly affect the sound. Even when new I would imagine they colour the sound somewhat. I doubt they are completely transparent but whether the difference is audible I cant say.

    Quote Originally Posted by mr_gray View Post
    I plan to take photos of the 4344 as i open them so i can log the work on here. for all the posts etc i never found clear photos of the 4344 3144 network with a clear listing of what needs to be replaced so maybe that is something i can contribute to the forum.
    cheers
    Most would just rebuild the networks completely rather then a recap. The capacitors aren't electrolytics so I doubt they are faulty. Not impossible but highly unlikely


    Quote Originally Posted by mr_gray View Post

    one more thing - what capacitors to use? any recommendations? i've been looking and the range is vast. i'm sorted on use of propylene but then note there are dozens of brands to choose from and a price range from a dollar per to in order to 500 per.

    cheers
    In Australia either Jantzen (Speakerbug) or Mundorf (SoundLabs) are you two best options. If using a Jantzen and on a budget the cross-caps are the way to go, Mundorf the white M-caps would be your starting point.

  6. #6
    Senior Member Ian Mackenzie's Avatar
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    Hi there and welcome to the forum.

    I am also a local in Melbourne and happy to offer guidance on your new acquisition.

    You have quite a shopping list and that is the right approach.

    To answer your questions in order:

    1. The existing capacitor are Mylar bypassed with either polystyrene or polypropylene.
    Based on my own investigations the stock capacitors are not up to par with modern
    loudspeaker capacitors.
    The question is then what to do. It depends on your overall plan? Do you want to
    preserve the original design and
    construction ? You have the option of removing the existing capacitors from the pcb
    ( l can advise you on that); you can
    build a new network internally; or build an external network.

    To answer your questions Yes and Yes
    Selection of the capacitors is not cut and dried. It depends of the associated components
    in your system and the
    loudspeaker drivers. Given the system is piston range it’s quite analytical towards the rest
    of the signal path. That’s both good and bad. Bright capacitors or overly detailed
    capacitors are inappropriate as you have metal diaphragms,
    but you also want a transparent neutral capacitor.
    The best value and balance l have experienced for the money is the Clarity SA capacitors
    bypassed with 0.01 Auricaps. The Clarity Cap ESA, MR and CSA are worth investigating if
    you are looking to upgrade the stock network. So called loudspeaker capacitors can be
    very expensive. I would avoid Mundorf capacitors in this system. They are really
    expensive and not necessarily the right match for this system.
    The Robert Hovland capacitors are very good

    The Clarity Cap SA and bypassed with Auricaps combination is transparent without fatigue
    and won’t need a 2nd mortgage.

    The Solen Fast Cap when charge coupled works very well. The presentation is clean,
    neutral with good transient detail.
    The construction of a charge coupled network is
    complex and expensive.

    2. See above.

    3. Other information and recommendations
    But you need to look at your whole system in terms of quality level and subjective
    characteristics.
    Do you want to hear each recording as it was produced or give the sound a characteristic
    you prefer generally on
    every recording such as a clinical presentation or a warm tonal characteristic?
    My recommendation is to keep the
    signal path as transparent and neutral as possible.
    A lot of people comment on what these systems do well and don’t do so well.
    My feedback is once you
    have the best amplification and source you can afford these monitors bring you very
    close to the recording as
    delivered by the engineer and the artist.
    For example being able to enjoy vinyl on your Rega Planer TT, Tidal MQA streaming or
    original Master tapes.

    To get to this point requires a process.

    1 Get your compression drivers and 2405 drivers check out. It maybe one or more of your drivers is faulty given your comments. Get them cleaned out and checked by a local technician.

    2 Decide if you want to keep the system authentic? You can disconnect the original network and put it in a safe place and build a new network either internally or externally.

    3 Work out your budget. It’s going to be expensive but very worthwhile.
    You don’t have to do it all at once.

    4. Who is going to upgrade or build new networks. Do you have the skills and knowledge to do it correctly.
    Allow a few months to upgrade the networks. Longer for new networks. Check your work or have someone check it. Mistakes are easily made due to the complexity. I can help you.

    5. Bypass the Biamp switch. I can help you.

    6. Replace the rear terminals with Cardas quality or similar. I find terminals more important than the cable.

    7. I would not replace the Lpads unless you can determine they are faulty. This is quite an invasive procedure.
    The problem with the Lpads is correct adjustment.

    8. Do not operate in full passive mode if you want the full potential of this loudspeaker.

    9. Set them up with REW or the Dayton loudspeaker measurement system. You can’t do it by ear. I can help you.

    10. Buy good active crossover like the First Watt B4. If you can’t do that right away leave it in full passive mode for now.
    There are reasonable analogue active crossovers like the Ashly but you will sacrifice transparency. Again think about your whole system.

    Power amp power is cheap when it comes to bass. I saw a a very nice locally made digital power amp at the HiFi show. I do not recommend dsp crossovers. Again reflect on the rest of your system. They work functionally but won’t give you the best outcome from an analogue source. The DEQX is entry level but start at AUD$5000. The problem is are you hearing the artefacts of hi sample rate ADC and DACs or not? Unless you use the same converters ax used in the studio it will never be quite right according to Bob Stuart co founder of Meridian and MQA. He knows what he’s talking about and the industry listens. Some may disagree.

    11. If you plan to build new networks l recommend making them external. That way you can put new Lpads or fixed resister values in to set the final levels. I can help you figure this out. I have built numerous networks and advised on upgrading quite a number of these systems.

    12. You can try other compression drivers like the Tad 2001, 2002 or the large format drivers. The later requires a rework of the network. My recommendation is start with what you have. I have found dusted diaphragms offer the best bank for the buck.

    13. Take your time. The devil is in the detail. Above all trust your ears before accepting an
    opinion and check and read check everything. I have listened to a number of stock and modified systems. In some cases the results are all over the place. This is often due to driver maintenance issues, changes made by previous owners, mistakes made during upgrades and inaccurate set up of the Lpads. If you put rubbish in you get rubbish out. Take nothing for granted.

    Ian

    Useful thread links
    http://www.audioheritage.org/vbullet...ial&highlight=


    http://www.audioheritage.org/vbullet...ade&highlight=


    http://www.audioheritage.org/vbullet...ect&highlight=

    http://www.audioheritage.org/vbullet...344&highlight=

  7. #7
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    Ian and Kelossus thanks for your replies. Ian i have pm'd you.

    My whole front end is setup for clarity and neutrality. I have a Chord Dave converting to analog and that goes into a 100 w.p.c tube amp (opera 880i). I am a detail freak who loves the dynamics and sheer scale of the JBL speaker (i believe being too detail obsessed is a trap at some point and I'm trying to quit to some extent).

    I will sift through your advice but essentially:
    1. i do want to keep it as stock as possible - changes which aren't easily reversible are less acceptable
    2. as such something which totally replaces the crossovers (going external) does appeal relative to changes to existing crossovers

    i will post a link once i start the "refurb" thread - even if that is just photos of interior in beginning.

  8. #8
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    Hi Again
    after doing more reading of your reply Ian would it be fair to say then that one upgrade path is:
    1. remove switch (or bypass)
    2. buy 2 First Watt B4's
    end

    That is, do the active crossover's from first watt remove need for anymore work on caps and crossover etc. i am acutely aware this is probably a stupid question but i have to ask.

  9. #9
    Senior Member Ian Mackenzie's Avatar
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    Quote Originally Posted by mr_gray View Post
    Hi Again
    after doing more reading of your reply Ian would it be fair to say then that one upgrade path is:
    1. remove switch (or bypass)
    2. buy 2 First Watt B4's
    end

    That is, do the active crossover's from first watt remove need for anymore work on caps and crossover etc. i am acutely aware this is probably a stupid question but i have to ask.

    1. Correct.
    2. One First Watt B4 (stereo 2 way)

    The active crossover functions to split the line level audio signal after your preamplifier between two stereo power amps into seperate frequency bands referred to the low pass and high pass frequency bands.

    In full passive mode the passive crossover uses lossy passive filter elements called inductors and capacitors to accomplish the woofer to midrange crossover function.



    In biamp mode:

    The passive filter elements are bypassed on the passive low pass filter for the woofer (with the bi amp switch).
    The low frequency power amp is directly connected to the woofer .

    The passive high pass section of the midrange passive bandpass filter is bypassed (with the bi amp switch).
    The mid range filter functions as a low pass filter only (with the bi-amp switch).

    The bi amp switch is a multi pole rotary type switch which also isolates the filter ground connection the woofer. This rotary switch causes significant losses in the signal path and effects audio quality.

    In summary you have to modify or build
    Mid range passive high pass filter
    Horn band pass passive filter
    Slot high pass filter

    There is more detail under this high level summary such as the internal wiring of the loudspeaker, the Lpads, 8 pole plug and socket (Speakon) and speaker cables and of course construction of the external passive crossover network and an enclosure to house it.

    Essentially you hardwire it for bi-amp mode. Although I know someone who wanted full passive mode and bi amp mode selectable via copper buss bars.

    (If you keep the original passive crossover intact they are quite valuable.)

  10. #10
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    Post

    If you intend to run the speakers with a single amp I would look at changing amplifiers. You run a near $20k AUD DAC with a cheapish Chinese Integrated tube amp. Plenty of high power SS Integrated Amps out there.

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