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Thread: Help for JBL k2

  1. #31
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    Quote Originally Posted by Odd View Post
    There is a possibility that this may sound better in your ears.
    There are many who think they can replace capacitors and hear improvements.

    But, if one tries to be realistic and think the following, the top models of JBL have never been produced in very large numbers. If it is the case that a few capacitors of possibly better quality will give significantly better sound what would it cost JBL?
    JBL, which is a very large customer, does not pay the same prices for components as one that buys 10 or 100 pieces.
    What would a small extra cost for capacitors mean for the price of the product to the consumer?

    Probably nothing.

    I agree, however in my experience the electrolytic capacitors can decline in performance after 20 years and it is not always measurable by a capacimeter.
    Chinese elytones are also very cheap in terms of electrolytics.

    I just think that in JBL they used that type of capacitors because they had full stock ....

    Probabilmente in un futuro non troppo distante si procederà per la modifica in SE sostituendo i condensatori elettrolitici con i solen MKP.

  2. #32
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    Your last line was a little hard to read.
    Probabilmente in un futuro non troppo distante si procederà per la modifica in SE sostituendo i condensatori elettrolitici con i solen MKP.

    But Google says
    Probably in the not too distant future we will proceed for the modification in SE by replacing the electrolytic capacitors with the MKP solen.
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

  3. #33
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    the Special Editions have the same filter but use solen mkp instead of the electrolytic of the normal version.
    It is a very easy modification, if you want to be picky you can also easily adjust the coil of the 435BE L4 by 0.1 mH


    http://www.audioheritage.org/vbullet...pecial-Edition

  4. #34
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    Yes, >> I know if I owned those networks I'd swap out all the yellow caps for 250Volt MKP Solens ( as used by JBL ) .

    I regularly listen to 400Volt MKP Solens ( dc-biased ) > BUT I do so at a drastically lower bias voltage ( compared to the STANDARD 9Volt DC Bias >> it's typically less than 1 Volt DC ).


    Considering that you've stated that like what you hear ( due to swapping out the Elytones ) you would do yourself a ( educational ) favor by measuring your existing DC voltage ( from the center of any pair of caps to ground > using a multimeter ) to see what your voltage is at today.
    - Remember that GT evolved the DC biased networks to being biased through a diodic "tap" taken from the LF drivers input voltage ( for when/if biamping is being used ).
    - That form of variable biasing can result in a much lower dc voltage if ones normal listening habits are well controlled.

    - It may turn out that you too prefer the sound of a lower bias voltage.

    It takes a while for the caps to charge up to a full 9 volts after they've been discharged ( the charging slowness is due to the 2.2 meg resistor ).
    - If your networks discharged when you were working on them // they might ( currently ) be only partially charged >> hence a lower bias voltage possibly being a contributing factor to a "different//preferred sound".

    It's worth checking just to get a snap-shot ( reality-check ) to create a marker that's connected to your current satisfaction level.


  5. #35
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    Quote Originally Posted by Earl K View Post


    Yes, >> I know if I owned those networks I'd swap out all the yellow caps for 250Volt MKP Solens ( as used by JBL ) .

    I regularly listen to 400Volt MKP Solens ( dc-biased ) > BUT I do so at a drastically lower bias voltage ( compared to the STANDARD 9Volt DC Bias >> it's typically less than 1 Volt DC ).


    Considering that you've stated that like what you hear ( due to swapping out the Elytones ) you would do yourself a ( educational ) favor by measuring your existing DC voltage ( from the center of any pair of caps to ground > using a multimeter ) to see what your voltage is at today.
    - Remember that GT evolved the DC biased networks to being biased through a diodic "tap" taken from the LF drivers input voltage ( for when/if biamping is being used ).
    - That form of variable biasing can result in a much lower dc voltage if ones normal listening habits are well controlled.

    - It may turn out that you too prefer the sound of a lower bias voltage.

    It takes a while for the caps to charge up to a full 9 volts after they've been discharged ( the charging slowness is due to the 2.2 meg resistor ).
    - If your networks discharged when you were working on them // they might ( currently ) be only partially charged >> hence a lower bias voltage possibly being a contributing factor to a "different//preferred sound".

    It's worth checking just to get a snap-shot ( reality-check ) to create a marker that's connected to your current satisfaction level.


    Interesting, and I could also adjust the bias voltage to my liking.

  6. #36
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    Quote Originally Posted by Paul001 View Post
    Interesting, and I could also adjust the bias voltage to my liking.
    Assuming you can hear the differences.

    So much of this all comes down to personal circumstances.

    For instance, ( even though the room where my speakers currently reside is very cluttered ) I have a fairly effective LEDE room treatment setup .

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    Figures like seen above, really helps one maintain focus on what's coming out of the speakers.

    ( Plus, I've made my living through my ears since about the mid 1970's . )


  7. #37
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    Penso spesso di rendere il crossover semplificato come da progetto JBL, fare delle bobine di qualità non sarebbe un problema, con questa realizzazione tutto sarebbe molto semplice e si potrebbero usare condensatori di qualità, I would remove battery and complications





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  8. #38
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    Quote Originally Posted by Earl K View Post


    Yes, >> I know if I owned those networks I'd swap out all the yellow caps for 250Volt MKP Solens ( as used by JBL ) .

    I regularly listen to 400Volt MKP Solens ( dc-biased ) > BUT I do so at a drastically lower bias voltage ( compared to the STANDARD 9Volt DC Bias >> it's typically less than 1 Volt DC ).


    Considering that you've stated that like what you hear ( due to swapping out the Elytones ) you would do yourself a ( educational ) favor by measuring your existing DC voltage ( from the center of any pair of caps to ground > using a multimeter ) to see what your voltage is at today.
    - Remember that GT evolved the DC biased networks to being biased through a diodic "tap" taken from the LF drivers input voltage ( for when/if biamping is being used ).
    - That form of variable biasing can result in a much lower dc voltage if ones normal listening habits are well controlled.

    - It may turn out that you too prefer the sound of a lower bias voltage.

    It takes a while for the caps to charge up to a full 9 volts after they've been discharged ( the charging slowness is due to the 2.2 meg resistor ).
    - If your networks discharged when you were working on them // they might ( currently ) be only partially charged >> hence a lower bias voltage possibly being a contributing factor to a "different//preferred sound".

    It's worth checking just to get a snap-shot ( reality-check ) to create a marker that's connected to your current satisfaction level.

    you're right the sound has closed and is back as before, so I could try to remove the battery to do the double check ..... in theory the sound should return more polished?

  9. #39
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    Partially Discharge the System

    Do you not have a multimeter to measure the DC voltages of the charged capacitor pairs?

    If not, buy one ( otherwise you're flying blind ).

    You can partially ( even fully ) discharge any DC charged system by ( unhooking the battery ) and then measuring the dc voltage with the meter ( set to measure DC voltage @ 20 V range ) .
    - One lead goes to the common point of the 2 capacitors ( + resistor ) while the other lead attaches either in front ( or behind the 2 capacitors ) .
    - You'll need to do this to each pair of capacitors.

    The meter ( itself ) will slowly discharge the capacitors charge ( once the leads are attached and meter is turned on ) .


    I would take all capacitor pairs down to a 1/4 volt ( 0.25V ) and then start listening for a few days ( or a week ) >> then re-install the 9 volt battery and let it recharge ( listen for more days ).

    Repeat ( ad naseum ) until you have formed a fully informed opinion ( for your preferred voltage ).



    PS; Yes I would encourage you to build a second set on networks ( that live externally to the 9800 ) where you can play with installing boutique capacitors .

    Build them for easy capacitor swapping ( even leaving room for DC biasing certain parts of the Horn circuit ).

  10. #40
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    yes of course I have a multimeter, I also play a little with the electronics ..... you gave me great advice, I will try the voltage that I like best ..... even if I am very determined to build a ex novo external filter with simplified circuit according to JBL specifications and without battery. Thank you

  11. #41
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    I built this simple system to power the armatures of the capacitors to 1.5V or 3V or 4.5v 0 6v instead of the 9v provided by origin. In the next period I will start to rehearse.







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  12. #42
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    JBL used that switch in a number of products and I suspect the choice had more to do with providing an 'elegant' customer facing solution more than saving a few cents on the switches. A high current, sealed switch solution would likely have required two or three large toggle switches that all needed to be switched simultaneously to avoid shorting amp outputs to each other and that would have looked like a bit of a kludge on the back panel.


    Quote Originally Posted by speakerdave View Post
    A counter example: JBL made 100 pairs of its top of the line 4345, but according to G.T. the sound quality was compromised by the cost engineer's choice of a cheesy biamp switch.

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