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Thread: 4343 crossover modifications

  1. #286
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Earl K
    Hi Jean

    So , is this semi-circular thingy that is stuck to the back of the cabinet supposed to hold all 3 of your 12" by 12" granite plates ( all at the same filled with sand ) ? I'm quite confused by the smallish size of it .
    ---Sorry I limit of my english this piece is not a final board : it is just gabarit for assume look and better easy to handle by chunky final board...

    --- Yeah, I realise couple of error because too small experience electronic...

    --- Of course I perform many tests and adjustement (I hope to not change caps of resistance...) for tuning response before final sand operation...


    --- I perform later comparison device exposure of vibration and attenuation resonse in epoxy and epoxy-sand and plain set-up but my experience is more is better...

    For Wax, Solen is not recommend because the eat destroye the caps...
    epoxy is limited because if one conponent is broken or fail, I'm not interested to put entire network in garbage... For my coil I paid extra charge for 3 dipp in emanel for solid core coil ( yuk yuk yuk )

    But you help my strongly in this project and I'm weeling to perform free a set of vibration response : one big day for work perform so later but try soon )...






    Quote Originally Posted by Earl K

    (iv) Worth considering about possible induced microphonics into capacitors is the effect of DC biasing . One purported benefit ( from the K2 S5500 copy ) to biasing is that it pre-"swells" the capacitors' dielectric layers.
    So; expanding on that thought :

    - If the caps inside expands against a flimsy wall ( like Solens ) / the resonant microphonic signature should be somewhat lower than a hard wall. This will need a specific approach to "energy" dumping to avoid so-called "blooming".

    - If the inside expands against a firm wall ( like some hard shell caps / or especially those already encased in epoxy ) / the resonant microphonic signature should be much higher ( perhaps supersonic ). This will need a different approach to "energy" dumping to avoid "UHF ringing".

    Example - My main "go to" RC surplus capacitors have the metallized polypropylene core encased into hard epoxy . They start off very quiet & once "DC biased" they are even "quieter" , offering ( I believe) a much deeper sense of resolution
    Well for this points it is really theorical and long response... the fundamental point is any solid is vibrate... Well, what better tecnique for reduce this natural response ??? The damping fator is same of ration of echo response in room to higher , the sound is run in bell concert, to dead, the sound is dead too... so the ideal approach is found good time damping factor and faster drain power vibration appear around or inside caps... Yeak epoxy is really hard and drain fast energy but I have not mass energy to put down level response... Let me know it you undertand ....

    Jean.


    BTW the shape of back is ideal dispertion panel so the standing wave on back speaker is broken and dissipate... Better flat response and less noise floor: better imge stereo, and details infor... (I hope in theory)


  2. #287
    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by Earl K
    Anyways, in looking at the above ( referenced ) network created by Jean, there seems to be a typo ( at least I hope it is )
    Hey, Earl...

    Sharp eye. I've edited the .jpg. Can you take another close and careful lookie at this - it's important it honour the design.

    Cheers...
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    bo

    "Indeed, not!!"

  3. #288
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    - Will Do ( this pm ).
    - I need to first assemble/compare the 3 varieties/styles of upper filter topologies.
    - This also means assembling a .jpg collage incorporating the two evolutions that Giskard did ( the type minus the autoformers ) .


  4. #289
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by boputnam
    Hey, Earl...

    Sharp eye. I've edited the .jpg. Can you take another close and careful lookie at this - it's important it honour the design.

    Cheers...
    Yiah realy sharp...

    bravisimo...

    Jean

  5. #290
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    Well this is getting messy .

    Jean

    - Here's another mistake found in the UHF section .

    - I haven't scoured your drawing for all others but this one stands out .

    Explanation : Typically , in an Lpad , the inline ( series resistor or "buildout resistor" ) is placed on the "source" side ( ie; amplifier, drive side ) of the network because it is usually present to correct an impedance mismatch / usually caused by placment of the parallel ( or Shunt or Conjugate ) resistor across the line .

    Jean ; please nuke ( remove ) the above drawing ,yes, the one you just placed with the correct 120uf value.
    - I think it's best to wait for some more corrections before putting a new one in.

    - For instance ( and this makes quite a difference to me ) . Each of your cascaded capacitor setups actually used just one resistor to deliver the 9 volt bias / instead of the usual 2 or 3 resistor that is shown on your schematic . So your reality is a different approach from the schematic.
    - Now, the reason this divergence matters to me is that the 2 or 3 pairs of capacitors now have a central connection point or crossover pathway . This is the way you have shown pictures of your wired setup ( & FWIW ) the way I prefer to connect all cascaded & biased teams of capacitors.
    - Why my preference : I believe that having that central connection ( the resistor "tie" point ) helps average out timing errors . ( Okay, This is truly geek-based tweaking stuff , only for those who care to listen this much to the effects of capacitors ).


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  6. #291
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    Quote Originally Posted by B&KMan
    Hi again Ian and thanks for many tips...

    (p.s. I love your pict member )


    AIIIIII

    I really sorry to read your post for manys reason and I feeling to start a another long long bing bang controverse...


    1--- First the SLM Radio Shack have a really poor response in high frecquency... ( I remember my friend I have one maybe it ispossible to create comparaison...).

    The flat response is not up to 15K it is ( in my memory below 12K)
    and the lower is not good below 100 or 80 Hz...

    Because the feeling of pitch or balance tonal is critical (0.2 -0.4 dB) the precision is THE difference. ut of course it is possible to feel coarse set-up in this...

    the SLM distord the field response and it big eratic alteration response mesurement...

    2--- Your method is classical for mesure acoustic response with minimise background interferance create by room.

    3--- Unfortunately the driver is fluctuate consistently in area of freq response... So 15K is maybe 2 dB higher of average power level of this driver of maybe below couple dB... In according .4dB variation is the best set-up the methos of only one freq is too aleatory... add imprecision tool ...

    4--- Well your method is explain in rane electronic crossover... and explain many tecnic for phase and SPL calibration with simple SLM... but it is really coarse adjustement and not create magical set-up...

    5 the magical set-up is very expensive in money and time...
    a--- big high end instrumentation and ultra high level mic (free field or and pressure field) 2 positions according to ansi or ISO standart... in regard of sweet height spot... generate pink noise (with high accuracy) and average over a 30 secor more record mesurement. (slow = 2 seconds but it is not satisfying the stabilisation of low frequency for accuracy mesurement...)

    b--- more records positions more accurate mesurements: mic is keep the node and modal response room, so the many different positions is cancel this effect by averaging result many positions...
    Of course you catch the response room and it is important factor, distance and angle and plane surface modifying response curve and it is important to set-up Lpad in this reagrs for better fla response possible... not theorical driver response....

    Of course the more sofistication analyse modal response room expose where specially bad or poor response area... If you have push the button , the treatment of echo and other modal parameters room influence the result...


    Finnaly the level of finest FFT analyser or RTA expose 1/24 oct is really surprise response in regard of 1/3 octave... and discovery the value is in realy just a small peak frequency to boost result Consequence : more details more precise value...

    But YES I go in your point of views, the subtil tune-up L-pad reveal the finest of nature of speakers and sound...

    After works this set-up, I realise many news details in music, subtility sound, many high frq. details but L-pad is lower than before perform test !!!

    Best regards,

    Jean.
    Your remarks in point 1 & 3 are all irrelevant (wrong). As I said earlier you are only measuring a relative difference, not an absolute value of each discrete driver. If the crossover voltage attentuation is correct then all that is required is subtraction of -4 db for the slot and horn and -3 db for the midrange.

    Surprised as you maybe , the Tandy measurement tool is quite capable is detecting a relative SBL difference and as it is affordable I would encourage other members to use it for this specific purpose.

    A top engineer can get the job done with even basic tools. Don't over complicate what you are trying to achieve

    Dalek

  7. #292
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Earl K
    Well this is getting messy .



    Earl, you have not only sharp eye , you have a mind too...

    Your argumentation a resistance dc and constatation for resistance UHF is entire correct...
    I fixe the schematic tonight

    Let me know other mistake...

    thanks a lot !!!!


    Jean.

  8. #293
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Ian Mackenzie

    Your remarks in point 1 & 3 are all irrelevant (wrong). As I said earlier you are only measuring a relative difference, not an absolute value of each discrete driver. If the crossover voltage attentuation is correct then all that is required is subtraction of -4 db for the slot and horn and -3 db for the midrange.

    Surprised as you maybe , the Tandy measurement tool is quite capable is detecting a relative SBL difference and as it is affordable I would encourage other members to use it for this specific purpose.
    Dalek
    Hi Ian, Maybe I'm not understand your procedure works...

    if you put 15K in uhf the mesurement: the response is produre only by UHF so it is not possible to perform absolute comparison at same frequency with HF ??? No ???

    My brother is keep mic in dolorama and the error is absolutely same in any mesurment so of course it is possible to produce high degree of precision for same conditions... But it is important for this forum all understand this is not a better approach but yes excellent start approach)... My point is not shocking anybody or put myself in higher than other...
    I pain many many weeks for discover with reading and experiencing the difference and why one record response big differt to other by subtil displacement or scale of data...

    I try to send later test for explain my point of view...

    and thanks for all.

    Jean

  9. #294
    Senior Member B&KMan's Avatar
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    Here again great members with , ( I hope ) stunning info pict...

    Well Before put by big network box on back speaker, I mesure response modal and resonnance cabinet...

    what difference ???

    Cabinet is resonnace produce by run speaker in pink nois or sweep sive wave and keep what is fr is exice the cabinet and what amplitude... This is important for catch the part of adding or supressing fr in final playback mode

    the modal property is extract motion and spectrum response of specific place on cabinet... In this I have info what exactly comportement backplat speakers without the rest of the response cabinet....

    Of course this is permit to keep signature ( 1" med density presswood) material and exclude internal resonnance or other...

    of course this is not a complete study and many aspect is neglected... Why ?? TIME bordel de merde the calibration and complete analyse is big big work and for this application a good average is OK for feell the better or worse modification...

    Ok resere and theory is pass now look result...

    the modal is multipoint mesures (equal distance and same line displaement point mesure)
    the hammer impact instrument and accelerometer is produce and keep signal.. the dual analyser is compute the datas and expose result... and a hand with no face is works the process
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  10. #295
    Senior Member B&KMan's Avatar
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    Comments result:

    Weel no surprise the presswood is specific signatue and is relatively altered by network fixed inside box...

    the material is good fixing inside and brce to keep excess natural amplitude response... No surprise is a JBL original box ( )

    Ok the dark side now... The persistance of signature all in points expose the transfert flavor to the drivers... fortunately the signature is relatively round and not too sharp peak and node...

    now part B pink noise run on speaker and listen the resonnace emmision on back panel... The track resonnace is the sum of panel resonnace and cabinet resonnace : no surprise the cabinet resonnace is more strong to backplate resonnance and produce peak signature.... note if you keep signature in upper pback panel the bass is dissapear for expose more med enrgy... again this is a good point and expose the resonnace cabinet is controled and relatively good dispertion response in all freqeuncy...

    Note I keep the level mesure of little cardboar plate where the post is fixed... look the difference signature and amplitude... ( the tribo-electric effect is back !!! ) yuk yuk yuk


    well I hope this info is ineresting for open put the phenomenon on your sharp eyes members.

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  11. #296
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    Hi Jean

    Cabinet is resonnace produce by run speaker in pink nois or sweep sive wave and keep what is fr is exice the cabinet and what amplitude... This is important for catch the part of adding or supressing fr in final playback mode
    ***Okay, that part I understood .***

    - With music ( or pink noise , swept sine wave ) as a source , one can excite the cabinet ( from the inside ) to find out its' modal resonant points . Then one can proceed to find a way to dampen them down or out .


    the modal is multipoint mesures (equal distance and same line displaement point mesure)
    the hammer impact instrument and accelerometer is produce and keep signal.. the dual analyser is compute the datas and expose result... and a hand with no face is works the process
    ***This last part I don't understand .***

    - What is the relevance in exciting those modal resonances with a hammer from outside the box ?

    - This approach ignores what is going on inside the box. That's where the energy generator is located

    FWIW : I agree that these stock boxes can use better bracing. Your "2in1" solution to firming up the back-panel with your "custom crossover sand-box" is one such approach.
    - But, personally, I'd like to see these two functions split, between a dedicated holder for the crossover ( that keeps the plates horizontal ) & better external bracing on that back panel .

    - Just My Opinion <> ( since I don't actually own any of these things to need to worry about them )

    EDIT ( after the second post )

    Okay , maybe I get it now . Please, tell me if I'm right or wrong.

    (a) The hammer was used to map out & clearly "identify" the backpanels' modal resonances from the point of view of a "worst case scenario " . This was to create a reference point so that one can see the effects from internal dampening.

    (b) The second test was with an "internal energy source". This revealed the damping effects occuring because of the cabinets fiberglass and the fixed location of the present crossover.

    Jean , what is your conclusion to this test ?

  12. #297
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Earl K
    Hi Jean

    ***This last part I don't understand .***

    - What is the relevance in exciting those modal resonances with a hammer from outside the box ?

    - This approach ignores what is going on inside the box. That's where the energy generator is located

    Okay , maybe I get it now . Please, tell me if I'm right or wrong.

    (a) The hammer was used to "identify" the worst case scenario so that the resonances from the back panel were clearly delineated. This was to create a reference point .

    (b) The second test was with an internal energy source. This revealed the damping effects occuring because of the cabinets fiberglass and the fixed location of the present crossover.

    Jean , what is your conclusion to this test ?
    Hi and thanks for interest,


    ---- the hammer keep signature and movement of back panel without consideration of tuned inside cabinet... in this you keep the real signature and effect produce by back panel.... the hammer produce a implct pluse inside material and the acc is keep this spectrum, amplitude, phase and distortion...

    after you understand a specific backpanel is play, you evaluate the entire speaker in normal mode and check if the signature of the backpanel is relevant

    if conclusion if yes = the back panel produre big effect in global signature playback !!! (same drum)

    if no = back panel not signifiant effect on global signature...

    I hope this second result (this is result of good speaker)

    if I put big box network on panel, and modifying the signature of back panel if mesur is expose it is not important I will go in this way, otherhand if back panel is contribute stongly of the global cabinet signature, the alteration is tricky to detune cabinet...

    And because the cabinet resonnace in a multiple additition signature, of course the even port and inside cabinet encluse is calculate for produce energy sounds (this is a concept of helmholz box resonnace...)

    Of course you understant the criterium strong signifiant and non signifiant is relatif and the ideal is no response material and just pure helmholz renonator... but the real is not utopic...

    the summary analyse expose -20 differencial in material and internal resonnance so this range is detectable... fortunately the boxNetwork keep energy backPanel and keep energy of flanking panel I hope to brop signature by 10 or (I dream... ) 20 db...

    The result is the micro information is drastic more relevant and clear, more deep, and better subjective transient amplitude... (the law of the mass )

    But maybe this higher resonnace material is balance the bass resonnance and if is desapear, the bass bloom is more more present...

    yurkk it is nothing to easy modified studio monitor...

    better comprehension phenomenon ???




    Jean.

  13. #298
    Senior Member B&KMan's Avatar
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    well look next page for other mistake netwoks diagram...



    jean.

  14. #299
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    Hi Jean,

    better comprehension phenomenon ???
    Yes, Thanks ! for the above explanation(s) .

    The result is the micro information is drastic more relevant and clear, more deep, and better subjective transient amplitude... (the law of the mass )
    - What about the wires inside the box ?
    - How does one disconnect them from induced microphonics ?

    NOTE: I've just downloaded your latest "corrected" N3145 network .

    - I'll print it out so that I can look at it outside of this office ( my listening chair ) .

    - If I don't look at these type of things ( off-screen ) I miss too many details .

  15. #300
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    Quote Originally Posted by Earl K
    - What about the wires inside the box ?
    - How does one disconnect them from induced microphonics ?

    the wire is original come with the JBL network and I do not perform any treatment for vibration control.......

    for the rest I expose my in naval war controverse argumentation

    http://www.audioheritage.org/vbullet...6119#post56119


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