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Thread: A horn throat distortion question, and eficiency Vs dynamics?

  1. #46
    pangea
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    Quote Originally Posted by Mr. Widget
    Roland,

    It's just that Zilch has been listening to pink noise too long.


    Widget
    OK, I think I've got it.

    Many thanks BTW for that paper on woofer speed. VERY interesting!!! I'll try to remember that and save the file.

    BR
    Roland

  2. #47
    Dang. Amateur speakerdave's Avatar
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    Quote Originally Posted by Mr. Widget
    Not sure we can... check this out.

    http://www.adireaudio.com/Files/Tech...ooferSpeed.pdf

    Widget
    A couple of questions from the techNOT about this paper.

    One: In inductors current lags voltage, so increased inductance will discharge more slowly. But the question about woofer speed does not regard comparisons of inductances. Also, I think adding inductance outside the magnetic gap may have a different effect from adding it in the gap. I would need to think more about exactly what the difference might be.

    Two: The way the math is managed the argument is foreclosed. He calls m a constant, but it is different sizes of this factor that he should be comparing. Given the same strength in the motor and the same current from the amp, if m is increased a must be less. Heavier cones will be slower unless the motor strength is increased. The difference between the JBL D131 and 124 is a good example of this truism.

    Three: His charts contradict his argument. The peaks in the red and blue lines occur at the same time, but the red peaks (increased mass) are lower, meaning that the cone has travelled a shorter distance in the same time; reason: it is slower.

    David

    Edit: Oops. No, I got my colors mixed up. Hang on.

    Edit 2: On the first half cycle the raw and mass-added curves are the same. On the second the mass-added curve goes FURTHER, suggesting the suspension is struggling to control the momentum. On the "ringing" cycles the mass-added curve does begin to lag the the raw curve.

    If the effect of adding mass does not change the initial response (according to the test data), and the BL and current are the same, it can only mean one thing, and that is that the change in mass is trivial for the given BL product and suspension effects, and the test setup is not sensitive enough to pick up the effects of the added mass on the first half-cycle.

    Additional hedging: The comparison of the D131 and 124 assumes that they both have the same voice coil depth. Of course, they may not.

    Edit 3: If the additional inductance were to be added within the magnetic gap, i.e.. by increasing the voice coil depth, then that would increase the BL product, tending to increase acceleration, not decrease. The effects of the additional BL and the added inductance, would tend to offset. Whether it would be direct and complete I don't know.

    Then there's the added back emf which would result from the increased coil windings. The effects of that I can't picture.

  3. #48
    RIP 2011 Zilch's Avatar
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    ***Zilch slaps Mr. Widget with a red herring....***



  4. #49
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by speakerdave
    A couple of questions from the techNOT about this paper.
    I have to admit I only glanced at it.... I did a quick google about BL vs. transient response and this popped up. I do agree with their premise, but can't vouch for their argument.


    Quote Originally Posted by Zilch
    ***Zilch slaps Mr. Widget with a red herring....***
    You keep that kinky stuff at home.

    Widget

  5. #50
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Mr. Widget
    You keep that kinky stuff at home.
    Widget

    oh oh oh jingle bell ROck...


    hi transient spanking with a full power velocity movement heres...

    your engine play bang!! dang !! pang!! or tang ???


  6. #51
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by speakerdave
    A couple of questions from the techNOT about this paper..
    My 2 cents here is :

    the electrical impedance is critical factor for fast transient and clear fundamental response.


    Krell have 12 of damping factor in amp and few crown have over 5000 damping factor. few amp (specific for live session) have over 10 000 damping factor. for complete depredation control (if you "spanking" the mic, the monitor survival)...

    my experience is the damping affect impedance => and consequenly the transient:

    less damping play more harmonical responses but you drop smash transient.

    inverse situation... too heavy damping: the driver is "over" tight smash but you lost the harmonics...

    equilibrium is one of part of signature sound: the match of

    amp- cable- driver affect direcly the balance of acoustics transient and harmonics response ...



    in general really high factor electrical and pneumatic factor affect transient. load with event port, etc, etc,


    in theorical the lightnest and rigid surface as possible with the small motion as possible garantee the fastest response and re-position for next impulse without external control...



  7. #52
    Senior Moment Member Oldmics's Avatar
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    B+KMan quote

    "Krell have 12 of damping factor in amp and crowm over 5000 damping factor. few amp specific for live session is over 10 000 damping factor."

    At what frequencys was the damping factor specified?

    Something to consider in woofer applications.

    Oldmics

  8. #53
    Senior Member B&KMan's Avatar
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    spec. for damping factor...

    Quote Originally Posted by Oldmics
    B+KMan quote

    "Krell have 12 of damping factor in amp and crowm over 5000 damping factor. few amp specific for live session is over 10 000 damping factor."

    At what frequencys was the damping factor specified?

    Something to consider in woofer applications.

    Oldmics


    mmmmmmmm this is a another story....


    many cie' print spec. in non accordance conformity to IEC , EIA, ISO, ANSI, standart...


    but in general the load impedance (8 ohms ex) and frequency is specified at serious cie'.

    normally 8 ohms and arround 50 Hz is good range...



  9. #54
    Senior Moment Member Oldmics's Avatar
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    Quote from B+KMan

    "normally 8 ohms and arround 50 Hz is good range..."

    Agreed,however find me anyplace Crown lists its damping with this spec in mind.

    Oldmics

  10. #55
    Senior Member B&KMan's Avatar
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    the power of ...... Google : Crown damping factor.

    Quote Originally Posted by Oldmics
    Agreed,however find me anyplace Crown lists its damping with this spec in mind.
    Oldmics
    As you wish...

    Attached Images Attached Images  

  11. #56
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by Oldmics
    B+KMan quote

    "Krell have 12 of damping factor in amp and crowm over 5000 damping factor. few amp specific for live session is over 10 000 damping factor."

    At what frequencys was the damping factor specified?

    Something to consider in woofer applications.

    Oldmics

    the rule is more damping more stiff but less harmonics. is you go in real sub below 40 or 30 HZ the higher damping the better smashing... because the harmonics is poor at this area, keep higher reasonnably...

    the non official rule is over 500 damping is consider very higner snap and image is terreffic and is for application mixing with more accurate space position sound in image sound on record session.

    over 1000 is for live for control displacement of diaghram for not convert it to rocket when the guy is drop the mic of over pressure displacement on diaghram mic...



  12. #57
    Senior Moment Member Oldmics's Avatar
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    Thanks for the Laugh

    Pull up the same page on your goggle search.You will see a pro sound website discussion regarding damping.

    http://web1.prosoundweb.com/communit...rd=2&id=143800

    The gentlemen who wrote the article is one of QSC designs engineers.While I don"t always agree with his beliefs,Bob Lee is a respected and well versed professional in the field.

    Basically he is saying that damping factor is marketing hype.

    He gives an example regarding a hypothetical damping factor of 124 (basically 20 feet of 12 gauge copper wire and a vaporware amplifier with an impossible to achieve damping factor spec of infinity)

    So how hard is it to achieve a damping factor of 400 @ 10hz? (Which is a shit spec factor!)

    Answer-Not very difficult.

    Damping factors are bullshit salesman dialogue.

    Although you did find the specs together-I did get a good laugh out of that!

    If your gonna critique amps,I would look at the storage capacity in the power supplys and see if they are overspec (as they should be-Crowns are not!) and if so by how much in comparision to rated wattage output.

    Oldmics-Where the hells that PSS guy when you need a laugh?

  13. #58
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by B&KMan
    many cie' print spec. in non accordance conformity to IEC , EIA, ISO, ANSI, standart...
    if guys is not refer at a standart, maybe is print anything as wish.

    I agree this factor and many other factor is a real real propaganda....


    but this fact is not cancel the reality of the bucle of conter-reaction control resistance on amp circuit... and the effect on the sound result...

    the damping factor is the trick for balance equilibrium on one side fundamental transient and propagation of the harmonics.... and each cie expose theories and who have a best point of view...

    anyway,

    thanks for link.... I check because I have a good experience of the phenomenon but not strong scientific comprehension of the phenomenon.


  14. #59
    Senior Member frank23's Avatar
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    Quote Originally Posted by Oldmics
    If your gonna critique amps,I would look at the storage capacity in the power supplys and see if they are overspec (as they should be-Crowns are not!) and if so by how much in comparision to rated wattage output.
    Yes, that is one of the reasons why I think my class-A amps sound so good. They are full class A, so they dissipate 4 times the rated output at any time they are on. Even when there is no signal at all.

    My 2*12Watt MF David class-A amp takes up about 100Watt's all the time its on, so the power supply is designed for that load, while in practise it only has to deliver a few Watts.

    Don't even get started with thinking about this ratio for single-ended-mosfet-amps though!

    frank

  15. #60
    Senior Member B&KMan's Avatar
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    Quote Originally Posted by frank23
    Yes, that is one of the reasons why I think my class-A amps sound so good. They are full class A, so they dissipate 4 times the rated output at any time they are on. Even when there is no signal at all.

    My 2*12Watt MF David class-A amp takes up about 100Watt's all the time its on, so the power supply is designed for that load, while in practise it only has to deliver a few Watts.

    Don't even get started with thinking about this ratio for single-ended-mosfet-amps though!

    frank
    well because the full class A built a full reserve power all the time so is convert just for replenish the level... the great advantage is time delay cancel and better phase.

    any style of amp the perfect admisibility of full transient impulse
    is possible only is rms is fixed at 1/3 of the full power rated...

    i have listen superbe pure class A accuphase A-50 (monster bigger than Krell) I listen mark levinson, Krell, and few other pure class a and if you respect the rule of max 1/3 power rms handling all is never shrink sound.


    but the damping factor change considerably the presentation of response and equilibrium of fundamental and harmonics proportion.

    shure many cie is print full or partial bullshit but the reality of control damping factor is here. many flavor amp is demernining by this aspect.... in regard of the interaction of the rest of the link with speaker....


    my 2 cents experience.

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