Custom Fxbus Prolog Epilog for Musicians

Discussion in 'Effects and the DSP' started by Lex Nahumury, Oct 10, 2003.

  1. Lex Nahumury

    Lex Nahumury DH Senior Member

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    >>hmm... what if i dont want 3536?

    I see. Well, it turned out that a lot of (new) users don't understand how an
    "open" project like kX works. I.e. they simply assume that every (not included) dsp plugin
    should automaticly work with every driver release.
    If it doesn't work ppl started reporting 'driver bugs' and stuff like that.
    To avoid such confusion there are no more "unsupported" plugin versions pubicly available for download.

    However, since this obviously doesn't apply to you (as a 'kX veteran') send me an e-mail,
    and I'll send you the 'old' versions, or contact Daniel Drummond for a copy.
    Note that I will not maintain any updates nor support for these old versions.
    All tech-info can be found in this thread.

    /LeMury
     
  2. Daniel Drummond

    Daniel Drummond New Member

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    Yes Kokoon, I can send those to you if you want. Just let me know!
     
  3. kokoon

    kokoon New Member

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    well since version 3536 looks pretty stable by now, i think i'll just try it out. thanks anyway!
     
  4. eyagos

    eyagos New Member

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    Hi.

    There is a bug in the plugin src included in 3536c: The Line In has a lower level than epilogs one (-12dB). I have been looking, and when any AC97 source is selected, the output is multiplyed by 0.25 :confused:

    Regards.
     
    Last edited: Nov 21, 2003
  5. Lex Nahumury

    Lex Nahumury DH Senior Member

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    >>There is a bug in the plugin src included in 3536c: The Line In has a lower level than
    >> epilogs one (-12dB). I have been looking, and when any AC97 source is selected, the output is >>multiplyed by 0.25

    First;
    You probably mean Prolog instead of Epilog, since Epilog does not do AC97 input at all.

    Second;
    Src's AC97 inputs uses NO digital attenuation/amplification like the new Prolog does!!!
    This is intentional to give better SNR. (the 0x20000000 mult is standard)
    Since 3535 now you can get ~-75dB noise floor instead of ~-63dB.
    (please read recent threads about ac97 input levels, SNR etc)

    I hope it's clear now. (nevertheless I will check it)

    Regards,

    /LeMury
     
    Last edited: Nov 21, 2003
  6. eyagos

    eyagos New Member

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    First:
    I not only have readed the recent threads, but I have checked too that multiplying by 4 were incorrect. I normally feed into the Line In the signal from a TV card and I got a maximum level of 0dB. But feedind in it the HI-FI, wich can provide more voltage, I can get +12dB, so the plugin is correct.

    Now I ask myself why in 3536c (the version I'm ussing now) prolog all AC97 inputs are multiplyed by 0x2000000, except Line In wich is multiplyed by 0x7FFFFFFF. :confused:

    And other thing, although I understand you, you are not talking well when you say that SNR is increased by multiplying by 0.25, because you are reducing noise and signal at the same amount. What you must say is that you are increasing the signal (and noise) range playable in the speakers.

    And second:
    Of course I wanted to say 'epilog' when I sayd 'epilog'. Sorry, prolog ;)


    Regards.
     
    Last edited: Nov 21, 2003
  7. Lex Nahumury

    Lex Nahumury DH Senior Member

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    >>you are not talking well when you say that SNR is increased by multiplying by 0.25,
    Sorry Eyagos, but that is not what I said.

    The SNR of 'kX's ac97's ADC to DSP signal path' *has* increased since 3535
    because there was an 'invalid' (digital) amplification *after* ADC stage.

    Eugene/Max please FIXME here..!


    Sorry Eyagos, I'm just getting tired of the subject since I already posted
    many posts with extensive details as did others.

    Regards,

    /LeMury
     
  8. eyagos

    eyagos New Member

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    Don't bother what you have concluded in other posts with other people, but SNR has not been increased at all:

    My TV card with 'old' drivers -> Floor = -60dB = 0.001 // Maximum = 0dB = 1 // SNR = 60dB
    My TV card with 'new' drivers -> Floor = -72dB = 0.00025 // Maximum = -12dB = 0.25 // SNR = 60dB

    If we are talking about 'the same SNR' ...
     
  9. Lex Nahumury

    Lex Nahumury DH Senior Member

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    >>My TV card with 'old' drivers -> Floor = -60dB = 0.001 // Maximum = 0dB = 1 // SNR = 60dB
    >>My TV card with 'new' drivers -> Floor = -72dB = 0.00025 // Maximum = -12dB = 0.25 // SNR = 60dB

    Yep, the above is correct.

    Only,..The difference now is that you can Increase the *analog* input signal to get to the same 0dB,
    but *without* digitally amplifying *after* A/D conversion.

    I.E. If you would take a pre-amp and amplify your TV-card's analog signal so that it uses ADC's full range
    you will get 0dB again..!
    But this time without digitaly amplifying ac97's noise floor..!

    So the SNR of AC97 input in kX has been improved.

    In your case, if you leave the analog TV-card signal the same, there is NO SNR improvement
    because you will (again) digitaly amplify just like it was before 3535.

    In (yet) other words;
    We do not have to digitaly amplify ac97's noise floor if we make sure our analog input signal
    is high enough to get 0dB.


    /LeMury
     
  10. eyagos

    eyagos New Member

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    yes yes yes. We say the same:

    Now we can achieve a -72dB floor noise. Suposing that these are the minimum that can be achieved with an Audigy2 (mine), and knowing that 'SigmaTel STAC9723' (mine) gives -90dB SNR, we can say that the Audigy introduces 18dB of aditional noise.

    Then, let's say that Audigy2's AC97 inputs (mine) have a -72dB SNR. Okey, but drivers can't increase/decrease this SNR!!!!!!! It's only that yesterday these SNR dBs where distributed between [-60dB, +12dB] (and then loosing that 12dB becuse of clipping) , and today are distributed between [-72dB, 0dB] (what is more correct).

    But the noise HEARD inside a 'clean' signal is the same today than yesterday or, in other words, the heard sound has the same quality, or the same SNR (think in a -20dB clean signal). Do you understand what I mean now?.
     
  11. Lex Nahumury

    Lex Nahumury DH Senior Member

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    >>Then, let's say that Audigy2's AC97 inputs (mine) have a -72dB SNR.
    >> Okey, but drivers can't increase/decrease this SNR!!!!!!!

    No, of course not. This is defined in hardware.

    >>It's only that yesterday these SNR dBs where distributed between [-60dB, +12dB]
    >> (and then loosing that 12dB becuse of clipping)
    >> and today are distributed between [-72dB, 0dB] (what is more correct).

    "Today" the analog Input signal, relative to ac97's noise floor, can be set ~10db higher without clipping.
    To me that translates as an SNR improvement. (or SNR correction, if you wish)
    I have no other word for it.

    But realy Eyagos,.. we probably mean/say the same but only interprete it differently.
    I understood your point but if you don't mind, let's drop this discussion.
    All I'm interested here in this thread is to make plugins that are within kX's I/O specs.

    Regards,

    /LeMury
     
  12. Max M.

    Max M. h/h member-shmember

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    >But realy Eyagos,.. we probably mean/say the same but only interprete it differently.

    yep, it seems like that.
    Although it would be more correct to say that "older versions just forced user to choose not correct settings with worse SNR" (and user can get the same signal path as it has now by setting "ac97" fader to 25%)...
    E.g. newer driver versions do not improve SNR itself but "force the user to deal with initially better setting which gives better SNR"... something like that...

    >knowing that 'SigmaTel STAC9723' (mine) gives -90dB SNR, we can say that the Audigy introduces 18dB of aditional noise.

    Well, i'd said that these values written in codec specification are more like "abstract values", like "the best expected SNR in ideal enviroment" (when chip is not in machine and when it is not connected to anywhere at all)...

    "that the Audigy introduces 18dB of aditional noise" - hmm, no, i would not say that...
     

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