Papareil Polivoks VCF highpass filter out?

Dieses Thema im Forum "Lötkunst" wurde erstellt von Anonymous, 30. April 2005.

  1. Anonymous

    Anonymous Guest

    Hi there,

    the Schaeffer front plate design for the Papare


    Hi there,

    the Schaeffer front plate design for the Papareil Polivoks VCF module contains an output named "HP" which seems to me like an high pass filter output.

    Does the module has the option to include such an output jack?

    In the documentation:
    http://m.bareille.free.fr/modular1/vcf_ ... s-Doc2.gif
    I don't see this option.
     
  2. Really ? :eek:

    Like the vintage, the Polivoks filter clo


    Really ? :eek:

    Like the vintage, the Polivoks filter clone is fitted with LP ( low pass) and BP ( Band pass ) outputs as well as the provided FPD files panels

    The HP output is not featured on this filter.It is +/- possible to add it anyway, like on most of SVF filters , with an additionnal output stage or may be a switch to select between the BP/HP for example and re-use the BP output opamp ... I have tried the HP output but i was not very convainced by the sonic results i get ... so i stay glued to the exact clone version...
     
  3. Moogulator

    Moogulator Admin

    maybe it is sometimes good to keep the idea of the original.

    maybe it is sometimes good to keep the idea of the original..
    not for "being original".. but for it's advantages ..

    one thing: do you think that even small changes in a design change the sound ?
    I hear from some guys that even the board or layout can change the sound results..
     
  4. Yes , a small changes in a design can change the sound ! Th

    Yes , a small changes in a design can change the sound ! The best way to realise this is to try :

    Build two small identical devices with different ( pin to pin compatibles) opamps ... Say for example a simple stero line preamp ( 2 single inverters in serie with 10K1% resistors everywhere...) Then perform A/B tests to compare, at the same level if possible ...If you monitoring system is good enough -Forget your PC speakers to do that - you should hear a difference , at least between someting like a 741 and an OPA604 ! :lol:
    It is just an example ...


    It happen often when you compare AB two 2 identical vintages devices that they have a different sound ! A lot of famous Roland drumboxes are like this but not only ... I saw this on many vintage Mutron Biphases , many old synths too ... The sound is very close , but not exactly the same due to parts age, repairs, but alos sometime to differences who exist since the day this device went out of the factory ! Never forget that all parts have a % range of error and that nothing is perfect in analog domain . So there is always a difference even on the most accurate analogue circuits !

    >I hear from some guys that even the board or layout can change the sound >results..

    Yes:
    1) each track is like a very low value resistor , but never zero ohms .
    2) Two tracks nearby compose a small capacitor ...
    3) The pcb material ( epoxy, fiberglass, bakelite, etc ) have a huge resistivity , but none is a perfect isolator between tracks ...
    All those small "parts" can have an big influence. It depend a lot of the device you design ...

    This kind of things is generaly more sensitive on HF circuits but it can be audible on audio designs too ( mic pre, etc ) or alterate perf ( ie: SNR, stability ...)

    A pcb can be good or not only because of the layout ... There are many "rules" a designer should follow to make a good pcb, ie : keep signal path away from psu rails, draw ground as a star to avoid loops etc ...
     

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