FIR on Output not as X-over filter, using imported coefficients.
If the user would like to use an IIR filter as X-over, being necessary in example a cutting frequency
below 250Hz, but still having available the FIR in the X-over section, a trick can be used for getting the
result.
Particularly, we could say that we have three possible way of using the FILTERS of the output channels.
1. 4 bands parametric Eq + IIR X-over (no FIR used): the X-over cutting frequencies can be set
everywhere by the user, without limitation
2. 4 bands parametric Eq + FIR X-over (no IIR used): the X-over cutting frequencies can be set
everywhere above 250Hz/300Hz by the user, no reasonable slopes can be achieved with the FIR for
lower cutting frequencies.
3. If necessary to set a cutting Frequency for a Lp or Hp below 250Hz, but still we'd like to have the IFR
available, eventually for working with imported coefficients, a trick for getting the result can be used.
If we'd like to combine the IIR filters for Hp/Lp for low frequencies and still have FIR filters available,
let say for further filtering, as PEQ one or any sort of phase configuration, then the user can operate in
the following way, "sacrificing" some of the filters of the PEQ: the user can create the Low Freq Hp or
Lp, using the variable Q Hp/Lp filters available in the Peq. They are in cascade, therefore, for a Hp/Lp
48dB/Oct, you can use the 4 Filters of the PEQ..
Anyway, in this way, the user can have the IIR Hp or Lp and an available FIR 512Taps which can be used
as the user desires if uploading the coefficients from an external source, using the FIR itself also for
eventual Peq setting together with other features.
The user can see each one of the PEQ Filters as a IIOrd Cell, which if set as Hp or Lp with variable Q,
can give a 12dB/Oct filter.
In example, setting the Filter N1. of the PEQ, set as Lp-Q at 1kHz and with Q=0.7, then can be gotten a
12dB/Oct Butterworth Lp Pass with 1kHz Cutting Frequency.
Selecting now the second filters also as Lp-Q, and also with 1kHz cutting Frequency, and setting the Q
of the first filter to 0.55 and the Q of the second to 1.3, then a 4th order Butterworth can be set up.
Summary of Contents for PDA500PF
Page 6: ...Processes Block Scheme...