Hi all,
I am working as a live sound engineer and want to build an analog finalizer which will be used on in-ear mixes, but might also serve as a mastering device.
Main features of the design should be:
-A 5-band parametric EQ with band 1 and 5 being switchable bell/shelving
-A multiband compressor, preferably with user-adjustable cross-over frequency (continuous variable or preset)
-A Width control, to alter the width of the stereo image.
Since this design will be stereo, the most important issue is to have the left and right side of the EQ and compressor being as
equal as possible.
To achieve this, it will probably be needed to use rotary switches instead of potmeters.
The range of the EQ can be as low as +/-6 dB (in half dB steps).
The ratio of the comp should be adjustable in between 1.5:1 and 4:1
Questions:
Which type of EQ is best chosen for this purpose? I like a lot the Midas XL4 state variable, which is very similar to the amek M2500
and fairly easy to build. Also the ability to easily disable one of the filter sections is an advantage.
Will clicks be audible when the pots in state variable designs are replaced by rotaries?
Compressor: What cross-over to use? Are there simple designs with variable XO frequency, and more important: after the summing
of the three bands will linear phase be retained? The standard XO is Linkwitz-Riley, but I haven't seen a lot of LR designs with variable
XO frequency.
The comp itself should be transparant. What gain reduction topology recommended, FET, VCA or opto/EL? I guess VCA will allow for best tracking.
The Width control circuit: I have no info at all about this. Any example schematics are very welcome.
If other people are interested in helping out, this might become a nice Lab project.
Since there has been a lot of comment about just copying existing stuff, I would like to customize the EQ and comp rather than just copy and paste something existing.
Comments please...
Greetz,
Rogy
I am working as a live sound engineer and want to build an analog finalizer which will be used on in-ear mixes, but might also serve as a mastering device.
Main features of the design should be:
-A 5-band parametric EQ with band 1 and 5 being switchable bell/shelving
-A multiband compressor, preferably with user-adjustable cross-over frequency (continuous variable or preset)
-A Width control, to alter the width of the stereo image.
Since this design will be stereo, the most important issue is to have the left and right side of the EQ and compressor being as
equal as possible.
To achieve this, it will probably be needed to use rotary switches instead of potmeters.
The range of the EQ can be as low as +/-6 dB (in half dB steps).
The ratio of the comp should be adjustable in between 1.5:1 and 4:1
Questions:
Which type of EQ is best chosen for this purpose? I like a lot the Midas XL4 state variable, which is very similar to the amek M2500
and fairly easy to build. Also the ability to easily disable one of the filter sections is an advantage.
Will clicks be audible when the pots in state variable designs are replaced by rotaries?
Compressor: What cross-over to use? Are there simple designs with variable XO frequency, and more important: after the summing
of the three bands will linear phase be retained? The standard XO is Linkwitz-Riley, but I haven't seen a lot of LR designs with variable
XO frequency.
The comp itself should be transparant. What gain reduction topology recommended, FET, VCA or opto/EL? I guess VCA will allow for best tracking.
The Width control circuit: I have no info at all about this. Any example schematics are very welcome.
If other people are interested in helping out, this might become a nice Lab project.
Since there has been a lot of comment about just copying existing stuff, I would like to customize the EQ and comp rather than just copy and paste something existing.
Comments please...
Greetz,
Rogy