Using the Precision MS Matrix for Mono Crossover LF Blending
Posted: Fri Feb 07, 2014 1:19 pm
I receive a lot of questions about using the MS Matrix in disc mastering transfer consoles to provide mono crossover.
I ran a quick test with a 12 dB octave Butterworth unity gain Sallen-Key HP filter in the Side channel.
The -3dB cutoff was approximately 20 Hz.
The "send" was point C, the "return" into point F.
This bypasses the 1646 and 1246 insert line drivers and receivers.
Precision MS Matrix with 12 dB per octave 20 Hz high pass filter in the Side channel to Provide Mono Blending vs. Bypass
Note however that the derived response is 6 dB per octave.
I often see and hear about references to the Neumann "elliptical" Filter shown here:
Neumann EE70 "Elliptical" Filter Schematic
There is an inductor that bridges L and R to blend low frequencies to mono.
But the EE70 does not appear to be an elliptical filter topology...
This is an elliptical topology.
The second-order elliptical part begins at R5.
It's a state variable filter with the low and high pass outputs summed.
http://sound.whsites.net/articles/active-filters.htm#s7
I'm curious to see how a true elliptical filter in the Side channel would steepen the response.
I don't think it will.
I ran a quick test with a 12 dB octave Butterworth unity gain Sallen-Key HP filter in the Side channel.
The -3dB cutoff was approximately 20 Hz.
The "send" was point C, the "return" into point F.
This bypasses the 1646 and 1246 insert line drivers and receivers.
Precision MS Matrix with 12 dB per octave 20 Hz high pass filter in the Side channel to Provide Mono Blending vs. Bypass
Note however that the derived response is 6 dB per octave.
I often see and hear about references to the Neumann "elliptical" Filter shown here:
Neumann EE70 "Elliptical" Filter Schematic
There is an inductor that bridges L and R to blend low frequencies to mono.
But the EE70 does not appear to be an elliptical filter topology...
This is an elliptical topology.
The second-order elliptical part begins at R5.
It's a state variable filter with the low and high pass outputs summed.
http://sound.whsites.net/articles/active-filters.htm#s7
I'm curious to see how a true elliptical filter in the Side channel would steepen the response.
I don't think it will.