DIY Mastering Console by ka-electronics.com / Wayne Kirkwood

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57sputnik

Member
Joined
Jul 8, 2010
Messages
17
Thanks everyone for the kind words and support.

I don't recommend using a mult-order filter in the Side channel of MS to provide EEQ unless you want an effect.

There are huge differences between HPF Side in MS and the Allpass-corrected EEQ when the filter is mult-order.

Few people think to look at the resulting crosstalk curves when a second or third order HP is used in Side and reconstructed back into LR. The crosstalk curve peaks horribly and the crosstalk slope - which has a huge effect on the sonic footprint - is still 6 dB/octave. An EEQ is somewhat analogous to a crossover.

An MS approach to EEQ with 12 dB/octave in Side produces peaking:

EE_Filter_Using_MS_Side_HPF.jpg


Allpass correction in Mid provides a 12 dB/octave slope for both Side (vertical) and crosstalk.

You can see the result of Allpassed-Mid here. Left channel is driven. Red is Lateral (mid, mono sum) . Green is Left. Violet Right. Blue is Vertical (side).

EE_Filter_Using_MS_Mid_Allpass_Side_HPF_800.jpg


Hear the crosstalk difference as it's switched between 6 dB and 12 dB/octave:


Ian Stewart did an EEQ comparison here that may provide some additional insight: Center That Sub! (A Guide to Monoing Your Low End) - Blog - Flotown Mastering
 

Slime_Lord

Member
Joined
Aug 27, 2020
Messages
19
Location
Chicago, IL
I'm going to use both, I'm curious as to how it sounds compared to an EQ inserted in the Side channel of the MS2. Since is uses allpass filters to align the mid phase to the highpassed side channel, I think the result will be cleaner.

Curious on the preferred order of these boards. Seems like most consoles have the EEQ last. What about the MS2, do you have a stereo insert before and/or after? Several inserts in the MS2? Details and thoughts welcome...

The MSII can take up one of your insert points but the encoding will happen before it goes through the insert chain and the decoding will be post insert chain (at least that's how I understand it and also how I'm currently using an M/S matrix in Wavelab).

I feel like there may be another way of routing the signal so that it doesn't take one of the inserts - Signal > IGFO > MSII Encode > Inserts > MSII Decode > Output, or Signal > MSII Encode > IGFO > Inserts > MSII Decode > Output? The amount of customization in this project is both awesome and confusing for me :).

Just finished stuffing the IGFO and started on the MSII today. I can't say I trust my previous attempt at soldering both PCB's and decided to start fresh. More than likely building this into a 1U rack with 4 insert points.
 
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