perfect mid/side encode/decode in PT?

[James Drake]

Hi,

I am trying to make a perfect mid/side encode/decode chain.

I take a normal L/R stereo track, duplicate it. On one of them put a trim plugin just to invert it.

One of them routes to my mix bus.

The other routes into the mid/side encode chain.

The mid/side signal is then on a stereo bus, which goes into the mid/side decode chain.

The mid/side decode then routes to the mix bus.

So, in theory the output of the mid/side decoder should be the same as the stereo track in the first place.

Since one of the stereo tracks is inverted, the mix bus should null.

But I can still clearly hear the programme, peaking around -35dBFS.

I have tried both the Waves mid/side matrix, and just routing in PT and the trim plugin.

Is it possible to have a perfect mid/side encode/decode chain in PT?

James.

[Frank Kruse]

make sure you have identical delays for all signal chains.

[James Drake]

ADC is on.

[Frank Kruse]

-35dB is a rather high "left over" from something that should null. can you post a screen shot or a template session so it´s easier to verify?

[James Drake]

i could, but it's pretty easy to recreate with any 2-track source i think.

maybe put up a PT session later.

the gist is that the output of a M/S endode/decode chain should be identical to the input.

but I can't get the input and output to null, pretty sure no delay funnies going on. the 'remainder' doesn't sound 'phase-ey'.

[Frank Kruse]

just to make sure ADC isn´t doing something weird:

insert a trim on the other leg(s) as well and but leave it at unity and no reverse to make sure all channels have the identical plugin delay applied.

have you tried switching ADC off/on? Any difference?

[James Drake]

Originally Posted by Frank Kruse

insert a trim on the other leg(s) as well and but leave it at unity and no reverse to make sure all channels have the identical plugin delay applied.

yeah, already tried that.

have you tried switching ADC off/on? Any difference?

haven't tried with ADC off. but do have DSP cache off since that was really screwing my ADC until Massey helped me out! (I'm on G5).

[mgoorevich]

Sure you checked it already but is the panning is 100% on all tracks?

[Frank Kruse]

I just did this:

Duplicate tracks with a stereo-music. Send both tracks to my stereo out.

On the first track I inserted a Soundhack MS-matrix in LR to MS mode all faders at unity.

second slot another instance same plugin but set to MS to LR. So the output of that track went through an MS matrix twice and should be identical to the original clip

On the second track I insert a multi-mono trim set to phase reverse.

When I play both tracks at same level they null completely.


Maybe somewhere in your chain a pan knob isn´t set fully L/R or something like that?

[James Drake]

i try to not use pans, instead just route directly to one side of a stereo bus.

would like to try the soundhack plugin, can't find it though.....