Topic: Sound Devices 744t inverted phase issues

[baustin]

...... Man today has been eye opening.

Wow! 

Posted this this morning while in NYC, get back to SC and 3 pages later! Glad we were able to get to the bottom of this so quickly.

Alrighty.... onto inverting some V3>digi>744t recordings.

-B

[MattD]

call me deaf, but I've never heard a deficit either.
I've been running V3 analog-out to either DSD or the 722, for over a year now, so, my sound memory is beyond wavering.

Well, you'll never hear a deficit with that configuration, since Jamie said it's only the digital outs that invert polarity. I wonder what that would do for the V3/722 tests Michael Miller and I ran last year. I don't think we checked for this.

[it-goes-to-eleven]

I wonder how long Grace has known about the problem but not mentioned it.

[wboswell]

So far, I havent had any phase issues running 4 channels with the v3 and 744....knock on wood

2 different sources so far 4 times....

run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(digi out)) + (Neumann km143) > Sound Devices 744t @ 24/48
&
run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(analog out)) + (Schoeps cmc621xt > Lunatec V3(digi out)) > Sound Devices 744t @ 24/96

I am recording in mono and using the 1 gig split if that helps...Cant think of what else I changed on the 744, but Charles did walk me thru each step like a baby

So did you invert the polarity on the digi in V3 sources in the post?  Since Charles noticed the issue, I'm sure he had you fix it in the post but it makes me wonder if the inverted polarity make as big a difference with a fig. 8 as it does with other directional patterns?

[Brian Skalinder]

So did you invert the polarity on the digi in V3 sources in the post?  Since Charles noticed the issue, I'm sure he had you fix it in the post but it makes me wonder if the inverted polarity make as big a difference with a fig. 8 as it does with other directional patterns?

Not quite the same scenario, but I ran C414's Blumlein (figure-8) > T+ UA5, mixed it with MK41 > V3 and had to invert the phase because the V3 source out of phase relative to the C414 source was audibly noticeable.  I forget offhand which source I inverted, but I distinctly remember inverting each source independently to see if I could hear a difference.  Once I achieved relative phase across all 4 channels, I could not audibly hear the difference.  If memory serves...

[pilgrims622]

So far, I havent had any phase issues running 4 channels with the v3 and 744....knock on wood

2 different sources so far 4 times....

run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(digi out)) + (Neumann km143) > Sound Devices 744t @ 24/48
&
run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(analog out)) + (Schoeps cmc621xt > Lunatec V3(digi out)) > Sound Devices 744t @ 24/96

I am recording in mono and using the 1 gig split if that helps...Cant think of what else I changed on the 744, but Charles did walk me thru each step like a baby

So did you invert the polarity on the digi in V3 sources in the post?  Since Charles noticed the issue, I'm sure he had you fix it in the post but it makes me wonder if the inverted polarity make as big a difference with a fig. 8 as it does with other directional patterns?

At first no I did not invert polarity, but I have done so now...Charles did have me fix it post...

As for the figure 8, I was wondering the same thing...I have not been able to hear much of a difference at all if any after switching the polarity of the midside sources...The V3 was decoding the midside on the fly, so that is my question too....Does it make a difference that anyone knows of when doing midside compared to say cards(din)...I would think that the polarity would be fine as the V3 is decoding the 2 mono channels to stereo then it was outputing them to mono tracks on the 744...that is confusing and if anyone can shed some light on that it would be great!!!

[Dr.FOB]

There was no indication that the decoding of MS was an issue.  The digital output was merely the inverse polarity of the input.

Phase issues with MS would result in swapping Right & Left.  (I don't decode on the fly, so I record a brief message to myself to insure proper R-L orientation on decoding)  This typically comes from the side capsule being oriented in the wrong direction.

With proper inputs Mid on Left, and Side on Right (badge facing right), the V3 will properly decode Left and Right channels, but still output them as the inverse polarity at the digital outputs.

[wboswell]

So far, I havent had any phase issues running 4 channels with the v3 and 744....knock on wood

2 different sources so far 4 times....

run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(digi out)) + (Neumann km143) > Sound Devices 744t @ 24/48
&
run for 2 shows
(Neumann ak40+ak20 > lc3 > km100 > Lunatec V3(analog out)) + (Schoeps cmc621xt > Lunatec V3(digi out)) > Sound Devices 744t @ 24/96

I am recording in mono and using the 1 gig split if that helps...Cant think of what else I changed on the 744, but Charles did walk me thru each step like a baby

So did you invert the polarity on the digi in V3 sources in the post?  Since Charles noticed the issue, I'm sure he had you fix it in the post but it makes me wonder if the inverted polarity make as big a difference with a fig. 8 as it does with other directional patterns?

At first no I did not invert polarity, but I have done so now...Charles did have me fix it post...

As for the figure 8, I was wondering the same thing...I have not been able to hear much of a difference at all if any after switching the polarity of the midside sources...The V3 was decoding the midside on the fly, so that is my question too....Does it make a difference that anyone knows of when doing midside compared to say cards(din)...I would think that the polarity would be fine as the V3 is decoding the 2 mono channels to stereo then it was outputing them to mono tracks on the 744...that is confusing and if anyone can shed some light on that it would be great!!!

The theoretical argument going on is that you may hear a difference when inverting the phase of the two V3 channels, but for practical purposes, I personally cannot hear a difference.  The difference becomes noticeable only when you add another stereo pair recorded 180* out of phase to the V3.