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  #481  
Old 01-03-2002, 07:22 PM
Disco_Doctor Disco_Doctor is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

Corey Shay wrote:
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Hey, where did Disco Doctor go? Is he missing out or what? <HR></BLOCKQUOTE>

No - I'm here. I've been following along, and doing my own reading to catch up on some of the math Nika and Chris have tossed around here...and I see, and understand, that they are totally correct - so I'm just trying to correlate that with what I hear and why I think I hear a difference. I'm perplexed and trying to figure it out.

Nika/Chris/Anyone - what about the pan pots? They also cause a volume change. How is the math done on those? Are they just another fader, with the same (or less?) resolution, or perhaps the same resolution, but with the result being quantized down to a smaller value before hitting the main channel fader? Of course - this has nothing to do with the master fader issue. Just trying to grasp it all...

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  #482  
Old 01-04-2002, 06:41 AM
Nika Nika is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Disco_Doctor:
Nika/Chris/Anyone - what about the pan pots? They also cause a volume change. How is the math done on those? Are they just another fader, with the same (or less?) resolution, or perhaps the same resolution, but with the result being quantized down to a smaller value before hitting the main channel fader? Of course - this has nothing to do with the master fader issue. Just trying to grasp it all...

[img]images/icons/smile.gif[/img]
<HR></BLOCKQUOTE>

Disco,

I assume it's as simple as multiplying the results of the master fader times a pair of coefficients that sum to a fixed amount that divide the signal into the appropriate amounts and route them to the two busses. Example: If your signal is panned up the center, the master fader would be multiplied times .5 and sent to the two main busses. If the master fader is 75% to the left it would be multiplied by something like .75 and sent to the left side of the main bus and .25 and sent to the right side of the main bus.

I'm not sure if this particular math happens before or after the master fader, but it doesn't matter: A*B*C = A*C*B - the order is irrelevant.

I also believe that the coefficients are not quite that simple as there's the whole thing about the center detent position as well, but the math would not be hard to figure out. More importantly, the concept of how panning works is pretty straight forward.

Does this help?

Perhaps Chris will give us the specifics when he gets a moment.

Thanx!
Nika.
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  #483  
Old 01-04-2002, 09:07 AM
Dr. J Dr. J is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

Nika, Chris, I understand the mathmatical difference between volume changes between the master fader and track faders, with or without automation, but what is the difference in math between using one of those vs. applying a fade or crossfade to a waveform using "fades"?
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  #484  
Old 01-05-2002, 12:07 AM
Corey Shay Corey Shay is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

Welcome back Disco Doctor, although I see you never really left. [img]images/icons/smile.gif[/img]

When a pan is center the gain drops 2.5 dB. This does not equal the exact same 2.5 dB as when you lower a fader by the same amount. I tried testing this too, and again the results did not cancel completely. Before, this baffled me, but now I'd imagine something similar to what we've discussed concerning channel fader vs master fader is occuring.


<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Dr. J:
Nika, Chris, I understand the mathmatical difference between volume changes between the master fader and track faders, with or without automation, but what is the difference in math between using one of those vs. applying a fade or crossfade to a waveform using "fades"?<HR></BLOCKQUOTE>

I'd imagine you'd be dealing with something completely different. Applying fades is like applying preset curves that can't really be matched by drawing volume. So there probably is no comparison. I know the fade is dithered after calculation to whatever value you set in the preferences menu. I don't worry too much about fades there because I use them to fix edits mostly, so they are so short as to not really matter.

Chris?
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  #485  
Old 01-05-2002, 04:38 PM
Dr. J Dr. J is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

My main reason for asking that question would be for example you have a heavy guitar part that needs to fade out over 4 seconds into a soft verse. Do you apply a fade, or do you automate the track fader, aux fader, or create a master fader for the aux and fade that? See, lot's of possibilities, but in editing, i'd like to just apply a fade and be done with it. (they're so easy to just keep changing the lengths etc..) However if the math of that fade is of less sonic quality than applying a fader fade, then i guess i better change the way i do things. (i have not had time to do any listining tests)

I guess i'm looking for opinions, but also the official digi reccomendation for this type of action. How is the system design intended to best accomplish long fades on individual tracks?
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  #486  
Old 01-05-2002, 07:27 PM
Nika Nika is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

I'm just thinking here...

I cannot think of an advantage to using fades, and although I can't specifically think of a disadvantage, I'll have an easier time conceptualizing that there would be one.

I think that using a volume automation is going to be no less accurate than printing a fade. But calculating a fade (and in the process adding dither) furthered by more volume changes and potential truncation therein certainly seems like it at least has the potential of being worse.

But I also have to admit that this is getting so minutiaetic that I've never thought of the differences being spoken of before.

Nika.
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  #487  
Old 01-05-2002, 09:43 PM
Dr. J Dr. J is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

Well, I never thought of it either, before this thread, but I figured I'd ask. My fear was not that using automation and a fader move was worse, but the opposite, that printing a fade could somehow be worse. I use that function quite often, and just wondered about the math going on there verses automating a track, aux or master fader.
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  #488  
Old 01-06-2002, 07:08 AM
jacquire jacquire is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

hello all,

i've been reading through this thread in
the last couple weeks and first wanted to
say thanks to everyone for this discussion!
i've gained some real important information.
i had a couple questions i wanted to ask
although the topics have been touched on.

first, as far as aux inputs are concerned,
i'm understanding that they accept a 24-bit
input. then they are capable of 48-bit
processing. what i'm wondering is at what
bit rate do they output?

second, what is the process that takes
place at a mixer output when two or more
tracks are assigned to it without any
processing. in other words, no change to
the tracks or audio, so that they arrive at the summing stage at 24-bit.

i hope my questions are clear and thanks
for any help!
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  #489  
Old 01-06-2002, 06:18 PM
Nika Nika is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

[QUOTE]Originally posted by jacquire:
first, as far as aux inputs are concerned,
i'm understanding that they accept a 24-bit
input. then they are capable of 48-bit
processing. what i'm wondering is at what
bit rate do they output?


I'm not sure I understand your question, but any fader (track fader or aux fader) brings in 24 bit data, does 48 bit math to them, and then sends 48 bits to the summing bus. If it's being sent to an aux bus instead of a main pair of outputs (summing bus) then it is truncated, rounded, or dithered to 24 bits again.

second, what is the process that takes
place at a mixer output when two or more
tracks are assigned to it without any
processing. in other words, no change to
the tracks or audio, so that they arrive at the summing stage at 24-bit.


If a track is sent to the master fader as a 24 bit piece of audio it first gets turned into a 48 bit piece of audio, though 24 of the bits are zeros. If two of these pieces of data are sent to the master fader then they are merely summed together and the result is either truncated or dithered back to the 24 bits to go to the interface output.

Nika.
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  #490  
Old 01-06-2002, 08:43 PM
jacquire jacquire is offline
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Default Re: setting record levels into ProTools with the intent of mixing in ProTools

thanks nika! you answered my questions.


jacquire
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