question about dither

[orvillej]

i'm fairly new to pro tools engineering tho i've done lots of studio work. I understand what dithering does but i guess i don't understand where it fits in my signal chain when i'm mixing.

So if i'm mixing in protools with a 24bit/96k session and i route the mix into the same session i end up with an audio track called, say, MIX1, that is still a 24bit/96k track. If i want to change it to a 16bit/44.1k so i can burn it to a cd what i have done in the past is bounce to disc and change the settings in the drop down menu and convert after bounce. i don't see a way for me to use a dither plug-in when i'm bouncing to disc which seems to be where the change is made and the dithering would need to be done. Is it done automatically when i bounce? Or am i missing something important here? How are the dither plug-ins used in my mixing workflow?

[Holly73]

Bouncing to disc is real-time in PT. Just put a dither plugin on the last insert of your master fader. This is described in the PT 7.3 Reference Guide on page 744.

[rkaynan]

Can anyone tell the difference with or without dither? I don't notice a difference.

[orvillej]

thanx for that reference holly73. it was helpful.

I still have one further query on the subject if anyone can help. let's posit two situations...

one-i've created a mix, all run to a master fader and now i select all trax and want to bounce to disc. in this case i should insert the dither plug in to the last slot on the master fader and let it run,correct? I then end up with a mix bounced to whatever bit rate and sample rate i chose in the bounce window and the dither will be properly applied.

situation two- i create a mix, record it to a stereo audio track in my session so i now have a completed mix, residing on a 24bit/96k track. If i now want to bounce that to disc and convert the sample rate do i need to mute all original trax, create another master fader, insert the dither plug in, and run the mix track thru that master fader as i bounce to disc?

this is what i haven't been able to figure out. any help is appreciated and i hope my description is clear enough...oj

[Phil Ogden]

1. Yes, as I understand it.

2. Yes. If you record the mix bus to a new stereo track, the resulting file will be at the same bit and sample rate as the session. If the session is at 24bit/96k, then so will the mix stem. In this situation there is no need to apply dither as you are not reducing the bit depth or sample rate.

Re the second part of your question - as you have said, you should mute all the original tracks otherwise the bounce will be the sum of both these and the new stereo mix file. It is not necessary to create a new master fader for this process but, as you're reducing the resolution of the bounce audio, the dither plug-in should be used.

http://www.myspace.com/philogg

[James Drake]

i'm fairly new to pro tools engineering tho i've done lots of studio work. I understand what dithering does but i guess i don't understand where it fits in my signal chain when i'm mixing.

I suggest 'record-to-disc' versus 'bounce-to-disc'. Do a search to find more info about it. Basically route your mix to a spare bus instead of your hardware outputs. Then create a new audio track to record the audio on that bus.

I find that this method fits with my way of working better and reflects the 'real-world' where a separate machine will be used as the master recorder.

If you take this route then you will end up with a master track that has your dual-mono 24bit files. To export that for CD or whatever then select the region and hit 'shift-apple-K'. This will bring up an export box which will let you do a sample rate convert and dither among other things. This is a faster-than-real-time process.

Can anyone tell the difference with or without dither? I don't notice a difference.

Dither affects low level signals, when your mix is approaching the least-significant-bit. For example, during fade-outs and reverb tails.

Without dither the signal will fade into complete, digital silence, through an area of distortion.

With dither the signal will fade into white noise without distortion, but the signal will never reach complete digital silence.

With high-level mixes (current pop songs), dither will not be heard since the signal never plays around near the least-significant-bit.

[orvillej]

Re the second part of your question - as you have said, you should mute all the original tracks otherwise the bounce will be the sum of both these and the new stereo mix file. It is not necessary to create a new master fader for this process but, as you're reducing the resolution of the bounce audio, the dither plug-in should be used.

Thanx for the replies.

James, I didn't know about the "record to disc" option. I;ll look into that.

Phil, in the part of your reply I've quoted do you mean that rather than use a master fader to run my mix track thru I should instead just put the dither plug-in on an insert of the mix track itself and then run the process?

[Phil Ogden]

The Dither goes on the (existing) Master fader.

http://www.myspace.com/philogg

[orvillej]

thanx phil, i think i get that now.

I checked out the "Exporting regions as files" command you suggested, james, and that's pretty cool. i thought there must be a way to export a mix that was not in real time and this seems be it. are there any other ways to do that?

thanx for all your help so far...oj