Avid Pro Audio Community

Avid Pro Audio Community

How to Join & Post  •  Community Terms of Use  •  Help Us Help You

Knowledge Base Search  •  Community Search  •  Learn & Support


Avid Home Page

Go Back   Avid Pro Audio Community > Pro Tools Software > Pro Tools

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 01-18-2022, 03:36 AM
oortone oortone is offline
Member
 
Join Date: May 2011
Location: Sweden
Posts: 63
Default Multi mono - Singal generator out of phase

ProTools Ultimate 21.10.67
Minimac (ca. 2018)

Can anyone else reproduce this bug:
  • Start blank
  • Add one audio channel and master out channel
  • Add some phase meter at master out
  • On the audio channel insert the built in "Signal Generator" as multi mono plug in
  • Twiddle the frequency
  • Somewhere you will find frequencies that are not 100% in phase L/R

If I close the project (but not necessarily ProTools) and re-open, the phenomenon goes away.
If I add a new track and repeat I get the same phenomenon, not necessarily on the same frequencies. It too goes away if I save and re-open.

Last edited by oortone; 01-18-2022 at 03:54 AM.
Reply With Quote
  #2  
Old 01-18-2022, 04:49 AM
midnightrambler midnightrambler is offline
Member
 
Join Date: Oct 2008
Location: London, UK
Posts: 2,607
Default Re: Multi mono - Singal generator out of phase

Why would you expect 2 different instances (because that's what multi-mono is) of a signal generator to stay in phase when you move frequencies? I'd be more amazed if they did stay 100% locked.
Reply With Quote
  #3  
Old 01-18-2022, 05:26 AM
oortone oortone is offline
Member
 
Join Date: May 2011
Location: Sweden
Posts: 63
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by midnightrambler View Post
Why would you expect 2 different instances (because that's what multi-mono is) of a signal generator to stay in phase when you move frequencies? I'd be more amazed if they did stay 100% locked.
It's not two instances.

I believe Multi Mono is offered to deliver the opportunity to use a plugin that's not available in Stereo or Multichannel to the user. I'd therefore expect it to be in phase which it usually is as far as I know.

Why would the two channels not be in phase when instansiated together and presented in one single plugin window?
Reply With Quote
  #4  
Old 01-18-2022, 06:58 AM
dominicperry dominicperry is offline
Member
 
Join Date: Apr 2019
Location: UK
Posts: 395
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by oortone View Post
It's not two instances.

I believe Multi Mono is offered to deliver the opportunity to use a plugin that's not available in Stereo or Multichannel to the user. I'd therefore expect it to be in phase which it usually is as far as I know.

Why would the two channels not be in phase when instansiated together and presented in one single plugin window?
Because two different frequencies are, by definition, not in phase.
If you wander off a base frequency and then come back to the original frequency, there is no guarantee that the zero-crossing point will be at the same place. So that will then be out of phase with a separate instance that has never been changed.
Reply With Quote
  #5  
Old 01-18-2022, 08:11 AM
albee1952's Avatar
albee1952 albee1952 is online now
Member
 
Join Date: May 2004
Location: Norwich, CT
Posts: 37,853
Default Re: Multi mono - Singal generator out of phase

Beyond what Dom is saying(which I tend to agree with), what's the end goal here? What are you trying to achieve(or is it just an experiment that isn't giving an expected result)?

In general terms, I don't think much time was spent creating the signal generator plugin and I would not count on it for critical purposes. Its handy for testing routing, dropping a 1KHz tone and such, but for critical work, I would lean on something else, like the Alan Parsons Sound Check CD or a hardware tone generator
__________________
Gigabyte X79/intel i7 3930K, 32GB RAM, HD/Native, 192 IO
https://www.facebook.com/search/top/...0sound%20works


The better I drink, the more I mix

BTW, my name is Dave, but most people call me.........................Dave
Reply With Quote
  #6  
Old 01-18-2022, 08:35 AM
Rich Breen Rich Breen is offline
Member
 
Join Date: Dec 1969
Location: Burbank, CA USA
Posts: 2,077
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by oortone View Post
It's not two instances.

I believe Multi Mono is offered to deliver the opportunity to use a plugin that's not available in Stereo or Multichannel to the user. I'd therefore expect it to be in phase which it usually is as far as I know.

Why would the two channels not be in phase when instansiated together and presented in one single plugin window?
Multi-mono instantiations of signal generator are not phase-locked. create a mono aux with a single instantiation of sig gen and bus to where it needs to go.
__________________
http://www.richbreen.com

----------------------------------------
MacPro 5,1 Dual Hex, OS 10.14.6, PT 2021.10 HDX, Avid HD I/Os and Metric Halo ULN8, Avid C24, 3xS1/Dock.
Also running a 2013 nMP / HDX / S6
Reply With Quote
  #7  
Old 01-26-2022, 04:43 AM
oortone oortone is offline
Member
 
Join Date: May 2011
Location: Sweden
Posts: 63
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by dominicperry View Post
Because two different frequencies are, by definition, not in phase.
If you wander off a base frequency and then come back to the original frequency, there is no guarantee that the zero-crossing point will be at the same place. So that will then be out of phase with a separate instance that has never been changed.
There're not multiple frequencies in a multi-mono instance of this plugin. There's one frequency - two channels.
Reply With Quote
  #8  
Old 01-26-2022, 04:45 AM
oortone oortone is offline
Member
 
Join Date: May 2011
Location: Sweden
Posts: 63
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by Rich Breen View Post
Multi-mono instantiations of signal generator are not phase-locked. create a mono aux with a single instantiation of sig gen and bus to where it needs to go.
That's interesting. Is this true for all Multi-Mono plugins; that phase coherency is not guaranteed? In that case I don't get what use Multi Mono is meant for.

Thanks for the tip on using an aux instead.
Reply With Quote
  #9  
Old 01-26-2022, 04:49 AM
oortone oortone is offline
Member
 
Join Date: May 2011
Location: Sweden
Posts: 63
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by albee1952 View Post
Beyond what Dom is saying(which I tend to agree with), what's the end goal here? What are you trying to achieve(or is it just an experiment that isn't giving an expected result)?

In general terms, I don't think much time was spent creating the signal generator plugin and I would not count on it for critical purposes. Its handy for testing routing, dropping a 1KHz tone and such, but for critical work, I would lean on something else, like the Alan Parsons Sound Check CD or a hardware tone generator
Actually, this was just something I discovered while trying to find an inconsistency in the analog part of my monitor system, so I used Signal Generator to generate different frequencies. Suddenly I saw the channels where out of phase and thought there was someting wrong with the amplifier.

I used a stereo channel just by accident, didn't think there would be a phase issue. In the case of Signal Generator there's no need for a stereochannel but if this phase issue exists in Trim (which is also only available as multi mono) then that's very bad.
Reply With Quote
  #10  
Old 01-26-2022, 06:20 AM
midnightrambler midnightrambler is offline
Member
 
Join Date: Oct 2008
Location: London, UK
Posts: 2,607
Default Re: Multi mono - Singal generator out of phase

Quote:
Originally Posted by oortone View Post
Actually, this was just something I discovered while trying to find an inconsistency in the analog part of my monitor system, so I used Signal Generator to generate different frequencies. Suddenly I saw the channels where out of phase and thought there was someting wrong with the amplifier.

I used a stereo channel just by accident, didn't think there would be a phase issue. In the case of Signal Generator there's no need for a stereochannel but if this phase issue exists in Trim (which is also only available as multi mono) then that's very bad.
The phase issue exists in the "generation" part, i.e. when you're sliding the frequency up and down even the tiniest amount of delay between the computer processing the left/right movement of the slider will knock the generator out of time (and therefore out of phase) ever so slightly. This isn't going to be an issue with "processing" - or at least you'd hope not, otherwise the whole system would fail, not just one multi-mono plugin.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Multi-mono Signal Generator TDM out of phase !!! mangoustine Pro Tools TDM Systems (Mac) 5 04-15-2019 04:53 AM
Signal generator TDM out of phase.... Kroger Pro Tools TDM Systems (Mac) 11 04-05-2009 12:50 PM
Phase coherency (multi-mono vs Multichannel) Ray Fabi Pro Tools TDM Systems (Mac) 0 01-21-2006 02:56 PM
Signal generator out of phase garret Pro Tools TDM Systems (Mac) 12 12-01-2005 10:19 AM
I Need Clarification. Difference between Multi Channel and Multi Mono Plugs citi 003, Mbox 2, Digi 002, original Mbox, Digi 001 (Win) 4 06-13-2002 11:08 AM


All times are GMT -7. The time now is 01:06 PM.


Powered by: vBulletin, Copyright ©2000 - 2008, Jelsoft Enterprises Limited. Forum Hosted By: URLJet.com