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ControlRoom signal leaking to Main bus Consoles
Old 16th July 2017
  #1
Gear Nut
 

ControlRoom signal leaking to Main bus

Hello dear gesrslutz fellows,

Title says it all
If I I assign anything as a ControlRoom source,even a 2TR return,PFL bus!,it will be present at the main out.At really low levels like -60dbfs peak/-70-80dbfs rms,but still there.(cal for 0dbvu=+4dbu=-18dbfs)
Especially,that 2TR return is post ad/da and mixbus processing,meaning quite delayed than original analogue console mix bus,it makes me worried if it can blur and affect low level informations and details in the mix.
What is your experience and any possible
remedy for that?
If someone ever measured crosstalk between CR and main out?
What are the specs of top noch consoles regarding that problem?
Any input and thoughts are Wellcome!!

Thank you

Cheers
Old 16th July 2017
  #2
Gear Guru
 
jwh1192's Avatar
Quote:
Originally Posted by sliwowitz View Post
Hello dear gesrslutz fellows,

Title says it all
If I I assign anything as a ControlRoom source,even a 2TR return,PFL bus!,it will be present at the main out.At really low levels like -60dbfs peak/-70-80dbfs rms,but still there.(cal for 0dbvu=+4dbu=-18dbfs)
Especially,that 2TR return is post ad/da and mixbus processing,meaning quite delayed than original analogue console mix bus,it makes me worried if it can blur and affect low level informations and details in the mix.
What is your experience and any possible
remedy for that?
If someone ever measured crosstalk between CR and main out?
What are the specs of top noch consoles regarding that problem?
Any input and thoughts are Wellcome!!

Thank you

Cheers
Hi, may i ask .. "If someone ever measured crosstalk between CR and main
out?"

"What are the specs of top noch consoles regarding that problem?"

on what unit are you asking about ?? you did not mention ..

or are you asking a GENERAL Question about consoles .. trying to Clarify what you are asking ...

thank you john
Old 16th July 2017
  #3
Gear Nut
 

Quote:
Originally Posted by jwh1192 View Post
Hi, may i ask .. "If someone ever measured crosstalk between CR and main
out?"

"What are the specs of top noch consoles regarding that problem?"

on what unit are you asking about ?? you did not mention ..

or are you asking a GENERAL Question about consoles .. trying to Clarify what you are asking ...

thank you john
Hi,

Thank you for your reply.

'If someone ever measured crosstalk between CR and main
out?"
I meant,if anyone who has an analogue mixing board,regardless exact model or brand,ever measured it.And,if it is something to be considered

In my case,it's an Amek Hendrix and soundcraft ghost.

Never seen in any specifications mentioning that specific measurement ,and always thought of it as almost not existent.Especialy not in amount I measured on mine.

"What are the specs of top noch consoles regarding that problem?"

Anyone owning well maintained API,SSL,NEVE,Calrec,...ever checked and measured that,or it is something that can
be completely ignored on that level of
quality?

Hope,that clarifies a bit what I am desperately searching for the answers

Thank you very much!

Cheers
Old 16th July 2017
  #4
Gear Guru
 
jwh1192's Avatar
Quote:
Originally Posted by sliwowitz View Post
Hi,

Thank you for your reply.

'If someone ever measured crosstalk between CR and main
out?"
I meant,if anyone who has an analogue mixing board,regardless exact model or brand,ever measured it.And,if it is something to be considered

In my case,it's an Amek Hendrix and soundcraft ghost.

Never seen in any specifications mentioning that specific measurement ,and always thought of it as almost not existent.Especialy not in amount I measured on mine.

"What are the specs of top noch consoles regarding that problem?"

Anyone owning well maintained API,SSL,NEVE,Calrec,...ever checked and measured that,or it is something that can
be completely ignored on that level of
quality?

Hope,that clarifies a bit what I am desperately searching for the answers

Thank you very much!

Cheers
perfectly .. thank you .. now maybe someone can come along with some good solid info for you ..
Old 16th July 2017
  #5
Lives for gear
 
Brian Campbell's Avatar
 

Lots of things could be happening but I'll hazard a guess that it's ground summing (inverted summing op amps). Check the bleed to see if it's reverse polarity.
It was (is?) common to beef-up or modify the grounding scheme in a desk. More importantly how the desk is grounded and interconnected to the rest of the studio make a difference.
Anyway some problems can be solved while others are fixed in the architecture of the desk and practically not possible/easy to correct.
Old 16th July 2017
  #6
Gear Nut
 

Quote:
Originally Posted by bcwiz View Post
Lots of things could be happening but I'll hazard a guess that it's ground summing (inverted summing op amps). Check the bleed to see if it's reverse polarity.
It was (is?) common to beef-up or modify the grounding scheme in a desk. More importantly how the desk is grounded and interconnected to the rest of the studio make a difference.
Anyway some problems can be solved while others are fixed in the architecture of the desk and practically not possible/easy to correct.

Thank you very much!

I will definitely check the bleed polarity
And,of course,the grounding..

Will report any news

Thanks again

Cheers
Old 16th July 2017
  #7
Gear Nut
 

Quote:
Originally Posted by bcwiz View Post
Lots of things could be happening but I'll hazard a guess that it's ground summing (inverted summing op amps). Check the bleed to see if it's reverse polarity.
It was (is?) common to beef-up or modify the grounding scheme in a desk. More importantly how the desk is grounded and interconnected to the rest of the studio make a difference.
Anyway some problems can be solved while others are fixed in the architecture of the desk and practically not possible/easy to correct.

Hi,

So,I checked it once again,and bleed is phase reversed and summed mono.
I suspect it is,as you last stated,fixed in the architecture of the desk.
However,found a workaround,which I hate,but reduces the bleed to -80dbfs peak/-94dbfs rms,as I dropped the level post da converter,and even that up with console's control room vol pot.
2 disadvantages:
1-When I switch main mix as CR source,it gets louder,so had to mark my usual vol level
2-my main VU meters working different when listening to 2TR return(showing lower level then when hit properly)

Still would like to know big name console's specs regarding that subject...

Thank you very much

Cheers
Old 17th July 2017
  #8
Lives for gear
 

returns might be returning audio on the ground. you should be using 2-wire balance method (no pin 1 or no sleeve). Its not the mixer fault. Its your equipment that you connected the mixer to has a higher impedance ground than the mixer. I experienced something like that when I switched to self powered monitors on a Amek M2500 and going two wire balanced solved it.
Old 17th July 2017
  #9
Gear Nut
 

Quote:
Originally Posted by Audiospacific2 View Post
returns might be returning audio on the ground. you should be using 2-wire balance method (no pin 1 or no sleeve). Its not the mixer fault. Its your equipment that you connected the mixer to has a higher impedance ground than the mixer. I experienced something like that when I switched to self powered monitors on a Amek M2500 and going two wire balanced solved it.
Thank you very much for your reply.
Do you mean using the method you mentioned just for 2TR RET or all of outboard?
Not quite sure how can I keep it balanced and remove pin1...?late here...
Will read your post in the morning again.
Thank you very much


Cheers
Old 17th July 2017
  #10
Lives for gear
 

removing pin 1 or sleeve connection forces balanced connection. Balance audio has no ground reference (because it uses signal non-inverted and signal inverted as the connection) and removing pin 1 removes any unbalanced references in parallel.

I don't run grounds on my balanced outboard. And I converted all unbalanced inserts to balanced (via transformers mounted under my frame that I installed)
Old 17th July 2017
  #11
Gear Nut
 

Quote:
Originally Posted by Audiospacific2 View Post
removing pin 1 or sleeve connection forces balanced connection. Balance audio has no ground reference (because it uses signal non-inverted and signal inverted as the connection) and removing pin 1 removes any unbalanced references in parallel.

I don't run grounds on my balanced outboard. And I converted all unbalanced inserts to balanced (via transformers mounted under my frame that I installed)

Got it
Thank you once again
Quite a task to do,hope will be worth it

Thank you very much!


Cheers
Old 18th July 2017
  #12
Lives for gear
 

no problem. btw I used 10K:10K transformers on my inserts in and out. But I did a few of my channels 10K:600 out 600:10K return for my old 600 ohm transformer balanced outboard, just to see if there was a difference, but I'm been thinking about eventually moving these 600 ohm compatibility to a patch panel and making all of the board 10K:10K inserts
Old 18th July 2017
  #13
Gear Nut
 

Quote:
Originally Posted by Audiospacific2 View Post
no problem. btw I used 10K:10K transformers on my inserts in and out. But I did a few of my channels 10K:600 out 600:10K return for my old 600 ohm transformer balanced outboard, just to see if there was a difference, but I'm been thinking about eventually moving these 600 ohm compatibility to a patch panel and making all of the board 10K:10K inserts

You mean,600 for some older,vintage stuff?
Have you got any schematics or drawing the way you did it?talked today to my tech,as I can only soldier a bit,and read schematics,..
Was too much of time and expencies consuming?in my case it would be for 40-60 ch.

Thank you!!


Cheers
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