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Pseudo-Balanced Cables, lets make it clear
Old 20th November 2013
  #1
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Thread Starter
Pseudo-Balanced Cables, lets make it clear

So I have currently been recabling my studio to correct my years of penny pinching that resulted in lots of unbalanced connections (and of course battling dreaded ground loops).
I have several pieces of gear (Moog Sub Phatty, Virus TI Snow, Watkins Copicat, Moogerfooger 104Z) which are unbalanced. I have been looking into making some pseudo-balanced cables to combat this.
I am getting very confused messages from everywhere on this. As I can understand it the simplest form of pseudo-balanced cable would be a TRS connector on one end of a balanced cable connected traditionally, then a TS on the other with both the cold connected to the sleeve and the shield unconnected.
Correct?
Because I keep seeing diagrams where both the cold and shield are connected to the sleeve of the TS connector.
What is the correct method and is it really going to remove my risk of grounding problems?
Thanks in advance
Old 20th November 2013
  #2
Lives for gear
 

get some transformers and…... wallah balance connection

not the plug adapters as most of them carry the ground over, and its nice to isolate equipment like that
Old 20th November 2013
  #3
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The correct way to do it is to connect the cold to ground, just like you already mentioned.
Old 21st November 2013
  #4
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Thread Starter
transformers will make this a pricey venture.

When you say cold to ground, do you also mean leaving the shield disconnected?
Old 21st November 2013
  #5
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Thread Starter
transformers will make this a pricey venture.

When you say cold to ground, do you also mean leaving the shield disconnected?
Old 21st November 2013
  #6
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The correct way is to follow the respective soundcard/converter manufacturer's instructions.
Old 21st November 2013
  #7
Gear Addict
 
UnDeFiNeD's Avatar
 

http://www.rane.com/note110.html

The table on the bottom will show you exactly what to do.

Unbal to bal:

Tip to tip, sleeve to ring, and connect cable shield only at the balanced sides sleeve

Alex
Old 21st November 2013
  #8
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Analok's Avatar
Great link - Thanks!!
Old 21st November 2013
  #9
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Thread Starter
Wow there we go, that Rane document has cleared everything up for me.

Thats happened to me before as well, I should think to check their site more often before posting on here.

Thanks very much Alex.

To the soldering iron!!!
Old 21st November 2013
  #10
Gear Maniac
 
readIcculus's Avatar
Someone should balance the GS logo cable!
Old 30th April 2015
  #11
Gear Head
Quote:
Originally Posted by UnDeFiNeD View Post
Sound System Interconnection
The table on the bottom will show you exactly what to do.
That's a great source indeed!
However, there's one option I've read about that I don't see there:
Connecting an unbalanced output to an unbalanced input using 2 conductor shielded wire.
What I was reading is you can make a pseudo balanced cable by soldering the shield and ground to the sleeve and signal to the tip of the TS plug on the output and on the input you leave the shield disconnected and solder signal and ground to tip and sleeve of the TS plug.
Has anyone here ever done it this way?



[edit] Oh I see now that they've done the same thing in drawing 11 & 12. No idea why they're using a TRS plug on the output side though: connecting ring and sleeve together is the same as using a TS plug. [/edit]

Last edited by Nisei; 30th April 2015 at 12:18 PM..
Old 30th April 2015
  #12
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Quote:
Originally Posted by Vitalis View Post
The correct way to do it is to connect the cold to ground, just like you already mentioned.
That means a direct short to GND for the negative leg. For a servo balanced output that is mandatory, for some outputs that is not optimum.

As living sound wrote, you really need to understand your topology and use the right layout for your specific set up.

A balanced input is happy with any of the legs tied to GND, it's the balanced output that needs to be configured depending on circuit topology.
Old 30th April 2015
  #13
Quote:
Originally Posted by readIcculus View Post
Someone should balance the GS logo cable!

Pretty sharp dude !
Old 30th April 2015
  #14
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Friedemann's Avatar
 

Fixed that for you.
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Old 26th May 2015
  #15
Gear interested
 

Quote:
Originally Posted by Nisei View Post
That's a great source indeed!
However, there's one option I've read about that I don't see there:
Connecting an unbalanced output to an unbalanced input using 2 conductor shielded wire.
What I was reading is you can make a pseudo balanced cable by soldering the shield and ground to the sleeve and signal to the tip of the TS plug on the output and on the input you leave the shield disconnected and solder signal and ground to tip and sleeve of the TS plug.
Has anyone here ever done it this way?

[edit] Oh I see now that they've done the same thing in drawing 11 & 12. No idea why they're using a TRS plug on the output side though: connecting ring and sleeve together is the same as using a TS plug. [/edit]
Nisei,
There's no such thing as pseudo-balanced cabling from an unbalanced output to an unbalanced input. By connecting an unbalanced output to an unbalanced input, you completely negate the possibility of pseudo-balancing since the input has no differential amplifier to take advantage of the common mode rejection technique. The proper way to do a pseudo-balanced connection from an unbalanced output to a balanced input is illustrated in drawing 14 on that page. Drawings 11 and 12 are for sending a balanced output to an unbalanced input.
Old 26th May 2015
  #16
Gear Head
Quote:
Originally Posted by SunCrushr View Post
Nisei,
There's no such thing as pseudo-balanced cabling from an unbalanced output to an unbalanced input. By connecting an unbalanced output to an unbalanced input...
You're right, I shouldn't have called it Pseudo Balanced SunCrushr. What I meant was that he Sound System Interconnection page lists all possible connections (balanced and unbalanced) and I thought this one was missing. It's a great way to get rid of ground loop.
Old 28th May 2015
  #17
Gear interested
 

Quote:
Originally Posted by Nisei View Post
You're right, I shouldn't have called it Pseudo Balanced SunCrushr. What I meant was that he Sound System Interconnection page lists all possible connections (balanced and unbalanced) and I thought this one was missing. It's a great way to get rid of ground loop.
Thanks for the clarification.

Yeah, I can see how this might help alleviate some ground loop noise, since the shield isn't connected to ground on the receiving end, though it might also exacerbate RF interference noise, since you're essentially doubling your ground wire length, or more accurately, hanging an antenna off of your ground wire connection. I'm no electrical engineer though, but I'd like to see the science behind this out of curiosity.

I'm lucky that I don't have to deal with unbalanced connections in my rig apart from my guitars of course, and one of my synths, a Waldorf Blofeld. I'm going to try the cable diagram in drawing 14 to see if it makes any difference to the noise floor on that connection, though being a short run, it doesn't pick up too much noise anyway.
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