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Why use stereo unbalanced jacks? (Culture Vulture) Dynamics Processors (HW)
Old 29th March 2016
  #1
Here for the gear
Why use stereo unbalanced jacks? (Culture Vulture)

In the manual of the Thermionic Culture Vulture it says:
Quote:
Inputs and outputs are unbalanced stereo jacks on the rear panel.
I asked about this and they replied:
Quote:
The jacks used are stereo jack sockets with the ring & shield wired together
to earth (i.e unbalanced).
The Tip is the "Hot" Pin
Why would one want to wire TRS-jacks instead of just using regular TS-jacks?
Old 29th March 2016
  #2
We do the same thing on unbalanced "TS" connections, especially Hi Z.
This gives much, much better ground connection compared to just the sleeve.
The other thing is insertion force which is much greater when using TRS jacks on TS lines. They stay put better.
Old 29th March 2016
  #3
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Because on an output jack going to a differential balanced input, you can use a TRS cable or TS cable and it won't matter. (Prevents user error)

Last edited by pentagon; 29th March 2016 at 08:00 PM.. Reason: clarification
Old 29th March 2016
  #4
Quote:
Originally Posted by pentagon View Post
Because on an output jack going to a differential balanced input, you can use a TRS cable or TS cable and it won't matter. (Prevents user error)
Yup, that takes care of this:
"When driving balanced inputs from an unbalanced output, pin 3 (or ring in the case of TRS) should be grounded at the unbalanced gear"
Old 29th March 2016
  #5
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By the way, the input jacks should not have shield and ring wired together. Ring should float. Otherwise there is the chance of error of sending signal into the ground (potentially doing damage to the gear.)
Old 29th March 2016
  #6
Quote:
Originally Posted by pentagon View Post
By the way, the input jacks should not have shield and ring wired together. Ring should float. Otherwise there is the chance of error of sending signal into the ground (potentially doing damage to the gear.)
Actually, shield should connect only at the unbalanced output, then ring and tip connect on both ends.

There are many electronic balanced outputs (DRV134, THAT1646, SSM2142) that need "-" tied to gnd to work correctly when driving unbalanced inputs.

And, if using gear with transformer balanced inputs, you MUST tie ring to gnd at the unbalanced end along with shield.

Here's a handy reference
Sound System Interconnection
Old 29th March 2016
  #7
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Quote:
Originally Posted by RogerFoote View Post
Actually, shield should connect only at the unbalanced output, then ring and tip connect on both ends.

There are many electronic balanced outputs (DRV134, THAT1646, SSM2142) that need "-" tied to gnd to work correctly when driving unbalanced inputs.

And, if using gear with transformer balanced inputs, you MUST tie ring to gnd at the unbalanced end along with shield.
Right. However, Thermionic Culture can only control their input jacks. And if the original OP is correct with the complete statement from Thermionic Culture, they should not be tying shield and ring together on the input. I doubt that's what Thermionic Culture meant but it does read wrong and is dangerous.
Old 29th March 2016
  #8
Not sure how much risk there is in putting small signal voltages onto shield, but I hear what you are saying.
I am just going by the correct wiring procedure.

Nobody is going to remember that certain pieces need non standard connections. Like when I fire up my Summit MPC100A and forget that pin 3 is hot just like old Ampex gear... Of course, now I have a reverse wired cable in the loom for that piece, so I don't have to think about it.
Old 30th March 2016
  #9
Here for the gear
So this basically mean that I connect the Vultures output to balanced gear with a balanced cable with no need of a DI box, right?

Quote:
Originally Posted by pentagon View Post
By the way, the input jacks should not have shield and ring wired together. Ring should float. Otherwise there is the chance of error of sending signal into the ground (potentially doing damage to the gear.)
Would this only apply if I use TRS cable on the input? No need to worry if I use TS?
Old 30th March 2016
  #10
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Quote:
Originally Posted by uc.t View Post
So this basically mean that I connect the Vultures output to balanced gear with a balanced cable with no need of a DI box, right?
This is about wiring and ground and a DI box does more than that. You'll have to check the output level of the Vulture and output impedance to determine if you need a DI box. But yes, you can use a balanced cable out of the Vulture into a balanced input without worry. I'm pretty sure impedance and gain are fine on the Vulture (I can't remember ever using a DI box with it) and it's just a quirk of Thermionic Culture to run unbalanced for their wiring.

Quote:
Originally Posted by uc.t View Post
Would this only apply if I use TRS cable on the input? No need to worry if I use TS?
For the input into the Vulture, it depends if your source is balanced (3 pin) or unbalanced (2 pin).
Unbalanced out into the Vulture using a TRS or TS cable won't make a difference.
Balanced out into the Vulture, you need to take pin 3 (cold) and wire it to ground (pin 1) in the cable on the signal source side (not near the Vulture) or you can just disconnect pin 3 (less good). The cable end at the source side can be TRS or XLR-F. The cable end at the Vulture can be TRS or TS.
Old 30th March 2016
  #11
Here for the gear
Quote:
Originally Posted by pentagon View Post
This is about wiring and ground and a DI box does more than that. You'll have to check the output level of the Vulture and output impedance to determine if you need a DI box. But yes, you can use a balanced cable out of the Vulture into a balanced input without worry. I'm pretty sure impedance and gain are fine on the Vulture (I can't remember ever using a DI box with it) and it's just a quirk of Thermionic Culture to run unbalanced for their wiring.


For the input into the Vulture, it depends if your source is balanced (3 pin) or unbalanced (2 pin).
Unbalanced out into the Vulture using a TRS or TS cable won't make a difference.
Balanced out into the Vulture, you need to take pin 3 (cold) and wire it to ground (pin 1) in the cable on the signal source side (not near the Vulture) or you can just disconnect pin 3 (less good). The cable end at the source side can be TRS or XLR-F. The cable end at the Vulture can be TRS or TS.
Thanks! For now I will only run synths and samplers thru the Vulture and the ones I have are all unbalanced. But the out may sometimes be connected to a balanced EQ or compressor. I use the 500 series for that stuff. I got a slot free so maby I´ll get a radial EXTC or something like that....
Old 30th March 2016
  #12
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Pred80r's Avatar
 

Unbalanced versus Balanced

I work in the LIVE audio world and the Recording/Studio audio world as well. I have decades of experience in both. I used to own a Neotek Series 1 console with unbalanced outputs, I am one of the few engineers left with insert cables that end up with an unbalanced input and output side, meaning the whole chain is unbalanced.

For ANYONE to stand by the performance of an unbalanced cable is similar to exerting that a tube TV has better qualities than an LCD.

Unbalanced Cables can work fine in an extremely limited environment, with no interference you can get significant signal to noise floor ratios. In their BEST case scenario you get the advantage of a better/higher quality signal path over short distances when they are not laying near any other conductive or inductive influences.


Balanced cables can do that in their worst case scenarios with their AVERAGE or best case conditions showing a MUCH higher signal to noise ratio than could ever be achieved by an unbalanced cable.


Just ask Mogami, Neutrik or Canare why they no longer build unbalanced cables except for instrument use. I am sure their years of experience must account for something...
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