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ts to trs, unbalanced to balanced
Old 20th January 2007
  #1
Gear Maniac
ts to trs, unbalanced to balanced

i'm setting up my home studio, trying to figure out how to route everything. one possibility involves going out from the unbalanced !/4 inch inserts of my mixing board into the balanced 1/4 inch inputs of my a/d converter.
would a trs to ts cable work well or would it be better to get some sort of transformer? thanks
Old 20th January 2007
  #2
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JohnRoberts's Avatar
 

Quote:
Originally Posted by mookie View Post
i'm setting up my home studio, trying to figure out how to route everything. one possibility involves going out from the unbalanced !/4 inch inserts of my mixing board into the balanced 1/4 inch inputs of my a/d converter.
would a trs to ts cable work well or would it be better to get some sort of transformer? thanks
I would first consider making a custom cable from 2 TRS plugs and some good 2-conductor shielded cable. The TRS on bal input end should be tip=+, ring=-,and sleeve=gnd/shield. At the insert jack end if you want the signal to still be available inside the mixer, connect the tip to ring, otherwise connect the wire coming from the bal end tip (+) to the insert plug lead which is the send, (either tip or ring). Check your owners manual. FWIW, I always tried to make sure that info was screened somewhere on the chassis too. Connect the wire coming from the balanced end ring (-) and the shield together at the sleeve lead on the insert plug.

In a properly designed mixer/console while the TRS insert is unbal, the signal should be forward referenced to the ground at that jack, using 2 conductor shielded wire to telescope the ground reference forward to the balanced (differential) input should give you good signal integrity and freedom from ground interference. That fact that it isn't balanced should be inconsequential for modest distance runs.

JR
Old 22nd January 2007
  #3
Here for the gear
 

After reading these two posts, I can't discern the answer to the following question:

In an unbalanced (originating) to balanced (receiving) connection, is it necessary to connect the "cold" {usually pin 3 on xlr but not always} to ANYTHING?

To be specific, I have an old ZOOM 9200 that I really like that has XLR balanced inputs but UNbalanced outputs. Historically, I always used it with my Mackie board's balanced sends so I never had any issues (other than getting the right hot pin on the XLR pin correct). Now, I want to use it with my amps effect's send/return which are both unbalanced (and probably -10 for that matter). So the connection I need to focus on is the send form the amp to the input of the Zoom.

Another assumption is that I assume that ANY balance input is expecting to "see" two 180 degree out of phase signals on pins 2&3. Therefore if I do not have this balanced phase inverting send, I would think I would NOT want to connect to both of the inputs 2 & 3 XLR pins as the received signal would be the very same on both (not inverted) and one would get inverted once the ZOOM received it casuing phase and level issues.

I know I could just make up several cables and see which one performs but I would like to know the science behind the wiring in this situation.

Any thoughts??
Old 22nd January 2007
  #4
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Wavebourn's Avatar
 

Quote:
Originally Posted by renkema View Post
In an unbalanced (originating) to balanced (receiving) connection, is it necessary to connect the "cold" {usually pin 3 on xlr but not always} to ANYTHING?
That ANYTHING is called "GROUND TO WHICH UNBALANCED OUTPUT IS REFERENCED TO". Because there always is some noise between grounds, the differences are in their level only. So the noises from the ground will go to both pins 2 and 3, and since pin 2 will receive noise plus signal, but pin 3 will receive noise only, differential input will substract what is on the pin 2 from what is on pin 3 so signal only will be received. However, no absolutely differential inputs exist, but anyway noise level will be much-much lower.
Old 22nd January 2007
  #5
Here for the gear
 

Okay, I think I've got it.

So in a unbalance to balanced configuration, connecting pin 3 (if pin 3 is cold on the balanced input) is all about noise reduction and not signal transfer as pin 3 will only be carrying noise.

So to recap, balanced to balanced equation: -signal+noise (pin 3) is inverted and summed with +signal+noise (pin 2) so that the result is 2signal, 0noise

unbalanced to balanced: noise only (pin 3) is inverted and summed with +signal+noise (pin2) so that the result is 1signal, 0noise

If the above equations and results are correct, that poses a question about signal level (which is what prompted this post originally). I really have to crank the input of the balanced unit (which is expecting a +4 signal) to get a decent level. I know a part of the problem is that the signal from the amp is much lower than +4. However, is the signal lower also lower because the unit is looking to sum 2 signals from pins 2&3 but only getting 1 signal on pin 2? If that's true, I'm not sure there is a way to compensate. Maybe my premise about signal being on pin 3 in a balanced to balanced config is wrong.
.
Old 22nd January 2007
  #6
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Wavebourn's Avatar
 

Quote:
Originally Posted by renkema View Post
Okay, I think I've got it.

So in a unbalance to balanced configuration, connecting pin 3 (if pin 3 is cold on the balanced input) is all about noise reduction and not signal transfer as pin 3 will only be carrying noise.
It depends on the input. If it is a true transformer balanced input pin 3 will "be carrying the signal" current as well, through the ground. The difference is where to ground it.
Old 24th January 2007
  #7
Gear Maniac
thanks for all the feedback, but i have to say, this is a bit above my head. i am but a mere songwriter and don't make cables...
i have a question that maybe you more technically learned people can help me with:
i'm using my mackie 1202 as a frontend router for monitoring purposes before my a/d and mbox 2. my setup: two tube pres through the mackie and into an rme adi-2 into the spdif of the mbox.
the rme takes balanced inputs, but i was hoping to go out of the unbalancede channel inserts so that the signal doesn't pass through the whole amp architecture of the mackie. another option is to pan left and right on channels 1 and 2 and go out the mackie xlr mains into the rme. which makes more sense sonically? if i go out the unbalanced inserts, what cost-effective non-cablemaking options do i have?
help is very much appreciated. thanks.
Old 3rd March 2017
  #8
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JblKid95's Avatar
 

I have a snake of Dsub to TRS? can I change the connectors to TS? I don't want to buy adapters it will be too expensive
Old 3rd March 2017
  #9
Gear Maniac
 

Quote:
Originally Posted by JblKid95 View Post
I have a snake of Dsub to TRS? can I change the connectors to TS? I don't want to buy adapters it will be too expensive
Not enough information to give a reliable answer. You are actually asking about how to connect (potentially but not necessarily) balanced to unbalanced interfaces together. Which is the output, which is the input? Is the output transformer balanced? Is the input transformer balanced? Answers to those questions will make a useable answer possible.
Old 3rd March 2017
  #10
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Quote:
Originally Posted by rfnoise View Post
Not enough information to give a reliable answer. You are actually asking about how to connect (potentially but not necessarily) balanced to unbalanced interfaces together. Which is the output, which is the input? Is the output transformer balanced? Is the input transformer balanced? Answers to those questions will make a useable answer possible.
Trs connector to Ts connector. Just the cable
Old 3rd March 2017
  #11
Gear Maniac
 

Quote:
Originally Posted by JblKid95 View Post
Trs connector to Ts connector. Just the cable
It may seem like "just the cable" but there is no single answer to your question without more information.
Old 3rd March 2017
  #12
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Quote:
Originally Posted by rfnoise View Post
It may seem like "just the cable" but there is no single answer to your question without more information.
I just want to know how to turn a trs end on my cable to Ts lol. I have the parts. I think I found a video that says you solder the out of phase and the ground together or something. Thanks anyway
Old 3rd March 2017
  #13
Gear Maniac
 

Quote:
Originally Posted by JblKid95 View Post
I just want to know how to turn a trs end on my cable to Ts lol.
Yeah I know what you want, a simple quick answer. It depends on "what" is being connected to "what" through that simple cable. Best wishes to you, I tried to help, sorry I wasn't able to break through.
Old 3rd March 2017
  #14
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Richard Crowley's Avatar
Quote:
Originally Posted by JblKid95 View Post
I just want to know how to turn a trs end on my cable to Ts lol.
It's NOT about the CABLE. Its about what the cable is connected to!

There are several ways of making a "balanced output", and there are several ways of making a "balanced input". Alas, here in the Real World, they are not all blindly interchangable and interconnectable. That is why people are reluctant to just offer a simple answer. Because there is a significant chance that it won't work, absent any details about the source or destination gear.

Quote:
I have the parts. I think I found a video that says you solder the out of phase and the ground together or something. Thanks anyway
Connecting the "cold" (out of phase) side (Ring, XLR3) over to ground is one way of dealing with unbalanced sources or destinations. Note that you don't need any "parts" to do that. You just solder a very tiny piece of wire from ring to sleeve, assuming you can access the inside of the TRS plugs. Of course, if they are molded, then you are out of luck.
Old 3rd March 2017
  #15
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JblKid95's Avatar
 

Quote:
Originally Posted by Richard Crowley View Post

Connecting the "cold" (out of phase) side (Ring, XLR3) over to ground is one way of dealing with unbalanced sources or destinations. Note that you don't need any "parts" to do that. You just solder a very tiny piece of wire from ring to sleeve, assuming you can access the inside of the TRS plugs. Of course, if they are molded, then you are out of luck.


Quote:
Originally Posted by rfnoise View Post
Yeah I know what you want, a simple quick answer. It depends on "what" is being connected to "what" through that simple cable. Best wishes to you, I tried to help, sorry I wasn't able to break through.
Into a DI, Neutrik gold connectors. thanks
Old 3rd March 2017
  #16
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mikefellh's Avatar
WOW, reviving a 10 year old thread! Talk about waking up the dead!
Old 3rd March 2017
  #17
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As often happens, R.C. responds with a correct, informative answer.
Old 3rd March 2017
  #18
Gear Maniac
 

Quote:
As often happens, R.C. responds with a correct, informative answer.
Quote:
Connecting the "cold" (out of phase) side (Ring, XLR3) over to ground is one way of dealing with unbalanced sources or destinations.
Richard keeps a level head around here and generally provides plenty of smart advice. With due respect, this is NOT the better answer when connecting actively balanced (transformerless) outputs to unbalanced inputs. Shorting two lines together (shield to signal) is bad practice even if it is commonly done. Avid and others caution specifically against it because doing so puts a direct short across one of the channel's output drivers. While that in itself does not usually cause permanent damage it does increase distortion, causes heat stress to the shorted output components, and dumps signal current onto the common shield which can show up as signal leakage on other inputs. Not ALL active outputs do that but many do. For these reasons I asked how the cable was going to be used before giving a poor answer.
Old 3rd March 2017
  #19
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Richard Crowley's Avatar
Quote:
Originally Posted by rfnoise View Post
Richard keeps a level head around here and generally provides plenty of smart advice. With due respect, this is NOT the better answer when connecting actively balanced (transformerless) outputs to unbalanced inputs.
I agree completely. People keep asking for a simple, universal answer, and as I said before there is not simple, universal and proper solution.

Quote:
Shorting two lines together (shield to signal) is bad practice even if it is commonly done....
Note that simply plugging a TS plug into a TRS jack with a balanced output is an extremely common practice. Yes, it shorts the "cold/-" side of the audio to ground. Yes, that MAY cause stress on an improperly designed circuit. However you would be hard pressed to find any modern line-level output circuit that was not designed to withstand a perpetually shorted output.

Modern audio circuits are designed with integrated (or discrete) circuits which have such low impedance that they add a "build-out" resistor primarily to better match the impedance of the line (and the load at the other end) This series resistance has the added effect of making the output short-circuit-proof. So while shorting an output is theoretically a bad idea. In the real world, it is not a practical concern.

Here is a typical example of a transformerless line-level, balanced (differential) output circuit:



Note that resistor between the non-inverting amplifier and XLR pin 2. Note also the resistor between the inverting amplifier and XLR pin 3. You will likely never find a modern piece of audio gear without these resistors (or their active equivalent).
Old 8th August 2020
  #20
Here for the gear
 

So to be clear for this knuckle head here:
Mic Preamp unbalanced out to Balanced in mixer
TRS to TRS cord MIGHT leave the ring (cold) floating.
However, my unbalanced output device ties ring and sleeve together at the output jack.
Is it worth making a custom:
TS to TRS and leave the TRS ring inside the shield floating at the TS jack?
This is in a ham radio shack and RF is strong, EVERYWHERE. Anything I can do to keep RF out of my audio is being done.

Last edited by W9BOQ; 8th August 2020 at 10:25 PM.. Reason: correction
Old 8th August 2020
  #21
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EvilRoy's Avatar
 

I hate you all.

I have read and studied this topic for years and it seems the more I read, the more I don’t understand. All I want to do is hook up unbalanced outboard to my mixer and I practically need a degree in electronics to do it. After reading the posts here, I’m as confused as ever. To heck with it. I’m disconnecting the shield at one end and crossing my fingers.
Old 8th August 2020
  #22
Gear Maniac
 

No need for that or any other spells or magic.

The readers digest of all this noise is that if either one of the two devices being connected has unbalanced connection points only then the whole interconnect will be unbalanced so no need for anything but an standard unbalanced cable... like a TS to TS 1/4" patch.
Old 9th August 2020
  #23
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EvilRoy's Avatar
 

Quote:
Originally Posted by paul o View Post
No need for that or any other spells or magic.

The readers digest of all this noise is that if either one of the two devices being connected has unbalanced connection points only then the whole interconnect will be unbalanced so no need for anything but an standard unbalanced cable... like a TS to TS 1/4" patch.
THANK YOU! 😁
Old 9th August 2020
  #24
Lives for gear
Quote:
Originally Posted by W9BOQ View Post
So to be clear for this knuckle head here:
Mic Preamp unbalanced out to Balanced in mixer
TRS to TRS cord MIGHT leave the ring (cold) floating.
However, my unbalanced output device ties ring and sleeve together at the output jack.
Is it worth making a custom:
TS to TRS and leave the TRS ring inside the shield floating at the TS jack?
This is in a ham radio shack and RF is strong, EVERYWHERE. Anything I can do to keep RF out of my audio is being done.
Make a custom TS to TRS lead using balanced cable and connect:

- T to T
- S to R
- cable shield to S

Quote:
Originally Posted by EvilRoy View Post
I hate you all.

I have read and studied this topic for years and it seems the more I read, the more I don’t understand. All I want to do is hook up unbalanced outboard to my mixer and I practically need a degree in electronics to do it. After reading the posts here, I’m as confused as ever. To heck with it. I’m disconnecting the shield at one end and crossing my fingers.
See above (if your mixer has XLR inputs, then TS to XLR with: T to 2, S to 3, cable shield to 1)

Quote:
Originally Posted by paul o View Post
No need for that or any other spells or magic.

The readers digest of all this noise is that if either one of the two devices being connected has unbalanced connection points only then the whole interconnect will be unbalanced so no need for anything but an standard unbalanced cable... like a TS to TS 1/4" patch.
This will work, but in a "This is in a ham radio shack and RF is strong, EVERYWHERE" situation as above, the custom cable described may work better.

As for balanced to unbalanced, see here.
Old 9th August 2020
  #25
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EvilRoy's Avatar
 

Quote:
Originally Posted by Cabirio View Post
Make a custom TS to TRS lead using balanced cable and connect:

- T to T
- S to R
- cable shield to S

See above (if your mixer has XLR inputs, then TS to XLR with: T to 2, S to 3, cable shield to 1)

This will work, but in a "This is in a ham radio shack and RF is strong, EVERYWHERE" situation as above, the custom cable described may work better.

As for balanced to unbalanced, see here.
Db25s for line in/out.

Just to be clear, positive to positive - negative to negative... and the shield can go f**k itself.

Don’t know why this has to be so hard.
Old 9th August 2020
  #26
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Quote:
Originally Posted by EvilRoy View Post
Db25s for line in/out.

Just to be clear, positive to positive - negative to negative... and the shield can go f**k itself.

Don’t know why this has to be so hard.
The shield should be connected to the sleeve / pin 1 / whatever corresponds to that in a DB25 at the receiving / balanced end, see attached (source).
Attached Thumbnails
ts to trs,  unbalanced to balanced-unbal-bal.png  
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