Simple Question regarding Balanced/Unbalanced Connections

[DarkEcho]

I have a pair of KRK V6 series II monitors and an Apogee Duet.

The KRK V6's are said to have XLR and 1/4"TRS combo; 10k ohm balanced inputs.

The Duet has only unbalanced outputs.

Conclusion:
I am not supposed to use a TS cable into my monitors.
And I am not supposed to use a TRS cable into the Duet.

So...how is the Duet supposed to be used in a serious audio application? I mean, arent all professional monitors going to have balanced inputs?!?!

[stuntbutt]

You can use a TS-TS or a TRS-TRS cable. Both will do the same thing in your applicaton.

[Dave12345]

I'm wondering the same thing - What's the best way for me to connect my Duet to Genelec 8040 ?


Cheers

[DarkEcho]

I'm battling a noise issue right now, and when I use TRS cables, the noise volume is reduced significantly compared to TS cables.

I don't understand how this can physically happen, as it seems I am benefitting from the effects of Balanced cables even though my Duet has unbalanced outputs.


Not sure whats going on- but I would probably recommend everyone who's wondering to use TRS cables- it might silence some noise you may have.


Then again- I am not happy hiding the noise with balanced cables- I need to figure out and solve the root cause.

[tINY]

The best way to hook it up is to use a TRS to TRS and short R to S on the unbalanced output side.



-tINY

[DarkEcho]

tINY, what is the concept behind that?

what makes that better than other ways?

and how would you go about shorting the R/S of the plug going into the unbalanced ouput jack?

[willythekid]

off topic maybe but i wish so much that apogee would release a duet with balanced outputs... it seems so perfect in all other regards. i would gladly pay some extra for this feature.... pleeease max!

-wtk

[tINY]

Since the output is unbalanced, the difference between the output and ground is the signal voltage. If the ground on the receiving unit (speakers in this case) is different from the ground on output, then the voltage between the grounds ends up as signal - if you just connect the shield and the output.

But, since the receiving unit has a differential input, you can connect the inverting side to the ground of the transmitting unit and the ground noise (usually hum) will get canceled out in the differential receiver.

This works even better if you know the output impedance of the driver (Duet) and add a resistor of the same value between the ring and ground on the output side.

You want to keep the shield for current to flow from one device to the other (low impedance connection between grounds).



-tINY

[drBill]

Originally Posted by willythekid

off topic maybe but i wish so much that apogee would release a duet with balanced outputs... it seems so perfect in all other regards. i would gladly pay some extra for this feature.... pleeease max!

-wtk

There's really no need for balanced outputs - just wiriing the cables correctly will alleviate all problems.

At the output (duet) end - use a balanced cable to a TS plug. Wire the hot (+) conductor to the tip. Wire the Cold (-) and the shield (ground) to the Sleeve of the plug.

At the input (speaker) end - use a TRS plug. Wire the hot (+) conductor to the tip. Wire the Cold (-) conductor to the ring. Leave the shield (ground) DISCONNECTED to avoid ground loops. If there is 60 cycle (doubtful) you can try hooking it back up, but most applications will work better with it disconnected.

[DarkEcho]

Hmm I don't get how a ground loop can form purely from using different cables... I'll study what you and tINY wrote more.. Thanks!

[Mayor999]

Here is a good article on wiring...

Farther down the article it shows the best way to interconnect various types of audio goodness...

Sound System Interconnection

Check out 14.

[drBill]

Originally Posted by DarkEcho

Hmm I don't get how a ground loop can form purely from using different cables... I'll study what you and tINY wrote more.. Thanks!

A ground loop is caused by more than ONE path to ground. This can be caused by:

Third pin of AC cable
Metal Rack Rails
Gear touching each other
And of course the obvious one, interconnects - audio, computer (USB/Firewire/SCSI,etc.), MIDI, etc.

As you can see, it's quite possible to have 2,3 & even more loops in one piece of gear. You can even have ground loops INTERNALLY in poorly designed gear.

[EvilE]

Originally Posted by drBill

As you can see, it's quite possible to have 2,3 & even more loops in one piece of gear. You can even have ground loops INTERNALLY in poorly designed gear.

yuk!

[DarkEcho]

I picked up an EBTech Hum-X and the noise went away. So I think tINY and everyone else is right about the groundloop forming due to improperly wired cables (TS-TS instead of TS-TRS).


will there be any difference between using proper wires and using the EBTech Hum-X?

The Hum-X says it filters out the bad voltage whereas proper cables would prevent the situation from happening in the first place- will the sound quality be better with proper cables versus the Hum-X?

Thanks!