Tech Tip: Unbalanced vs. Balanced I/O & How to Work with Them

Posted on .

Understanding the differences between balanced and unbalanced analog inputs and outputs and how to deal with them in signal chains will help keep your sound clean and free from noise and signal loss. We’ll first explain the technical differences then give you practical advice on how to interface these two types of signals.

Unbalanced Signals

Most unbalanced music instrument cables have two conductor wires. One wire carries the signal and is referred to as the hot line. The other is the ground wire that’s connected to to an insulated wrap and is also called the common ground, earth, or shield. In theory, the ground wire with its insulation shield isolates the hot lead conductor from external interference that can cause hum and other electronic noise. Unbalanced cables usually are terminated with two-wire ¼” phone connectors or the RCA plugs and jacks usually found in consumer audio gear. As we explain below, the ground conductor and insulating shield are only partially successful at eliminating electronic interference.

Signal Conductor Grounded Shield

The signal conductor has a grounded shield that only partially isolates it from electronic noise.

Most instrument amps and guitar effects processors and stompboxes have unbalanced inputs to provide compatibility with standard unbalanced ¼” guitar outputs. This eliminates the need for line-level adapters or preamps with signal-matching capabilities.

Balanced Signals

In balanced signal paths, there is a second signal conductor referred to as the “cold” line. The hot and cold lines transmit identical signals that are 180 degrees out of phase with each other. As the signal voltage in the hot line increases, the cold line’s signal voltage decreases, precisely mirroring the hot signal in reverse. The combined hot and cold signal is fed into a circuit containing what’s known as a differential input that detects any difference between the signals. Because hum and other noise are present in both conductors more or less equally, they appear to the input as in-phase signals.

Balanced Circuit Phase Mirroring

A balanced circuit uses out of phase mirroring to filter out noise.

The differential circuit ignores such in-phase signals, hence canceling out the noise. Amplifiers with differential circuits can cancel out most interference—up to 90 dB or more—essentially reducing noise to inaudible levels.

Balanced Circuit Phase Mirroring

A differential amp “sees” noise as an in-phase signal thus canceling it out of the transmitted sound.

Balanced lines are ideal in situations involving lengthy cables and low signal levels where noise can be a problem. Mic cables are a good example of such situations. On the other hand, short cable runs carrying higher signal levels are less prone to audible noise.

Balanced Line Connectors

Balanced XLR connectors have 3 pins. An international standard dictates that pin 1 is the ground, pin 2 carries the “hot” signal, and pin 3 is neutral. A few manufacturers unfortunately wire their I/O so that pin 3 carries the hot signal. This can be addressed by reversing the pin 2 and 3 conductors inside the gear or by using an adapter cable that does the same thing.

A cross-connect adapter cable reverses the pin 2 and pin 3 signals.

A differential amp “sees” noise as an in-phase signal thus canceling it out of the transmitted sound.

In addition to XLR plugs and jacks, stereo ¼” TRS phone connectors are also wired for balanced operation. The jack tip (T) is hot, the ring (R) is the neutral lead, and the sleeve (S) carries the ground lead.

Auto Balancing Input Circuits

In the past transformers were used to convert unbalanced signals to balanced operation. They were imperfect, introducing distortion and other artifacts that affected the purity of the signal.

Focusrite Scarlett 2i2 USB Audio Interface

The Focusrite Scarlett 2i2 USB Audio Interface has combination line/mic inputs on its front panel that accept ¼” TRS or XLR connectors.

Today’s gear typically has active circuits that produce less coloration while automatically detecting the signal type based on the type of jack inserted, routing the signal accordingly. Gear with auto-switching I/O often provides a spec referring to the function as “mic/line level I/O”. Such gear usually has level adjustment capabilities to handle varying input voltages. They also often contain 6 dB pads that equalize balanced/unbalanced gain.

Similarly, an XLR balanced input can be fed from an unbalanced output. In this scenario, the hot signal is output the the XLR pin 2 while pins 1 and 3 carry the ground.

XLR connector configured for an unbalanced output

An XLR connector configured for an unbalanced output.

Having cables with this kind of output makes it easy to directly connect unbalanced sources such as guitar effects directly into recording gear, DAWs, and signal processors with balanced inputs.

In many cases you can reverse the process when feeding a balanced output signal to an unbalanced input. However, some older gear with poorly designed balanced outputs could potentially short the output to the ground, producing a noisy, unbalanced signal, or worse, damage the input stage it’s connected to. This is a pretty unlikely scenario, but if you have older gear that has outputs that do not use transformers, and are handy with a soldering iron, you can wire an adapter cable as illustrated below. For safety’s sake we’ve added a couple of 100 ohm resistors in series with pins 2 and 3. The resistor wired to pin 3 prevents short circuiting with the ground. If the resistor becomes warm within a minute of operation, remove it and leave pin 3 unconnected. By connecting pin 1 to the ground and pin 2 to the hot conductor you’ll still get an unbalanced input signal.

XLR balanced to unbalanced connector

Resistors add insurance to this XLR balanced to unbalanced connector.

Female/Male 3-pin XLR connectors

Female/Male 3-pin XLR connectors

Do I Really Need Balanced I/O?

Unbalanced connections are usually adequate for home studio and stage rigs where there are no long cable runs. But if if you need lengthy cables in your setup or are working with very low signal levels such as recording a softly played acoustic guitar with a dynamic mic, balanced connections will help keep your high-gain signal noise-free.

Tags: Audio Interfaces


# nahtanoj 2016-11-27 07:00
not really useful information. It still tells me nothing how to terminate the cold signal at a TS plug. Shield or terminate to hot???????
# Christian 2016-03-07 12:27
Thank you, very clear.
Q: Can you tell me if I can balance my turntable output, without installing a SUT?
# Asghar 2016-02-24 04:41
I have Lexicon LX-7
There Humming after RCA Input
give me solution

# Brian 2016-01-06 07:11
I'm looking at your last two diagrams, with a view to fitting an XLR socket onto a guitar for a friend. That would be the first of those, with pins 1 and 3 bridged. Would that circuit not benefit from a 100 ohm, or larger, resistor between those pins?

Secondly, on your last diagram for feeding a balanced signal into an unbalanced input, would a larger resistor between pin 3 and ground not be better?

What I'm looking at achieving by asking these questions is less pickup of interference on longer cable runs. My questions are on minimal, passive, circuitry and I appreciate using an inverter on the hot connector inside a guitar, then wiring an XLR conventionally, would be the ideal solution.

# Keith 2015-12-16 19:04
I have a question, I have a balance trs aux output in my mixer, but I need to run a long way to a unbalanced input of a monitor. How can I reduce to nosie?or can I balanced it?
# Martin 2015-11-30 02:00
My problem is I have a Yamaha S70XS keyboard, and use it in a live band. It has a jack output and I have tried to use 1/4 jack to male XLR to plug into the stage box. However I'm getting a loud buzz from that channel on the mixing desk when I do so. However if I go 1/4 Jack to 1/4 Jack direct into the mixer it disappears? Why is this and can I solve the situation to utilise the stage box? Hope someone can help. Thanks
# some guy 2016-02-22 14:51
Get yourself a cheap D.I. (direct injection box)
You plug the 1/4 jack into the D.I and xlr from the D.I to the stage box. this will give you a balanced output. They can be battery powered or phantom powered via the stage box if the mixing desk allows. This is standard procedure for handling unbalanced instrument signals direct to PA.
# Sean 2015-10-17 17:42
Great info, question... I'm hooking a bass head into a power amp from the preamp out... The power amp says that it is designed to take unbalanced there a benefit to using a trs vs ts in this situation? Is there an added benefit to using expensive cables like Mogomi?
# astroboy2005a 2015-07-20 11:54
Hi there, excellent article. Question… Quasi-balanced connection are the same thing that unbalanced connection?. Thank you.
# Dave Golber 2015-06-04 17:04
I need a little help: I have an instrument microphone ending in a mono plug. I'm wiring up a cable to connect it to a mixer. The cable is a standard XLR mike cable. The mixer end of the cable is an XLR. At the other end, I cut off the XLR, and I'm connecting a mono plug. I know that I connect the hot and cold of the XLR to the tip and sleeve of the mono plug. But what should I do with the XLR shield? I could connect it to the sleeve, or just leave it unconnected. Which is better?

Thanks for the help
# Jerry 2015-07-13 18:17
Yeah, bridge slave and shield
# Rafa 2015-02-26 03:32
Excellent article, very clear. Thanks a lot.
# Bruce 2015-02-25 07:34
Very insightful article thanks for posting. Question - I have an Empirical Labs distressor compressor which has unbalanced inputs/outputs. I am trying to connect this with an unbalanced TRS line into my Apogee Ensemble (early model) which has balanced. I do get a signal but in only one of the monitors. Will using balanced patch cables resolve this issue? Any help is appreciated.
# dave 2014-12-11 16:01
Perfect! Thanks
# John 2014-11-18 05:05
Hi JP,

Your comment was great,very funny :-)
# jp 2014-10-14 03:46
The groundwire must be placed carefully behind the g spot in the kringspier. After that the cold and hot myst get a smeer of smegma and replaced in the analconfusion s3ctor 3 from the ground to the hotwired one
# Rich Wahne 2014-02-26 19:53
Great article here!!! Question...I've got an Audio Technica lapel microphone with a 3.5mm Dual Mono plug, and I need to plug it into my sound board, which is XLR. Do I need the XLR male plug to be wired pin 1=ground, pin 2= tip pin I need the XLR male plug to be wired pin 1=ground, pin 2=tip & pin ?
Thank you so much for your wonderful resource, and I look forward to your reply.
# jp 2014-10-14 03:46
Read my explaining pls carefully

Add comment

Security code

The HUB by Musician's Friend Logo



Stupid Deal of the Day (SDOTD) Musicians Friend Backstage Pass  Open Box Musical Instruments at Musician's Friend


  • BACKSTAGE PASS Rewards Program
  • Guitar Case Finder
  • Give a Gift Certificate
  • Clearance
  • Private Reserve Guitars


  • Hot Deals
  • On Sale
  • Pre-Order the Latest Gear
  • New Gear
  • Top Rated Gear