Balanced (XLR, TRS) Vs. Unbalanced (RCA, TS) Connection

[Big Daddy]

The best way to understand the difference between balanced and unbalanced cables to think in terms of signal separation.

BALANCED CABLES

A balanced cable has three wires, one for ground (earth), one for the positive (hot), and one for the negative (cold).

Common Balanced Connectors

The two most common balanced connectors are XLR and TRS.

XLR Connectors:

In the case of an XLR cable, the three wires are called, X (ground), L (left, hot) and R (right, cold). There are both male and female XLR connectors.

Pin 1: Shield (G)
Pin 2: Hot (L)
Pin 3: Cold (R)

XLR Connectors

TRS Connectors:

TRS is the abbreviation for Tip (Left), Ring (Right), Sleeve (Shield, Ground). Although it may look like a standard 1/4" (6.35 mm) or 1/8" (3.5 mm) phono plug, it does have an extra ring on its shaft. TRS cables have two conductors plus a ground (shield). A TRS cable can carry either a balanced mono audio signal or an unbalanced stereo audio signal.

TRS Connector

How Does Audio Transmitted in Balanced Cables?

The audio signal is transmitted at the source on both the positive (L) and negative (R) lines, but the voltage in the negative (R) line is inverted (i.e. the polarity is changed). When the signal is positive on the hot (L) line, it is negative on the cold line (R). They appear as if they are 180 degrees out of phase. However, it is more technically correct to say one signal has reverse polarity. The signal in the left (R) line is not delayed 180 degrees. It is only flipped upside down.

Removing Noise at the Destination

It is possible that along the length of the cable, noise is encountered from external sources such as other electronic devices or RF interference. This noise will be identical on both hot and cold lines. When the balanced XLR cable is plugged into the input of other balanced equipment, the cold (R) line is inverted again. Now the two audio signals in both hot (L) and cold (R) lines are identical in every way. However, the noise that was introduced along the way is now inverted on the R line. When the L and R signals are combined at the destination, the inverted noise on the R line is combined with the original noise on the L line, they cancel each other out. All that is left is the original audio signal.

Fully Differential Balanced Circuit Design

Most professional audio products provide balanced inputs and outputs through XLR or TRS connectors. In almost all cases, a balanced input signal is internally converted to an unbalanced (single-ended) signal by using a transformer or amplifier. After the internal processing is finished, the signal is converted back to balanced signal and sent to an XLR/TRS output.

A very small number of professional products may exist that use balanced signal from input to output without ever converting it to unbalanced signal. This is referred to as fully differential balanced circuit design. In very critical applications (not home theater), such a design offers better signal integrity by avoiding the extra transformers or amplifiers required for unbalancing and rebalancing. It is claimed by promoters that fully balanced internal circuitry can yield 3dB of additional dynamic range. Don't believe everything that is claimed.

UNBALANCED CABLES

An unbalanced cable has two wires, one for the positive and one that acts as both the negative and the ground. Because the negative wire has to do more work than the positive wire, such a configuration is called Unbalanced.

Common Unbalanced Connectors

The two most common unbalanced connectors are RCA and TS phono jack. Even XLR cables be used for transmitting unbalanced audio. Unbalanced speaker connectors are speakon, and banana plugs.

RCA Connectors:

RCA connectors are associated with the RCA Corporation. Most home audio/video equipment use RCA connectors. They are even used for S/PDIF connections in digital transmission of audio signal.

RCA Connectors

TS Connectors:

There are 1/4" (6.35 mm) or 1/8" (3.5 mm) TS jacks. TS is the abbreviation for Tip and Sleeve. One insulator ring separates the tip and sleeve. The tip is considered to be the positive (hot) and the sleeve is the ground or shield is connected. The most common applications of TS cables are in guitar or line-level instrument connections.

1/4" TS Connector



COMPARISON OF TRS AND TS JACKS

TS and TRS connectors look almost identical. Some equipment accept a TS connector in a TRS socket, but it may be a good idea to check the equipment documentation to be sure. Remember that 1/4" TS connectors connect to –10 dBV line level equipment, whereas 1/4" TRS connectors expect a +4 dBu line level (for explanation, see the section below on balanced vs. unbalanced reference voltage levels).

1. Sleeve: Ground (Shield)
2. Ring: Right channel for stereo signals, negative polarity for balanced mono signals, power supply for power-using mono signal sources
3. Tip: Left channel for stereo signals, positive polarity for balanced mono signals, signal (hot) line for unbalanced mono signals
4. Insulating rings

Phone jack connectors are available in 1⁄4" (6.35 mm), 1/8" (3.5 mm), and 3/32" (2.5 mm) sizes. All three sizes are now readily available in two-conductor (unbalanced mono) and three-conductor (balanced mono or unbalanced stereo) versions.

2.5 mm mono (TS), 3.5 mm mono (TS), 3.5 mm stereo (TRS), and 6.35 mm (1⁄4 in) (TRS) phone connectors

If a mono TS plug is inserted into three-conductor stereo TRS socket, the result is that the right channel (ring) of the socket is grounded. The signal from the right channel will be lost. If the grounding of the right channel short circuits the right channel of the amplifier, this could damage the amplifier.

MIXING WIRING CONFIGURATIONS

One Mono XLR Connector to One RCA Connector:

When connecting a 3-pin XLR to one RCA, the negative (-ve) and shield of the XLR are joined together, either at the RCA end or at the XLR end. The end result will be unbalanced.

Stereo TRS Phono Jack to Two RCA Connectors:

When a stereo 1/4" phono jack is used, the left and right parts of the stereo signal are split off to two separate connectors.

One Mono XLR Connector to 1/4" (6.35 mm) TRS Connector:

Normally, the 3-pin XLR is connected to a 1/4" TRS phono jack for balanced mono applications as in the following. This type of wiring will give you a balanced mono connection.

• Pin of XLR to TRS Phono Jack Sleeve
• Pin 2 of XLR to TRS Phono Jack Tip
• Pin 3 of XLR to TRS Phono Jack Ring

One Mono XLR to One 1/4" or 1/8" Mono TS Phono Jack:

When connecting a 3-pin XLR to one mono TS phono jack, the negative (-ve) and shield of the XLR are joined together, either at the phono jack end or at the XLR end, and connected to the sleeve of the phono jack. The end result will be unbalanced.

ADVANTAGES AND DISADVANTAGES

A balanced XLR cable has three major advantages over an unbalanced RCA cable and that is why pro users prefer them.

These are the advantages:

1. XLR connectors are more robust. They do not come loose as easily as RCA cables. Imagine in the middle of a rock concert with lots of speakers, amplifiers, cables, and all the craziness, some RCA cables become loose. You will have a riot.
2. Because they are balanced and are grounded better, XLR cables are relatively noise free. RCA cables, on the other hand, can drive you crazy with noise and hum.
3. There is a limit on how long you can make an RCA cable (normally below 10 meters) before it significantly attenuates the signal. XLR cables can be as long as a few hundred feet.

Unbalanced RCA cables, on the other hand, have a few advantages:

1. Unbalanced RCA cables are less complicated.
2. They are less expensive.
3. They are readily available in almost all retail stores.
4. Many manufacturers include them with their products.

The biggest disadvantage of unbalanced cables is that they are susceptible to noise problems. In general, hey should be kept as short as possible.

If the signal is unbalanced out of you receiver, it will arrive that way. Using an RCA to XLR cable will not be of any advantage nor will an RCA to a balanced 1/4''. When you use a cable with an unbalanced RCA connector on one side and a balanced XLR connector on the other side, the end result will become unbalanced and you will lose all the advantages of an XLR cable. That is why the use of a converter box such (described below) is recommended.

USING BALANCED/UNBALANCED LINE LEVEL CONVERTERS

Balanced and Unbalanced Reference Voltage:

For consumer audio products using unbalanced RCA connectors, the reference signal level is -10dBV. This is equal to reference voltage level of 0.316 Vrms. 0 dBV is a voltage reference point equal to 1.0 Vrms. Remember that the dB level is a LOG ratio of two voltages.

=20*LOG(0.316/1) ˜ -10 dB

For pro audio products using balanced XLR connectors, the reference signal level is +4dBu. This is equal to voltage reference level of 1.23 Vrms. 0 dBu is a voltage reference point equal to 0.775 Vrms.

=20*LOG(1.23/0.775) ˜ +4 dB

When a home audio equipment with an RCA output is connected to a pro audio equipment’s XLR input, the signal will have to increase by as much as 12 dB. The casual observer would think to convert -10 dBV to +4 dBu, you would need 14 dB of gain. The casual observer would be wrong. You only need 12 dB of gain. The reason is not only do you change levels, you also change reference levels -- from dBV to dBu. The first (dBV) references everything to 1.0 volt, while the second (dBu) references everything to 0.775 volts.

=20*LOG(1.23/0.316) ˜ 12 dB

As soon as you make an unbalanced connection at one end of a wire, the whole thing becomes unbalanced. So for maximum noise immunity, you should use balancing adapters.

Unbalanced lines should always be kept under 10 feet (3 meters) to prevent undesirable effects such as hum and noise. There are balancing transformers available for long runs of cables. For example, if a microphone with XLR connectors is to be connected to a prosumer camcorder, an XLR adapter such as BeachTek or Studio 1 should be used for converting unbalanced outputs to balanced lines, allowing for long runs of XLR cable.

Converter Boxes:

A converter box can solve input/output level problems for level matching consumer and professional audio equipment. For example, if you use an RCA to XLR cable from your receiver/preamp to your amplifier, you will notice a drop of a few dBs. The biggest advantage that XLR offers is grounding and less noise problems. A lot of time, when you connect an RCA device to an XLR device, the level may not be sufficient and you need to increase the output level of the source to match the input level of the destination. For example, I own a couple of pro amplifiers with XLR inputs to power seveal passive subwoofers. I bought two Samson S-Convert boxes to connect the unbalanced line output from the receiver to the XLR inputs on the back of the pro amplifiers.

This is from the Manual:

S-convert provides a convenient solution for matching levels and interfacing audio devices, either on stage or in the studio. The S convert is a specially designed miniature level matching device that allows you to convert stereo –10dBV (RCA) signals like those from consumer CD players and cassette recorders, to +4 dBu (XLR) signals like those from professional mixers, outboard effects processors and DAT machines to name some. The S-convert works in both directions and features male and female XLR connectors for the balanced +4dBu inputs and outputs, along with RCA connectors for the unbalanced –10dBV inputs and outputs. The addition of +4 and –10 LEVEL controls allows you to use S-convert to calibrate your signals to an exact level.

A converter box is not an absolute necessity, but if the pro equipment do not have enough gain "reach", an active interface may be necessary.

In my case, I connected the Samson S-Convert between the subwoofer output on the back of the receiver and the Behringer EP4000 amplifier. The basic procedure is summarized below:

• Connect the sub cable to the RCA input of S-Convert.
• Connect the XLR output of the Samson S-Convert to the XLR input #1 of the Behringer amplifier with a female XLR to male XLR cable.
• Leave the level controls of the Samson S-Covert at the default.

It is amazing what a difference this simple gadget can make. Before I had connected the S-Convert, the Behringer amplifier’s level was set at the midpoint and the sub signal had reasonable sensitivity. With S-Convert, the signal became so much stronger and the subwoofer started shaking the room. I had to turn down the amplifier’s level to around 10%-15%. Afterwards, I tried to calibrate the subwoofers again, I realized the bass output was too loud. I had to lower the sub gain in the receiver’s menu to -4.5dB. Prior to adding the S-Convert, the gain was set at zero.

I highly recommend a converter box for balanced to unbalanced connections. Samson no longer sells the S-Convert. You can buy Art CleanBox Pro or Rolls from Amazon or other pro audio dealers.

http://www.amazon.com/ART-CLEANBOXPR...udio+converter

http://www.amazon.com/Rolls-MB15b-MB...+RCA+converter

REFERENCES

http://en.wikipedia.org/wiki/Balanced_audio
http://en.wikipedia.org/wiki/Balanced_line
http://www.audioholics.com/education...-interconnects
http://www.videomaker.com/article/10209/
http://www.mediacollege.com/audio/ba...-balanced.html
http://www.ehow.com/about_5090903_xl...#ixzz2HWfem7ll
http://www.mediacollege.com/audio/ba...nbalanced.html
http://www.audioholics.com/education...-interconnects
http://www.hottconsultants.com/pdf_f...onnections.pdf
http://www.rane.com/note110.html
http://rane.com/note151.html
http://www.dplay.com/dv/balance/balance.html
http://www.montagar.com/~patj/db_db.htm
http://www.swamp.net.au/balanced-stereo-trs-cable.html
http://documentation.apple.com/en/fi...5%26tasks=true
http://en.wikipedia.org/wiki/TRS_connector

[Big Daddy]

Pro XLR, TRS, TS, MIDI, & Speakon Cables:
http://www.monoprice.com/products/su...02&cp_id=10244
http://www.ebay.com/sch/i.html?_nkw=xlr+cables
http://www.amazon.com/s?ie=UTF8&keyw...3Axlr%20cables
http://www.amazon.com/s?ie=UTF8&keyw...eakon%20cables
url=search-alias%3Daps&field-keywords=xlr+to+RCA+Adapters&rh=i%3Aaps%2Ck%3Axlr+ to+RCA+Adapters
http://www.ebay.com/sch/i.html?_nkw=xlr+to+rca+cable
http://www.ebay.com/sch/i.html?_odkw...cable&_sacat=0

Mono and Stereo Jack Adapters:
http://www.monoprice.com/products/su...04&cp_id=10429
http://www.amazon.com/s?ie=UTF8&keyw...+jack+adapters

Speakon to Banana Adapters:
http://www.amazon.com/s?ie=UTF8&keyw...adapter+cables
http://www.ebay.com/sch/i.html?_odkw...at=0&_from=R40

[rpatt]

Thanks for the information BD. Somehow you seem to know what questions are going through my mind.

[Big Daddy]

Originally Posted by rpatt

Thanks for the information BD. Somehow you seem to know what questions are going through my mind.

I am a mind reader.

[joie]

Does a mono TS plug convert stereo to mono? Is it a mixer, if it's plugged into a stereo output that would normally use a TRS plug?

[Big Daddy]

Originally Posted by joie

Does a mono TS plug convert stereo to mono? Is it a mixer, if it's plugged into a stereo output that would normally use a TRS plug?

If a mono TS plug is inserted into three-conductor stereo socket, the result is that the right channel (ring) of the socket is grounded. The signal from the right channel will be lost.

In some situations, this could be dangerous to the amplifier. This may happen if the grounding of the right channel short circuits the right channel of the amplifier.

[pentatonic]

Darn Big Daddy, love your stickies. This is a subject I know fairly well but for the heck of me couldn't explain it even remotely close to your sticky. I also feel that the timing for this is just perfect. As I said before you are invaluable to this forum, so much bad or false info can sometimes be reported (Like me and gain control on pro amps )

[Big Daddy]

Originally Posted by pentatonic

Darn Big Daddy, love your stickies. This is a subject I know fairly well but for the heck of me couldn't explain it even remotely close to your sticky. I also feel that the timing for this is just perfect. As I said before you are invaluable to this forum, so much bad or false info can sometimes be reported (Like me and gain control on pro amps )

Thank you for boosting my ego.

[Mr.Terry]

Excellent,you get

[cembros]

I wonder if the pro amp thread influenced this post

[Big Daddy]

Originally Posted by Mr.Terry

Excellent,you get

Thank you.

[Big Daddy]

Originally Posted by cembros

I wonder if the pro amp thread influenced this post

Not really. I have been wanting to do this for a long time and have been collecting information since the time of Adam and Eve.

I had included some of this information in the Behringer Pro amplifier thread and that thread is a couple of years old. The main influence of the new pro thread was that I realized that there are too many questions and I should get off my tush and create a balanced/unbalanced thread.

[Saril]

Great information and an easy read. The illustrations were most helpful. Thanks BD!

[Big Daddy]

Originally Posted by Saril

Great information and an easy read. The illustrations were most helpful. Thanks BD!

Thank you.

[Nickeleye7]

I use my Onkyo TX-NR809 pretty much as a pre-amp and have all pro amps for power. I recently got a ART T8 and in the manual it says that it can take the unbalanced RCA and make the signal balanced when using the XLR as output. I contacted ART about this and they confirmed that it does do that. I was just wondering if this works like the clean box mentioned above except it just doesn't have the option to adjust the gain.

http://artproaudio.com/art_products/...ys/product/t8/

[Big Daddy]

Originally Posted by Nickeleye7

I use my Onkyo TX-NR809 pretty much as a pre-amp and have all pro amps for power. I recently got a ART T8 and in the manual it says that it can take the unbalanced RCA and make the signal balanced when using the XLR as output. I contacted ART about this and they confirmed that it does do that. I was just wondering if this works like the clean box mentioned above except it just doesn't have the option to adjust the gain.

http://artproaudio.com/art_products/...ys/product/t8/

It should work. All these boxes work about the same. Some are made better and some are a lot more expensive.

[rpatt]

I would really appreciate some help with the math on how to set the pots on my 5250 v.2 amp. The specs on the amp are as follows:

1-V in = 28.28-V out.
1.6-V input is required to reach full rated output of 250-W.
The pots have a range of -10-dB to +10-dB (500-mV to 5-V).

My Pre-Pro has RCA & XLR outputs. The RCA outputs 1.2-V and the XLR outputs 2.4-V.

Since the 5250 v.2 only has RCA inputs I have the option of connecting from the Pre-Pro outputs and turning up the pots or Connecting from the XLR outputs with an adaptor and turning down the pots.

The question is, which would be the better option and how much would I have to increase (with RCA outs) or decrease (with the XLR outs) the pots to get the full 250-W/Channel output?

[IAmAbe]

I have some general cable questions for a specific setup. I know that this is completely not related to Blu-Ray at all, but it seems that the most knowledgable people post here regarding audio.

My setup is like this, I have an iPad 2 with a 30 pin to 3.5mm output cable that is connected to a TRS adapter. This is going to my 1000 watt powered mixer, which in turn goes to to one 500 watt passive speaker through a 2 conductor NL4 cable.

My question is regarding how I am connecting my iPad to the powered mixer. I am currently hooking it up through the ST Returns socket on the mixer, which does not allow me to use the mixer's equalizer. Is this just a limitation to the iPad for audio connection types, or is there a way to connect this so I could use the amplifier's mixer settings?

I am completely new to how this all works, and want to make sure I don't damage anything by connecting the TRS cables into any of the sockets where it is not supposed to go. I also want to get the best audio quality possible from what I currently have, although I would be willing to get new cables and connectors if necessary.

Please let me know if you have any advice. I would greatly appreciate it.