5

Could you point be out why XLR output is so important? I’m thinking to buy bass processor Zoom B3 or Boss gt-1b and first one has this output onboard.

Thanks everyone for your help!

2 Answers 2

8

XLR output is useful when connecting directly to mixing console or audio interface with XLR cable (rather than connecting to a guitar amplifier with instrument cable).

XLR connection is differential. The main advantage is that the ground can be disconnected (e.g. using switch on ZOOM unit) which helps to fight ground loop noise. Also XLR cable is more resistant to interference and typically will introduce less noise.

2
  • 1
    "XLR connection is differential" – While this happens to be true for this particular device, there is no guarantee that this is always the case. XLR simply says something about the physical dimensions and layout of the pins … you can transport anything across those pins. Heck, I have devices that use XLR for the power adapter! Dec 26, 2021 at 11:22
  • @JörgWMittag Good point. I was referring to this specific use only. Dec 26, 2021 at 14:12
1

The physical format of the plug (XLR) is irrelevant. What is relevant is that the output is

  • balanced and
  • line-level

An XLR plug can be used for balanced or unbalanced signals and it can be line-level, instrument-level, or mic-level, or even high-voltage speaker-level. It doesn't even need to be analog audio at all, it could also be AES3 digital audio.

On the other hand, a balanced and line-level output can be TRS or XLR.

The physical format of the output doesn't tell you anything.

The output of the Zoom B3 is a line-level, balanced output. That is what is important, not the fact that it is physically an XLR output (although that is nice, too, since it is the de-facto standard for transporting analog audio signals in professional environments).

Balanced connections use differential signaling, where the original signal is transmitted over one wire, and the equal but opposite signal is transmitted over another wire. The two wires are kept in close proximity to each other (typically, they are twisted together into a twisted pair). Now, when external noise is introduced into the cable, the noise will be roughly the same on both wires.

At the receiving end, we receive on the two wires:

  • the positive signal +S and the noise N
  • the negative signal -S and the noise N

And we take the difference of the two wires:

  +S + N - (-S + N)
= +S + N + +S - N
= +S + +S + N - N
= 2S + N - N
= 2S

in other words: since we take the difference between the two wires but the noise introduced is roughly the same on each wire, the noise cancels out.

This allows transporting analog audio signals over relatively large distances with very little noise.

This differential signaling is used in many other applications, for example in Ethernet. In fact, because of the high demands of Gigabit Ethernet, Cat5e cables are typically much higher quality than standard audio cables, and because of the much bigger IT market compared to the pro audio market, they are also much cheaper (cents per meter for Cat5e compared to tens of cents per meter for microphone cables). And they contain 4 twisted pairs, so you can actually transport 4 audio signals on a single Cat5e cable for cheaper and with higher quality than you can through a microphone cable, and with a connector that has roughly the same footprint as a single XLR. (This is a nice trick to keep in mind when building small multicores.)

4
  • You would also want the cat5e to be shielded, right? Also, would network cable has the same mechanical durability as audio cables? Dec 26, 2021 at 14:27
  • Yes, at least shielding for the whole cable, i.e. S/xTP, F/xTP, or SF/xTP. I don't think shielding for the pairs (x/FTP) is necessary. The durability, like with audio cables, depends. There's different kinds of cables for different kinds of applications. But even 50m ruggedized S/UTP Cat5e with "obviously Neutrik etherCON but we're not allowed to call 'em that because it's a Chinese clone" connectors is less than $2/m which is less than twice that of a comparable microphone cable of the same company and brand and about 2/3 of a 4-channel multicore cable without connectors. Dec 26, 2021 at 15:22
  • Now the only mystery left is why it is significant that a guitar processor has line-level, balanced output.
    – ojs
    Dec 26, 2021 at 17:42
  • And btw, I'd claim that in practice the physical format of the plug is insignificant only if the users of the device carry a set of connectors and soldering tools and are willing to take the time to build adapters.
    – ojs
    Dec 26, 2021 at 17:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.