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Comment by derriz | Hacker News Reader

Why would you choose XLR as a connector for an application like this? Why choose one of the most common connectors you’re likely to see in an environment where someone will be mixing audio for a completely incompatible application? Hope the devices can handle accidental 48V phantom power without damage.

The audio world has history here. A simple TSR audio jack can be used for either stereo or balanced audio, headphone or mic or (multiple) line levels, hi-Z instruments, two incompatible MIDI (digital) connectors, multiple incompatible foot controller connectors, etc.

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The options for connectors that are robust enough for stage work is limited and the alternatives tend to be expensive since they are no where near as ubiquitous. 1/4" Phono plug and XLR have proven themselves and only take a couple minutes to replace when an accident happens. So we use XLR and Phono everywhere for audio. The real question is why fragile barrel connectors in three different sizes and no wiring standard for power? And now we have just as fragile USB in three different sizes, but at least the wiring is standard. You can't power up but you can still plug it into the board!

It is rare you see anything in the audio world with an XLR that can not survive an accidental encounter with phantom power. People are paranoid about it but for some reason have no issue with phono being use for speaker connects which is far more likely to kill gear. I used to repair audio gear, every bit of gear I encountered that got fried by phantom power had an XLR to TRS in the mix.

XLR with Neutrik Plugs + high quality cables is crazy robust.

You can tow a car with it and then use it to work a festival with Tier 1 bands afterwards without any problems. Most likely it will work even better than before.

Also differential signal nature by design is the standard - It's like CAN. This kills 99% of non-wanted signals coming from the wire physically.

XLR is a perfect: it'd literally designed for differential signal transmission, they're in plentiful supply on the jobsite, and 48v isn't a concern if you understand how differential and phantom feeds work anywwy.

Fortunately the audio industry isn't plagued with Apple-like "engineers" removing headphone jacks, SD card slots, USB ports, and replaceable batteries. Sure something could be "better", but there doesn't need to be.

XLRs are everywhere and already installed. You could choose cat5 but it's not as common.

That’s my point - reusing an existing connector type for a new and completely incompatible role will not make life easier.

I joked to a friend once that it would be far better if we just used a single connector type for everything in audio and get rid of jacks, XLR, power connectors, MIDI, etc. They liked the idea - I deadpan suggested regular mains plugs and sockets would be good - cheap, ubiquitous and sturdy.

That's fair point - I can imagine someone plugging a digital out into analog in, not expecting the hell that's about to break. Probably it sounds like digital noise, not sure about levels.

But the advantage of reusing cabling that already exists in 100% of the venues, stages and churches cannot be overstated. It is literally a drop-in upgrade, boom, now a single cable carries 32 channels instead of 1.

> reusing an existing connector type for a new and completely incompatible role will not make life easier

I don't think it's completely new purpose for XLR, I'm fairly sure I've seen other stuff than audio being pulled through XLR more than once even in professional environments.

DMX over three-pin XLR is extremely common, and it’s also rather common for lighting equipment to be right next to the sound equipment.

Exactly - AES/EBU over XLR has been a thing in the broadcast world for ages. The Behringer WING mixer even has a pair of AES/EBU ports on the back.

I've seen XLR used for DMX lighting. The advice for stage techs seems to be "don't do that". Same thing applies to this standard probably.

I was a lighting designer for several years and in that time in don't think I ever saw a proper 5-pin DMX512 connector. Even in venues with millions in house lights, the connection backstage to the house was XLR.

The proper DMX512 connector is XLR, though? The 5-pin variant, that is.

I worked as a tech at a stage for a short while. We always used XLR5 for lighting and XLR3 for audio.

Yes, I only saw 3-pin XLR for DMX512, while being aware of 5-pin XLR as "correct". Everything from the lighting console, to dimmer packs and moving heads, to the aforementioned connection to house lights. This was 2009-2013. Maybe it was regional?

Technically DMX needs 110 ohm cable - the connector is less relevant. But most DMX devices are forgiving, and will accept whatever rubbish cable you throw its way.

It's the same thing as USB-C, actually. The connector looks the same, but the cable can vary a lot. At least audio cables are labelled.

It's already common to put digital data over XLR in stage environments, like DMX lighting and AES3. Also venues will have an XLR snake but definitely not a TRS jack snake from stage to mixer.

As a person who routinely uses XLRs to carry stereo headphone feeds with TRS converters on each end, I kind of like that there are only a few connectors that do different things. I have a pelican that's already heavy enough and adding more adapters to my kit doesn't sound great.

Once you know that just because you can fit a jack in something you can't rely on it not to have 48 volts across pins, you stop putting fingers in light sockets or hooking your laptop to XLR inputs using TS->XLR adapters.

Aren't there already a number of applications using canon connectors with digital? What's your opinion about AES/EBU using XLR? Or DMX over 3-pin xlr?

XLR is balanced, meaning you can transport a voltage accurately over a longer distance.

There is a mirror voltage on a second line that is mirrored and summed with the first again at the receiving end.

All noise picked up underway will affect both lines fairly equally, so the reversed line has the same noise as the normal line.

The noise will be inverted and summed with the regular noise, theoretically nullifying it completely.

Because it is everywhere and very robust. And phantom power is called "phantom" for a reason. It does not harm the most devices, if they do not support it, because the voltage just cannot apply, except on some rare old devices.

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