Anyone here who has thoughts on latency over AoIP via fiber? If I was to buy a length of fiber, would 500' v. 1000' make a serious difference in the result of audio via Dante?

In other words, does it make sense to buy a longer piece of fiber (less money per foot) or only enough to serve my usual needs?

Cisco SG300 switches, 1.25G 1310nm fiber adapters.

D.

Typing with thumbs...
Signal propagation speed on fiber is 1.5-nanoseconds per foot. 1000-feet is 1.5-microseconds.

Thanks. That actually answers my question (I think).

D.

There's not going to be any perceivable latency from any length of fiber that you'll be carrying in your vehicle. Maybe if you stretched it from one side of the country to the other. The speed of light is 186,000 miles per second (The distance from NYC to LA in a straight line is 2,246 miles). You'll get more latency from the analog to digital and back to analog conversion than from any length of fiber cable, or from the processing inside your computer of the Dante chips themselves.

Well, yes and no.

186,282 miles per hour is the speed of light in a vacuum. Glass has a "refractive index" of some number because it's not a vacuum and the ability of glass tubing to conduct light is due to the fact that attenuated light tends to bounce off the walls of the fiber like mirrors, increasing the relative distance the light must travel. Single mode fiber has a refractive index of around 1.467, although a number of factors too numerous to go into here affect this number, but it's a general "rule of thumb". Take 186,282 and divide by the refractive index (1.467) and you get the speed at which light travels through fiber optic cabling, or 124,188 miles per hour.

Miles per second, not hours. Still negligible for all human purposes.

That's about 300,000 kilometers per second for our friends in the rest of the world.

Which is about the same speed of data through copper wire, like XLR or Ethernet cable. (About 2/3 the speed of light)

...except that via multimode, you get as far as 2km at best and ca. 10km via single mode (without repeaters).

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[i'm using two multimode 150m cables (with opticalcon duo plugs) on my main rig and several shorter cables to get to/from stageboxes and add a 300m and a 700m for large outdoor events; my bonsai rig uses three multimode 50m cables with sc plugs (mostly two for madi and one for dante or control data)]

But those are limitations imposed by our inexact manufacturing processes and signal degradation from our current power output.

Even at 10km, the human metronome will perceive no delay time from just the fiber transport. Like I said earlier there will be delays in the conversion and processing systems, but all else being equal will be the same no matter how long the fiber cable is.

When using fiber as a transport snake it will take less time to go from the stage to FOH (~100 feet) and back to the stage than it will for the audio to move acoustically through the air in the same space.

I'll add that I dislike using fiber unless I really have to. Even the super tough "tactile" fiber cable is decidedly fragile compared to copper. If it breaks, it's like a shotgun blast going through your PA system (Yes, I've heard it). It's less forgiving to dust and moisture contamination. And if it gets too cold it will give you random errors and pops. We traveled our fiber spools on the bus with us during the winter to help keep it warm and not making noise. For most theatre applications, the 100 meter length of coax or Ethernet is sufficient.

i wasn't commenting on the speed of data transport, i was commenting on practical limitations of cable lengths.

but yes, there are additional aspects to be considered with each technology: in opera houses/concert halls around here, i come across lots of fibre cables/plugs which broadcasting companies have been using for ages. for r'n'r/touring, cat and coax cables prevail.

Was surprised recently to see contamination of optical fibre cables and interconnects after a relatively short time (12 months). Explains some issues we were having. Testing equipment revealed failures that were disappointing and annoying. Another weak link possibly.

We use quite a bit of fiber, not only for a few long Dante runs but also for SDI video lines across the building. Latency hasn’t been an issue.

I think our use case is ideal, though, as it’s all running through conduit and protected from almost any potential environmental damage.

Yep, I am a bit scared off by the dirt contamination prospect. And maybe even the idea that tactical fiber is still fragile. It would be costly to have some stage hands roll a piano across it. I was thinking about it for longer runs (which happen, well, never). I think it would be smarter just to put a repeater switch between two 100m runs of Cat5e.

Or find a fiber rental if I ever needed 1000'.

Thanks for all the advice.

D.

There are valid reasons to use fiber in a touring or mobile set up. And lots of touring shows do carry fiber for their main snake runs. You just have to know the draw backs and be willing to work within them. Like everything in audio, it depends.

If you aren't using fiber all the time, it probably makes sense to find a shop with what you need and arrange for a rental if you only need it a few times a year.

I really do know that. My bad...

I claim fatigue -- I was smoking a turkey overnight and trying to stay awake reading GS.

No worries.

I'm going to be smoking brisket all night tonight.

Nice! This is my "busy time" of year, so I've been smoking turkeys since Sunday night. I think I'm going to do a brisket for Christmas just because I haven't had one in a while, or maybe a prime rib -- with beef prices the way they've been over the past couple of years, it's a bit of a thing.

But that prime rib -- Oh. My. God...

I am SO thankful!

Brisket last night, prime rib tomorrow (did I mention how little I like turkey).

Life is good.

Happy Thanksgiving USA.

D.

This is the first time I've smoked brisket since I got off the tour over 8 months ago when this pandemic started. Normally I would do 1 or 2 per month. But things were just too depressing this year. I'm also doing a small turkey breast because I wanted to try it out and see how it comes out. But it's just the three of us this year. The whole extended family has decided to isolate and we're not getting together. Normally we'd have 15 to 18 people over including at least 8 kids.

Sadly my dad is spending Thanksgiving alone because he doesn't want to catch the Covid.

You're in Tulsa? I'm in (ok, "near") Tulsa! Hey, it's a small world but I wouldn't want to paint it...

I hear you - it looks like it's going to be just "me and my three", although my oldest and his wife may want to bring me over and look at the table he's crafting.

Well, Chouteau actually. I do most of my work in Tulsa (when I. Not on the road) and used to be the head audio at the Tulsa PAC.

Send me a PM, we should hook up at some point.

Man, that's a lot of thankfulness!

I never really liked turkey growing up, because the people in charge of preparing it never actually did anything to it, so it was always overcooked in that odd electric oven, and looked like a big boiled chicken with a funny taste.

But about 30 years ago I found a secret: brine!

Pork and poultry get the same treatment, which is at least 24 hours in a brine solution:

1 gal. water
3/4 cup kosher salt
1 1/2 cups brown sugar (2:1 ratio of brown sugar to salt)
1 tbsp granulated onion
1 tbsp granulated garlic
1 tbsp poultry seasoning

Heat just enough to dissolve the salt and sugar, then add the spices.

You can line a 5-gallon cooler with an unscented trash bag or some other thing to make cleanup easier, but you can put your frozen turkey into the cooler with the brine, seal it up and let it marinate for 24 hours, which equalizes the temperatures, thaws the turkey and really get all that flavor goodness into the meat. The salt of the brine is a bacterial inhibitor that will kill any nasty bugs providing you completely submerge the bird, and the dilution presented here is good for a long brine. Check the temperature after about 12 hours and add some ice to the outside of the bag in the cooler if the brine isn't cold.

When it's time to cook, I do two things: First, I chop half an onion, half an orange, a sprig each of rosemary, thyme, oregano and sage, along with a few cloves of smashed garlic and 1/2 stick of butter. All of this gets wrapped up into a cheesecloth bag and stuffed into the bird, which helps maintain moisture and really imparts a lot of aroma and flavor. Then I wrap the bird in about 3 yards of cheesecloth soaked in a solution of water, Lea & Perrin's Worcestershire Sauce (all others need not apply), a dash of molasses and a really generous splash or olive oil, whisked thoroughly and add the cheesecloth. This is crucial if smoking the bird, because the soaked cheesecloth keeps skin moistened during the smoking process. This part came after my first attempt to smoke a turkey, which came out really great but the skin had the consistency of a basketball.

I smoke these turkeys for 6-8 hours at about 210-225 deg/F in an offset smoker with charcoal (to keep the temperature up) and green hickory for the smoke flavor. After 6-8 hours, all the smoke flavor it's gonna get is there and the rest is just finishing the cooking, which I do back inside, in a 250 deg/F oven for about 3-4 hours in a sealed roasting pan. I'll check this about an hour before service by piercing the breast, checking the temperature of the knife and looking at the color of the juices that run out (because, juicy turkey man!) -- if they're pink, I'll bump the temperature to 375 deg/F for about 45 minutes.

The last step is to let the turkey rest upside down. Seriously, the resting process is just to redistribute the juices back into the meat, but doing it upside down with a turkey lets gravity assist the process by drawing most of them back into the breast.

Yeah, it's a lot of work, but it's *so*, so worth it...

Happy Thanksgiving everyone!

Claremore here, but my day job is downtown Tulsa.

Definitely will hit you up!

And happy Thanksgiving.