Random Strobe - Am I missing something?

[comebacktomorrow]

A question that I thought should be fairly obvious but has me questioning myself:

What is your understanding of how a random strobe should work?

I'm asking because I've got a bunch of LED fixtures that have a strobe channel, but when I set them all to the same random strobe value (ie. slow random), regardless of when they turn on (randomly), they all turn off simultaneously.

Sort of as if there's a tempo that the fixture has to stick to, so no matter when the fixture turns on, it must stick to the beat and turn off on the beat.

Is that typical of random strobe? If not, how do you understand random strobe to work, and how do you use random strobe?

(I had assumed that there would be some kind of tempo, but it would be a little bit drunk and have its speed drift fast and slow, and so I could just choose random strobe and it would just work).

Just thought I'd ask here and see if my assumptions were correct or not. Thanks!

 

[cbrandt]

It is all per fixture. Half of my inventory responds the same way as your LED, and half of it responds the way you'd like to to. I've found that in general, the internal random strobe functions on most fixtures are too inconsistent, and too slow.

If I want a random strobe t hat is fast, I generally just give all my fixtures a slightly different strobe value. If I want one that is slow, I usually use the effect engine.

 

[phenry]

Well, it depends on the how the manufacturer does “random”.
A computer can’t just generate a random number. (For a good explanation, watch the numberphile channel on YouTube. They did a really good episode on random numbers.) So for the software to make a random sequence, it needs a starting value. A manufacturer has to set how to obtain this starting value. Could be DMX address, could be fixture number, could be some value that is unseen and set at the factory, if the fixture has a clock, it could use the current time… anyway, there are lots of ways, but as you can see, some of those ways like DMX address or fixture number could result in two fixtures strobing at the same rate. Vari-Lites use the fixture number on our led fixtures that way if you want them all to strobe the same, you can set them to the same fixture number. If you want them different, just give them different fixture numbers.
I know I didn’t do anything to solve your problem, but I hope I helped in some way.

 

[JD]

Random is actually very hard to achieve in digital! Computer studies show that as much as you may try, patterns develop. Even Analog random is hard! I had a series of drum strobes I used with one act, and I ended up going in and changing some component values so each one was a little different. Still wasn't totally random, but the effect had a brief duration so it was over before an apparent pattern developed.

You may be better off running the effect with direct DMX addresses and "create" a sequence that "appears" to be random and then just fire it as a cue.

 

[comebacktomorrow]

Thanks to everyone for your replies! I'm actually in contact with the manufacturer but wanted to inform myself a bit more as to what the norm was when it comes to random strobe (so it seems there isnt really one).

I actually really like the functionality of random strobe on my fixtures, it's just the practical implementation has been different from my expectation. I was really hoping to avoid creating a separate sequence, and had hoped it would not require too much fiddling. More of a convenience!

I did a recording last night to document what I was seeing; this one is probably the most concise: https://dl.dropboxusercontent.com/u/9083940/SLPar_Strobe_Small/Random Pulse + - Wi-Fi.m4v

All fixtures are on different dmx addresses and are running the same fixture profile/mode. You'll also notice a group turns on as a group as well.

Thoughts? Impressions?