Dimmable LED Par can or similar, 'affordable' a must.

[maskedwarrior]

Hello,

This is my first post here. I am sorry this is such a mouthful, I have spent all day googling this subject to death! I would be extremely grateful for any perspective to help me assimilate all this new information. http://www.blue-room.org.uk/public/style_emoticons/default/smile.gif

 

I run a tiny theatre company with my partner - we are a performing duo, who run our own sound and lights from on stage.

 

We have a 'stained glass window' set-piece which disguises our PA (an LD Maui 28 which runs off qlab from a macbook pro, plugged into a Roland audio interface with balanced XLR outs, which I trigger with a remote in my pocket).

 

We also need the window to be lit from behind, and this is where I need help. The space behind the window is enclosed, as we don't want light to spill onto the stage, so we really require a low-powered lantern which doesn't get very hot. Up till now we've been using domestic LED 40W (equivalent) light fittings, which we've had to operate with a crude switch (which looks rubbish, incidentally).

 

I'd like to be able to fade these lights in and out and change the colour. I'd also like to trigger DMX with qLab, and change states seamlessly as I trigger sound cues, if possible!!

 

Therefore I think an RGB/W LED par can, or similar, could answer all our problems. And some sort of Node, or an affordable DMX console with midi input (which I can connect to the 'midi out' serial port on my audio interface and hopefully trigger with a midi note inside Qlab?). The advantage of a console is that it will free up connections on my mac, allow us to run the console from other locations and make adjusting the colour of the LED Par a lot more convenient.

 

As a side note, coming from an audio background, I am concerned about ground loops and hums being created if I connect lighting and sound through one mac, if you have any words of warning about that I would be most interested!

 

I have looked at some really cheap RGBW lights, like this one - but am very concerned about them flickering when dimmed or, even if not visible to the naked eye, causing strobing video artefacts whenever we film our show. I have read that PWM / frame rate phasing is a problem if LEDs are driven at a low frequency, and cheap ones often are. Expensive lights often say 'suitable for film and tv use' or 'high refresh rate for flicker free operation' or the like.

 

I looked at this one from Chauvet. It has a PWM frequency of 1.2khz.

 

I looked at this one from AmericanDJ - which says "Flicker-free operation for film and television" but doesn't specify a PWM frequency.

I looked at this DMX console from Chauvet.

I am aware that this is not high-end stuff - mostly DJ gear. I want something that'll work reliably and effectively, but because it's illuminating a window (and this is a subtle effect), I don't feel it has to be the richest colour or the brightest light. It doesn't have to do much, just fade in and out. As you can imagine our budget is minimal. However, if you agree I don't have the budget to achieve what I'm after, I won't bother wasting my time on sub-standard stuff!

Any suggestions anywhere would be really appreciated. Thank you so much in advance.

Anthony

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[Don Allen]

You would get better lighting for your stained glass window by using RGD LED tape. Have a read of this LED tape Blue Room thread to get you started. You can get DMX led drivers for the led tape. Using led par's behind the window is not ideal as they will produce hot spots and require more depth. Using rows of led tape will provide an even wash. You could even make it as a light box. A led par may have a beam width of about 25 degrees, led tape has a beam width of about 120 degrees.

[timsabre]

I agree with Don about using LED tape, I would make a light box painted white inside and put the tape round the sides (i.e. not in direct view). You'll probably need 3 or 4 loops of tape to get a decent brightness.

 

I can address 2 of your concerns...

1-flicker, you should not have a problem with camera flicker on anything from Chauvet or ADJ. Some of the cheaper no-name stuff you might. However the problem you will see is "steps" in the dimming if you do a slow fade up from zero or down to zero. The last 16 or so steps at the bottom of the dimming curve are very obvious to the eye and you can see them go clunk clunk clunk. Especially if you're changing colour slowly e.g. blue to red, it can be very offputting.

2-audio buzz/ground loops. Run your laptop sound through a DI box or isolating box, then you will not get any problems here. You might not anyway, it depends if the laptop psu is earthed. I don't know how it is on macs.

[alistermorton]

I'd third the LED tape. Use a suitable low voltage dimmer (the RC4 dimmers are particularly good I've found when dimming tape, but cheap they aren't) to control it. You could add a DMX interface to your Mac and get qlab to control the lighting too, cutting out any midi link to a separate controller - there a pros and cons to this of course. On the one hand all your eggs are in one basket, on the other you have fewer controllers to worry about.

[maskedwarrior]

Hi, thanks so much for your kind and thoughtful replies. What a great resource this forum is.

 

A few questions in response....

 

You would get better lighting for your stained glass window by using RGD LED tape... You can get DMX led drivers for the led tape...... A led par may have a beam width of about 25 degrees, led tape has a beam width of about 120 degrees.

 

Yeah tape seems to be the consensus atm! I have taken a look at the link, thanks. Would someone please be able to recommend an affordable DMX driver or DMX Driver/fader, preferably branded, which I can buy in the knowledge I will have no problem with camera flicker or stepped dimming et al? Or if there aren't any 'affordable' ones please point me to a pricey one! ** laughs out loud ** I really need a frame of reference here or I'll get lost in the google maze again.

 

Really the last thing I want is to make a beautiful window display and then find out it looks like a huge strobe unit when we pay someone to film us!

 

Incidentally the link I provided to the ADJ Micro Wash RGBW has a beam angle of 6 degrees, I guess that's very tight for my purposes then?

 

 

I can address 2 of your concerns...

1-flicker, you should not have a problem with camera flicker on anything from Chauvet or ADJ. Some of the cheaper no-name stuff you might. However the problem you will see is "steps" in the dimming if you do a slow fade up from zero or down to zero.... [snip]

 

Thanks for answering my concerns directly, timsabre, that is really reassuring. Do you mean the problem of stepped fading applies to cheap no-name gear mostly, or that this is a problem I will probably encounter with ADJ and Chauvet and most LED lanterns/light strips, generally?

 

 

I'd third the LED tape..... You could add a DMX interface to your Mac and get qlab to control the lighting too, cutting out any midi link to a separate controller - there a pros and cons to this of course. On the one hand all your eggs are in one basket, on the other you have fewer controllers to worry about.

 

Thank you alistermorton. Again, if you have any thoughts on a (preferably) affordable driver with flicker-free on and off camera use (a higher frequency pwm) then please point me in the right direction :)

 

Indeed, if you had to grab a package of tape, driver, dimmer and DMX controller here in the UK where would YOU start?!!

 

Lastly, there is something about the repurposeful nature of a lantern which I like. I won't be doing this show forever and I like the idea of still having an adaptable lantern at the end, to point at things if I want to provide my own special in a future show.

 

I believe that with use of white fabric diffusers I may be able to light inside this window with a single lantern, or two. So... if this was your limitation, do you think it could be done effectively? Your opinions - as people who have actually handled lights and have actually, you know, LIT things - is helpful to say the least.

 

Here is a screen-cap of our show. The window is the glowing thing http://www.blue-room.org.uk/public/style_emoticons/default/biggrin.gif https://www.dropbox....Photos.jpg?dl=0

 

Thank you so much for your time,

Anthony

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[timsabre]

I think you will struggle to light that backing evenly with an LED par can close up, with any amount of diffuser.

A COB par can would be your best bet as they have a much wider beam, but even then I think you would struggle with hot spots.

 

A standard light bulb works quite well, why not go old skool and use a tungsten lamp with a little DMX dimmer pack? Or even just a remote control domestic dimmer. Obviously you could not change colour. But it'll be cheap.

 

 

Regarding steppy dimming, everything I have seen at the low end of the market does it. Chauvet's Colorado range of pars are the cheapest I have seen which have nice smooth dimming.

[alistermorton]

Indeed, if you had to grab a package of tape, driver, dimmer and DMX controller here in the UK where would YOU start?!!

 

 

For a DMX interface to work with Qlab I'd consult the manual (I'm not currently a Qlab user) but I bet an enttec adapter is supported.

 

This is an RC4 4 channel dimmer. I've used the 2 channel version of one of these to dim tape, and it really does fade very smoothly, without steppiness. We used one channel with a halogen MR16 in a birdie and the other with tape around a the inside of a set and you couldn't tell one was LED and one not. But as I said, it's not cheap. It's usually paired with a matching wireless transmitter, but it can be configured to accept DMX from a cable. If you're interested, they're handled in the UK by Lamp and Pencil. I have no connection with either Theatre Wireless or Lamp and Pencil BTW.

 

Alternatively I have also used a sub 20 quid ebay special from China, and, as Tim suggested, that was extremely steppy, each change in level being very obvious. Also, you have no control over the dimming curve or the modulation frequency.

 

In terms of tape, there's plenty of suppliers of RGB 5m rolls of tape on the bay, which can be powered from a 12V wall wart or even a battery if you're so inclined. Tape is cheap, you can consider it disposable.

 

May be worth talking to some of the usual theatrical lighting suppliers and ask them what's available to dim LED - I'm probably way out of touch with the current crop.

 

Here's an alternative driver. This from Prolight's site.

 

I've never used this one, so have no idea about smoothness or PWM frequency, but I'm sure someone will b along soon to fill in the details.

 

Also, City Theatrical might be worth checking out. A D3 or D4 dimmer would work well with tape, and is less pricey than the RC4 equivelent. The RC4 one has wireless as standard, the CT one has to have a receiver added as far as a I can see, which you may not need.

[J Pearce]

I believe at present qlab only supports artnet devices (not sACN or other flavours), and they don't support any usb devices.

 

I'd look at LED tape using one of the drivers that takes artnet natively, nice simple one box solution - run a CAT5 and mains to the window and job done.

[DrV]

The City Theatrical dimming curves are certainly very good at the bottom end. The D2 and D4 are available as wireless or wired units and you can select from a range of quite high frequency PWM modes to prevent flicker. You'd need an external power supply but a wall wart or a cheap CCTV style PSU would do.

 

They also sell decent quality tape if you don't want to risk the unbranded eBay stuff.

 

Disclosure - I do some freelance work for CTI but don't get commission, only smiles and the occasional cake!

Dave

[ANDYLASER]

If you go the LED tape route. Rather than making 3 or 4 loops around the edges of the box, use a (much)longer length and spiral it round the inner edges, thus preserving it as one long piece. You should then be able to remove it at a later date and use it again in a different project.

[maskedwarrior]

Hello everyone! Thanks for your replies. More on those in a sec. First, a question about art.net/ethernet interfaces. I found THIS one and THIS one. They are both within my budget if art.net is free (more on that n a minute). However nether look as good, or have as much general respect, as THIS one, which blows basically my whole budget even before drivers and lights.

 

I'm in that annoying position of trying to get something for nothing - i.e.. quality for a budget price. It's time consuming, often impossible and you end up wishing you'd just raised your budget. However I really can't justify that, so I must continue to try!

 

My budget is £200 max, to get some dimmable RGB/W lights, a controller and means of automating with Qlab. It can be done, using an OBEY 40 Console (with midi cuing capability built in), my existing Roland audio interface with MIDI OUT, and a light or lights for around £100.

 

Considering I am a lighting novice, tbh, I like the simplicity of this setup. There are multiple youtube tutorials on the Obey console. It is also a physical thing, as opposed to a virtual program, which is reassuring to a noob like me http://www.blue-room.org.uk/public/style_emoticons/default/smile.gif

 

 

For a DMX interface to work with Qlab I'd consult the manual (I'm not currently a Qlab user) but I bet an enttec adapter is supported.

 

This is an RC4 4 channel dimmer.

 

The RC4 probably delvers the smoothest dimming I could possibly imagine but, a bit soul-crushingly, it is so hugely out of my budget I can only dream that one day I'll be able to ring up the shop and order a couple of these with the breeziness I'd order a takeaway. One day? Yes. Now? Sadly no.

 

 

I believe at present qlab only supports artnet devices (not sACN or other flavours), and they don't support any usb devices.

 

I'd look at LED tape using one of the drivers that takes artnet natively, nice simple one box solution - run a CAT5 and mains to the window and job done.

 

I agree re. art.net devices. I have to say I'm really not familiar with art.net., never having used it before or heard of it until the other day. Is it essentially free, then? Can anyone download and use it to program DMX with or do you need third party software to actually make it at all easy to use?

 

I also like the suggestion about native art.net LED drivers. However I'm struggling to actually find one of these. I thought THIS was one. I also thought THIS was a cheaper one. It seems, on double checking, I'm wrong. In any case, neither lists anything about its PWM frequency rating or tv/film compatibility. Nor would I expect it to at £40, though, in fairness. I'd dread that, if I bought one of these, or anything that didn't list these specs, they'd give me a big ol' strobe window when we get this show filmed.

 

I'd be interested if you have any leads on more professional LED drivers with art net built in. With the LED tape side of things I'm finding that, unless I go for Christmas tree light technology, things can quickly get extremely expensive for pro/semi pro use.

 

 

The City Theatrical dimming curves are certainly very good at the bottom end.

Dave

 

Ohh... expensive http://www.blue-room.org.uk/public/style_emoticons/default/sad.gif. Oh to have a proper budget for these things. One day we shall, but not right now.

 

 

If you go the LED tape route. Rather than making 3 or 4 loops around the edges of the box, use a (much)longer length...

 

Not a bad idea, thanks for your help.

Thank you EVERYONE for all your time on this - and especially Alistermorton for your huge and helpful reply. Invaluable.

All the best,

Anthony

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[J Pearce]

Qlab4 (with appropriate licensing) will program your lights and output to artnet to control them.

There are several artnet to led drivers on eBay, though mostly for pixel tape rather than single circuit tape.

To get the guarantees you want of quality you'll need to spend out. The cheaper stuff is usually pretty good but it can be a gamble and can take a second attempt to get what you want working in the way you want it to work.

[Shez]

I have to say I'm really not familiar with art.net., never having used it before or heard of it until the other day. Is it essentially free, then? Can anyone download and use it to program DMX with or do you need third party software to actually make it at all easy to use?

ArtNet is just a communications protocol, like MIDI, Ethernet, DMX etc. As long as the devices you want to use can speak that language, you're good to go. It works over Ethernet so a little bit of networking know-how is useful.

[maskedwarrior]

Fantastic guys, thanks so much for all of this. I have since discovered a bit more about art net and I feel a bit more informed now!

 

 

So, would anyone have any feedback on THIS ART Net to DMX ethernet device??

 

It seeeeems to be made by Thomann, but they don't seem to do it anymore, it's not on their site. It's a bit of a mystery. I'm going to try ringing them up to see if they know about it.

 

However it's available in a few places online and it's affordable.

Thanks for everything

Anthony

[timsabre]

That one is for pixel tape not RGB tape (pixel tape allows you to individually control each LED, rather than the simpler RGB tape where you control the whole tape at the same time)