Zero88 Alphapack LED dimming

[klaasvt]

Hi all!
I'm looking for information on if it is an option to use a Zero88 Alphapack 2 or 3 to control our house lights... it's 80 6.5w dimable LED bulbs (integral LED). Could I run into issues with the type of dimming or minimum load on the alphapack?
Or is there a better 1-3 channel DMX dimmer pack out there for doing this, that will work with the LEDs?

Thanks in advance!
Klaas

 

[klaasvt]

Just to say... I was looking at the Anytronics Prodim, but the manufacturer told me that I might run into issues dimming my LEDs with that one... would have been perfect!

 

[microstar]

I've found that any implementation of dimmable LED lamps on "standard" theatrical dimmers requires some experimentation and a little luck. Dimming two lamps is different that dimming 10 lamps. It also depends on what your standards are regarding smoothly dimming all the way to blackout. One recent retrofit at a local high school auditorium with 1980's-era Electro Controls Quad dimmers using their early generation SSR's ended up needing about 190 watts of LED load to dim to black; they will normally dim a 25-watt incandescent lamp smoothly. With the LED load there is a very slight drop-off going to black and bump-up coming on. Other than that, they look pretty good. I used a GE 32-watt PAR-38 for the high ceiling fixtures and a 17-watt Ushio R-40 for the over/under balcony, all 3000K. I've also discovered that the LED lamps you spec today may not be available tomorrow, so that is a concern as well. Obviously the better (and way more expensive) route is to retrofit with actual LED fixtures, either mains or DMX dimmed.

 

[klaasvt]

I've found that any implementation of dimmable LED lamps on "standard" theatrical dimmers requires some experimentation and a little luck. Dimming two lamps is different that dimming 10 lamps. It also depends on what your standards are regarding smoothly dimming all the way to blackout. One recent retrofit at a local high school auditorium with 1980's-era Electro Controls Quad dimmers using their early generation SSR's ended up needing about 190 watts of LED load to dim to black; they will normally dim a 25-watt incandescent lamp smoothly. With the LED load there is a very slight drop-off going to black and bump-up coming on. Other than that, they look pretty good. I used a GE 32-watt PAR-38 for the high ceiling fixtures and a 17-watt Ushio R-40 for the over/under balcony, all 3000K. I've also discovered that the LED lamps you spec today may not be available tomorrow, so that is a concern as well. Obviously the better (and way more expensive) route is to retrofit with actual LED fixtures, either mains or DMX dimmed.

As this is just for controlling the house lights, I'm not too concerned about smooth dimming at the bottom end. But I am looking at a good 520 watts of load so maybe this won't be an issue. Any reccomendations on a dimmer for this? I'm doing a retrofit from a normal switched control to a DMX control.

 

[DrewE]

What about a Doug Fleenor Design DMX8DIM? It seems exactly the sort of application it's designed for.

 

[RonHebbard]

What about a Doug Fleenor Design DMX8DIM? It seems exactly the sort of application it's designed for.

Calling @jfleenor
Toodleoo!
Ron Hebbard

 

[microstar]

Calling @jfleenor
Toodleoo!
Ron Hebbard

Just an annecdotal case, but I considered the Fleenor DMX8DIM for a different project still using the GE 32-watt LED lamps in my earlier post. DFD was kind enough to test using a couple of the lamps I supplied. It turned out they were far from compatible. Just shows nothing is a sure bet and that some testing is necessary.

On their website ETC has a database of LED lamps and several of their past and present dimmer models. One can also submit lamp samples for testing and they will add to the database.

The ETC Foundry series 600 watt dimmers would be another candidate; it is listed in their database as well.

 

[klaasvt]

Hey, just thought I'd circle back on this and post my solution... We just tested running the LEDs off our already installed Betapack 3's, and at first the LEDs just flickered horribly. Then we added a power resistor across the output (essentially simulates adding a 120w incandecent bulb to the circuit) and the leds dim just beautiffuly now!

Hope that helps sombody in the future...

 

[almorton]

That's quite common, because the leakage through the triac snubber network is enough to charge up the SMPSU in the LED lamp and briefly light, as it discharges again. However, the dummy load is of course dissipating that power, somewhat negating the point of going over to nice low power LEDs.

The usual solution is to use LED lamps that are specifically marked as dimmable, with a trailing edge rather than leading edge dimmer. This usually works far better. However, even with this arrangement you still usually get a snap off at the bottom, and on coming back up you get "popcorning" where not all the lamps switch on together smoothly at the same brightness.

It's for this reason that we're switching over in our theatre to dedicated LED house lights and dedicated specialized LED dimmers, rather than trying to coerce (essentially) domestic fittings to behave in a "professional" manner. I'm pretty sure we're putting in the ETC system.

 

[klaasvt]

That's quite common, because the leakage through the triac snubber network is enough to charge up the SMPSU in the LED lamp and briefly light, as it discharges again. However, the dummy load is of course dissipating that power, somewhat negating the point of going over to nice low power LEDs.

The usual solution is to use LED lamps that are specifically marked as dimmable, with a trailing edge rather than leading edge dimmer. This usually works far better. However, even with this arrangement you still usually get a snap off at the bottom, and on coming back up you get "popcorning" where not all the lamps switch on together smoothly at the same brightness.

It's for this reason that we're switching over in our theatre to dedicated LED house lights and dedicated specialized LED dimmers, rather than trying to coerce (essentially) domestic fittings to behave in a "professional" manner. I'm pretty sure we're putting in the ETC system.

Yes, I would rather have gone with something more "professional" but the LED bulbs (all 80 of them) were installed a few years back, and they were switched at the door. Now we are adding dimming from the desk, so we have to work with what we have. I'd be super interested if you could point me toward a proper dedicated LED dimmer (dmx controlled) that would do the job better.

 

[almorton]

We're pretty much settled on ETC's ArcSystem which is dedicated and dims really smoothly, has outstations and DMX takeover and all those good things. But it's not cheap. We're looking at several thousand GBP to refit our auditorium (which currently uses PAR38 halogens on an Act6).