Shubert Theater house lighting

SteveB

Well-Known Member
On a visit to Lite-trol yesterday to get a D50 fixed, Steve Short shows me this:

6 - 50 amp Luxtrol auto-transformers in a vertical stack, plus a few sitting off to the side. Being repaired.

These belong to the Shubert Theater, NYC and are the dimmers for house lighting. Along with the multitude of AT dimmers are the associated "paralleling chokes" that combine the outputs of 2 50 amp dimmers into one 100 amp output (the choke accounts for slight variations in individual dimmer output voltage). With 6 dimmers in a stack, you get 3 - 3 phase/100 amp dimmers that feed the branch circuit breaker panels. There was a 2nd stack being repaired as well, that one was a motorized stack.

As Steve and I chat, I recall that the Shubert was the theater that A Chorus Line went into on it's Broadway run, and that I would venture that these AT dimmers replaced the existing DC dimmers when the theater converted to AC for ACL. That places the install possibly at 1975'ish.

Converting to AC meant that you either A) Go to autotransformers or B) Convert to 100 amp capable SCR dimmers and associated control system. Or C) Convert every branch circuit to a single 15 amp SCR circuit with associated control system.

Even now, 38 years later, 100 amp SCR dimmers, while "doable" are not always the best solution (for reasons I've never determined).

As well, I doubt that ANY electronic control system installed in '75
9191-shubert-theater-house-lighting-luxtrol-1.jpg
9192-shubert-theater-house-lighting-luxtrol-2.jpg
would still be in use, having developed it's own issues long ago and having been replaced possibly at least twice, if other systems are any track record.

The Shubert Organization has a warehouse in NYC that contains extra and stored away for future use, AT dimmers just for this eventuality, of the dimmers failing over time, in this case, 37 years later.
 

Attachments

  • Luxtrol 1.JPG
    Luxtrol 1.JPG
    280.4 KB · Views: 882
  • Luxtrol 2.JPG
    Luxtrol 2.JPG
    200.5 KB · Views: 949
Last edited by a moderator:

DavidNorth

ETC Rigging General Manager
Premium Member
Fight Leukemia
Departed Member
Ha!

I was on the phone with Steve for about a half hour yesterday catching up and talking about how to repair a system made by another manufacturer that is down the street from us. He was thrilled about working through the dimmer stack for the Shubert as they had tons of spare parts laying around that he could use.

He said it felt good to do a dimmer repair using a 3/4" wrench. I think that's a hoot and I agree.

David
 

SteveB

Well-Known Member
Ha!

I was on the phone with Steve for about a half hour yesterday catching up and talking about how to repair a system made by another manufacturer that is down the street from us. He was thrilled about working through the dimmer stack for the Shubert as they had tons of spare parts laying around that he could use.

He said it felt good to do a dimmer repair using a 3/4" wrench. I think that's a hoot and I agree.

David

Hey David,

I had a lot of skepticism when I saw this at Litetrol, wondering why in hell the Shubert had never converted to SCR. Then as I was writing the post here on CB, it all came together that then new stuff is not always better then the old.

Then I watched Steve Terry's USITT video and was reminded that the technology supports the art, not the other way around. It's always been that way in theater, always will be.
 
Last edited:

DavidNorth

ETC Rigging General Manager
Premium Member
Fight Leukemia
Departed Member
Converting to AC meant that you either A) Go to autotransformers or B) Convert to 100 amp capable SCR dimmers and associated control system. Or C) Convert every branch circuit to a single 15 amp SCR circuit with associated control system.

Even now, 38 years later, 100 amp SCR dimmers, while "doable" are not always the best solution (for reasons I've never determined).

Do know that most 100A dimmable circuits for houselighting are often in fact 100A dimmers feeding branch circuit breaker panels that use 20A or 15A circuit breakers to branch out to multiple houselight circuits. Why not just put in a bunch of 20A/15A dimmers? Back when this was commonplace, dimmers were very expensive so it made more sense to use fewer of them at higher current ratings.

100A SCR dimmers are in fact doable for refits as they take up only a few slots in a rack but if you have to replace the branch circuit wiring and breaker panels due to age and code, or are doing a new install, why not just move over to several 20A dimmers and wire the circuits directly into the rack. It saves wall space and installation labor plus you benefit from having more control.

There is still one more bonus keeping an AT dimmer - no filament noise. AT dimmers are one of the original versions of sinewave dimming family, which is complemented by resistance dimmers, saturable core dimmers and salt water dimmers.

Good to see the various technologies that support the art......

David
 

JD

Well-Known Member
What a beautiful piece of equipment! Loved those old things.

Even now, 38 years later, 100 amp SCR dimmers, while "doable" are not always the best solution (for reasons I've never determined).

Reason for that has changed but the outcome is the same:

Old- Back in the day there was a huge price jump in SCRs when you went to that much current. Remember, Dimmers were using SCRs with a safety factor of 3 to 5 times the run rating.

New- Trend has been towards Dimmer-per-circuit, with most systems settling on the 2.4Kw dimmer as a happy compromise. Rare to need very big single dimmers.

As for the autotransformer on the house lights- Well, short of a pure sine-wave dimmer, you can't get much cleaner of an output! No lamp sing, and with the drop ratio, you're not chopping up the supply line with noise either.
As long as they don't mind the weight, or having someone actually heft down on the control to lower the light, no need to go modern!
 

SteveB

Well-Known Member
I was also thinking that over 38 years, had they gone to SCR back when, the control end would have most likely been replaced a multitude of times.

The dimming might have gone to Strand early on. Did Strand have an architectural controller in say '75 or '78 ?.

Then maybe updated in mid-80's to newer Strand controls, especially if the dimmers stayed.

Then maybe upgrade the dimmers in the late 90's, early 2000's, as well as a Unison.

Then possibly replace that control along the way (though maybe not).

Remembering that it's used 8 nights per week and has never been a dark theater as far as I know (it's the premier house for the Shubert Organization)

That control stuff's expensive as opposed to the every 40 year tune up of the auto-transformers, though Steve S. would've had the gear.

OTOH, when a dimmer goes bad, modular with SCR does not involve a 3/8" socket wrench !
 

BGW

Active Member
I like AT dimmers. While they aren't as easily controlled as SCR dimmers, they're a heck of a lot more robust. You'd either have to be an idiot or intentional in order to break one.

I've never seen a stack that large before, thanks so much for sharing.
 

MPowers

Well-Known Member
................Converting to AC meant that you either A) Go to autotransformers or B) Convert to 100 amp capable SCR dimmers and associated control system. Or C) Convert every branch circuit to a single 15 amp SCR circuit with associated control system. ................

Ummmmm, actually, converting to AC meant that you COULD use Autotransformers or electronic dimmers, NOT that you had to. Piano boards worked just fine on AC or DC, any voltage, any Hz, 25hz or 60hz or anything above or below or in between.

The stage I was brought up on ran a mix of piano boards and Luxtrol AutoTransformer dimmers, all running from the same feed. Two 14 plate 3K boards, one 12 plate 6K board and two luxtrol "portable" 6+1 (six 1K dimmers and one 6K that could be either a 7th dimmer or a master to the other 6).

I ran salt water dimmers for my mother's March of Dimes presentations (early '50's) and those ran just fine on the AC available in most places and in a couple of very rural areas, the dimmers ran on tractor batteries because the old (new then) 16mm projector was plugged into the only AC circuit.
 
Last edited:

SteveB

Well-Known Member
Ummmmm, actually, converting to AC meant that you COULD use Autotransformers or electronic dimmers, NOT that you had to. Piano boards worked just fine on AC or DC, any voltage, any Hz, 25hz or 60hz or anything above or below or in between.

The stage I was brought up on ran a mix of piano boards and Luxtrol AutoTransformer dimmers, all running from the same feed. Two 14 plate 3K boards, one 12 plate 6K board and two luxtrol "portable" 6+1 (six 1K dimmers and one 6K that could be either a 7th dimmer or a master to the other 6).

I ran salt water dimmers for my mother's March of Dimes presentations (early '50's) and those ran just fine on the AC available in most places and in a couple of very rural areas, the dimmers ran on tractor batteries because the old (new then) 16mm projector was plugged into the only AC circuit.

Thanks Michael, I never knew that resistance/piano boards could run on AC and always assumed they only ran on DC (or forgot completely, which is very likely)

So goes my nice theory of dating the install !
 
Last edited:

Footer

Senior Team
Senior Team
Premium Member
I had two stacks of those at my last gig. However, both had been motorized. They controlled two 1930's chandeliers. Still working great.
 

Users who are viewing this thread