# Dimmer Doubling/120 volt devices (ETC/Sensor)



## dukeofmuffins (Apr 1, 2011)

Lets say we have an auditorium where all accessible dimmer circuits are Dimmer Doubled (ie 77v). If you wanted to say, use a 120v fixture or special lighting effect how would it be done? Besides rewiring the rack/adding a seperate dimmer. 

My understanding is that the AC wave is split at the dimmer, giving 77v to one channel and 77v to another. If you were to join two channels with say a twofer adapter, then plug your device into that (think y adapter in reverse), would the device then see both sides of the wave form, hence 120v? I guess its late and the physics are eluding me, but I've always wondered. Or do the dimmers (sensor rack/etc) have some form of protection to prevent this? This is assuming both channels are raised and lowered simultaneously, and that you find two channels on opposite sides of the wave.

This is purely theory, I have never done this and wouldnt even try it without a major bit of research. I just know the auditorium I work in, everything except the work lights and strips are doubled.

And I know this solution or any other probably wouldn't be ETC endorsed, I want to hear your thoughts even if they are the unofficial approach.


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## Footer (Apr 1, 2011)

You can just remove the dimmer doubler and use the dimmer straight. It will require you to go to the rack or the console and set that dimmer to standard dimming, non-doubled. You can not use a twofer to get 120v out of the dimmer. Dimmer doubling mode actually sets the dimmers to their peak, outputing more then 120v.


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## MNicolai (Apr 1, 2011)

Dimmer doublers are remote devices, plugged into the 120v circuit and spitting out two opposing halves of the AC waveform. No modification of the dimmer rack is required to use or cease use of those devices.

If you wanted to use a 120v lamp, you would unplug the dimmer doubler from the 120v dimmer circuit and plug the fixture in directly to the 120v coming from the dimmer rack. In exchange, that gives you control of one circuit where you earlier had two.

The only adjustment that need be made to the dimmer rack is through the facepanel of the control module is to disable dimmer doubling for that dimmer. That can also be done through the Sensor+ Connect web interface for racks with CEM+ control modules, which allows users to login to the control module through Internet Explorer to view and modify rack settings.


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## rochem (Apr 1, 2011)

Footer said:


> Dimmer doubling mode actually sets the dimmers to their peak, outputing more then 120v.



Are you sure about this? I don't have a huge amount of experience with dimmer doubling, but I thought the only change when you set it at the rack is how the control data goes to the dimmer, and that the dimmer is still outputting 120V RMS. Because it's alternating current, how could the RMS voltage go above 120V if the peak voltage stays at ~169VAC?


MNicolai said:


> Dimmer doublers are remote devices, plugged into the 120v circuit and spitting out two opposing halves of the AC waveform. No modification of the dimmer rack is required to use or cease use of those devices.
> 
> If you wanted to use a 120v lamp, you would unplug the dimmer doubler from the 120v dimmer circuit and plug the fixture in directly to the 120v coming from the dimmer rack. In exchange, that gives you control of one circuit where you earlier had two.


 
Normally true, I get the impression from reading his post that he's in a house where dimmer doublers are permanently wired into the system somewhere and not simply plugged in to the end of a 120V line. So presumably, the dimmer doublers are buried somewhere in the install and he doesn't have easy access to them. I've never seen or even heard of an installed dimmer doubling solution, and I'm not even sure such a thing exists, but this is what it sounded like to me.


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## MNicolai (Apr 1, 2011)

> Normally true, I get the impression from reading his post that he's in a house where dimmer doublers are permanently wired into the system somewhere and not simply plugged in to the end of a 120V line. So presumably, the dimmer doublers are buried somewhere in the install and he doesn't have easy access to them. I've never seen or even heard of an installed dimmer doubling solution, and I'm not even sure such a thing exists, but this is what it sounded like to me.



I received the same impression, but like you, I've never seen or heard of an install with permanently wired dimmer doublers. If that is the case, the doublers should exist somewhere (possibly in the dimmer room but not within the dimmer rack itself) accessible where they can be removed from the circuit and the hot wires leaving one of them can be reconnected to the 120v that was going into the doubler from the dimmer rack.

I'd be a little surprised if the doublers were not at the lighting position locations though -- I don't even know anyone who manufacturers (ETC or otherwise) dimmer doublers in a rackmount form, so all I can imagine is that there would be a room somewhere with a mess of doublers in a patch bay).


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## derekleffew (Apr 1, 2011)

1. ETC is the only company using dimmer doubler technology.
2. Putting the dimmer doublers anywhere other than at the fixtures would require twice as much installed wire and labor, thus negating the savings on the dimmers.

OP, as everyone else has said, 
a) unplug the DimmerDoubler, 
b) on the CEM set the dimmer to normal, non-doubled, and 
c) plug in your 120V conventional fixture. 
d) At the console, you can unpatch the (B-side or 256+1) half dimmer, or just leave it be as there won't be anything to listen to it.


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## dramatech (Apr 1, 2011)

Is it possible, that during installation, the male connector of the dimmer doubler was removed, and wired directly to a juction box. This would make it appear as though the the two outputs of the dimmer doubler were two seperate circuits coming from the rack. This install might have been done this way assuming that the folks operating the system, might not really understand how to properly install and remove the doublers as required, such as a high school, where the operators change every few years. This would protect the system from requiring different lamp voltages, while giving a maximum of circuits to work with.


MNicolai said:


> I received the same impression, but like you, I've never seen or heard of an install with permanently wired dimmer doublers. If that is the case, the doublers should exist somewhere (possibly in the dimmer room but not within the dimmer rack itself) accessible where they can be removed from the circuit and the hot wires leaving one of them can be reconnected to the 120v that was going into the doubler from the dimmer rack.
> 
> I'd be a little surprised if the doublers were not at the lighting position locations though -- I don't even know anyone who manufacturers (ETC or otherwise) dimmer doublers in a rackmount form, so all I can imagine is that there would be a room somewhere with a mess of doublers in a patch bay).


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## JD (Apr 1, 2011)

Regarding the "over-voltage." ETC dimmers are designed to regulate their output should the line voltage go over 120 volts. Examples:
In / Out
127 / 120
120 / 120
115 / 115

(perfect world where dimmers would be 100% efficient)

They do this by dimming back a bit if the voltage is over 120 volts. They do not however have any ability to add voltage at the full setting. If your line voltage is below 120 volts, your output will be below 120 volts at full.

The result is that if the line voltage were to increase, you would not see any effect on stage. The same is not true if you have a large sag.

As line voltage often is around 125 volts, this supplies a nice cushion of regulation. I believe this can also be set up to regulate output at 115 volts, but I may stand corrected on this.

As we all know, "Normal Line Voltage" is whatever the power company feels like giving you and varies quite a bit from location to location.


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## farmerjo1111 (Apr 1, 2011)

In case anyone is wondering. There are a few installations out there that have permanently mounted boxes with integrated Dimmer Doubler in them. ETC has made boxes and strips with the dimmer doubler mounted and hardwired to them. For some spaces it is the best option.


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## dukeofmuffins (Apr 1, 2011)

WOW! Thanks for all the responses guys. I just got out of work to read these. 

The system I currently work with is a high school auditorium. The tech support department has been cut back so far that they've been paying me and other alumni to come back and handle lights and sound for the shows. 

This is really just curiosity for me. The other day I realized that all of our lamps are 77v, which led me to a "wtf have I been doing all those years" moment. Then I read about dimmer doublers. Then I checked the patch settings. Sure enough, doublers everywhere. 

For 42nd Street (many a year ago) I had a bunch of Broadway-esque signs made out of masonite and lots of christmas lights, as well as lit staircases with rope light. In my high-school naivety I thought that the lights were 120v, so I could just wire up a stage-pin plug and presto! While everything worked out well enough, I'm rather sad to realize I wasn't using the full brightness of my signs and other special effects.

I also can't imagine the doublers being located in the racks, since they are all the way down in the green room, and bolted to the brick wall. We do have the black pigtail boxes from ETC running along the catwalk, and on the ends of all the fly pipes with lights. Could the doublers have been built into those as previously mentioned? If so, for future reference, would it be as simple as removing the cover to one of those boxes and disconnecting the doubler? Assuming they aren't hardwired. I honestly can't picture anywhere else they could be located.


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## Footer (Apr 1, 2011)

farmerjo1111 said:


> In case anyone is wondering. There are a few installations out there that have permanently mounted boxes with integrated Dimmer Doubler in them. ETC has made boxes and strips with the dimmer doubler mounted and hardwired to them. For some spaces it is the best option.


 
Wow. That makes me sick to even think about that ETC would even consider doing that. Having a lighting system that was locked down to only etc units is pretty much the most unusable system possible. Dimmer doubling works great in a touring system. It is also great for adding a few circuits in an installed system. The idea of it being hard wired into raceways is just unfathomable. It amazes me ETC would even consider doing that. 

...... Something involving tapatalk.......


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## theatrelighting (Apr 1, 2011)

Has anybody ever come across any other dimmer doubler? ETC's requirements are extremely limiting! I have always been a fan of ETC's equipment, but some of this sounds ridiculous. It seems that there are a ton of permanently installed Strand racks out there that could really use some doubling...


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## derekleffew (Apr 1, 2011)

theatrelighting said:


> ...ETC's requirements are extremely limiting! ... but some of this sounds ridiculous. ... some doubling...


Help me understand this: so you're mad at ETC because neither Strand nor anyone else has been able to copy their dimmer doubler technology (see U.S. Patent number 5323088)? What's "extremely limiting"? The 77V lamp? I'm sure if someone made a 77V GLA or BTN or FEL, it would work fine.



Sent from my iPhone using Tapatalk


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## JD (Apr 1, 2011)

The dimmer doubling splitter boxes are simply two diodes so the two fixtures only see one side of the waveform each. If you would plug the module into a regular wall outlet or an non-doubled dimmer, both fixtures would come to full, but that's about it. Each fixture would see 1/2 of the waveform. The split duration works out to an equivalent of about a 77 volt RMS waveform. No real magic, but a real cool idea that works well! (Just don't plug the fixtures directly into anything!) 

The real heart of the system is the firing circuit that allows the two SCRs inside the SSR to be fired independent of each other. 

As far as I know, ETC has the wrap on that.


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## SteveB (Apr 1, 2011)

I share somewhat, Kyle's concerns at having the DD two-fer built into the raceway, as it severely limits (pretty much prohibits the use of and) the flexibility of the system to use fixtures other then those accepting 77v lamps. 

That said, I think the fault lies with the consultant and/or architect that allowed this in the first place. For all we know there was a Project Manager at ETC who has a 'puter hard disk full of e-mails stating that it's not the best idea in most instances. At some point the manufacturer is going to build what the consultant spec's, or lose the project, as well as potentially future projects down the road. That's probably not good business practice and in truth has anybody ever heard of permanent DD systems prior to this ?. I never knew it was an option, not that I'd go that route anyway. 

I am also not a fan of DD in permanent facilities in general, feeling that the need to keep track of A and B sides to a dimmer when patching, dealing with visiting consoles, etc... make them a pain to deal with.


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## STEVETERRY (Apr 1, 2011)

MNicolai said:


> I received the same impression, but like you, I've never seen or heard of an install with permanently wired dimmer doublers. If that is the case, the doublers should exist somewhere (possibly in the dimmer room but not within the dimmer rack itself) accessible where they can be removed from the circuit and the hot wires leaving one of them can be reconnected to the 120v that was going into the doubler from the dimmer rack.
> 
> I'd be a little surprised if the doublers were not at the lighting position locations though -- I don't even know anyone who manufacturers (ETC or otherwise) dimmer doublers in a rackmount form, so all I can imagine is that there would be a room somewhere with a mess of doublers in a patch bay).


 
There are no permanently installed dimer doublers--only cord-connected.

ST


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## Footer (Apr 1, 2011)

STEVETERRY said:


> There are no permanently installed dimer doublers--only cord-connected.
> 
> ST


 Thanks Steve! 


...... Something involving tapatalk.......


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## theatrelighting (Apr 2, 2011)

derekleffew said:


> Help me understand this: so you're mad at ETC because neither Strand nor anyone else has been able to copy their dimmer doubler technology (see U.S. Patent number 5323088)? What's "extremely limiting"? The 77V lamp? I'm sure if someone made a 77V GLA or BTN or FEL, it would work fine.



I'm sorry... I'm really not _mad_ at ETC, I think I'm just frustrated that I can't use it in my application. Kudos to ETC!


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## dukeofmuffins (Apr 2, 2011)

Well I suppose I'll do some poking around. I know the bulbs are 77v, the board says Dimmer Doubling is enabled on both racks, and I know we don't have enough dimmer for all of the channels. So by logic, there are dimmer doublers SOMEWHERE in the installation. Going to double check the patch settings and see if perhaps certain floor pockets are still 120. The striplights are old too, so I would think those are 120, and the doublers must have been left off those.


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## techno89 (Apr 2, 2011)

Is there a reason you can't just go on a ladder or lift and look for one? Wouldn't that clear everything up? They would only be attached to the Source Fours


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## dukeofmuffins (Apr 2, 2011)

All that is visible in the catwalk rows are the black boxes with pigtails. They connect to the S4s hanging up there (60ish of them)

The stage has 2 fly bars of PARnels, using the same 77v bulb (30 of those).

There are no visible doublers. All of the drop boxes are connected to conduit which presumably works it way back to the dimmers.

Well I'll be back there in a week to handle their talent show, I'll try and find time to unscrew one of those box panels and peek inside. That's the only place they could be, hardwired or not. I'll take some pics as well.


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## xander (Apr 2, 2011)

Out of curiosity, what kind of connectors are on your pigtails and S4 caps?


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## dukeofmuffins (Apr 2, 2011)

Stage Pin connectors (3 pins) all around. Lights, strips, floor pockets, everything.


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## xander (Apr 2, 2011)

That's disconcerting. If everything you are saying is true, I don't see how this could be an authorized ETC install. ETC insists on L5-15 connectors so that it is harder to plug a 120v load into a doubler. IF everything in the entire building was doubled and using 77v lamps it would be one thing (I would say still not a good idea), but you said you have other instruments like strip lights running on 120v. Everything being 2P&G sounds like you are asking for trouble.


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## shiben (Apr 2, 2011)

xander said:


> That's disconcerting. If everything you are saying is true, I don't see how this could be an authorized ETC install. ETC insists on L5-15 connectors so that it is harder to plug a 120v load into a doubler. IF everything in the entire building was doubled and using 77v lamps it would be one thing (I would say still not a good idea), but you said you have other instruments like strip lights running on 120v. Everything being 2P&G sounds like you are asking for trouble.


 
I agree with this. My guess is that its not all legit, especially if there are actually doublers in the wall soemwhere. Now, its also possible that someone set it to on thinking it sounded like a good idea, and then never bothered to put in doublers.


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## ScottT (Apr 2, 2011)

shiben said:


> I agree with this. My guess is that its not all legit, especially if there are actually doublers in the wall soemwhere. Now, its also possible that someone set it to on thinking it sounded like a good idea, and then never bothered to put in doublers.


 
Wouldn't doublers be considered a "temporary" install and therefore shouldn't be used as such?


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## dukeofmuffins (Apr 2, 2011)

Alright I'm packing my multimeter next week as well. I'm going to confirm all of this. 

I'm waiting to hear back from an old teacher about the designer of the system. I know it was a third party contractor (will get that name too). Does ETC ever do installs themselves? 

I love how this has sparked so many questions! If anything I hope to figure out exactly whats doubled and whats not, so the plugs could clearly be labelled. The school is relying more and more on students handling ALL aspects of lighting. Even with liability issues they often don't have a choice. I'd like to clarify this so future users don't destroy any of the bulbs we have, or cause fires, etc.


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## MNicolai (Apr 2, 2011)

dukeofmuffins said:


> Alright I'm packing my multimeter next week as well. I'm going to confirm all of this.
> 
> I'm waiting to hear back from an old teacher about the designer of the system. I know it was a third party contractor (will get that name too). Does ETC ever do installs themselves?
> 
> I love how this has sparked so many questions! If anything I hope to figure out exactly whats doubled and whats not, so the plugs could clearly be labelled. The school is relying more and more on students handling ALL aspects of lighting. Even with liability issues they often don't have a choice. I'd like to clarify this so future users don't destroy any of the bulbs we have, or cause fires, etc.


 
It varies. ETC is more closely involved with large, unique, and/or custom installs. Turn-key basic systems installs usually fly in more under the radar, but ETC retains as-built drawings on almost every system they turn on. For that matter, an ETC-trained service tech is required to sign off on dimmer rack installs before the systems can go hot, and as I recall, a service tech technically becomes an ETC employee for the duration of time they spend installing systems.

Unless the doublers were an add after the initial install, ETC should still have drawings of your facility showing how the system is arranged. If they were added after-the-fact, there may or may not be a paper-trail describing how the system was setup.

You can always call Tech Services @ 1.800.444.8825 and someone can tell you what was part of your system when it was installed, and if the doublers were an add after-the-fact, they can probably still talk you through figuring out how exactly the doublers were implemented into your system and what the process would be for removing them as-needed.


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## SteveB (Apr 3, 2011)

It's beginning to sound like at one time the system had, or was supposed to have DD's but possibly got removed ?, or never purchased ?, but possibly the 77v lamps came and were installed anyway ? Possibly the lamps always look dim ?. Ask yourself how many custodians know a 77v HPL from a 120 ?. 

Just a thought

Sent from my Android Incredible


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## JD (Apr 3, 2011)

I don't think a 77 volt lamp would last one second at 120 volts. If the fixtures have 77s in them, then those DD modules are somewhere!


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## DuckJordan (Apr 3, 2011)

JD said:


> I don't think a 77 volt lamp would last one second at 120 volts. If the fixtures have 77s in them, then those DD modules are somewhere!


 
I'd have to agree they would most likely catastrophically fail within 10 seconds of being lamped on.


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## Footer (Apr 3, 2011)

DuckJordan said:


> I'd have to agree they would most likely catastrophically fail within 10 seconds of being lamped on.


 
Not even 10 seconds. They instantly blow. This is why you are supposed to have twistlock connectors on all basecaps for the 77v lamp caps so it is impossible to plug a 77v lamp into a 120v outlet. Now, I have seen more then one venue that simply converted the dimmer doublers over to stagepin or made twist to stagepin adapters. In these venues, you have to cleary mark all dimmer 77v basecaps. Even with a good system in place, it is pretty common to hear lamps blow when during ring out.


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## MNicolai (Apr 3, 2011)

Footer said:


> Not even 10 seconds. They instantly blow. This is why you are supposed to have twistlock connectors on all basecaps for the 77v lamp caps so it is impossible to plug a 77v lamp into a 120v outlet. Now, I have seen more then one venue that simply converted the dimmer doublers over to stagepin or made twist to stagepin adapters. In these venues, you have to cleary mark all dimmer 77v basecaps. Even with a good system in place, it is pretty common to hear lamps blow when during ring out.


 
It's worth noting that using anything other than 2P&G or L5-20 male connectors on the source side and L5-15 female connectors on the load side voids the UL listing. As per the user manual:


> C A U T I O N : Dimmer Doublers and Source Four fixtures are UL Listed as an integrated system
> using the connectors indicated in this manual. They are not UL Listed when used
> with any other connector.



Maybe STEVETERRY can comment on whether or not the UL listing is maintained if a dimmer doubler is hard-wired on the source side.


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## SteveB (Apr 3, 2011)

Footer said:


> Not even 10 seconds. They instantly blow. This is why you are supposed to have twistlock connectors on all basecaps for the 77v lamp caps so it is impossible to plug a 77v lamp into a 120v outlet. Now, I have seen more then one venue that simply converted the dimmer doublers over to stagepin or made twist to stagepin adapters. In these venues, you have to cleary mark all dimmer 77v basecaps. Even with a good system in place, it is pretty common to hear lamps blow when during ring out.



I've never used DD stuff except as part of a tour rig, so have no idea how long a lamp runs on 120, so not surprised it goes Jimi. Remember that the OP hasn't stated that any of this 77v stuff is actually working !. Wouldn't surprise me if the custodians took away the DD's and poof went the lamps, especially given everything as 2P&G, which is a major problem.


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## STEVETERRY (Apr 3, 2011)

MNicolai said:


> It's worth noting that using anything other than 2P&G or L5-20 male connectors on the source side and L5-15 female connectors on the load side voids the UL listing. As per the user manual:
> 
> 
> 
> Maybe STEVETERRY can comment on whether or not the UL listing is maintained if a dimmer doubler is hard-wired on the source side.


 
No, it is not.

ST


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## icewolf08 (Apr 4, 2011)

There are two really fast ways to figure out what is going on here. First, open up a fixture and actually confirm that it is running a *77v* lamp. Could quite simply be a lip of the tongue having meant to say *750w*.... Second, check the configuration in the CEM in the rack to see if DD is enabled for any of the dimmers.

Unless the system was installed and commissioned by a non-ETC dealer and technician then it should have been done correctly. If DD was enabled, then the doublers should exist in the code-compliant form, and the fixtures would have the appropriate connector. If they don't exist, it is a fair bet that the system is set up for standard dimming. Also, given the body of evidence the OP has given, like having fixtures that work that are not Source 4s, it is probably safe to assume that the system is set up for standard dimming. I would check these things before we continue to toss out ideas based on incomplete information.


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## bdkdesigns (Apr 4, 2011)

I have only used them once. The venue swapped out the dimmer doubler L5-20's with 2P&G with bright red cap covers. Once an instrument went to 77v, it too had the cover replaced with a bright red one until it was swapped back. 

Out of curiosity, would anything happen if they had 77v lamps and changed the CEM to say that dimmer doubling was enabled on a circuit without actually using the doubler? If it would still work with that one lamp, I wouldn't put it past a school to have heard somewhere "Dimmer Doubling saves money on an install"......and stopped reading there.

I know that personally, a third party contractor with no theatre experience initially put the specs on my new system. I initially told them that I was concerned about the process in my interview when they stated that they were not sure what was going on with the renovation. This was concerning since the install was supposed to be happening at that moment of time. Luckily they had an illegal bid process and had to start over and fixed a lot of things (as well as switching from Strand to ETC). Funny story, I have never seen ETC drawing for my space. Even during the install in the demo stage, they had the original Strand drawings and said "we are just simply switching from Strand to ETC so those differences don't matter". Luckily the people with those drawings were not the same people who installed the racks.


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## Footer (Apr 4, 2011)

bdkdesigns said:


> Out of curiosity, would anything happen if they had 77v lamps and changed the CEM to say that dimmer doubling was enabled on a circuit without actually using the doubler? If it would still work with that one lamp, I wouldn't put it past a school to have heard somewhere "Dimmer Doubling saves money on an install"......and stopped reading there.


 
It will still blow the lamp. The dimmer still puts out the full voltage, the voltage it just chopped in a weird way. You get an even weirder looking light if you have a dimmer set up for doubling that does not have a doubler and a 115v lamp on it. It give it this odd flicker and never gets all the way up to full.


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## jglodeklights (Apr 4, 2011)

I agree with IceWolf, we should wait until all the evidence is gathered. 

I would, however, not necessarily be surprised if not all the circuits in the building were doubled, while most of them are. Again, third party installations can lead to some strange things, especially when the third party does not do their homework.

The now torn down auditorium of the high school I work with had their first electric refitted into a pipe with a raceway versus the 40 foot long strip light pipe as originally installed. The retrofit resulted in some very odd hardwired twoferring in the raceway. Additionally, the halogen house lights were placed in a group of 6 of the dimmers randomly located, rather than starting at the beginning or end of the circuits. And despite having a rack of 96 Strand dimmers, I could only find circuits up to 84 or 90.

In the new auditorium they are building, everything was specified by the consultant to have twist lock connectors. When I asked why, he stated it was so the TV studio and theaters (auditorium and black box) can use the same lights, and so we can do dimmer doubling. However, no dimmer doublers were specified in the package, nor was any twist lock cable. He had obviously failed to do any form of research on who the end user is. The high school rents from one small local rental shop in which all units are stage pin, all 40 units we are carrying over (and need, the new package isn't large enough for the shows they do) are stage pin, and all our existing cable is stage pin. This same person also specified a 14 inch LCD monitor for our Express lighting console that is already equipped with a 15 inch monitor, and an additional Lycian Midget spotlight when they haven't used the one they have now in about 5 years (they use S4's with irises on the catwalk). 

Thus, as I said, I wouldn't be surprised.


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## JD (Apr 4, 2011)

Ahhhh... There is actually one scenario where the doublers could be missing and the lamps not blowing, but its a stretch:

In theory, if doubling was enabled and all of the "B" channels were parked at zero, the 77 volt lamps would only see one-half the waveform from the SSR, as only 1/2 of the SSR was being fired, and the lamp would not blow. Of course, if any of the "B" channels were brought up at the same time as the "A" channel was up, POP! 

The purpose of the fixture-end modules is to block 1/2 of the AC waveform to each of the fixtures. (Fixture "A" sees one polarity, fixture "B" sees the other.) A pretty rock solid idea, as even it the doubler module was plugged into a non-dim outlet, each lamp would still only see one side, and both would simply come on full brightness. This is why the input to the module is Stage pin. (Doesn't matter if it gets patched wrong, the lamps are safe.) The same is NOT true on the lamp side of the module. You could plug a 120v fixture into it and it would just be dim, but plug a 77 volt fixture into 120 volts and watch your wallet shrink. Thus, the non-standard connectors.

Outside of the highly unlikely scenario I started off with, there are only two possibilities: 

1) The fixtures actually have 120 volt lamps in them, any your stock was a goof. 

2) Someone did something naughty and built the modules into a hidden location.


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## Grog12 (Apr 4, 2011)

SteveB said:


> I share somewhat, Kyle's concerns at having the DD two-fer built into the raceway, as it severely limits (pretty much prohibits the use of and) the flexibility of the system to use fixtures other then those accepting 77v lamps.
> 
> That said, I think the fault lies with the consultant and/or architect that allowed this in the first place. For all we know there was a Project Manager at ETC who has a 'puter hard disk full of e-mails stating that it's not the best idea in most instances. At some point the manufacturer is going to build what the consultant spec's, or lose the project, as well as potentially future projects down the road. That's probably not good business practice and in truth has anybody ever heard of permanent DD systems prior to this ?. I never knew it was an option, not that I'd go that route anyway.
> 
> I am also not a fan of DD in permanent facilities in general, feeling that the need to keep track of A and B sides to a dimmer when patching, dealing with visiting consoles, etc... make them a pain to deal with.


 
I have to agree with SteveB here..this sounds like a descion made outside of the ETC family. Someone thought it was a "smart" way to save and didn't plan for every eventuality.


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## JD (Apr 4, 2011)

If they are in the raceway, that is bad news. The diodes inside produce about one watt of heat for every amp running through them*. With two 750w loads, that comes to 15 watts. No problem out in the open, but sealed in a raceway with no air circulation could cause a problem. 

If a diode were to go, it would fail as a short, allowing the full 120 volts to hit the lamp. 

Easy way to figure this out. Plug in a 120 volt test light. If you cannot get it to full intensity, then they are in there somewhere.

* 750w 77 volt lamp would draw 9.74 amps, but duration would only be 50% with half-wave.


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## zmb (Apr 4, 2011)

Is it possible that somewhere, the max output is 77v and is keeping the lamps from blowing?


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## jglodeklights (Apr 5, 2011)

zmb said:


> Is it possible that somewhere, the max output is 77v and is keeping the lamps from blowing?


 
Only if the following weren't true:

A. ETC's Dimmer Doubling system is the only system (that I know of) in the world to use dimmed 77 volts. (I know some Middle East hotels use sine wave splitting at 230 volts to increase the efficiency of their system in allowing more lamps to be mounted on it) and as such would require expensive custom electrical installation to create.

B. Enabling Dimmer Doubling on the console and racks (as is stated is probably the case by OP) would result in 33.5 volt sends to units, at best. And only if dimmer doublers were actually installed.

Combined with the fact that there are some non-dimmer doublerable units, that seems unlikely, especially since it wouldn't allow for increasing the number of usable channels.


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## xander (Apr 5, 2011)

There is a lot of information being thrown around in this thread without much knowledge of the real facts of the OP's venue. Before the OP goes off and does something that gets himself or the equipment damaged, maybe we should lay off the theories and speculation. The simplest way to find out whether the system has DD modules somewhere is to open up a S4 cap (making sure it is off and unplugged, first) and checking the lamp. 77v or 115v?


I mean no offense and I'm sure these are just slip ups, but just to make sure no one is getting fed misinformation, here are some minor corrections.


bdkdesigns said:


> I have only used them once. The venue swapped out the dimmer doubler L5-*20*'s with 2P&G with bright red cap covers. Once an instrument went to 77v, it too had the cover replaced with a bright red one until it was swapped back.


Dimmer doublers come with L5-*15* connectors. L5-20 are a common connector used in theaters for line voltages and would therefore not accomplish one of their goals, that of avoiding plugging higher voltage loads into the 77v output.


JD said:


> If they are in the raceway, that is bad news. The diodes inside produce about one watt of heat for every amp running through them*. With two 750w loads, that comes to 15 watts.......
> 
> * 750w 77 volt lamp would draw 9.74 amps, but duration would only be 50% with half-wave.


77v HPL lamps for use in a dimmer doubled system are 550w, not 750w.

-Tim


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## domiii (May 8, 2011)

xander said:


> 77v HPL lamps for use in a dimmer doubled system are 550w, not 750w.
> 
> -Tim


 
They do have 750W/77V lamps. I purchased some from BulbAmerica.

USHIO HPL 750w /77v halogen bulb


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## xander (May 8, 2011)

domiii said:


> They do have 750W/77V lamps. I purchased some from BulbAmerica.
> 
> USHIO HPL 750w /77v halogen bulb


I stand corrected. I had never heard of this lamp until 60 seconds ago. It must be relatively new as it's not on ETC's list of Source4 compatible lamps.

-Tim


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## nray6905 (Sep 9, 2011)

I wasnt sure if anyone had really found a probable solution to this yet but i thought i would chime in anyway and i do hope it makes sense.

I would for a profession regional theatre company and i make complete use of the dimmer doubler technology. We only have 250 dimmers but currently have 400+ fixtures in the current working inventory. Now with the 550w 77v lamps they will ONLY work with dimmer doublers, if they are connected to straight (un dimmer doubled) circuit they will blow! Now, that being said, if a dimmer is set for doubling you can still run a 575w or 750w on that circuit with basically "half" the power. But from speaking with ETC, there is no such thing as permanent dimmer doublers.

With the dimmer doublers that i currently use, we have taken all of the 15amp twist locks that come with them off and replaced them with stage pin connectors because there is no reason to have to make up a completely new cable library of twist locks. All you need to do is use E-tape and tape the connectors that have the 77v lamps in them.

You can also with the doublers "two-fer" the A and B sides of the doubler with a totally of 4 77v fixtures, two on each side.


I really hope this helps.

Nathan Ray
Lighting Designer/Technical Director

The Renaissance Center
Nashville, Tn 37055
The Renaissance Center


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