Control/Dimming "Facts" about DMX

[Kelite]

Do you think that stuff will be too crappy for me to get working for them?

Caveat emptor!

 

[misterm]

Everything I have bought there (including a wireless DMX transmitter and reciever) has worked fine. Not the highest quality, but we're a small program and don't need top-end stuff. On a budget of $2,500 for the whole year, we can't afford it either. So I'd say anything like cables and trees, etc you could get there (just double check those trusses when they arrive!) but for instruments, I won't trust them.

 

[derekleffew]

I'd be more concerned with how effective 4x 300PAR38s would be, on all but the tiniest of stages with an 8' ceiling. But there are plenty of vendors with similar prices that don't have misinformation/falsehoods on their websites.

 

[JD]

DMX is a hearty format that takes a lot of abuse before problems start. This is why mic cables work on small systems. The cable itself, however, is what is known as a "transmission line." It therefore has a reactive impedance. "DMX" cable is matched to the impedance intended by the driver chip (transmitter) and the terminator at the end of the chain. Mic cable is a mismatch. Think of a transmission line as a Slinky (long spring-like toy.) Shake one end, and that pattern then flows down the coil. The terminator is like a piece of foam rubber and absorbs the signal at the other end. (Reflections would be bad.) Now, imagine what would happen if you connected several "Slinkies" together end to end, and that they were different diameters and thicknesses. That smooth ripple would break up where the size changed. Some would be reflected backwards, some distorted version would flow forward. This is what happens when you have an impedance mismatch, you just can't see it! The problem with digital signals is you don't know how bad things have got until they no longer work right. (Which usually shows up on the 30th cue on opening night.)

As for 5 vs 3 pin connectors... If the 5 pin connectors were not twice as much as the 3 pin ones, I would suggest staying on format and using only 5's. However.... (fill in the blank)

 

[photoatdv]

They rented a very similar system (2 trees w 4 pars) this summer for a show and it worked pretty well. I thought they were 300w pars, but I'll have to check. They could have been 500Ws.

Does anyone know where would be a good place to get cheap 4ch dimmers (pref DMX). And another question as far as when we upgrade the board-- if everything we're using is 3pin, any real reason I shouldn't use a 3pin connector? I could always make an adapter later if needed (and it wouldn't be terribly hard to change it if need be).

 

[gafftaper]

ALWAYS try your local dealer first (relationships pay off), after that try Production Advantage, Full Compass, or give CB member BillESC a call and see what he can do for you. You might not get quite as cheap of a price but you'll get better gear. Be honest say, "This is what I want to buy and how much another company is going to charge. However, I'm concerned about the build quality. How close can you get with equipment of known quality?"

 

[STEVETERRY]

Here's the thing, with the right adapter one could run DMX down an edison extension cord. Would it work? Probably. Is it a good idea? Not at all. It is all about using the correct tool for the job. Mic cables might work in a pinch, when you just have to get something working 5 minutes before a show, but they should not be used for long term, show critical use.

Well said!

ST

 

[headcrab]

I ran across that cheaplights page today and I nearly choked.

 

[cprted]

Not that I was ever likely to buy anything from a company called "Cheap Lights" before I read this thread, but that certainly sealed the deal.

 

[Les]

Basically they sell Chauvet, American DJ and Elation but usually without the brand name printed on them. Essentially - A Neo-Neon dealer.

As far as buying from them, they are no better or worse than any other online DJ lighting retailer. If not for them I wouldn't have had my rig back in my mobile DJ years, because everything was 1/4 the price of everyone else's gear. Obviously, don't trust their 'how-to' pages but remember that these are written by DJ's who have used insecticide hand pumps as fog machines back in the '70's, not us hard-to-impress theatre peeps

Don't get me wrong, I agree with everything that has been said in this thread, but remember who it is coming from and who the target audience is.

 

[epimetheus]

They rented a very similar system (2 trees w 4 pars) this summer for a show and it worked pretty well. I thought they were 300w pars, but I'll have to check. They could have been 500Ws.

Does anyone know where would be a good place to get cheap 4ch dimmers (pref DMX). And another question as far as when we upgrade the board-- if everything we're using is 3pin, any real reason I shouldn't use a 3pin connector? I could always make an adapter later if needed (and it wouldn't be terribly hard to change it if need be).

Springtree Media Online Store

I've got the 3-pin DMX veriosn of the NSI D4DMX shoebox. Not a bad little dimmer for the price. Glad to see Leviton is offering a 5-pin version now. I probably would have gotten that if it was available when I bought my pack. I've also have pretty good customer service from Springtree.

 

[photoatdv]

Hey here's another good one:

"Double black P64 fishing light with deluxe 9 foot stand and high quality 1000 watt bulbs. [...snip...] (These packages do not include a frame for a color gel because a 1000 watt bulb would melt a gel)"

Uh, yeah... I've used 1000W parcans w/ gel before. And just about every theatre in the world uses gels of their ERS. Really makes you question the quality of their gel...

Also there's a thread going on lightnetwork about this... and you were right about they are MUCH harsher on cheaplights.

 

[Chris15]

I'm just going to touch on one point:

At High Energy Lighting (CheapLights.com), we currently buy "MIC" cables and "DMX" cables from over 22 different suppliers. Regardless of how they are marked, we test samples from each different "MIC" and "DMX" cable model to make sure they work in a DMX chain before we ever offer them to our customers

I'm curious to know how they are tested, do they do a straight continuity test or *gasp* an actual bandwidth test to see if they are happy with the bandwidth of a digital signal...

But probably it's a case of plug it between 2 devices and if they work then it must be compliant, right?

Keith, noting you wanted the US perspective, you're going to get mine anyway. If it's not 5 pin it is NOT DMX compliant. I don't want it. There are already too many standards for things and too many attempted compliances that I just don't want the headache.

Personally I don't want to see "real" manufacturers making splitters etc with 3 pin outputs. They are conceding defeat to these penny pinchers.

What's say we have a lil fun now. From now on any product we want to say is DMX but persists in using non DMX connectors is banished to being DJMX equipment, for DJ Multiplex, or more accurately Digital Junk MultiPlex?

Derek, 300w PARs here would be PAR56.

 

[shiben]

Derek, 300w PARs here would be PAR56.

I was under the impression that the number designation of a PAR was the size of the lamp, not the wattage (For example, I own PAR 16s with 40W and 60W lamps in them, but they are all PAR 16s)

 

[gafftaper]

Basically they sell Chauvet, American DJ and Elation but usually without the brand name printed on them. Essentially - A Neo-Neon dealer.

Yeah they are selling Neo-Neon/Irradiant or some other direct from China OEM products. It's the supposedly the same stuff as the name brand, made in the same factory, with a different sticker. Whether they actually use the exact same parts is up to debate depending on who you talk to and which OEM and product you are talking about.

That said, just because you are buying low budget gear doesn't mean you have to settle for a dealer who doesn't have a clue. There are lots of other dealers out there who sell DJ gear who actually know what they are talking about. As I said above, talk to your local dealer about what DJ gear they carry, check with some of the national dealers, Contact Neo-Neon to find the nearest dealer, or just call Bill (It seems like there was someone else around CB who works for a Neo-Neon dealer... was it Pie?)

Too often people get stuck on the idea that they will save lots of money by ordering from some secret cheap place on the internet. I've have established long term relationships with several dealers. I get VERY good prices. They aren't always the same price as the cheapest on line, but they are close and the relationship means I get better service. Having that local connection when you get into trouble can be CRITICAL. Cheaplights can't save your butt if your console dies on Friday night and you have a gig Saturday... your local dealer can. If you don't have/can't stand a local dealer, developing a relationship with a national dealer can still have financial benefits. When you call a dealer up and they know who you are (and know you will be back to spend more money soon) you are going to get a better price than the person they've never heard of.

 

[Chris15]

I was under the impression that the number designation of a PAR was the size of the lamp, not the wattage (For example, I own PAR 16s with 40W and 60W lamps in them, but they are all PAR 16s)

Yes, PAR does still equal 8 x lens diameter in inches (horrible units they are). However everyone lamps their 56s at 300w here and if you say PAR38 to me you are talking about a floodlight used in your garden...

 

[photoatdv]

The ones I was looking at were 300W par56s. ;-)

 

[icewolf08]

If it's not 5 pin it is NOT DMX compliant. I don't want it. There are already too many standards for things and too many attempted compliances that I just don't want the headache.

Personally I don't want to see "real" manufacturers making splitters etc with 3 pin outputs. They are conceding defeat to these penny pinchers.

Umm, there are plenty of "real" manufacturers who put 3-pin XLR connectors on their DMX controlled gear. For a long time, Martin exclusively use 3-pin, and now they supply both. Doug Fleenor makes opto-splitters in both flavors. It may not technically be compliant with the standard, but that does not mean that the devices are not worth using, many are some of the best devices on the market.

 

[Chris15]

Umm, there are plenty of "real" manufacturers who put 3-pin XLR connectors on their DMX controlled gear. For a long time, Martin exclusively use 3-pin, and now they supply both. Doug Fleenor makes opto-splitters in both flavors. It may not technically be compliant with the standard, but that does not mean that the devices are not worth using, many are some of the best devices on the market.

I'm not debating that respectable manufacturers are making splitters with 3 pin, they are and they are worth using, but is the process of these real players dropping to the level of the DJ world by including those 3 pin outputs giving tacit acceptance of their practices?

 

[David Ashton]

the 3 pin plug is structurally a much better connector, the larger distance between pins make it easier to solder to and therefore more inherently reliable, compliance and common sense are not necessarily synonymous.