i dont want to start a led neon fight but here is the deal.....i had a customer that had a set of 4' dark blue antique letters "helvetica" that i built 5 years ago. the antique mall changed locations and wanted to ad a script letter style above the word antiques, so i had to make a new set of letters. with the 4' antique letters using 15m white neon.....the new set of script letters on the top line we used sloan blue leds, at thier request for new leds (they wanted to jump on the led band wagon) now when the signs light up the led letters on top light the dark blue plex light up like fire. so what im saying is the quality pumped, and bent neon, properly populated doesnt "hold a candle to the blue leds" especially in the cold. that job has been installed two years, no service calls. we now use agilight as our preffered led componets.we use neon about 25% of the time. so in closing, i have only used red and white leds from agilight, more than satisfied with the company, and even light ouput. 0 service calls from agilight leds. i have had a couple service calls from the sloan leds, also i have had population problems out of sloan leds. with my tests i have found things i like about leds and i have found things i like about neon......most of all american craftsman having glass work.
Cold weather is another strength for LEDs. Being in the cold, they actually light up brighter and will last longer.
Being an LED guy myself, I have to caution you about AgiLight, though, especially if you're using the SideWinder product. Those are what are called T1-3/4 (or 5mm) through-hole LEDs and they're not well suited to dissipating heat. They're great for "striplights" (I make them myself and use them for edgelit displays) but with the narrow beam emission, you have to mount them sideways, which is less efficient. Also, I would never use them for outdoor channel letters - especially not Blue or White. You'll be lucky to get 25,000 hours of decent brightness out of them and the fibreglass circuit board don't like moisture.
I strongly recommend using surface mounted LEDs (little squares, as opposed to bullet shapes). Always watch for a wide angle LED (better diffusion, no hotspots) and look for either an aluminum circuit board, or a waterproof (potted) module.
Standard white neon is at best a poor choice of color for dark blue faces.
YYZ, please correct me if I'm wrong, but I believe that would hold true for LED's as well: Using white behind a dark blue face.
Mark
Using a blue light source would always give you a deeper, more intense color - but as I mentioned, blue can be a funny color to observe at night - and it depends on what color you're trying to achieve.
It could be that they are trying to match a certain color, which is sometimes easier to do with a white light source behind a vinyl faced letter, as vinyls can be matched to Pantones and other non-illuminated signage or printed materials.
I've sampled most of those LEDs. Each has it's pros and cons.
Here's my take on each mfr you listed:
Sloan:
Decent, but counter-intuitive technology. The Great White, for example, has "high flux" LEDs mounted to an aluminum PCB (which is required for heat sinking), but then they mount the PCB in a plastic case which insulates the unit away from the letter, which itself becomes an added heat sink. It could be they do this to avoid PermLight's patent - which they have enforced against USLed and are now chasing Gelcore. I would throw away the plastic case and mount the modules directly to the letter. The smaller modules (with "superflux" LEDs) do the same thing with the plastic carrier, but in this case you need to keep the plastic since it's a fibreglass PCB with thru-hole components, and the contacts would short out if mounted to the letter. Brightness is suitable for small letters.
PermLight:
Again, better in thoery than practice. Their smaller Twist'r and PaletteLight modules are their best and are good for lighting small and medium sized letters. I bought a batch of their ElBlanco and while the light is adequate and the aluminum PCB does properly mount onto the can, the components on the circuit blew me away. They simply had 2 LEDs and a resistor, which works at lower amperages and/or Red LEDs (15-50mA) but is grossly inadequate to properly drive 350mA "high flux" LEDs of White or Blue tones. The board is designed for all the correct components whish I assume they do sometimes use, but they took a shortcut for this batch for some reason. Their new PZ modules use a very nice new LED, but I haven't seen this exact product yet so I don't know how wel the unit is designed, but I do know that they way they promote it on their website will cause people to be unhappy with the brightness. You'll need 3 or 4 units per foot, not 1 or 2 as they suggest.
Gelcore:
Never used them, but seen the mused a lot. All the Home Depot retrofits around here are Gelcore and they do a pretty good job - but so do most LED systems with Red. They originally used the "superflux" LED and still do, but offer a "high flux" diode for their super white systems, but I understand they're pretty expensive (>$50 foot in Canada, for 3 diodes a foot). 3 diodes is a decent brightness, but 4 or 5 would be ideal. It's nitpicking, but I dislike how you have to change settings on their power supplies depending on what color you're using, etc. This is actually good for the diodes, but leaves more room for user error.
USLed:
Their smaller modules are almost direct knockoffs of Sloan, but are made a little more cheaply. Sloan uses an IC to drive the diodes at a specific amperage, whereas USLed uses a simple resistor, which is less accurate and doesn't account for voltage drop or variation sin voltage. I have to gve them credit for their + and - tabs, which makes splicing connections within a letter very easy. No wires cutting or wirenuts. Their ModLight was the first to use the "high flux" LEDs, but using one 3.5V diode in a 12V system isn't very efficient. Also to their credit, they realized that paying PermLight for their patents is better than reducing the quality of the system.
ElectraLED:
I ordered some of their older series 12 and Genesis and thought it was complete crap. They may have improved their diode selection and/or brightness since, but I wasn't impressed. The miniflex looks like it would be good for smaller letters and their FLEX system actually looks pretty good. They use the "high flux" diodes, mount them to a heat sink and even color code the covers. I haven't used these before, but if the onboard driver is properly designed, it should be a good unit. Also, they use AC power, which is better for travelling over greater distances without a voltage drop that occurs with DC, but requires more on-board componentry, which affects price and AC transformers, while reliable, are often noisy.
I've never heard of Lindo and couldn't find anything thru google.
Allanson makes their own and while their system is fairly easy to use, their fatal flaw is that they mount "high flux" LEDs onto a fibreglass circuit board. They do try to dissipate heat with an exposed rear "tinned" surface, but it's still inadequate and I think they're going to experience premature degradation. Even the demos I saw in a distributor's showroom were starting to get brown around the drive components.
There are several other smaller companies as well as offshore products. France imports theirs, and the exact same units are sold by a couple of other companies as well, such as Teledyne and AcTown. They're well made, in that they're potted for moisture protection and heat dissipation, but they often use 2nd grade diodes to keep the prices down. I had factories over there quote me for production using my diode specs, and the pricing went up substantially and in some cases, the top diode manufacturers would not even sell to them.
You have to remember that the systems integrators (companies making sign modules) DO NOT manufacture the actual LEDs that are used in their systems. There are dozens of diode manufacturers and the quality varies. You get what you pay for.
It's up to each user to determine which LED product they like, but I woudl generally stay away from anything with the 5mm round LEDs and don't recommend buying from companies like LEDtronics, AgiLight, LED Inc, theLEDlight, etc. I realize that this might attract some negative attention from those companies I just listed, but it's their use of 5mm thru-hole LEDs that I disagree with and have unbiased data to back up my claims that those diodes, especially Blue and White, simply don't last long enough to make them suitable for channel letter applications.
Hope that helps.
You're in luck. I actually had some Avery A-9588T (Pantone 281) sitting on the shelf.
I applied the vinyl onto 1/8" sign white acrylic and did a quick comparison between White and Blue LEDs. The White LED gives a more accurate 281 color when illuminated, whereas the Blue LED makes it look more like Reflex Blue. White LEDs are brighter than Blue ones, especially if you stick to something with a high Kelvin temp, which is more blue anyways.
The modules I used for the test were our own, which worked for my little comparison but aren't avaiable for sale yet. The Whites are a high output (60 lumen per 1.5W module) that we're testing and a similar unit will be available in Blue, but the Blue I actually used for the test was a flat-top 5mm diode, which is not suitable for an outdoor letter. Our new HB system (Green, Blue, White) will blow away everyone else's product in terms of lumens per $, but it will be a few months before it goes to market.
That said...
If I had to buy a system that's currently on the market, today, I'd probably choose between Sloan's Great White and ElectraLEDs FLEX series - depending on cost and availability. In either case, use 2 modules per foot, per 4" in width. If you go with the Sloan, pull the aluminum PCB out of the plastic carrier and use 3M 468 adhesive to stick the aluminum PCB directly onto the aluminum letter back (. This will dissipate heat away from the LEDs and extend their usable life.
Good luck.
what is the highest CRI value of these led's? that is what will determine how well a dark faced letter will look. you can always boost power to increase brightness with whatever light source is used. seems to me technolux has a tri phosphor white that comes close to 100. are there any led's out there with a CRI of 90+?
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I think the idea of using a dark blue face is where your difficulty comes from, regardless of the lighting technology.
Even the darker tones of blue neon are difficult to read at night, since the human eye has trouble distinguishing that wavelength from the night time sky.
It's why companies like Old Navy use a white outline to define the letter. White neon is often used to light this kind of letter, since it won't make an already dark color even darker, and would give you a closer match to a printed or Pantone color tone - which I assume is why you're stuck with this problem in the first place.