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Title: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 16, 2019, 06:43:20 PM
I've been looking at getting some LED par lights and have wondered how the rating work. For example, When rated at 18 LEDs at 18w each and is 'six in one', what does this mean?
My guess is that in each LED is a cluster of (in this case 3w) leds in different colors.
For example

Red 3w
Blue 3w
Green 3w
White 3w
Amber 3W
UV 3W

So the total for one LED is 6 x 3 = 18w. Is this correct?

So if the light is 100%  on one color, the total light output is 18 x 3w = 54w

That is a far cry from the 324w the light would appear to have.

Or am I missing something?

Thank you.








Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Jeff Lelko on January 16, 2019, 08:08:03 PM
Yes, in general that's correct.  As a disclaimer, not all multicolored LED light sources weigh evenly between colors, but yes, that's essentially a fair statement.  LED lights are an additive light source, meaning that you only add the discrete colors in amounts that you need to create the color and output you intend.  That generally means you rarely use full output of a fixture.  In contract, subtractive light sources (gelling a par or CMY mixing) work by masking various wavelengths of lights that come from a full-spectrum source.  Subtractive works best for light colors, additive excels in deep, dark colors.  Hope this helps! 
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Mark Cadwallader on January 16, 2019, 08:12:06 PM
You are basically correct. However, watts don't tell you anything meaningful. The information you should look at is the photometric specification. That tells you how much illumination of a surface there is, as measured at one or more distances. That and the beam and field measurement (in degrees of spread) will give you useful data. Lumens don't measure illumination of a surface; lux is the correct unit to consider.

If there is no photometric data available for a lighting fixture, that's an indication that the fixture isn't intended for serious lighting use. (But they might have pretty effects, anyway.)
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Paul G. OBrien on January 16, 2019, 11:35:34 PM
Earl your math is correct. As indicated the relative brightness a fixture produces depends upon the beam angle and for uplighting purposes a narrow beam is typically used... something like 15-20deg. For this use 50w of LED output would be quite good, below is a pic of my uplight fixtures that are only 27w per color(9 18w hex diodes). One thing I would suggest for your purchase is to buy fixtures with wireless DMX built in, battery powered is also an option but in my experience is if little use as the battery charge doesn't last from setup time all the way to the end of an event which is often 12-14hrs for me.

https://c1.staticflickr.com/5/4874/46047072464_df8da155e3_b.jpg
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 17, 2019, 11:32:38 AM
Thank you for all your responses. This is good information to know. My use if for a dance I put on once a month and is very Non-Critical.
In fact if the lights do work I will make no difference.

With that in mind, I am looking to get some of these lights.

https://www.aliexpress.com/item/Aluminum-shell-2pcs-lot-18x12W-RGBW-Led-Par-Light-DMX-Stage-Lights-Business-Lights-Professional-Flat/32800418414.html?spm=a2g0s.13010208.99999999.267.30453c00SSXmGT

They are bright, aluminum case, fanless (silent) and relatively inexpensive. The company that sells them has a very good rating and reputation with there other lights. Any Thoughts?
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Jeff Lelko on January 17, 2019, 12:10:43 PM
Any Thoughts?

Glad to hear our input is useful.  As far as the ebay and direct from China lights go...  It's a gamble.  Several members here such as Steve Garris have had excellent luck with the very cheap generic fixtures.  If that's the route you'd like to go I'd suggest searching the forum for his suggestions.  I personally choose to use at least lower-end name brand fixtures such as Chauvet SlimPar Pros and above - it just aligns better with my business model. 

Either way, I'd never spend $123-180 per fixture on LED Pars from AliExpress.  $30?  Maybe, if it fit what I needed.  For the same $123-180 you're in SlimPar territory, and I'd take one of those anyday over a generic fixture.  Output quality aside, I know I have a warranty that will be honored and replacement parts that will be available - two things that are very scarce with direct from China fixtures.  I vote to either get the $30-60 lights that Steve often recommends or spend the budget you have now on something from a reputable supplier.  Hope this helps!
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Jason Fultz on January 17, 2019, 01:00:06 PM
Thank you for all your responses. This is good information to know. My use if for a dance I put on once a month and is very Non-Critical.
In fact if the lights do work I will make no difference.

With that in mind, I am looking to get some of these lights.

https://www.aliexpress.com/item/Aluminum-shell-2pcs-lot-18x12W-RGBW-Led-Par-Light-DMX-Stage-Lights-Business-Lights-Professional-Flat/32800418414.html?spm=a2g0s.13010208.99999999.267.30453c00SSXmGT

They are bright, aluminum case, fanless (silent) and relatively inexpensive. The company that sells them has a very good rating and reputation with there other lights. Any Thoughts?

I have  Experience with those  particular lights.
They are light in weight,  small ,but not very bright in actual use.
I would suggest that you find some of the 7x10 watt lights.
Cost wise a little more but way more useable output.
I have a pretty good handful of both . The smaller ones like in your link will provide some was up a wall, but its oversll pretty dim and if you have as anything else going on they will soon be washed put by brighter stuff.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 17, 2019, 01:45:29 PM
Ive got some 7 x 12w (3w per led color) but wanted brighter lights.

These are 18x15w (3w per led color) so they should be much brighter. I realize that lumin output is not always exactly the same but normally fairly close for a give wattage. This is 18x3w per color vs 7x2.5w per color in a 7x10. This is going to be way brighter.

I have  Experience with those  particular lights.
They are light in weight,  small ,but not very bright in actual use.
I would suggest that you find some of the 7x10 watt lights.
Cost wise a little more but way more useable output.
I have a pretty good handful of both . The smaller ones like in your link will provide some was up a wall, but its oversll pretty dim and if you have as anything else going on they will soon be washed put by brighter stuff.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: TJ (Tom) Cornish on January 17, 2019, 02:01:05 PM
As has been pointed out by others, comparing brightness based on spec sheets is difficult.  The number and wattage of emitters is important, but so is beam angle.  The best judge of absolute brightness (not considering beam angle) in my experience is the electrical draw of the fixture - e.g. a fixture that draws 50 watts will be half as bright as a fixture that draws 100 watts all else equal. 

Beam angle makes a huge difference in apparent brightness - don't underestimate this.  A narrow beam fixture will seem much brighter than a wider angle fixture of the same wattage, but it may not cover what you need it to cover.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 17, 2019, 02:26:01 PM
Tom, Thank you. I totally agree with your statement. More wattage equates to more output in general, given a bit of variation between manufactures. I totally get that a narrower beam angle looks brighter. I can't see anything wrong with these lights so im going to give them a try. cross my fingers. xx


As has been pointed out by others, comparing brightness based on spec sheets is difficult.  The number and wattage of emitters is important, but so is beam angle.  The best judge of absolute brightness (not considering beam angle) in my experience is the electrical draw of the fixture - e.g. a fixture that draws 50 watts will be half as bright as a fixture that draws 100 watts all else equal. 

Beam angle makes a huge difference in apparent brightness - don't underestimate this.  A narrow beam fixture will seem much brighter than a wider angle fixture of the same wattage, but it may not cover what you need it to cover.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 17, 2019, 02:45:12 PM
Jeff, thank you for your feedback. That's the price for 2 fixtures, BTW,  not one. I get them for $72 each with the volume discount. I hear you that it is a gamble. That's why I try to do my research and get feedback like yours. These look solid, but looks can be deceiving. I wish this light had a bunch of reviews on this light already...but for the most part their lights get high reviews.

Glad to hear our input is useful.  As far as the ebay and direct from China lights go...  It's a gamble.  Several members here such as Steve Garris have had excellent luck with the very cheap generic fixtures.  If that's the route you'd like to go I'd suggest searching the forum for his suggestions.  I personally choose to use at least lower-end name brand fixtures such as Chauvet SlimPar Pros and above - it just aligns better with my business model. 

Either way, I'd never spend $123-180 per fixture on LED Pars from AliExpress.  $30?  Maybe, if it fit what I needed.  For the same $123-180 you're in SlimPar territory, and I'd take one of those anyday over a generic fixture.  Output quality aside, I know I have a warranty that will be honored and replacement parts that will be available - two things that are very scarce with direct from China fixtures.  I vote to either get the $30-60 lights that Steve often recommends or spend the budget you have now on something from a reputable supplier.  Hope this helps!
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Rob Spence on January 17, 2019, 03:02:30 PM
Note the spec says nothing about brightness.

Watts is heat, not light.


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Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Earl Teigrob on January 17, 2019, 03:27:17 PM
Watts is power. In electrical terms, this current (I) * Resistance (R). Power can be consumed as light, heat, energy, work, ect. LEDs convert more of the power to light then the old bulbs did, thats why they are more efficient and run cooler.

In the old days when you bought a 100w incontinence bulb, you know about how bright it was going to be. Same wtih LED's in general

The bottom line is that for a given wattage, the same type of LEDs produces around the same light output, give or take a little.

In the case of LED lights, wattage gives you a good idea of about how bright the light is going to be.



Note the spec says nothing about brightness.

Watts is heat, not light.


Sent from my iPad using Tapatalk Pro
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Dave Garoutte on January 17, 2019, 04:47:24 PM
But not how bright the 'stage' will be lit.  The 'beam' angle has as much to do with it as the power.
The effective brightness changes by the inverse square of the change in beam angle; twice the angle has 1/4 the brightness.
( That pesky inverse square again! )
That's why you need to look at the lux at x meters to really make a valid comparison or evaluation.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: TJ (Tom) Cornish on January 17, 2019, 04:58:56 PM
Watts is heat, not light.
This is roughly true, however considering LEDs of similar vintage - technology within the last couple years - efficiency should be similar, meaning that a 200 w LED fixture will create approximately twice the lumens that a 100w fixture would (and twice the heat).  If you're designing a space shuttle and need to know the absolute answer you'll get an integrating sphere and measure everything.  Short of that, comparing power consumption is as good or better than anything else.

Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Rob Spence on January 17, 2019, 06:39:29 PM
This is roughly true, however considering LEDs of similar vintage - technology within the last couple years - efficiency should be similar, meaning that a 200 w LED fixture will create approximately twice the lumens that a 100w fixture would (and twice the heat).  If you're designing a space shuttle and need to know the absolute answer you'll get an integrating sphere and measure everything.  Short of that, comparing power consumption is as good or better than anything else.

I buy that from reputable companies using known LEDs.

At the bottom of the pile you may find a 100w fixture half as bright as another.


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Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Jeff Lelko on January 17, 2019, 06:55:05 PM
At the bottom of the pile you may find a 100w fixture half as bright as another.

And that's another reason why I personally don't use direct from China lights - the consistency between units can vary greatly.  If this is a route that you (Earl) still would like to pursue, I'd at least suggest buying from Amazon if possible - somewhere that has a generous return policy so that you're not stuck with dysfunctional units should some be DOA or out of family with the others. 

$72 isn't bad.  Is there anything in particular besides wattage that brought you to these particular units?  What's been said already is correct in that the photometric data is what you should be comparing - not wattage.  Should said data not be available you can get a ballpark idea of brightness from wattage, but other factors such as beam angle also need to be considered.  As far as reviews go, DOA issues aside you have to take them with a grain of salt, as you don't know the credentials or expectations of the people reviewing them.  I could say that a $30 generic light is great if I'm just a parent wanting something cool for a child's birthday party, whereas if I'm a theatrical lighting designer I'd probably have much different feelings about the same light!  All food for thought though. 
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Dave Garoutte on January 17, 2019, 09:43:34 PM
There are a few things that effect the cost of LED fixtures;
Build quality - the likelihood of a long life.
LED quality - the better the consistency in color and output between individual LEDs, the more it costs.
Support - can you call someone with problems?  Can you get parts?

IMHO you get what you pay for.

Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Len Zenith Jr on January 17, 2019, 11:57:36 PM
One of the biggest differences between cheap lights and more expensive ones are not in the LED's themselves but the electronics that control them. Where you notice this the most is in the dimming curves of cheap vs pro lights. The cheap ones tend to go down in steps then suddenly cut out, the pro ones are much more smoother.

Also, Chinese lights rarely have any CSA/UL listing which might matter a lot if this is an install. Inspectors/insurance companies may have a big problem with that.

If you go with the lights in the link you provided with the aluminum housing I would also be opening them up to make sure that the aluminum shell is grounded. Chinese lights often fail to utilize the ground plug on the IEC connector inside the unit. A fault inside the light could energize the housing and potentially the entire truss without it.

Just a heads up so you know what you are getting into.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Noah D Mitchell on January 18, 2019, 10:50:14 AM

In the old days when you bought a 100w incontinence bulb, you know about how bright it was going to be.


I interrupt your discussion to ask where one might purchase 100w incontinence bulbs.


Asking for a friend.


Carry on.
Title: Re: Understanding LED Par Light Wattage Ratings
Post by: Dave Garoutte on January 18, 2019, 12:19:32 PM

I interrupt your discussion to ask where one might purchase 100w incontinence bulbs.


It depends.