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Thread: Cree XM-L vs. Luminus SST-90?

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    Default Cree XM-L vs. Luminus SST-90?

    Can someone give a brief explanation in the difference in these two emitters? I am a novice and have searched both this site and Google and can't really find a simple answer. I'm considering two similar lights with these two emitters and wondered the difference in throw / flood, etc. Thanks.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    The XM-L can be run up to 3 amps and is a smaller chip

    The SST-90 can be run at up to 11 amps, so it will put out more total light, but it's a larger chip and older generation so it will be dimmer for a sharply focussed image, even when drawing a lot more power.

    Go to the Cree and Phlatlight sites to download the datasheets.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    XML is good to about 1000 lumens if sinked well. SST-90 is good to about 3000 lumens. But compared to each other, the SST90 is huge next to a XML. Maybe 7-8X bigger, maybe more. The SST90 needs to be in a big flashlight to make it throw due to its size. In smaller lights it makes a great flood though.
    Keep it between the ditches and the shiny side up.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    J: Which lights are you looking at?

    H: BTW, welcome. I'm pretty new too.

    J&H

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    Default Re: Cree XM-L vs. Luminus SST-90?

    The SST-90 has an emitter surface area of 9 square millimeters. The XM-L's emitter is 4 square millimeters. Thus if you're looking for a light that can project a tight beam a long distance, the SST will require a much larger reflector. The SST also requires much more amperage to reach its maximum output. That means more and/or bigger batteries unless you're willing to settle for significantly decreased runtimes. This increased amperage also creates lots of heat rather quickly. Figure on seeing 1800 to 2200 actual "out the front" lumens from the SST-90 in most lights. Conversely, the XM-L is more efficient but only capable of around 750 to 1000 lumens in most lights. Still it will provide very good throw with a relatively smaller reflector.
    --Semper Fi--
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    Default Re: Cree XM-L vs. Luminus SST-90?

    The Luminus SST-90 is a 3mm x 3mm square for a total of 9 mm square die size.
    The Cree XM-L is 2mm x 2mm for a total of 4mm square die size.
    The Cree is newer in design, so it is more efficient.
    The Cree XM-L can be driven up to 3 amps within recommended specifications to produce 1000 emitter lumens.
    However old, the SST-90 is still much larger in size, so it can withstand more heat build-up, thus it can be driven to 9 amps in recommended specifications to produce some 2200 emitter lumens.

    Because the SST-90 is larger in size, and produces more lumen output, it will tend to have a larger hot spot, and have a brighter spill, and more overall flood.

    I am not exactly sure of the surface brightness of the SST-90 versus the XM-L, however from my memory, the SST-90 is no slouch in surface brightness at all - in fact it's surface brightness is better than the old XPG-R5, and only slightly inferior to the very old XR-E R2.
    Thus, throw will be mostly dictated by the diameter of the reflector, not the surface brightness of the emitter.

    Btw, just because the surface area of an emitter is large, it doesn't necessarily mean that it's surface brightness will automatically be low.
    Also, just because the emitter is larger, it doesn't mean that it must have a proportionately larger reflector to throw as well as the smaller emitter.
    These are common mistakes I use to make myself in the understanding of throw etc.

    Don't focus too much on paper specifications, and generalisations about emitters.
    At the end of the day, the best way to compare the two flashlights is to switch them on, and test them side by side.
    If not possible, look for youtube videos of their beam performance to help.
    Or if worse gets to worse, start a new thread on cpf like this one, for help...
    Last edited by peterharvey73; 11-26-2011 at 12:12 AM.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by peterharvey73 View Post
    Thus, throw will be mostly dictated by the diameter of the reflector...

    Also, just because the emitter is larger, it doesn't mean that it must have a proportionately larger reflector to throw as well as the smaller emitter.
    I appreciate your attention to detail, but two such seemingly contradictory statements might be confusing to someone like the OP who's relatively new to the high performance flashlight game. If we control for the most important variables (i.e. limit ourselves to discussing reflectored lights, assume that the manufacturers have selected reflector shapes that are reasonably well suited to the respective emitter sizes and allow for similar surface brightnesses) then it's generally the case that the larger emitter will require a larger reflector to match the throw of a smaller emitter.
    --Semper Fi--
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    Default Re: Cree XM-L vs. Luminus SST-90?

    to make it short:

    the XM-L is the newer one and can give really MUCH light.
    the SST is older, can give double than that really MUCH light but needs 4 times the power for it.

    when both are inside a housing that can move the heat away from the led - that is necessary!!! -
    the one with the XM-L will get really hot,
    the one with the SST will get burning hot, coocing the led to death.

    the XM-L (which is floody in itself) will give a "tighter" beam, while the SST will be some kind of a flood beam.
    Like double (?) the diameter.


    PS: I con not think of any battery source that might be able to power up the SST, when it really can be driven with 11 Amps.
    Even the 2.8 A for the XM-L is hard for most setups (at least for some useable time)

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Both the XM-L and SST90 have Lambertian angular distribution - i.e. beamwidth of about 120 deg at 50% brightness.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by peterharvey73 View Post
    Thus, throw will be mostly dictated by the diameter of the reflector, not the surface brightness of the emitter.
    The surface brightness + the size of the reflector is the key to throw. Take two leds and put them in a reflector, the one with the highest surface brightness will have the best throw in any reflector. The reflector shapes the beam, but it focuses on a "point source". If that point on the led is brighter, the hotspot will be brighter. All lights have better throw in hi mode than lo mode because surface brightness is better in hi mode.
    Last edited by jorn; 11-26-2011 at 06:10 AM.

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    Thinking Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by peterharvey73 View Post
    The Luminus SST-90 is a 3mm x 3mm square for a total of 9 mm square die size.
    The Cree XM-L is 2mm x 2mm for a total of 4mm square die size.
    The die of SST-90 is 8mm diameter and the base is 10x11mm, this should be 50mm square die size?;
    http://www.luminus.com/products/SST-90_2_3543760270.pdf
    Last edited by HB021; 11-26-2011 at 06:09 AM.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    When talking about the image size etc all that matters is the silicon die size, which is 3 x3 mm for the SST-90 - the yellow square you can see through the lens. See page 9 of the Rev 7 Datasheet.

    No, it doesn't look 3x3mm, but that's because it gets magnified by the lens.
    Last edited by MikeAusC; 11-26-2011 at 06:55 AM.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by peterharvey73 View Post
    . . . . . The Cree XM-L can be driven up to 3 amps within recommended specifications to produce 1000 emitter lumens. . . . . .
    According to the SST-90 datasheet, the N3 bin delivers 950 to 1000 lumen at 3.15 amp.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    the SST-90 has a much bigger die than the XML, so it will require a bigger reflector to get it to throw. The SST-90 can be driven at much higher currents, and can achieve higher output than the XML.

    There aren't many flashlights using the SST-90, you are only gonna find SST-90 "searchlights" that are much bigger and bulkier. On the other hand XML are available on much smaller form factors such as 2xCR123.

    I'm guessing that are considering the Olight SR90 vs SR92 or RRT-3 or TK70, since they are more or less in the same size category. Not that the XML models use 3 XML chips and will give you more output than a single SST-90.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by yliu View Post
    the SST-90 has a much bigger die than the XML, so it will require a bigger reflector to get it to throw. . . . .
    The XM-L is 2x2mm, the SST-90 is 3x3mm - so does the reflector need to be 1.4mm wider ????

    Please explain why, and by how much, the reflector needs to be bigger.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by MikeAusC View Post
    The XM-L is 2x2mm, the SST-90 is 3x3mm - so does the reflector need to be 1.4mm wider ????

    Please explain why, and by how much, the reflector needs to be bigger.
    I don't really know how to calculate it but perhaps some expert could say, but it's not 1,4mm bigger it's more likely 30mm bigger (my guess is based on YouTube video looking at beampattern and size of the reflector). U'll need to take footprint size, die size, beamangle and surface brightness into consideration....

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    Default Re: Cree XM-L vs. Luminus SST-90?

    If you take an XM-L out of a Reflector/Aspheric that shows a focussed image of the die, and replace it with an SST-90 with the same surface brightness, you will end up with -

    - A hotspot that's 50% wider (3/2)
    - A hotspot that has 2.2 times the area (9/4)
    - A hotspot that's the same brightness.

    It's simple geometry and physics.
    Last edited by MikeAusC; 11-26-2011 at 10:34 PM.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by MikeAusC View Post
    The XM-L is 2x2mm, the SST-90 is 3x3mm - so does the reflector need to be 1.4mm wider ????

    Please explain why, and by how much, the reflector needs to be bigger.
    I think you'll need a much more wider reflector to compensate for the bigger die size.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    A closer comparison would be the Cree XML and the SST-50.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by yliu View Post
    I think you'll need a much more wider reflector to compensate for the bigger die size.
    Please explain why a 1.4mm increase in Die diagonal requires a "much more wider " reflector.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by MikeAusC View Post
    If you take an XM-L out of a Reflector/Aspheric that shows a focussed image of the die, and replace it with an SST-90 with the same surface brightness, you will end up with -

    - A hotspot that's 50% wider (3/2)
    - A hotspot that has 2.2 times the area (9/4)
    - A hotspot that's the same brightness.


    It's simple geometry and physics.
    Exactly. Or put another way, if you want the two emitters to project a hotspot of a similar diameter, the SST-90 will require a larger diameter reflector.
    --Semper Fi--
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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by Bronco View Post
    Exactly. Or put another way, if you want the two emitters to project a hotspot of a similar diameter, the SST-90 will require a larger diameter reflector.
    No, the diameter of the reflector is not what determines the size of the focussed image.

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    Default Re: Cree XM-L vs. Luminus SST-90?

    but its 99 % of what determines the size of the image,

    and constantly typing something else only raises additional questions of the ppl who dont know the whole thing


    short:
    with the SAME focusing device, a
    XP-G makes a small dot,
    XM-L makes a dot double the diameter (4 times the surface)
    SST 90 makes a dot of again (almost) double the diameter (to the XM-L)

    so when the goal is a focused, bright beam, a XP-G with 1/3 lumen less will still be brighter, while the other 2 will be floody.
    The "higher" brightness of the latter must be "purchased" with a considerably higher power consumed.

    ... or with a MUCH bigger (wider + deeper) reflector

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by peterharvey73 View Post
    . . . .
    We should never say that "the emitter is larger, so it needs a larger reflector to maintain the throw".
    I used to mistakenly think like this myself...
    Thankyou. And to answer the question about what affects hotspot size . . . . it's the focal length of the reflector/aspheric. And that's most visible in the curvature of the reflector/aspheric.

    Big reflectors/aspherics can have long or short focal lengths. Small reflectors/aspherics can have long or short focal lengths.

    Now if only Dr Jones were still around . . .

  25. #25

    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by Jekyll & Hyde View Post
    J: Which lights are you looking at?


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    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by MikeAusC View Post

    Now if only Dr Jones were still around . . .
    Good grief.

    Yes, that's exactly what a new member with one post who's just now being introduced to the hobby needs, a post graduate equivalency lecture on the esoterica of focal length and voltage sag from Dr. Jones. While we're at it, why don't we bring in a few M-Theory physicists to discuss the finer points of phosphor excitation at the sub-atomic particle level.

    All I'm trying to do is help the OP figure out whether he wants his light to throw well, flood well or do something in-between and then explain to him in very general terms what the likely real world consequences of that decision will be with respect to the emitters he's mentioned based on the current offerings of most flashlight manufacturers. Like it or not, because of the way manufacturers produce torches these days an XM-L based flashlight advertised as being primarily a flooder (think 4Sevens Quark MiNiX 123), is likely to look very much different from an SST-90 based flashlight advertised as being optimized for throw (think Olight SR-90). It may be helpful to the OP to understand how these differences are likely to manifest themselves in terms of length, diameter, weight, run time, etc.

    I think the kind of discussion you and Peter are trying to have can be very interesting and informative. I'm just questioning the appropriateness of such a focus in this particular thread.
    Last edited by Bronco; 11-27-2011 at 05:48 PM.
    --Semper Fi--
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  27. #27

    Default Re: Cree XM-L vs. Luminus SST-90?

    Quote Originally Posted by Bronco View Post
    Like it or not, because of the way manufacturers produce torches these days an XM-L light advertised as being optimized for flood, is likely to look very much different from an SST-90 light advertised as being optimized for throw.
    Yes, you're right - we're getting too technical for the new cpf member; we'll keep it simple.

    Just another very important point.
    We have three factors at play here:
    1) Emitter die size, eg
    - small XP-G @ 1.38x1.38=1.92 mm sq,
    - midsize XM-L @ 2x2=4mm sq, and
    - large SST-90 @ 3x3=9 mm sq.
    2) Surface brightness in lumens per mm square.
    3) Total output of light in lumens.

    Firstly, die size and surface brightness.
    We note that the size of the emitter or die, doesn't necessarily determine the surface brightness at all.
    The surface brightness, and hence the throw, can be whatever the engineers squeeze out.
    Note how the biggest emitter, the SST-90 can still pump out a whopping 300 lumens per square millimeter in surface brightness - better than the small XP-G, and the medium sized SST-50 @ 5mm sq.
    Thus, a big emitter doesn't necessarily have less surface brightness - a big emitter can have high surface brightness if the engineers wish so.
    Eg, if Saabluster or Ra Ma Sha uses active fan cooling or liquid cooling etc, they could overdrive the emitters even more, to produce more lumens, and hence more surface brightness within any particular die dimensions.
    We shouldn't be embarrassed by the term "overdrive", since overdrive only means driven harder than the manufacturer's maximum specs, but who is the manufacturer to set the maximum specifications in the first place?
    Only God knows what the maximum specifications really are.

    Secondly, die size and the total volume output in lumens.
    The big emitters certainly have more total volume output in lumens.


    Therefore, unfortunately we can't say that an XM-L is optimised for flood, while the SST-90 is optimised for throw.
    - Both the XM-L and the SST-90 can throw, depending on their surface brightness, [which I don't know exactly, but does not vary greatly].
    - However, when it comes to total volume output in lumens, the bigger emitters like the SST-90 wins hands down, over the midsize and smaller emitters like the XM-L etc!


    Effect of Reflector Diameter
    Note that both the midsize XM-L and the large SST-90, in a small 25 or 30 mm bezel diameter, are relatively floody; an excellent example is the Zebralight SC600.
    However, when both emitters are in say a large 60mm bezel diameter like a 2x18650 like M3X/Catapult V3/M3C4 etc, then both emitters become very throwy!
    When both emitters are in an oversized 100 mm bezel diameter like an SR90 etc, then both emitters become super-throwy!

    In fact, with a large bezel diameter of 60mm, or an oversized bezel diameter of 100mm, the only way to get flood here, is to use a "Triple Emitter" eg a triple XM-L which draws 3x 3 amps.
    A Triple SST-90 would draw 3x 9 amps = 27 amps; thus we don't see any triple SST-90's around.

    In short, the bigger SST-90 emitter etc is floodier than midsize XM-L.
    Meanwhile, both XM-L & SST-90 emitters are relatively floody in small reflectors.
    Both XM-L & SST-90 are throwy in large reflectors.
    One can be slightly moreso than the other depending on it's surface brightness.


    Surface Brightness vs Reflector Size
    We know both surface brightness & reflector diameter are important.
    Notice how surface brightness varies by only 20%, eg 250 lumens/mm sq versus 300 lumens/mm sq.
    However, notice how reflector diameter can vary four-fold or more! Four times larger!
    Eg a 23mm bezel diameter of a V10R versus the 106mm bezel diameter of the TK70!
    Thus, although we should pay attention to the emitter type and the surface brightness, we should pay a lot lot more attention to the bezel hence reflector diameter...
    Last edited by peterharvey73; 11-28-2011 at 12:46 PM.

  28. #28

    Default Re: Cree XM-L vs. Luminus SST-90?

    Very nice post, @peterharvey73!.. - Responding to the Op;

    Per CPF here; the XM-L (T6 bin) emitter can survive being driven at up to 10 Watts and, similarly, the SST-90 can survive being driven at up to 32 Watts! Respectively, that's 910 and 2250 emitter lumens; assuming that those emitters are dissipating all the waste heat they generate properly. That's why hot lights [pun intended] have to throttle themselves down to sustainable power levels after a few minutes.

    Fyi, 70% or more of said power must be dissipated as heat when operating at mid to max levels. Subsequently, the thermodynamics of a given flashlight body limits the maximum sustainable output more than anything else. Got fins? Size matters! Further, although the SST-90 can become almost 2.5 times as bright as the XM-L, the SST-90 requires more input power to generate the same number of lumens. But, the XM-L can't compete above 910 lumens without teaming up.. This is why triple-XM-L's are competing with single SST-90's for raw output numbers in the marketplace today; three XM-L @ 3A > one SST-90 @ 9A..

    Keep-in-mind though, if you want to focus & throw 800+ lumens within a nice beam-shot; you're probably looking for a single emitter SST-90 - as the preceding posts have excellently explained. As others have already said too; you've gotta consider the light as a complete unit - there are numerous trade-offs.
    Last edited by WmArnold1; 11-27-2011 at 06:00 PM. Reason: typos

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    Default Re: Cree XM-L vs. Luminus SST-90?

    Peter, I agree with WmArnold wholeheartedly. That was a very informative post presented in a way that is accessible to all.

    We may have had a very minor misunderstanding relative to your point below:

    Quote Originally Posted by peterharvey73 View Post
    Therefore, unfortunately we can't say that an XM-L is optimized for flood, while the SST-90 is optimised for throw.
    I've edited my original post to make it clear that I was referring to various production flashlights being manufactured with these emitters rather than the emitters themselves.
    --Semper Fi--
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  30. #30

    Default Re: Cree XM-L vs. Luminus SST-90?

    OP here - sorry I've had a real hard time posting to CPF in the past day or so. But wow, thanks to everyone for all the super informative and educational replies in this thread. I'm fairly sure I learned as much in this thread as I have to date here at CPF.

    As fyi, I was looking at some smaller lights - the Maelstrom S12 (SST-90) and the Maelstrom X10 (XM-L). Maybe I should be considering other makes / models? I'm just not familiar enough to look elsewhere yet. I have a Quark 123 and love it so I was sticking to what I know and appreciate. Those two lights are both running on the same battery and seem to be in the same host. I'd prefer a tighter beam on throw so perhaps I should choose the X10 this time?

    Thanks again to everyone.

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