P4 vs Q5

everyone out there with both of these led's.... can you really tell a big difference in the brightness??? or is it all just a numbers game???

If you have any thoughts/experiences... let me know...

KraZy

krazy89 said:

everyone out there with both of these led's.... can you really tell a big difference in the brightness??? or is it all just a numbers game???

If you have any thoughts/experiences... let me know...

KraZy

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P4 - 80-87 lm/350mA
Q5 - 107-114 lm/350mAh

So Q5 is anywhere from 23% to 43% brighter than a P4 at a given current.

For more info, check out:
https://www.candlepowerforums.com/threads/156772

Sorry if this is a thread hijack... but its kind of relevant.
Does the Q5 emit more L than the P4 for all drive currents? Or are there some current levels where they level off?
Does the P4 need less heatsinking than the Q5?

kramer5150 said:

Sorry if this is a thread hijack... but its kind of relevant.
Does the Q5 emit more L than the P4 for all drive currents?

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Within operating range, yes.

kramer5150 said:

Does the P4 need less heatsinking than the Q5?

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Q5 emits less heat at a given Luminous Flux level, because less drive current is required to achieve it. However... because the differences are within less than 2-fold of each other, using the same amount of heatsinking is only prudent.

In the end, if there is a 20% difference in dissipated heat at any given luminous flux, it likely doesn't warrant a redesign.

Furthermore, most people prefer higher flux with incremental bin upgrades, and this allows to keep the same circuitry for subsequent bins, so the issue is largely moot.

That being said, a counter-example I know of, is Gene Malkoff's M60LL dropin, which uses a Q5 to produce something like 80 lumens for almost 8 hours on a single set of 123s.

Just to be sure, you are talking about the Cree P4 bin, and not the SSC P4, right?

You can tell a difference in brightness, but it isn't dramatic. I think the rule is you need 4 times as much light to look twice as bright? So a Q5 isn't going to look twice as bright as a P4 by any means.

The Fenix P2D P4 was rated at 135 lumens, the P2D Q5 is rated at 180 lumens. It's noticeable, just not dramatic.

There should be a visible difference but not significant.

The P4 should need more heatsinking then the Q5. The Q5 is more efficient, meaning the LED produces more light and less heat for a given power.

Presuming the Cree XR-E P4 bin VS the Q5 bin.

I thinks it depends on how the led is being driven. I have a p4 cree dx1447 at 900mA that is probably as bright as some underdriven Q5's.

Is he talkin about SSC P4 vs Cree Q5 perhaps?

hey guys...

well... cree p4 is $5.... cree q5 is $9...

that's a whopping 1.8x in price... i know.. it's only $4.... but i can almost get 2 p4's for the q5 price....

i'm just trying to justify modding with P4's rather than Q5's....

then again... i guess this is just like computers... it's always a huge premium to get the latest and greatest.... however, for myself... i don't like being left behind... but at the same time... don't wanna be at the front...

so for me the P4's seem to be the sweetspot for price/performance...

KraZy

What about Cree R2's?

meuge said:

That being said, a counter-example I know of, is Gene Malkoff's M60LL dropin, which uses a Q5 to produce something like 80 lumens for almost 8 hours on a single set of 123s.

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So if Gene can do it, why can't or don't other manufacturers do the same? I've been wondering about this for awhile.:thinking:

roymail said:

So if Gene can do it, why can't or don't other manufacturers do the same? I've been wondering about this for awhile.:thinking:

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Some do, it's just a matter of the right drive current.

I have several cree P4 lights that are excellent and very bright. I can hardly tell a difference between them and my Q5. A lot depend on drive current and reflector size and quality. A good u bin seoul SSC is also an excellent choice in many cases.

So if Gene can do it, why can't or don't other manufacturers do the same?

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Gene holds a unique position in a niche market that few other makers want to enter. He has developed brand loyalty similar to Harley-Davidson, because he provides leading edge designs made to the highest possible quality standards.

Most makers who install an XR-E Q5 will drive it at or near the max ... and Malkoff does this too in the original M60. But no one else offers a Q5 driven at 80 lumens for 8 hours, probably because the demand is not great enough to justify the cost. For me, the combination of beautiful color temperature, near perfect beam spread, long run time & highest quality were the reasons. Most people will settle for less, as long as it costs less.

roymail said:

So if Gene can do it, why can't or don't other manufacturers do the same? I've been wondering about this for awhile.:thinking:

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From a larger manufacturer standpoint there are 2 reasons I see:
- Simplicity - Less need to reengineer driver circuitry. Just slap in the new LED for the "updated model" and get brighter with the same runtime.
- Marketing - The brighter is better phenomenon. Slap the new higher lumen number on the marketing and its "better". Even among the obsessed here there's a strong brighter is better preference, I have noticed, let alone for those less educated about lights. So the market provides what is easy to advertise, and is generally asked for.

Gene designs a dropin to service a very specific niche of the market, not to sell thousands of lights. At least someone does. :twothumbs

krazy89 said:

hey guys...
well... cree p4 is $5.... cree q5 is $9...

then again... i guess this is just like computers... it's always a huge premium to get the latest and greatest.... however, for myself... i don't like being left behind... but at the same time... don't wanna be at the front...

so for me the P4's seem to be the sweetspot for price/performance...

KraZy

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I dunno, for $4, I would just get the better bin. R2 is the cutting edge anyways, Q5 is merely high end at the moment.

If you want the best performance out of your mods, may as well get the Q5. I do know a few people willing to sell you P4s tho I'm sure.

:naughty:


I decided the same thing with my mods. I only do seoul mods, but it's always the ones from PhotonFanatic. Not worth the risk, cheaping out a few $ for ones from DX etc.

Please note, that sometimes (sometimes) the Q5s have higher Vf so may draw more power than you'd like. DOn't know if this was universal or just early batches.

Great answers, guys... thanks for the insight. I'll have a M60L one day. :huh:

well... i know it's only $4....

but like i said... i can do almost 2 mods for the same price... so that is big price diff.... but in the end... it still is only $4... haha

i think i am gonna do the Q5 swap... probably more worth it... and later on... if it's not enough light... i can always just swap out the driver and put in a higher mA one...

KraZy

How do you guys know how to do this stuff. I'd love to be able to swap out parts like that. I'm pretty handy but I don't know a lot about electronics (I have a volt/ohm meter & soldering iron... haha!) Is it hard to learn... I'm willing. :thinking:

krazy89 said:

well... i know it's only $4....

but like i said... i can do almost 2 mods for the same price... so that is big price diff.... but in the end... it still is only $4... haha

i think i am gonna do the Q5 swap... probably more worth it... and later on... if it's not enough light... i can always just swap out the driver and put in a higher mA one...

KraZy

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