You dont need any spacer. Maybe just solid central rod with thin tube for 21700.
Yes, I dont have decision for negative end springs. So let it be 3x21700.
I would like to see another successful triple design from Sofirn. IMHO, they did a solid job on the C8F. I think a Q8-inspired, C8F hybrid has a good potential, provided the design is nailed right. I think a triple design would make a good sweet spot. Plus, the cost–performance ratio would be desirable, as far as Sofirn is concerned, which means better pricing for the K6. By triple design, I mean three (3) strong LED emitters that can really deliver. As suggested above, XHP 50.2 makes sense considering the cost. The only problem, I think, is containing the heat. Maybe three (3) XHP 50.2 in 6-volt configuration at half of their max forward current?
Also, it would be superb if they could make the K6 host available for sale, in the same spirit and continuing the tradition of their C8 versions.
Suggestions above added! 
BTW, seeing some suggestions, I remind that Sofirn has a 3x18650 / XHP50 flashlight, reviewed here by Lexel .
Maybe this helps on thinking the design/functions of the K6 as well
Interested I want 3 xhp70.2 emitter and 4×18650
Suggestion added
Interested I want 3 xhp70.2 emitter and 4×18650.
Suggestions added!
BUT:
PLEASE NOTE that this is NOT a groupbuy !
This is a discussion thread about the possible specs of the new Sofirn model!
I listed your names (suratyu and Andybibbville) under the interest list for reviewers/testers, not for a “group buy!!
I had forgotten about that.
After re-reading the review, it might be a worthy venture for Sofirn to address the shortcomings and produce a great performing light, even if they go with a different platform (4x18650 and different emitter setup).
I wonder what pricepoint they’re going after. If it’s going to be less expensive than a Q8 or similar 4x18650 lights that have been released recently, what options are they willing to lose? Simpler UI? Less machining? Less involved emitter setup? No spring bypass?
I’d say that dealing with heat and having an up to date UI are the most important features. Ramping is popular right now and I’ve got four lights with it and don’t really want anything else. I love my D4, but it makes me a bit nervous with the amount of heat on tap and the risk of melting/burning something (especially me!). XHP70 emitters put out a lot of lumens, but dang they get hot! I know practicality isn’t on everyone’s agenda, but I’d rather have a light that put out a good amount of lumens with a good balance of throw and flood instead of a hot rod. Making it moddable (no glue!) would satisfy those who want to tweak it and still keep it usable and safe for those who don’t.
Since Sofirn came on the market as a budget priced light, are they going to follow that model or is this going to be in the $80-$100+ price range? If it’s going to be less expensive, drop any ideas of changing ports and box candy. A few extra o-rings should do it.
Comments and questions added
NOTE
To the members that have already posted and that may post from now on, please do not update your previous posts if I already added the given suggestions.
You can “quote” yourselves on a new post and add the information there!
Or, if you want to update/edit the posts, please make a “EDIT” note so that I can easily spot what you’ve written recently!!
The only posts I wanted to be continuously updated/edited are posts #1 , #2 and #3, where emerging information is being added from the member’s posts or from other relevant things for the discussion/organization!
Sorry folks, but it is better for me to follow your suggestions this way! I hope you understand! 
Thank you :nerd_face:
Let me show you why i think 7 is best:
It uses almost all of the front surface, without dramatic cutting of the cups.
So no dramatic petals in the spill and decent throw.
(Yeah, i photoshopped it myself, couldn’t find a suitable picture…)
The difficulty with XHP LEDs is the voltage.
You’ll need expensive buck or boost drivers.
The .2 versions of these LEDs have some serious tint shift issues in aluminium reflectors.
You need more complicated battery contact boards too.
I don’t know what Sofirn wants to make, but it looks like a simple 1S4P battery set up, they’re thinking of 6 LEDs.
So why not 7? 
Either way, you don’t have to have a buck or boost driver to drive multiple LEDs in parallel.
I do hope they will choose a current limited FET driver though.
But this light would be awesome with 219C, but the beam pattern and tint shift problems would be better with TIR optics.
If they want to go for BIG output, they should use the new Luxeon V LEDs, have them run on 4.5 Amperes each, which means 31.5 Amperes in total, divided by 4 batteries is 7.875 (let’s say 8) Amperes per 18650.
Shouldn’t be a problem.
Luxeon V is quite good in regular aluminum reflectors.
And with their low Vf (forward voltage) you can run them current regulated for a good part of the battery charge, unlike with FET DD drivers (which is why i don’t like DD drivers, they’re actually not even drivers…)
understand this:
FET DD driver lights usually have high Vf LEDs like XP-L and XP-G2, because they don’t draw too much current on a freshly charged cell.
Batteries and low Vf LEDs can get into trouble with DD drivers, unless you use lossy springs and thin wires, which is just a lame solution.
I don’t know if Sofirn is into driver design, but it’s only a few more parts from and FET DD driver to a FET regulated driver.
Probably they want a LED board with all LEDs in parallel config, only need two fat wires (16 or 18 AWG should do).
But i’m no driver expert either…
With 7x Luxeon V it is quite possible to reach 14000 Lumen (before optics) on freshly charged (high drain!) cells.
Here’s a good example. DQG Tiny 26650. Even though it’s TIR
Thanks.
But the DQG leaves a lot of space unused.
I should have looked harder though :person_facepalming:
That’s from Sofirn store on AliExpress…
So they have the reflector already. :+1:
The one with 8 LEDs looks well spaced too.
You could run LEDs in pairs or fours with that.
With 8x Luxeon V it’s easy to get 8000 lumen, regulated for the most part of the battery charge.
Turbo could be 16000 lumen. 
Hmmm… Quite nice i.m.o.
(searched for “8T6”)
why not what looks like the acebeam x80 configuration?
Look at Acebeam X80 25,000 Lumen Flashlight Review - YouTube
Created by scannerguy1968
There’s not much left of the reflector cups, and with those big LEDs, it’s flood only.
But if that’s what you want, sure.
I also vote for 7 as most efficient reflector or TIR lens usage. Then don’t need to push every led so hard and they can work more efficient.
And I think battery carrier is better than fixed tube because it is easier to mod 2S2P and replace the leds with 6V ones
Thank you Sofirn for the opportunity to make suggestions.
The BLF Q8 UI is too complex. Three weeks with the Q8 and I still need to refer to the documentation. I’m about ready to reflash a cut down version of the firmware.
The K6 is a better balance between complexity and flexibility. I especially like the side switch battery indicator. The lack of strobes is another plus.
I’d like to see a 90+ CRI 4500K option.
Batteries should be 18650 or 26650. I don’t want to invest in another battery size.
4x 18650 is a bit too fat. How about 2 x 26650 in parallel? An oval cylinder battery tube might be easier to hold.
Is a single emitter possible? If it is I would prefer a single emitter in a flood pattern.
Hi there and a Happy 2018 for all of you
Thanks for the suggestions, only today I had the opportunity to update the post #2 with your words! If I missed something important, please let me know. :+1:
There are some things that are “shorter” others that are longer on the suggestions, because it is hard to understand if I cut the text in pieces. So I copy and paste more text!
Tracy Wan and Cissy are probably following this thread, so despite the texts are being “cut” they are able to see what is being said along the thread.
I don’t know (yet) if there is a deadline to give the suggestions. So, feel free to give your contribution here!
Also, please remember this if you want to update your posts
Next updates, if needed, will probably arrive later today or tomorrow!
Best regards to all! :+1: