Clearance will help for a bigger coil, and depends. For example on the original BLF GT buck driver DEL designed, he had designed in more amp capability, think ~5 amps or so, if I recall.Of course there was plenty of room on that driver in that light.
Can someone to tell me what is the driver diameter of new S21B. It is 22mm? From Simon store I saw that XHP50.2 version used the new 3A boost driver which is 22mm. Also now we also have very good buck driver for 3V in 22mm so we have nice S21B host for new switching drivers from Convoy, if it used 22mm drivers.
It is 22mm.
Thanks.
Can’t wait to mod my L6 with FC-40 and a 4A driver, Simon please make it happen 
Anything change? 
To be more precise, since output data was collected each 0.25A, we need to analyze previous and subsequent data:
- 2.25A: 2500 lemmings
- 2.50A: 2570.
- 2.75A: 2580.
- 3.00A: 2530.
Peak was somewhere between 2.5 and 2.75A. Since 2.25A shows a lower value than 3A, we can infer that the peak was closer to 2.75 than to 2.5A, probably at ≈2.66A.
Test data shows that at 2A output was already above 92% (2380/2580) of the measured peak, and 96.9% at 2.25A. In my opinion, 2.1A is already hot enough (close to 94%), imho. There's simply not enough XHP35 test data, just (!) one test. For a driver which must be paired with all sorts of XHP35 emitters, I think it is wiser not to go overboard. Not all emitters peak the same, check SST-20 tests for example: 6500K (peaked at ≈6.75A), 4000K (peaked and died at 7A?), 3000K (peaked at ≈6.15A).
One more data point, Koef3 with his more powerful cooling setup observed a peak at 3.2A:
But I agree, 2A is enough and 2.1 is even more so. I’d go with no more than 2.25 and even that only as a Turbo mode or in a huge host.
Gents don’t forget we’re asking Simon for Amp increase for use with FC40 emitter.
Present 2.5A driver is more than enough for tiny XHP35
14500/AA headlamp with LH351D and low (< 0.5 lumen) moonlight when? 
and accessible so I can swap out the emitter if desired
(Simple Olight/thrunite UI plz)
I should learn these 3D modelling apps…
Just to clarify, will there be a listing for completed M21C w/FC40? I would be extremely interested in that.
Before the Chinese New Year, we have to stock up for many customers, and the employees are also unstable. After about 3-7 days, I will update the product link.
That’s great! No rush, just wasn’t sure if the completed light or only components for modding were being discussed.
Simon, will there be black S11 with a reverse switch?
This driver? Specs say 2.3A maximum. Tiny bit high for XHP35s imho, but bearable.
On the other hand, just 3A for XHP50s here and there is comparatively low. XHP50 tests show peaks a little above 9A (XHP50.2 J4 3A by djozz, XHP50 J4 1A by Texas Ace) and at 11A (XHP50.2 J4 4000K by Texas Ace) on testbeds. A ≈6.5A driver would allow better squeezing of these big emitters without being over the top… 
Are orders still being shipped out? Hoping my emitters go out ASAP (and that the more expensive shipping options are actually quick)
Simon, very serious question on behalf of many here. You seem to have access to early samples of emitters from Luminus like the SFT-70. Whoever your source is, could you inquire about potential availability of 95CRI SST-40 ? We’re missing a good 5050 HiCRI option.
+1 - really wish there was effectively the sst20 4000k but 5050. Anything 4000-4500k 5050 with good CRI.
I can give feedback to Luminus, but I feel hopeless.
I can ask Getian to produce some 5050 90CRI LEDs, but the brightness may not be very high. Are you interested in this?
it’s reverse switch by default
Very interested.