What’s the word on details for that S21D replacement? How far out is it (e.g. start of 2023?)
Per Simon through PM today: “1 to 2 months.”
Might be in time for something under the tree. 
Think I will have to follow the Convoy thread and “click in” my order as soon as this thing is available. Would be very nice to get it as a “self serve” Christmas gift.
I am PM’ing Simon to ask if (hopefully) the new S21D will retain the same quad LED and TIR optic configuration. I hope it would as TIR optic in this light (and Emisar D4V2) produces a floody (“even”), near perfect (artifact free) beam for Nichia LED’s. To my eyes it is fantastic for close-up, around the house work, and for seeing the rosiness of 219b, or the neutral tint of 519a.
Per Simon regarding new S21D with side-switch and integrated USB-C charging: “the same lens but different MCPCB.”
I’m getting my CC ready 
.
Report on Nichia “BAM” with more use. This evening I took 3 lights for our walk, S21D w/ Nichia 219b, M21F with GT-FC40, and M21B w/ B35AM, all 3 with CCT 4500k. In actual use in nature (not white wall hunting), the beam colors are nearly indistinguishable, just a touch less magenta with BAM, and more “less magenta” with FC40. The main point here is they are much more alike than different.
Beam profile wise for short distance I actually prefer M21F-FC40’s balanced floody-throwy character, to M21B-BAM’s throwiness. For distance BAM is slightly better and a throwy beam is always more “fun,” for me.
I admit much fascination with CRI specs of B35AM. It manages to have a near perfect R9 spec of 99, the highest that I’ve seen. Many LED’s have high Ra, but… high R9 to reproduce red accurately is rare and difficult to achieve. I made a point to compare the 3 lights on red bougainvillea and some wild red-orange cherry along our walk. I just wanted to see what 99 R9 means, and BAM does indeed reproduce red beautifully, so very saturated.
Recommend this B35AM light extremely highly, and probably the bin that Simon has. For any collection it adds to, it would likely be the LED with the highest CRI rating. IMvHO it represents “state of the art” CRI in 2022 and an absolute steal at 30 bucks.
Beam profiles of 3 lights:
D4V2 = floody
M21B w/ FC40 = flood + throw
M21B w/ B35AM = throwy
Color of the 3 lights, showing gradual change in color from 219b to FC40:
219b is the classic rosy LED, more so than any other LED I have,
B35AM also rosy, but not as much as 219b 4500k,
GT-FC40 less rosy, more neutral (“golden”) yet.
All 3 gold standard for accurate color rendition IMHO.
OT - in case you’re interested. I think he has 3 ready for shipping and another person and I bought 1 each. The last one is waiting for you. :+1:
I don’t really need this, but just couldn’t resist another toy. Should be a lot of fun.
While waiting for new S21D, allow me to show my latest toy, Texas Ace’s Calibrated Lumen Tube. The key word being calibrated, and for me this alone is worth the price of admission. As I read through his thread here I realized that the cost of the tube is nothing compared to the blood sweat and tears that would befall me were I foolish enough to try to make one, let alone one that’s calibrated.
Note the 3 diffuser membranes, and the little black tape that’s part of the calibration. (I thought the idea of the black tape is ingenious but maybe I’m too easily impressed.) I have 4 light meters including one for my hometheater stuffs and they more or less have 4 different brains (4 different readings for same brightness) so I understodd immediately why the tube and meter together are calibrated as one unit.
The quality is beyond reproach; everything fits tightly and solidly. It is truly plug and play and already calibrated so there is no multiplier to worry about. You just read off the numbers at the meter, as simple as could be. Preliminary, the readings match factory specs of only my Fenix and Nightcore lights. For situations where factory specs are on optimistic side, the Texas Ace Tube matches trusted reviewers’ numbers, for example those of the amazing TS30S by 1lumen and Zeroair. I am not in the business, nor am I a “reviewer” by any stretch of imagination, so honestly still wondering why I bought it . Kidding aside it’s absolutely fun to use for exploring and comparing lights, and I’d recommend it extremely highly.
^ Excellent! Looks like such a well though-out design. You’re going to have a lot of fun checking the output of all of your flashlights!
It looks nice, well done! ;)
I'm working on my new Ulbricht sphere DIY, little by little.
Cool, Glad you like it!
@ Argo: Very nice. Best of luck and have fun. I have no experience but just from reading Texas Ace’s thread it seems the calibration part could be quite hellish?
The TA Lumen Tube came with 5 discs of different opening sizes. Note the reflective aluminum tape on the side facing the lumen tube’s interior. For measurement it doesn’t have to be exact fit between flashlight and opening, but tighter fit is better and IME so far shows higher reading. More importantly a tight fit means I don’t have to stand there and hold the light during a runtime check, so I’m making custom made disc using cardboard box.
Because of my (very) slight problem with OCD, I asked TA what exact brand aluminum tape he used, and if I may paraphrase, TA said just chill and get the cheapest one from Home Depot lol (he said “best deal” not cheapest ). Kidding aside, I found only one at Home Depot and the size and reflection seem same as what TA used.
If the charging port is hidden under some kind of metal cover ( like a mobile metal part with a thread or something) i`m in 100%. If is with a rubber cover like all the rest i`m only 30% in. I`d even like the side switch without usb charging port option.
If I have to guess it would have rubber cover, similar to the side-switch Convoy M21E and M21F pictured below.
The old S21D has a beautiful smooth floody/”diffused” beam that, for me, is the best way to appreciate color rendition of Nichia (as opposed to a throwy beam with bright hotspot). Besides USB-C and side-switch, I hope Simon keep all other aspects (TIR optic, etc.) the same. Can’t wait for its release.
With a sphere there is less problem of calibration:
you just have to multiply the lux by the square area to know lumen output.
knowing the radius of the sphere is a breeze.
It is important to treat the sphere internally with the appropriate paint after having applied a suitable base.
I already have the primer and the paint, this weekend I should work on this sphere hoping that everything goes for the best. fingers crossed.
@Argo, that sounds like a lot of fun - best of luck! I just looked at some integrating sphere videos on youtube. It seems so complicated but that could just be my brain not absorbing science anymore.
Will you be using one of those “inexpensive” light meters from China? They have so much variation from one another. I have 4 including Opple and they read 3-4 different numbers 
, probably the most inconsistent of light parameters I’ve measured. (This why Texas Ace calibrates the lumen tube with its light meter as one unit.)
yes you are right but I will use a philips e27 with declared number of lumens, cct and CRI, to have a reference on the reading of the luxmeter and light master.
yes Chinese instruments also have a large confidence interval on measurements, so I have to take this into account too, but I’m not a professionist, I don’t care about absolute accuracy, but making measurements all with the same error in order to be able to compare the various flashlights I own.
however the sphere is the best geometric shape to have repeatable and reproducible values with the various flashlights.
(EDIT: Updated with more info and comparison with Convoy newer light S21F 4/23)
Thermal regulation of S21D has been a puzzle and topic of discussion for a long time. We know it’s there because output goes down within a few minutes, but… output then stays at a constant level of about 40% of max (and NOT lower) even temp remains high.
In nearly all other lights, including the newer Convoy light S21F for example, output would drop much lower than 40% and temp regulation clearly active as shown by a zig-zag runtime curve. As temp goes up, output goes down, as temp goes down output goes up, etc., resulting in the zig zag pattern. S21F for example would zig zag to keep temperature for example would stay in the 40’s centigrade. Not so S21D - you would see a straight line as illustrated below. (I hope I’m making sense here LOL.).
The bad thing is it could get really hot as owners have found out. The possibly “good” thing is that sustained output is higher and more stable than any other quad Nichia lights that I have.
Well, the design is very much overdriving the emitter and the heat dissipation capacity of the host is far exceeded…as the current drops the emitter is still supplying waste heat so the saturated host isn’t going to cool down quickly. Starting on the lower current mode never supplies as much heat to begin with, but the host does saturate eventually of course. Aluminum is good at dissipating heat but there’s a point where physics wins so we either shut the light off, provide cooling, or switch to more mass in the host (which only delays the inevitable when such heat is still being supplied at the source).
If your DMM will take a thermocoupler those are fairly inexpensive and can be taped to the host for better readings (they are notoriously inaccurate between the thermocoupler itself and then the meter inaccuracy, but in this case they will at least be consistent even if they’re off by a number of degrees). IR guns are tricky to use correctly and get their rated accuracy. Some black gaffer’s tape or berlin black will go a long way to repeatability as long as the distance is correct for the emitter in the gun.
An important note: As expected, in a larger host with more thermal mass/- less heat+ from LED, the temperature does not get nearly as high as in S21D, and the temp difference is much smaller. For example in my M21B with single Getian GT-FC40 LED (vs quad Nichia in S21D), at 30 min mark, T-35% is about 55-56 C° and T-100% is about 57°C.
For me the most interesting question arising from the graph: If there is temperature regulation, why did brightness not decrease further from ~37%? IMHO, there’s a trade-off involved with this algorithm: On the plus side Convoy lights have great sustained brightness that I love, on the minus side, small hosts with multiple LED’s like S21D could get very hot. (Not complaining, still buying mostly Convoy lights. 
)
As always I should note this is a home test done indoor, not some professional lab w/ actual internal T monitoring outdoor, so although I think it’s done carefully and results correlate with actual observations (S21D feels very hot during my walk, etc.), pls take with a table-size grain of salt .
I don’t know if anyone has found a definitive answer for how this works in Simon’s recent drivers other than simple observation like this. It’s probably something as simple as “if T=x then I=x” without any sophisticated regulation. Simon would have to answer that, and/or he may need to ask his driver manufacturer about the details. But it’s just how this driver works. I don’t want to put words in his mouth but it seems like he’s maintained a perspective that max/turbo is just for brief use (as it was always mostly intended…because heat saturation) so straight run graphs like this don’t equate to real world use for most users. I’d mostly agree with that, and for those that do need to run higher outputs for longer times, well, you let physics dictate the host you buy for the arrangement of emitters and current delivery.
This is a lot like bringing a pot of soup to a rolling boil and then turning it down to simmer vs. bringing it to a point that is just below simmering. The burner is never turning off.