Victor

I'm also not sure how precise are the TS parameter numbers. If I have enough time someday, I may try to measure them. I do have a relatively good measurement microphone so technically it should be doable.
In any case, I'm extremely pleased by the performance and sound quality. In terms of the performance it's in a different league compared to my old 18" sub (on the picture on the left, B&C 18DS115-8)
I do have another such 21" driver and going to build another Skram soon.
I also have a 24 inch driver I bought on Alibaba, and will need to use hornresp to calculate the correct enclosure for it

One more happy builder of this excellent design! Going to make another when time permits.



I bought the drivers from China, for $450 + shipping. The TS parameters:

Ningbo Vejoworks Technology Co., Ltd
MODEL PR21SW150
coil winding height 48mm
top plate 18mm
XMAX ~15-21mm
Fs 28.3
Diameter 460.0000
Re 2.2
Z 4ohm
Rms 18.8 (calculated)
Qms 3.783
Qes 0.165
Qts 0.158
Cms 0.090
Mms 393.137
Mmd 352.897
BL 30.555
Vas 328.388
dBSPL 98.4
SD 1698.23

First post on this forum, hi Guys! Really like all the content here and wish I would find it sooner.
Looks like a pair of Ckrams is my next dream build. Big thanks for the design and detailed information! Frankly would prefer to build Scrams instead but the size and weight scares me (me and my spine, to be precise), don't think I can handle it. The biggest sub I built so far is vented B&C 18DS115-8 and so it's very interesting for me to see how a couple of NSW21 in Ckram cabs will sound. I will do some measurements after I'm done and will post here.