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Get familiar with the reaction system: Introducing the Reaction System

Gradient Select Series 4" Paper Woofer 8 ohm

Not going to go into as much detail on this one as I just did with the 8", because of a couple things. Most importantly, the Qts is way higher than advertised so use as a woofer will be of limited value:

Loudspeaker parameters:

Fs  = 85.90 Hz
Re  = 6.52 ohms[dc]
Le  = 122.37 uH
L2  = 324.19 uH
R2  = 12.14 ohms
Qt  = 0.75
Qes = 1.01
Qms = 2.98
Mms = 6.21 grams
Rms = 1.126984 kg/s
Cms = 0.000553 m/N
Vas = 2.27 liters
Sd= 54.11 cm^2
Bl  = 4.663819 Tm
ETA = 0.14 %
Lp(2.83V/1m) = 84.38 dB

Added Mass Method:
Added mass = 15.00 grams
Diameter= 8.30 cm

Do your own modeling, of course, but if you are willing to tolerate a slight rise centered at 110Hz or so, a 6L vented cabinet tuned to 65 Hz yields similar extension numbers as the 8".  Also, the 4" I was unable to bottom out against the backplate, indicating a more correctly spec'd out soft part assembly. 

Impedance curve is very smooth, with no indication of the crazy "oh-shit lookit that cliff!" shown in the advertised response:

There is a mild wrinkle around 4K, but nothing too drastic. 

For reference, here is the advertised response:

They actually provide CSD waterfall, which shows heavy ringing at 4K or so. I think this might require some creative crossover work on the low pass side of things. See what I can do.

A perfect cosmetic match for the 8":

This should make for a very attractive, basic value oriented 3-way. 
I have a signature.
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