SI BM mkIII T/S parameters

[Electrodynamic]

The below parameters are with the dual 4 Ohm voice coils wired in series:

Fs: 15.8 Hz
Qms: 5.22
Qes: 0.421
Qts: 0.386
Vas: 130 liters
Re: 6.1 Ohms
Le: 2.4 mH
Sd: 490 cm²
Xmax: 14mm one way linear
Xsus: 16mm one way (coil hitting back plate).
SPL: 83 dB @ 1W, 1m
BL: 19.6 N/A
Mms: 263 grams

[Subwoofery]

hmm... Less sensitive than I expected. Believe the Mag was 87dB @ 1w/1m

[Electrodynamic]

But it works in half the volume the Mag v4 did, and if you want deep bass out of a small sealed enclosure you don't want an efficient/sensitive driver.

You can read why high sensitivity isn't a good thing for small enclosures by reading this paper we have hosted on our technical page.

[jdc753]

mmm 4 BM's sealed in 2cubes wired to my sundown 1500D at 0.5ohm

Can't wait to see how they look and hear they are shipping

[negative3five]

wow thats the lowest fs I ever seen Outa all the subs I tested the Ava was the lowest at 17hz...

[toyrunner]

When is it going to be available ?

[bill poster]

Originally Posted by Electrodynamic

But it works in half the volume the Mag v4 did, and if you want deep bass out of a small sealed enclosure you don't want an efficient/sensitive driver.

You can read why high sensitivity isn't a good thing for small enclosures by reading this paper we have hosted on our technical page.

Just my opinion but 83 db is not ideal for matching, wd be great if they were a couple of db higher per W, even if sacrificing a little here and there.

[bill poster]

After plotting this on winISD it looks like it needs a bigger box imo.. 55 litres optimum (??)

but I reckon a 10 or even an 8" version wd be killer.

[Electrodynamic]

Originally Posted by bill poster

Just my opinion but 83 db is not ideal for matching, wd be great if they were a couple of db higher per W, even if sacrificing a little here and there.

A more sensitive driver would have less low end. Mass (low sensitivity) is required to get LFE out of a tiny sealed enclosure.

[Electrodynamic]

Originally Posted by bill poster

After plotting this on winISD it looks like it needs a bigger box imo.. 55 litres optimum (??)

but I reckon a 10 or even an 8" version wd be killer.

You can put it in a larger enclosure if you want to but you will sacrifice power handling considerably (this is covered in our FAQ page). Qtc goes out the window when you put a woofer in a vehicle due to the +12 dB / octave you get at roughly 45 Hz. Bandwidth trumps Qtc for transient response (which is the Fourier Transform) and the BM mkIII will play flat to 20 Hz in it's tiny 0.5^3 sealed enclosure. Also the rise in that alinment is less than 1.3 dB, which is extremely hard to detect.

FWIW, WinISD is great for determining port length and extremely rough F3 estimates in an anechoic chamber, but that's about it.