SW-12A seems to be a decent 12 inch

[mannthey]

From GR Research. I am not sure who makes is but GR Research dosen't sell junk stuff.

SW-12A parameters:
Mechanical Parameters:
* Fs = 20.5 hertz
* Qms = 4.85
* Vas = 3.56 cu.ft or 101 liters
* Cms = 0.057 in/Ib
* Mms = 5.964 oz or 169.1 grams
* Rms = 9.843 Ibs/sec
* Xmax = 16 mm
* Sd = 72.5 sq.in or Dia = 9.6 in or 244 mm
Electrical Parameters:
* Qes = 0.440
* Re = 6.7 ohms
* Le = 5.16 mH
* Z = 8.0 ohms
* BL = 18.5
* Pe = 200.0 watts
Combination Parameters:
* Qts = 0.40
* Sens = 87.03 dB (2.83 V)

I just happened onto the driver and thought others might want to know.

[ThomasW]

Don't know about you, but I certainly wouldn't use a driver with an Le of 5.16 mH.

For comparison purposes look at the driver being discussed in this thread.....
ibsubwoofers.proboards51.com/index.cgi?board=talk&action=display&thread=1127588266

[mannthey]

Is there a list of suggested reqirments for an IB driver. I didn't know an Le of 5.16 mH was bad for IB.

So far I know
xmax > 10
Qts < .5

Thanks.

[ThomasW]

I didn't know an Le of 5.16 mH was bad for IB.

It's higher than I'd want for any alignment, let alone an IB. The goal is to have a low Le, that's why I linked to the thread about the new RS drivers from PE.

Xmax, 14-16mm or higher.
Qts, around 0.5,
Fs, midteens is nice.
Vas, low is nice but not mandatory depending on the particular install

[mannthey]

Lower vas == lower distortion? 2 12's are better than 1 15? Cost not a factor.

It seems to me with an IB the power is low to the driver (IE the motor dosen't work as hard) distortion caused by the larger cone area would not be a big factor.

[ThomasW]

Lower vas == lower distortion?

Nope, but generally speaking the lower the Le the lower the distortion

2 12's are better than 1 15? Cost not a factor.

Not necessarily just depends on the T/S of the drivers. 2-12"s will give roughly 30% more displacement than a single 15". So buying multiple 12"s to get the same displacement as a pair of 15"s isn't a cost effective approach.