[hasselbaink]

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PDN.18BR40 is the name. 97 db sensitivity which is good, Fs 27 Hz could be deeper but I'm not complaining, Qts 0.336, Xmax 10.5 mm. That is a good value for open baffle.

Graphs here: http://www.precisiondevices.co.uk/asps/uploads/super/77.pdf

Notice that the amplitude is above 90 db all the way down to 30 Hz! Looks like it could be crossed to a fullrange unit at 200 Hz.

Does anyone have experience with the Precision Devices brand? Give me your opinion.

BTW. I do not drive my speakers actively.
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[srb]

Looking at the bulleted features list, I notice it has a "Field replaceable magnet".  (one of the other bullet features is "Bass") 

I've seen surrounds and voice coils go bad, but don't recall ever seeing a magnet needing replacement.

[JoshK]

Looks like a nice driver.  How much?  I'd call that driver 94-95db/w for the range your interested in using it for.  The only thing that might make this driver tricky to work with is the rising impedance with freq.   This may or may not be a problem, but inductive modulation can produce higher nonlinear distortion sometimes with drivers with higher impedance at higher freq.

I'd also compare with 18Sound's 18" neo offerings.  Their higher end woofers use active impedance control specifically to get around this issue.   Then the Ciare 18ndw1 (i think that is the right acron.) is also a force to be recon'd with.  Both of these woofers are quite reasonably priced and are apparently easy to source in Europe.

[hasselbaink]

I'd also compare with 18Sound's 18" neo offerings.  Their higher end woofers use active impedance control specifically to get around this issue.   Then the Ciare 18ndw1 (i think that is the right acron.) is also a force to be recon'd with.  Both of these woofers are quite reasonably priced and are apparently easy to source in Europe.

I remember the price of 18Sound drivers to be a bit on the expensive side and I'm not really impressed with their Fs. They look like typical PA drivers but I am sure they are excellent at what they are supposed to do. The Precision Devices are about 180£ a piece (350$) in the UK, including VAT.
They look very well made.
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[JoshK]

The Ciare's are $220/ea here and the 18Sounds are ~$250/ea iirc.  They could very well be more expensive in EU, most everything else is.  The Fs of the Ciare's are 29hz and the 18Sound 9300 were 31hz and the LW1400 were 35hz.  All in the same ballpark imo. 

I am not arguing for either of them, I just thought I'd offer some comparable woofers to compare to.  18Sound & Ciare both have exceptional reputations for build, quality and sound.

[el`Ol]

The Ciare HW450 has lower Fs than Ciare`s pro drivers.
From the other specs it looks a bit deplaced in the home section.