[totti1965]

Hi Dave,

Oscar Wroending does the selection of the Hiquphones and you select the Excell W-18 E 001 Woofers.

Do you only do the measuring of the sound pressure over the frequencies or do you measure the Thiele/ Small parameters of each Chassis?

If you do,
Can you give us some statistics?

I think it is beautyful that the northcreek people did many many measurings in the Vifa P13WH-00-08 and so they can tell the average Thiele Small Parameters.

It is not easy to trust the manufacturer of the chasis!

For those who have not the possibilities to do their own measuring:

Do you have the exact average of your measurings   (Q ts;   V as and Fs)??


The Manufacturer (Seas) says:

Qts  0,34
Vas  37,0  liters

and
Fs   31 Hz


Normally they manipulate the truth a little bit (e.g.  the V as is slightly higher!)

[David Ellis]

I have measured 150+ of the W18s and they are pretty darn close.  The Fs is extremley accurate.  It hovers from 30-33hz.  The Qts hovers from .38 - .42, and the VAS is about 30 liters.  I must admit that my measurement jig is quite tedious at times, and that I keep an old driver for reference.

Unfortunately, I cannot provide solid "statistics" as I have not maintained a database of drivers.  

Probably the only significant W18 change I have found over time is a slight change in the roll-off shape around 2700hz a couple years ago.  A new batch of drivers measured consistenly about 2db higher at 2700hz.  This wasn't terrible, and luckily corresponded with the redesign of the 1801b crossover.  I learned that slight changes in the rubber surround material will impact the shape of the driver's natural roll-off.  The rubber surround material impacted the roll-off.

Overall, I am very pleased with the QC of the SEAS W18 woofers.  I have only sent 1-2 back for scratchy voice coils.  This is very minor IMO.  When this happened SEAS was VERY interested and very eager to research and fix the problems.  They are a very solid company.