The thread title asks the question. How accurate are they? Are there manufacturing allowances/tolerances?

I have heard that most published T/S specs can be off by as much as +/- 20%, is this so for Soundsplinter?

I want to know mainly because I want to make a maximally flat (.707 Q) sealed enclosure for my RL-p15 d2 and no matter how I run the numbers, I end up with ~1.75 cubes (I am excited about being able to use such a small box). I know the website says 3 cubes, but is this a low Q design by intention?

Mike always recomends larger boxes than what simulation programs come up with in case of sealed designs

Unfortunately, there is always going to be some variance in the T/S parameters. These drivers are assmebled from a variety of metal and soft parts, and small variances in the production of a single part can in turn create a variance in the parameters. Additionally, all our speakers are assembled by hand, and of course not everything can be placed and glued in exactly the same manner as every other piece. We try to keep our tolerances tight, and we also try to run our drivers for at least an hour or two before publishing the parameters as even the extent of usage on a specific driver will cause the parameters to change over time. To be sure, if you are seeking perfection, you had better pull your own parameters off of the driver prior to designing and building your enclosure (but after having exercised it overnight to help loosen the suspension)!

Unfortunately, there is always going to be some variance in the T/S parameters. These drivers are assmebled from a variety of metal and soft parts, and small variances in the production of a single part can in turn create a variance in the parameters. Additionally, all our speakers are assembled by hand, and of course not everything can be placed and glued in exactly the same manner as every other piece. We try to keep our tolerances tight, and we also try to run our drivers for at least an hour or two before publishing the parameters as even the extent of usage on a specific driver will cause the parameters to change over time. To be sure, if you are seeking perfection, you had better pull your own parameters off of the driver prior to designing and building your enclosure (but after having exercised it overnight to help loosen the suspension)!

Thank you, Mike. I understand the manufacturing variance thing all too well. I think I probably will pull my own specs, I am eyeing one of the new WT3 speaker testers that PE just came out with (a steal at $100). The driver is pretty well burnt in by now. I have had it in a 3 cube ported box in my car for about the last 2 months plus I ran it on a 15hz sine @ around 1" peak-to-peak excursion for a few hours before installing.