Being dd has always been low excursion high force design. Spl does not require high xmax at all, it can use speed to create the same amount or in many cases more spl just like DD always has done. Basket wise I'm not sure if it is strong enough to hold that motor and not bend when mounted horizontally.
I have been planing to buy both the sundown and this for a while.
If you compare this to the SA-8 v.2 at a higher frequency (stock SA-8 v.2 copper coil) I have no doubt it would be significantly louder on the SPL meter (meaning the 2508). In a compact box at 30 Hz the SA-8 v.2 will without a doubt be substantially ahead in output. In all of our testing we've found that if you increase one end of the spectrum the other end has to be sacrificed -- this is all real life under-power testing which varies a good bit from modeling them up.
EG: Stock copper coil v.1 SA-8 is louder for higher frequency burps than stock copper coil v.2 SA-8 -- but the v.2 is the winner at the very lowest frequencies.
What you are trying to describe about DD subs is basically the following :
1) High motor force factor
2) Stiff suspension with rapidly tightening CMS curve
High motor force helps to pressurize the port -- very important in SPL. Quite often directly related to SPL output. Most folks know this.
The second part is often over-looked and something I've messed with alot recently in developing the SA-8 v.2 -- the DD spider tightens quickly by design. So you can have a sub with a relatively low FS at-rest that quickly turns into a higher FS woofer as it moves -- as the woofer resonance gets closer to port resonance it needs to move less to produce a ton of pressure. This is what you are experiencing with the DD subs -- a combination of these two factors. Non-Linear parameter shift is very rarely discussed.
As a sub that is very often used in SPL this spider design has proven successful but by definition has a high level of distortion -- any shift in parameter over stroke directly equates to distortion. The DD signature sound is often described as "warm" or "punchy" which are characteristic of the 2nd order distortion caused by suspension non-linearity -- so in fact many people like that sound. BL and Inductive distortion are odd order and are the really "bad" sounding types of distortion.
I DID notice that DD recently implemented a bigger spider on some of their larger cone size products -- so this may be changing a bit... not sure. I would suspect they will maintain a similar roll type to exhibit similar dynamic behavior but are exploiting the larger diameter for more maximum throw / durability -- which is a great move on their part, IMO.
When I made the new SA-8 v.2 spider that is very linear and doesn't shift (Klippel verified) I noted a loss in SPL at 55+ Hz with the same starting FS as I had before using a less linear spider. What we did was reduce MMS for an SPL model -- (we can also stiffen the spider if needed) this resulted in the SA-8 v.2 SPL model being at only half throw with 3.5kw on tap and producing the best SPL figure to date (1 extra spider / SPL coil). The stock unit moved a TON with much less output at our high frequency burp. As the sub and port resonance were not matching up with one another. The opposite would be true if I changed the tuning to 30 Hz... the SPL sub would be moving alot with much less output than the stock sub moving much less.
So in short -- if you want to use an SA-8 v.2 for higher frequency SPL, as you mentioned you plan to buy one, you should ask for the SPL coil option which we will have in stock at the same price in D2 and D4. So just be sure to let that be known if you do decide to pick one up... extra spiders or a D1 coil do cost more but are available too.
The standard version was optimized for the lowest distortion levels we could get at a reasonable price and to increase the very bottom octave as much as possible over the old model -- high frequency SPL had to be sacrificed to make that happen so I am stocking two versions and also raw motors for customized specialty units that may need more spiders.
Anyway... as I said on CACO I am excited to see more Monster 8s out there. Making loud 8s is the most fun I've had in the business. Of course I think ours is super competitive and the best at what I designed it for -- but there is no magic bullet that does it all -- not from us or from anyone else... if the 2508 super loud in SPL it will have to do it at the cost of some bottom end or at the least the cost of a much bigger box.
All of this is well know in the speaker design community so hopefully it's not taken the wrong way. I am actually very happy to see more big 8s as more real competition will drive everyone to make better stuff, IMO!
PS: I am only posting my thoughts because OUR product was mentioned first... so lets keep it a real discussion and not hate on either brand. I think my post is fair and talks about strengths in either design.
