Weighing in at nearly 25lbs, the DD2512 bares some resemblance to it's slimmer 1500 series counterpart. It boasts a 160oz double-stacked motor, a tall EROM surround, direct wire-to-wire connecting leads--check out the Digital Designs products page for more details.
My first noteworthy experience with this woofer was during the break-in; even at high excursion, there was virtually no mechanical noise that I could discern.
Even after an extended break-in period (~48 hours in all,) there was a surprisingly minor T/S parameter shift:
Pre break-in:
Re: 6.728 Ohms
Fs: 44.41Hz
Qms: 7.81
Qes: 0.8867
Qts: 0.7963
Le: 3.041mH
Post break-in:
Re: 6.601 Ohms
Fs: 43.07Hz
Qms: 7.316
Qes: 0.8796
Qts: 0.7852
Le: 3.148mH
These parameters make the 2500 series very unique. At a glance, an efficiency bandwidth product of ~48 implies proficiency in a sealed enclosure--which can, by all accounts, be construed as the woofer's forte--but there are a couple of hidden talents which make this sub a gem in it's own rite:
Besides holding it's ground as DD's little known sealed enclosure solution, the 2500 series is exceptionally well suited for use in wide-bandwidth 4th order alignments as well as low power class SPL bass-reflex alignments. By the virtue of it's electro-mechanical characteristics, the woofer's infinite environment response--even in a standard recommended enclosure--tends to look a bit awkward:
Regardless of the system Fb, employing a 2500 series driver in a bass-reflex enclosure will almost invariably produce a lethal peak above 50Hz which can prove quite essential in competition while still maintaining a degree of proficiency in daily listening applications. With it's inherent efficiency and the bandwidth along which it occurs, you may find that, given an input signal of 2000W or less, the 2500 series will outperform it's 3500 and 9500 counterparts.
To shift the overall emphasis further down without sacrificing additional enclosure space or acoustic impedance, a 4th order alignment can be devised and manipulated to offer an amazing degree of flexibility in countering the naturally occurring cabin modes resulting in a near flat response at the headrest.
Overall, the DD2512a is a very unique, very specialized driver with a lot of hidden talents that can keep the competition guessing for a very long time. Be on a lookout for a continuation of this review featuring my listening impressions of the DD2512a loaded into a 4th order test enclosure.
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