With over 18 years in the business, what sets Tang Band apart from most other OEM companies is the amount of research and development behind every component. The W4-1720 is a good example of both the engineering and manufacturing diligence. It is a cost-effective high performance solution with a small footprint, featuring a 1.25" under-hung voice coil design, a very thick top plate mounted over a 3.5" diameter / 0.78125" tall ferrite stack, and a copper shorting ring to reduce the effects of the second and third order harmonic distortion.
The T/S parameters that I extracted from these drivers were actually very close to the LMS parameters included in the data sheets sent to me from Tang Band:
Re: 3.713 Ohms
Fs: 72Hz
Qms: 2.917
Qes: 0.7544
Qts: 0.5994
Le: 0.124mH
The above electro-mechanical characteristics make the W4-1720 quite cooperative in virtually any vented alignment (as gauged by an efficiency bandwidth product of 95.) For this review, the drivers are auditioned as part of the Sculpture 102.1 surround sound upgrade set along with a set of Vifa D19TD-05 tweeters crossed over at 3kHz.
The below graph isolates the midbass driver's on-axis 1W/1m response, illustrating it's ability to cover a wide bandwidth while maintaining reasonably consistent efficiency:
All of my listening tests confirm the response graph; for the majority of Jazz and classical music, these speakers perform flawlessly in the front stage position of my dedicated listening room. Every note, regardless of pitch, is represented with an equal degree of authority and accurate placement along the sound stage. From ~50Hz up, the sound is very transparent and doesn't show any signs of the "hooded" effect that is typically present in the upper mid-bass/mid-range region with most store-bought speakers.
Overall, the W4-1720 is an excellent driver that, with some care, can be implemented into just about any audiophile-grade stereo listening room or a home theater.
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There's something quite innovative on the horizon. Deep within the Addictive Audio assembly bay, a new driver has been built. A driver unlike most others...
A driver the geometry of which will allow for space-efficient distribution of cone area without the inherent compromise in linearity resulting from reduced mounting depth.
Surface-bound tinsel leads will ensure slap-free operation at high excursion, while multiple spiders will maintain control over the cone when a large amount of power is applied to the voice coil.
In the end, it's a driver which, at just under 6.5" minimum internal enclosure height, is capable of delivering as much piston displacement as most 8" speakers. What is it?
It's the upcoming Peter W. Kulicki edition subwoofer from Addictive Audio. Count on seeing some of these in 2009 pre-loaded into a line of Addictive's low-profile subwoofer enclosures.
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Unquestionably, the most overlooked can of whoop-ass in the Digital Designs woofer isle is the 2500 series driver. The DD2512a is no stranger to the arsenal, which begs the question: "Why post a review about it?" Because, as an enclosure designer, I'm not entirely satisfied with the context of what minimal exposure this particular woofer has received in the consumer market.
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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First up, I'd like to cast the spotlight on the new aa8v1b, a.k.a. the Excruci8 subwoofer from Addictive Audio. Making it's September debut on FreBass.com, this recent addition to Addictive's lineup is geared to address the ever-growing consumer demand for small diameter woofers.
As the name cleverly implies, the Excruci8 is an 8" subwoofer; it features a 2" voice coil and a very conservative input power rating of 250W continuous, 600W peak. Two 5.375" diameter Ferrite stacks make up the 2.75" (top plate to back plate) tall motor. Bryan from Addictive Audio was quite prompt in sending me several of these little monsters for a more hands-on examination.
Initial impressions: This driver screams versatility; aside from it's sheer weight my attention was drawn immediately to the traditional foam gasket extending from the mounting ring. This is an increasingly rare trend among car audio subwoofers, where mounting versatility tends to take a back seat to aesthetics. An emerging trend, however, is the direct wire-to-wire connection method of which the Excruci8 is a proud participant; two sets of tinsel leads follow the surface of the spider out to the edge of the basket, then continue out as pairs of 8AWG connecting wire. Upon arrival, the woofer's suspension was surprisingly stiff. The initial parameters prior to break-in (measured in series) were as follows:
Re: 7.418 Ohms
Fs: 61.91Hz
Qms: 6.18
Qes: 0.8205
Qts: 0.7243
Le: 2.445mH
The derived EBP (Efficiency Bandwidth Product) of 75.45, though indicative of a driver suitable for use in vented applications, is still sufficiently low to where a sealed or a 4th order bandpass alignment can be viewed as an option. The break-in process consisted of four 2 hour sessions with the woofer brought to 75% peak excursion at 20Hz:
After a several hour cool-down, the parameters were re-measured. One of the most commonly overlooked factors in benchmarking T/S parameters is the ambient temperature as well as the temperature of the voice coil; if the results are to be accurate, these conditions have to remain consistent from one test to the next. The final parameters following the break-in (again, measured in series) were as follows:
Re: 7.287 Ohms (-0.131 Shift)
Fs: 47.78Hz (-17.13Hz Shift)
Qms: 4.213 (-1.967 Shift)
Qes: 0.6415 (-0.179 Shift)
Qts: 0.5567 (-0.1676 Shift)
Le: 2.48mH (+0.035mH Shift)
As expected, we can observe a significant downward shift in the free-air resonant peak along with a decline in the driver Q which is proportional enough for the EBP to remain within ~0.9 units of the product derived from the initial measurement.
For the listening portion of this review, I decided to try a pair of the Excruci8s in a rear-loading horn that I designed around the most recently derived T/S parameters and the cabin geometry of my '91 Honda CRX. They were quite compliant and didn't impose any significant degree of ripple along the predicted efficiency curve; this made the task of countering the cabin's naturally occurring resonant spikes and nulls all the easier.
With the subsonic filter and bass boost disabled, the in-cabin performance was very rich, with a response that remained consistent well into the lower 20Hz region. The Excruci8s offered a very "large" presence; many times that of what you would typically expect with merely 45 square inches of effective piston area. Pressure-wise, the woofers sustained an average Term-LAB SPL reading of 143.8dB at the dash, with a peak of 147.1dB at 48Hz. Given an adequate degree of acoustic suspension, the Excruci8s handle themselves quite well; at peak each woofer was receiving approximately 1100W across the entire frequency range.
All in all, the Addictive Audio Excruci8 is a well engineered, well put together piece of hardware. At just 8.25" in outer diameter, it makes for a very surface-efficient solution, especially when mounting space is at a premium. If you're looking to strike up the "shock factor," I can vouch for the Excruci8 as an excellent woofer to design your system around. A pair of these in a proper enclosure can be sure to overwhelm just about any conventional front stage.
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