Floor-standing Speakers

Definitive Technology BP-8040ST SuperTower Speakers

ARTICLE INDEX

Design of the Definitive Technology BP-8040ST SuperTower Speakers

The overall design is typical Definitive, understated; it's literally covered head to toe with a black fabric and pulled tight at the top under a molded gloss black cap. The 8040 is modest in size at about 39" tall. Because the speaker is unlike me and rather narrow, Def Tech incorporates speaker legs that look like out riggers to keep them from tilting over and can be fitted with either carpet spikes or rubber feed.

The rear shares similar design and layout with the Mythos STS; sturdy speaker connections, a line level LFE input with subwoofer volume control, and a detachable power cable.

def-tech-bp-804-speakers-binding-posts-closeup

So what else, and why that giant sock?! Well, if you have a speaker that has drivers on all four sides, it may be a little distracting and probably expensive to build the finished enclosure I suppose and invest the cost on performance. Frankly, I like the design, it's totally non-assuming.

Although narrow, its depth is sized to hold side-firing sub-woofers by using the wider depth of the speaker, Def Tech places a 300 watt Class D amplified side-firing subwoofer. In addition to the 8" active driver, 2 passive radiators are placed, one on each side.

When I realized that the each speaker is identical, that is the powered woofer is on the left on both speakers, I wondered why if the intent was to create more ambient sound, why not place them both firing out, using perhaps the side walls? Paul's answer, well for simplicity – why make setup even harder for the average consumer.

Similarities to the Mythos Series are a plenty, besides powered subwoofers, they share the same woofer and tweeter drivers. The same 1" pure aluminum dome tweeter in the BP-8040ST's can be found in the Mythos.

The BP-8040T has 2 front firing (and 1 rear facing) 3 ½" mid-range drivers arranged above and below 1" tweeter. The drivers are the same found in the Mythos towers. Cast iron baskets used are more rigid and eliminate any interference with the magnetic coil which hopefully reduces distortion and plays cleaner. The mid-range drivers have molded butyl rubber surrounds for longevity and mineral filled polymer cones for natural sound, all especially for voices.

Front without sock

Rear without sock.

Def Tech uses their patent Balanced Double Surround System (BDSS) driver design. The critical part is the cone is supported on both the inner and outer edges. Def Tech designed it to have a longer excursion thereby improving output.

A frequency multi-band digital signal processor (DSP) constantly adjusts the cross-over while monitoring woofer overload and applying compression to prevent distortion.

Care went into the layout of the internal structure. The mid-range drivers are isolated with their own MDF enclosures. This is not new or unusual but Def Tech employed a system of proportions to the volumes. From my architectural background I'm familiar with the principals of golden mean. Used in the Renaissance because it represents the most "pleasant" proportions found over and over in nature golden mean, or rather golden ratio is the relationship of larger to the smaller. The idea that from a perfect square we can mathematically develop a length to width ratio, specifically 1:1.6. (Ever wonder why we find a 16:9 screen more appealing than a 4:3?)

Def Tech further uses Fibonacci mathematical principles of order. Taken the sequence of numbers adding one to the next highest; 0 +1 =1, 1+1=2, 1+2=3, 2+3=5, 3+5=8, and so on, a spiral is created using the resulting numbers, 1,1,2,3,5,13,21, etc. That resulting geometric enclosures might be considered the most important aesthetic principal of proportions.

What does all that mean to sound? By adjusting the volume of the driver enclosures by the size of the driver, in theory the sound should be balanced. Def Tech engineers believe these volumes perfectly proportioned reduce unwanted resonance and vibrations.