John Darko
The Pulsar S 130 is a new metre-tall floorstander from T+A: a 3-way bass-reflex loudspeaker – made in Germany – that features two 15cm bass drivers, two 11.5cm midrange drivers and a 2.5cm magnesium dome tweeter.
About each ‘StarStabilizer’ bass driver, the press release states that: “The StarStabilizer membrane structure reinforces the drivers with a star-shaped brace, preventing resonances and standing waves before they even arise. As a result, all diaphragms in the Pulsar speakers operate in perfect piston-like motion, transmitting only the pure audio signal, free from unwanted vibrations.”
It also says that “the two 115 mm high-performance midrange drivers in the Pulsar speakers are equipped with high-powered magnets for optimal control and drive.”
Nominal impedance on the Pulsar S 130 clocks in at 4 Ohms and sensitivity at 86dB. The German manufacturer also says it is good down to 32Hz and claims that this floorstander’s “compact dimensions no longer compromise expressive bass reproduction.”
So far, so hi-fi marketing.
However, this sentence in the press release caught my eye: “This [Symmetric Directivity System] system channels the speaker’s energy toward the listening area, minimising floor and ceiling reflections that might otherwise disrupt the experience, as is often the case with conventional designs.”
How had the Pulsar S 130’s design team done this? The press release didn’t say. So I pulled on the coat of T+A founder Siggi Amft.
Amft explained via email that the two midrange drivers that straddle the tweeter might look like a point source D’Appolito array — but they aren’t. For that, according to Amft, “the distance between the diaphragm centres of the two mid-range units must be no greater than two-thirds of the wavelength of the crossover frequency between the mid-range and treble drivers.”
The midrange-to-tweeter crossover point in the Pulsar 130 sits at 2200Hz. According to Amft, a 2000Hz crossover point would require the midrange driver centres to be placed a mere 11cm apart – those drivers would therefore be too small and their performance insufficiently linear.
Now comes the clever bit: “By employing two 11.5cm midrange units and a carefully optimised crossover design we have achieved a significant vertical concentration of the sound due to interference above and below the two midrange drivers”.
“The Magnesium tweeter employs 25mm diameter, endowing it with excellent horizontal radiation characteristics, which harmonises perfectly with the dispersion characteristics of the mid-range units at the crossover frequency.”
We can see the vertical dispersion differences in these two graphs provided by Amft:
Our biggest challenge isn’t only finding the right loudspeakers for our taste and budget but finding the right loudspeakers for our taste, budget and room acoustics. As acoustics expert Jesco Lohan has told us many times, when we listen to music through loudspeakers in a room, we hear more room than loudspeaker. The culprits? Low-frequency resonances and midrange/treble reflections.
Two of the most overlooked reflective surfaces in any room are the ceiling and the floor. Left naked, they reflect sound to deliver it to the ear late and comb-filtered. Most of our kind must leave our ceilings bare in the interest of domestic harmony. And as we have noted previously, a rug will only effectively absorb sound above 1000Hz; lower midrange frequencies pass through the rug to reflect as if it were not there.
A loudspeaker that fires less sound downward and upward might be the next best thing to installing acoustic panels. From T+A’s press release: “The Symmetric Directivity Design focuses the entire mid- and high-frequency spectrum within the listening area, minimizing reflections from floors and ceilings before they can interfere with the sound.”
The Pulsar S130 are available now for US$7490/pair.
Further information: T+A
