Buchardt Audio S400 loudspeaker
Implemented properly, waveguides for tweeters make a lot of sense. A waveguide can control the directivity of a tweeter’s output to better match and blend with that of the lower-frequency driver(s), and it can increase a tweeter’s acoustical output enough that it will need much less power from the amp to produce a certain sound-pressure level.
Enter the S400, a two-way minimonitor (€1600/pair) from Buchardt Audio, a Danish company I’d never heard of, and whose website states that they’re a company-direct seller of speakers designed in Denmark, made in Indonesia, and shipped worldwide. There’s some good tech in the S400, including a large waveguide surrounding a 0.75” silk-dome tweeter crossed over to a 6.5” aluminum-cone midrange-woofer, this in turn supported by a 5” x 8” passive radiator on the rear.
As their website makes plain, Buchardt Audio, like so many Danish companies, is big into measurements: “5402 acoustic measurement points [were] conducted with a robotic nearfield scanner. With this measurement accuracy it was possible to achieve a seamless transition from the woofer to the custom-made constant directivity tweeter/waveguide.” Their measurement protocol also indicates why they positioned the tweeter and waveguide below the midrange-woofer: “A challenge that had to be solved using such a deep waveguide was the phase-shift between the woofer and the tweeter. This was solved by placing the waveguide under the woofer as well as a very discreet tilt of the cabinet at only two degrees, this aligns the drivers in phase.” As soon as I finish writing this article, I’ll contact Buchardt to arrange for review samples of the S400 to be sent to one of our writers.