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Intro

On a beautiful January Saturday afternoon in Alameda, CA, The Audiophile Foundation hosted presentations by Andreas Koch, founder of Playback Designs, and Dr. Frank Brenner of Linkwitz Audio. We listened to two engaging presentations in a sold-out event lasting well over two hours. We were treated to an opportunity to listen to a system that included two flagship products, the LX521-The Reference (aka LX521.4MG) loudspeaker from Linkwitz Audio and the MPD-8AI Dream DAC from Playback Designs.

Part 1
 
The afternoon began with Dr. Frank Brenner giving the first presentation that started with a brief history of Siegfried Linkwitz and his notable achievements, which included the perfectly summing Linkwitz-Riley Filters, the Linkwitz-Transform, and his unique design of the Linkwitz dipole speaker family. Animations in the presentation (see below) showed the dispersion differences between boxed and dipole* speakers, illustrating the superior dispersion characteristics of dipole speakers compared to traditional box designs, emphasizing the LX521's distinctive "sweet area" advantage over conventional speakers' limited sweet spot.

*Dipole speakers require more design effort than open-baffle construction. Open-baffle speakers are not full-range dipoles; they cannot radiate as dipoles above 1 or 2kHz. Only full-range dipoles maintain the same radiation pattern at higher frequencies. -Dr. Frank Brenner

Following Frank's presentation, we started a listening session that began with Rebecca Pigeon's "Spanish Harlem." The audio signal chain started with a customized Intel NUC that stored single- and double-rate DSD (*.dsf) files locally on internal SSD storage. The NUC was connected via USB to the MPD-8AI Dream DAC. The DAC's internal analog volume control was used, and analog audio was fed via balanced XLR interconnects directly to the Linkwitz PowerBoxes which house analog crossovers and multichannel amplification.

At the time, my listening position was less than ideal. I stood to the right of the system's right speaker about five or six rows back. In this position, the best I could hope for is a sense of tonal and timbrel accuracy, which was very good for the most part. Rebecca's voice was thicker than expected, the maracas sounded live and had a good amount of detail, but the bass was a bit full for my taste. I'm unsure how much the new magnesium lo-mid-woofer played in the sound presentation. Frank discussed how the LX521 can project a large "sweet area."  I have no doubt this is true, but even a "sweet area" has limitations when listening from my extremely offset listening position.
 
For the next track, I moved to the center of the room and stood behind the last row of the seating area. "España," played by the Detroit Symphony Orchestra, was the next rack, and from this vantage point, the system produced an almost life-sized soundstage with good separation and excellent detail. The sound was realistic and effortless, and the tympani sounded especially real. My experience with this second track contrasted my initial impressions from my less-than-optimum first listening position. After moving to this new position, I could experience LX521's "sweet area" in its full glory.

We listened to a few more tracks, including "Poem of Chinese Drum" by Yim Hok-man, which was particularly interesting. On this recording, the drum's skin was timbrelly spot on, and each drum strike had a visceral impact that listeners could feel. "Poem of Chinese Drum" is a highly realistic recording, and the Linkwitz/Playback design system played the recording beautifully.

Part 2
 
Following the first listening session, the second part of the program featured speaker Andreas Koch, Founder and CEO of Playback Designs, who led a team of Sony engineers who designed the world's first multichannel Digital Stream Digital (DSD) recorder and participated in standardization committees that developed the Super Audio CD (SACD) format.
 
Andreas began the second half of our event with his "DSD Explained" presentation. In it he described the differences between the Pulse Code Modulation (PCM) and Digital Stream Digital (DSD) recording chains, with DSD having a much simpler chain. He then spoke about how the output of a DSD encoder was able to more closely match a 10kHz input square wave.

Andreas touched on how PCM 96/24 files and single-rate DSD (DSD64) files require the same bandwidth to transfer, which piqued my interest because, for me, the inordinately long download times of large DSD files were a primary reason for not adopting the format. Andreas also discussed how the DSD-over-PCM (DoP) standard is used for digital connections via AES/EBU, S/PDIF, and USB. Another interesting point from Andreas' presentation is that Playback Designs is one of only a few companies that offer DACs that convert DSD to analog directly, bypassing all intermediate PCM conversion.
 
Conclusion
 
This afternoon, we experienced two outstanding products, the LX521.4MG-The Reference loudspeaker from Linkwitz Audio and the MPD-8AI Dream DAC from Playback Designs. Set up in an enormous ~20'x40' room (estimated room size) in the California Historical Radio Society building in Alameda, CA; these flagship products did not disappoint. If you are in the "sweet area," this system can fill the room with life-sized, detailed, and dynamic sound.

While I've always appreciated the sound of Linkwitz speakers, after listening to presentations by Dr. Frank Brenner and Andreas Koch and hearing the varied music selections at this venue, I have a newfound appreciation of Linkwitz speakers, DSD recordings, and Playback Designs equipment.

Linkwitz Website
Playback Designs Website
2025 Linkwitz/Playback Design Event Photo Album

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Manufacturer's Comment

Dear Audio Fellows,
It was a tremendous honor to be invited to speak to your foundation.

When setting up the (5th gen.) Linkwitz LX521.4MG system, I was delighted to see that the SFAF had newly acquired a (2nd gen.) LX521 Linkwitz system. These, along with other vintage gear, filled the room with many memories of past audio decades.

Not only did SFAF give me the opportunity to speak, but also the opportunity to provide you with a listening experience that many consider “beyond words” or videos.

For those who attended, you understand what this means. For those who couldn't make it to Alameda, you have the chance to visit one of the nearby LINKWITZ Lounges (e.g., in Healdsburg, Sonoma, or Fremont).

I hope I satisfactorily answered your very qualified questions. If any details remain unclear, please feel free to contact me at info@LINKWITZ.audio

With Best Regards,
Frank Brenner / LINKWITZ.audio