Music in the Round

Krell Foundation preamplifier-processor
I've been waiting for the Foundation, Krell Industries' lowest-priced preamplifier-processor, ever since its first appearance, at the 2013 CES. Krell announced at the New York Audio Show in April 2013 that they had started shipping Foundations, but apparently sales were so brisk that no review sample could be shaken loose—I was left to envy happy users posting their joys on the Internet.

At $6500, the Foundation is priced significantly above the range occupied by pre-pros from Integra, Marantz, Onkyo, and Yamaha. In common with $10,000+ devices from Bryston, Classé, and higher in the Krell line, it lacks many features that some consider bells and whistles. These include myriad DSP processing and simulation modes, streaming capabilities, and onscreen display. Strangely for its heritage, the Foundation also lacks a multichannel analog input. Still, if these are the only sacrifices made to preserve true high-end sound, the Foundation may be configured quite comfortably.

The Foundation is appropriately hefty and surprisingly compact. I slid it into my rack on the shelf sized to accommodate such behemoths as Krell's Evolution 707 surround processor, so the cool-running Foundation had much more ventilation space above it than it would ever need. The new Krell aesthetic has been somewhat controversial, but there's no doubt that it's quite functional. The central design element, in brushed aluminum, glows gently red in standby, cool blue in operation. It's flanked by matte-black panels, the one on the right bearing a two-line LED display, a jack for the calibration microphone, and an HDMI input; on the left are the control buttons, including four directionals and Enter, Standby/Operate, Source, Mode and Menu.

The rear panel is equally straightforward. From left to right across the top are nine more HDMI inputs and two HDMI outputs, one USB connector, and three optical and three coaxial digital audio inputs. Below them, on the left, are three component- and two composite-video inputs, four stereo analog inputs, and a stereo pair of XLRs. In the middle is a panel with RCA analog outputs for 7.2 channels, and a stereo pair of RCAs for Zone 2. To the right of those are XLR analog outs, also for 7.2 channels. At the extreme right are RC-5, RS-232, Ethernet, and 12V trigger connectors, and an AC power inlet and switch.

As you might expect from Krell, the remote control is a robust metal slab with myriad identical, small, non-illuminated buttons. I first thought this might be frustrating to use, but the buttons are logically grouped and their operations more granular than the front-panel controls. With little practice, I could easily navigate the menus and operate the Foundation in the dark. It took a bit longer to get comfortable with the menu hierarchy: For a selection to be retained, one must remember, after making it, to hit Enter, then back out of the menu system.

I connected sources—Oppo BDP-105 universal Blu-ray player, PC, and cable box—to the Foundation via HDMI; and, from the Oppo, via XLR and S/PDIF. The XLR outputs were connected to the Bryston 9B five-channel amplifier, and the subwoofer output, via RCA, to the subwoofer. I used the Krell's default input assignments, but renaming/reassigning was straightforward. The Foundation is amazingly adaptable. Krell says that it incorporates Intelligent HDMI Switching, in which all 10 source inputs are always active, their parameters stored in memory. Changing sources or channels was instantaneous and noiseless.

My initial impressions of the sound via the Foundation were exceedingly positive: the balance was really satisfying, and images stood firm against a background of absolute inky black.

Other than the audible LF modal variations imposed by my half-cube room, I enjoyed the sound without making any adjustments, bass management, or EQ. The Foundation's characteristic sound was wide-range and beautifully smooth, with an expansive soundstage, stable imaging, and great dynamics. It seemed obvious to me that, with or without EQ, the sound had an overall integrity that went beyond that of the pre-pros from the AVR companies. Design and construction no doubt contributed to this, but, as in other high-end processors, this quality of sound might be correlated with the exclusion of video-processing circuitry that would compromise the digital audio processing.

Unlike some pre-pros, Krell's Automatic Room Equalization System (ARES) software passes along signals at resolutions of up to 24-bit/96kHz without downsampling, so it incurs minimal sonic cost compared to bypass, and one I gladly pay. ARES is in two parts. The first is Calibration, which measures the speaker levels, distances, and frequency responses for the purposes of bass management. The second is the Equalization itself. And here the fun began.

The Foundation's calibration microphone, a flyweight device molded onto the end of a ¼"-diameter plastic tube (footnote 1), did not inspire confidence. The element is covered by a cap with narrow parallel slits, and the plastic base is flimsy and unstable. I tried two samples, with the same results: The only way either mike would recognize the presence of a subwoofer was if I removed the base and taped the tube firmly to the boom of my mike stand. After that, calibration and EQ ran smoothly.

The results of ARES Calibration were accurate in terms of distance, good in terms of level, and as usual for bass management: The subwoofer levels, depending on the run, were set from 6 to 12dB too high, and all the speakers were set to Full Range. Since the Foundation can store three different setups, I kept one with the Full Range setting and another with my usual crossovers: 40Hz for the left, center, and right front speakers, 80Hz for the surrounds. Both arrangements worked well, but I preferred the latter bass-management arrangement, especially after EQ, for its better bass definition.

ARES EQ also ran successfully. I decided to store three new results: Memory 1 was with calibration/bass management but no EQ; Memory 2 added Full Range EQ; and Memory 3 added EQ, but was applied only below 250Hz. I really liked having the option of defining the range for equalization—in my opinion, the most important corrections are below the room's "critical frequency" (the frequency below which standing waves cause significant room modes), which for most domestic rooms is in the range of 250–350Hz. I also measured the frequency and impulse responses for each of these settings with an Omnimic2 mike, but my ears told me the same things as I would measure.

Performing EQ only below 250Hz, the Foundation was amazingly effective at cleaning up room modes. My favorite test for this is Berliner Dom: Music for Brass & Organ by Gabrieli, with organist Andreas Sieling and Lucas Vis leading the Berlin Brass (SACD/CD, Pentatone PTC 5186509). The acoustic of the Berlin Cathedral is rich and reverberant, and, if one superimposes one's own room modes, becomes as thick as mud. The sub-250Hz EQ applied to all channels by the Foundation clearly revealed the Cathedral's spaciousness and allowed me to hear all the instruments as well as their reflections. The various ranks of organ pipes, too, were easily discernible.

This EQ setting was also excellent for all other recordings, including music that makes few bass demands but requires transparency in the treble. Martin Fröst has a new recording of Mozart's Clarinet Concerto in A, K.622; the Trio for Clarinet, Viola, and Piano, K.498; and a fragment, the Allegro for Clarinet and String Quartet, K anh.91/516c (SACD/CD, BIS-1893). In the concerto, in which Fröst also conducts the German Chamber Philharmonic of Bremen, the woody overtones of his basset clarinet interacted beautifully with the orchestral winds; and, in the trio, the Foundation finely delineated the delicate blend of his clarinet with Antoine Tamestit's viola and Leif Ove Andsnes's piano. With this EQ setting, the frequency responses of the speakers measured quite flat from top to bottom.

Switching to ARES's Full Range EQ drained much of the air and blood from the sound. The highs were still fine, but presence and impact were lost. This surprised me—with other EQ systems that permit restricting the range of the filters, the result has been a slightly emphasized and etched quality in the highs. The effect of ARES was the direct opposite, as I confirmed with measurements that showed a depression of up to 10dB that began above 250Hz and recovered above 10kHz (fig.6). Repeated attempts at EQ, all with the same microphone position and orientation, gave the same result. I wonder if the mike's slotted cap was interfering with its reception of these frequencies.

Throughout the two months I listened to the Foundation, Krell proved itself impressively responsive to customer comments, with three useful firmware updates that included: adding manual calibration of individual speakers, linking HDMI video to the user's choice of audio input, better input-selection options for Zone 2, adding two-channel downmix to the HDMI output, and adding support for 24/192 PCM coax inputs. They've also tweaked the test-signal levels to improve detection of subwoofers during ARES Calibration and EQ, and promise that DSD via HDMI will soon be available.

This admirable level of attention indicates that the Foundation is being supported in the manner that a product of this caliber deserves. I have no hesitation in recommending the Krell Foundation; its inherently excellent sound quality, the flexibility of its configurations, and its expanding capabilities make it competitive with cost-no-object pre-pros. My only suggestion: So good a product as this requires a better calibration microphone, even as an extra-cost option.

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Footnote 1: The microphone's packaging identifies it as a MIC48 Multimedia Microphone, which can be found on the Internet for as little as $3.98—or, in bulk quantities from alibaba.com, for between 55¢ and 80¢!