Ayre C-5xe universal disc player The MP Upgrade, July 2009

Wes Phillips reviewed the MP firmware upgrade for the C-5xe in July 2007 (Vol.32 No.7)

About a year ago, I found myself included in an e-mail conversation in which Stereophile's John Atkinson, Wavelength Audio's Gordon Rankin, and Ayre Acoustics' Charlie Hansen were attempting to explore and create better methods of digital measurement. I felt honored to be included, but in such august company I felt rather like the waiter at a table where Isaac Newton, Robert Hooke, and Robert Boyle were hashing out natural philosophy. I could follow the conversation up to a point, but I was clearly out of my league.

Hansen's interest was not academic. He was wrestling with a new digital reconstruction filter that improved not only on the classic "brick-wall" filter but also on the "apodizing" filter first seen used in Meridian 808i.2 CD player. Hansen's new filter was a carefully tuned apodizing filter, one designed to eliminate the pre-ringing on transients and reduce post-ringing to a mere one cycle. (Hansen has published an excellent white paper outlining his design process here.)

Ayre's Minimum Phase (MP) filter is implemented with a field-programmable gate array (FPGA) that is also used to oversample the digital audio data by 16x. This ratio was determined by listening tests to offer greatest realism. The dither algorithms were also determined through listening tests.

MP filters will be incorporated in all CX-7eMP CD players going forward, as well as in the C-5xeMP universal player and the upcoming QB-9 USB DAC. Ayre is offering the MP firmware as a $200 upgrade for C-5xe units and between $250 and $900 on the CX-7e and in the field (depending on the age of the unit). These upgrades are handled through their dealer network (footnote 1). It doesn't matter if you bought your player new or used—Ayre will upgrade any unit brought to one of its dealers. There is also a hidden benefit of the upgrade: Ayre has rewritten the operating system for the CX-7e, adding some features. New firmware for the C-5xe remote control has eliminated my only cavil—the hair trigger that distinguished between Next Track and Fast Forward when advancing through a disc. Yay!

Ayre sent me a C-5xeMP to compare with my stock C-5xe. Like the C-5xe, the C-5xeMP has two filter positions: Measure and Listen. Measure uses an apodizing filter similar to that in the Meridian player; Listen uses the new optimized minimum-phase filter, which I auditioned almost exclusively.

For "Red Book" CDs, the MP upgrade is definitely worth every penny. Guitarist David Russell's interpretation of Silvius Leopold Weiss's Tombeau sur la mort de M. Comte D'logy (CD, Telarc CD-80693) had more string tone and less "bite" with the MP set to Listen, and an absence of the brightness audible through the unmodified C-5xe. Day and night? Not really—the C-5xe has been my reference for a few years now, and obviously I think it sounds pretty good. But the MP was a noticeable improvement, sounding more focused and a lot more relaxed.

The C-5xeMP also allowed me to hear deeper into the decay of Russell's tones in the acoustic of the Peggy and Yale Gordon Center for the Performing Arts, at Owings Mills, Maryland. Digital ringing obscures details—who knew? Most of us, I guess, but Charlie Hansen seems to have actually done something about it.

The ability to hear deeper into the soundstage, to separate notes from the acoustic that supports them, and a deep sense of "rightness" carried over to Paganini's Dreams, by violinist Ruggiero Ricci and pianist Brooks Smith (CD, John Marks Records JMR11). The C-5xeMP just sounded so right that it wasn't so much any detail, but the gestalt. It was the best of CD, only better.

I wanted to hear a CD I really knew, so I pulled out Rhapsody (CD, Stereophile STPH010-2) to listen to Joe Cea's arrangement for chamber orchestra of Gershwin's Three Preludes. The lovely acoustic of Albuquerque's First United Methodist Church was all there (and there's a lot of it), but the crisply articulated sound of Hyperion Knight's Steinway was front and center and very palpable. Naturally, I got into it, and then had to listen to Knight performing Earl Wild's arrangements of four Gershwin songs and, well, everything else on the disc.

Integral to my enjoyment of CDs through the C-5xeMP was how well music flowed in time. Hansen doesn't mention this benefit in his white paper, but time after time, I experienced superior "flow," or pace, or whatever you want to call it. Given that music is defined as a series of tones moving in time, this was no trivial improvement.

At the CES press conference announcing the MP filter, and in most of my correspondence with Ayre since then, everyone at the company has concentrated on its performance as a corrective to flaws inherent in the "Red Book" standard. So I wasn't expecting any huge improvement in the sound of high-resolution audio formats.

Cantus's remarkable While You Are Alive (CD, Cantus CTS-1208) is commercially available only as a "Red Book" CD, but engineer John Atkinson slipped me a DVD burned from the 24-bit/88.kHz master files. Wowsers! When I said that MP excelled at separating the primary tones from the acoustic with "Red Book," with hi-rez, it was all that in spades! And those Cantus basses? Holy moly, were they rock-solid. And this recording's spatial dimensionality? Holodeck-solid.

Hats off to Charlie Hansen and the Ayre design team. They've designed a better gizmo that benefits every digital format I've heard it process—and they've done so cleverly and at little cost (footnote 2). If you own an Ayre C-5xe or CX-7e, save your pennies and have your dealer send it in for an upgrade. If you don't already own an Ayre, the Minimum Phase mod might make you wonder why not.—Wes Phillips

Footnote 1: The MP upgrade for the C-5xe costs $200.

Footnote 2: John Atkinson will be writing a further Follow-Up on the C-5xeMP in a future issue.—Ed.