Apogee Electronics PSX-100 digital converter

Can a piece of studio gear find happiness on an audiophile's equipment stand? More important, can an audiophile derive satisfaction from its sound?

That's what I was determined to find out when I took delivery of this $3900 converter, which, though designed for professional recording studios, has found favor with audiophiles (so far, mostly Japanese) wishing to transfer their LPs, 78s, lacquers, and other analog source material to a high-density digital format.

The PSX-100 is an extremely flexible two-channel, 24-bit/96kHz A/D and D/A converter featuring Apogee's exclusive UV22 processing, which the company says translates 24-bit audio to 20- or 16-bit with "minimal quality loss...while maintaining much of the detail of the original 24-bit signal." This is key—Apogee claims the PSX-100 converts all analog source material at 24-bit resolution (for 117dB of dynamic range), and can sample at 44.1, 48, 88.2, and 96kHz. That accomplished, the end user sets the digital output to conform to the capabilities of the storage medium being used.

Apogee trumpets UV22 processing as being superior to dither, noiseshaping, Bit-Mapping, and other attempts at shoehorning greater-than-16-bit performance onto a CD. As for HDCD, Apogee is willing to admit that "Encode/decode systems may sound good if they are decoded, but almost nobody owns a decoder!" That's not true in audiophile circles, where most high-end processors sold in the past five years have featured HDCD decoding, but if Apogee's claims for UV22 are valid, you can't really argue with their logic.

According to Apogee, word-length reduction is "a tricky business at best"; they suggest leaving a signal at its highest resolution until the final 16-bit mastering step. When you merely truncate 24 bits to 16, you get distortions that are higher in level than the signals you've removed, and that create amusical artifacts.

For the CD and DAT formats, the PSX-100 uses UV22 to "capture 24 bits of information onto a 16-bit/44.1kHz medium," in the words of an Apogee spokesperson. Apogee claims that UV22 is useful even when making copies of 16-bit recordings—in other words, when copying CDs—and that UV22 processing "smooths out the rough edges on even the most inexpensive CD player or external converter" to actually improve their sound.

What, exactly, is UV22? According to the spokesperson, it's a proprietary algorithm—analogous to bias on an analog tape recorder. By adding narrowband noise around half the sample frequency—22.05kHz in 44.1kHz-sampled data— as the digital wordlength is reduced, it encodes the +16-bit data in that high-frequency energy . Again according to Apogee, UV22 creates a "constant white noise floor, very similar in character to analog tape noise, no matter what the input source. If you listen to the noise on a UV22-encoded recording, you can hear a stable, accurate soundstage and faithful tonal balance more than 24dB into the noise—just as you do on analog tape. Yet the low audible noise floor sits at the theoretical limit for a 16-bit system. Nothing is lost—but a great deal is gained."

The PSX-100 is slim, compact, sturdily built, and sports a front panel that's as busy as the Gowanus Expressway during rush hour (an analogy our Brooklyn-bound editor will soon appreciate). Out of necessity, studio gear must be ultra-flexible; the PSX-100 can interface with just about every format known to man, and do just about everything possible in terms of A/D and D/A conversion.

You home audiophiles can ignore many of the possibilities and be ready to go with the push of a few buttons, as long as you're equipped with RCA/XLR adapters or a preamp with balanced tape-out jacks: the converter is fully balanced, including its analog inputs. The unit comes set for pro-audio +4dBu input and output levels, but those are easily changed to –10dBV consumer settings via two rear-mounted dip switches.

The PSX-100 can accommodate all of the most common digital formats—AES/EBU, Alesis ADAT, TDIF (Tascam interface), and S/PDIF (coax and optical)—and its unique Apogee Bit-Splitting feature (ABS) allows 16-bit ADAT and Tascam DA88 MDM recorders to store 24-bit signals by using up to four tracks for each channel. You could pick up a used Tascam or ADAT for under $2000 and archive your LPs or other analog recordings at full 24/96 resolution. Unfortunately, I did not have access to either of those, so I made CD-Rs using a Marantz DR17 as a transport/recorder. Of course, I could also A/B the analog signal from the phono section with the twice-converted output of the PSX-100.

The PSX-100 operates in three modes: Confidence Monitor, Analog Monitor, and Digital Copy. In Confidence Monitor mode, the A/D and D/A converters operate independently, each using one of the unit's two low-jitter clocks. With the appropriate recorder, you can monitor your results as you would with a three-head analog machine. Or you could archive an LP to CD-R while using the D/A to listen to a CD from another transport.

In Analog Monitor mode, the A/D input is routed directly to all of the digital outputs and to the D/A converter. This lets you, among other things, determine the transparency of the A/D–D/A conversion process. Digital Copy mode feeds the digital "in" signal to all of the outputs as well as to the D/A converter. Both clocks are synchronized to the digital input. So, for example, if you've archived an LP to your ADAT or DA88 at 24/96, you could play it back, convert it to 16/44.1, and cut a CD-R.

Apogee Electronics Corp.
3145 Donald Douglas Loop South
Santa Monica, CA 90405-3210
(310) 915-1000