Lucid Technology AD9624 and DA9624 Converter

When I was assigned to review this set of 96 kHz Lucid converter boxes, I was a bit underwhelmed. High-end audiophile engineer that I am, I thought that these little Symetrix-built Lucid units might be cute, but hardly distinguished. Turns out I was wrong - these boxes sounded very nice and, in fact, proved to be among the most useful gadgets I had with me at my recent weeklong Denver recording extravaganza.
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When I was assigned to review this set of 96 kHz Lucid converter boxes, I was a bit underwhelmed. High-end audiophile engineer that I am, I thought that these little Symetrix-built Lucid units might be cute, but hardly distinguished. Turns out I was wrong - these boxes sounded very nice and, in fact, proved to be among the most useful gadgets I had with me at my recent weeklong Denver recording extravaganza.
Product PointsApplications: Recording; mixing; mastering; monitoring

Key Features: Stereo A/D and D/A conversion at 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz; AD9624 provides user-selectable, 16-bit noise-shaped dither, separately programmable on simultaneous AES/EBU and S/PDIF (coaxial and TOSlink) outputs; DA9624 has separate headphone volume control and front panel output level controls

Price: AD9624: $899; DA9624: $749

Contact: Lucid at 425-742-1518.

Plus

+ Excellent sound

+ Compact size

+ Flexible I/O possibilities

Minus

- External AC power supply

- No power on/off switch.

The Score: Best-sounding converters for the money - and they look really cool, too!
Features

The AD9624 is a 24-bit analog-to-digital converter that samples at all the standard rates - from 96 kHz down to 32 kHz - packaged in a half-rack-sized chassis. It can sync to an external word clock input, and has numerous I/O possibilities. It accepts analog input via XLR connectors, and outputs its digital bitstream simultaneously through AES/EBU XLR jacks and S/PDIF coaxial and optical TOSlink connectors.

For maximum flexibility, the DA9624 24-bit digital-to-analog converter receives input via these same three connector types and delivers its analog output through XLR and 1/4" connectors for interfacing with balanced or unbalanced equipment. A front panel headphone jack provides a convenient way to monitor the audio output; its volume control is separate from the one used to regulate the level at the balanced XLR and TRS connectors.

Both units feature easy-to-read 20-segment peak reading LED ladder meters (and a separate clip LED) for level setting purposes. Peaks are held for several seconds. The input level controls on the AD9624 have a convenient link switch for making the left channel pot control both channel inputs simultaneously. There is an in-line power supply, but no AC on/off switch. I wish there were, for these units run rather warm.

In use


I first got to test the DA9624 on an elaborate organ music recording remote session in Denver during the first week of October. After a day and a half in the Cathedral of the Immaculate Conception hooking up the most extensive batch of recording equipment I've ever brought on a remote, I realized that I needed to be able to monitor my various 88.2 kHz data streams, within the digital domain, from my control room. While this may seem obvious to many of you, please appreciate that I keep my converters out in the recording space (along with the mic preamps, equalizers, compressors, mixers, and other analog front-end equipment) and transmit their bits via glass fiber-optic cable hundreds of feet to wherever my control room is located. In this case, that was up one, and then down two, flights of stairs to the cathedral's "coffee hour" room.

I used two separate sets of 88.2/96 kHz converters; a pair of Apogee PSX-100s (feeding two DTRS MDMs); and a Merging Technologies Sphynx eight-channel box, which fed my Mac PowerBook hard disk recording system -this time based upon the Sonorus STUDI/O PCI card, and Cubase VST/24 4.1.

Although both converter sets feature simultaneous A/D and D/A processing, all the converters are, unfortunately, located within the same chassis. I sent the converters' DACs' analog outputs down 150 feet of copper snake but I wanted to monitor and play back my recordings without all that copper between the various DACs and my Dynaudio BM6As. The Lucid DA9624 helped me out of this dilemma.

I prepared a nifty digital switching matrix setup using a new Z-Systems z-16.16 on location detangler, so my multiple digital inputs and outputs could be routed anywhere I wanted. Then I connected its S/PDIF output to the appropriate input on the DA9624. This custom box was recently built for me with eight AES/EBU I/O connectors, three sets of ST glass fiber-optic ports, four pairs of TOSlink plastic fiber jacks and a single BNC for S/PDIF I/O.

The four analog channel sources were a 0.9-micron Stephen Paul SM 69 stereo mic and a pair of mixed ambience tracks composed from a combination of Manley M 50s, BLUE Bottle mics with pseudo-M 50 B4 capsules and a pair of 1-micron Stephen Paul KM 54s. To monitor a mix of those four channels - as built upon the PowerBook within Cubase - I simply routed the Sonorus card's S/MUX "A" output back upstairs via glass fiber to the channel 5/6 input on the Merging Technologies box, then sent its AES/EBU output back downstairs again through one of the four twisted pairs within a 150' run of Belden 1872A MediaTwist cable.

Since the eight "Cat. 5" twisted pairs within the two MediaTwist snake runs had already been hooked up to the Z-Systems digital matrix switcher, I simply set the proper source and destination numbers on its front panel appropriately, then looked up to the colorful display panel of the little Lucid DA9624 I had perched on top of it. Within a second or two, the 88.2 and lock indicators lit up on the Lucid box and I was in digital heaven. Not only had all my digital up and down and back up and back down again cabling worked, but what I heard coming out of the DA9624 sounded glorious!

The sound coming out of the Lucid box was always much better than the analog outputs of the built-in Apogee and Merging Technologies converters after they had been sent down 150' of copper snake cable. This comment casts no aspersions on the Apogee and Merging DACs; it merely reflects the great loss one experiences with extensive lengths of copper cable and reinforces the reason I started to send digital data down glass fiber back in 1988.

Back home, in Studio Dufay, I spent a couple of days listening to just about every kind of source material I could find through both Lucid boxes in series. I connected the AES/EBU digital output of the Lucid AD9624 to the AES/EBU input of the DA9624 and inserted this A/D/A path into my monitoring chain in such a manner that I could instantaneously switch the Lucid boxes in and out. Here are my observations and conclusions:

The sound gets better and better as the sampling rate goes up. This may not seem obvious to those of you who have not experienced 88.2 or 96 kHz sampling, but it is, indeed, true. Furthermore, I'm sorry to report that I've become spoiled. Ever since I got my first Apogee PSX-100 about six months ago, I've been extolling the virtues of double sample rate recording to anyone who will listen.

The Lucid units' sound at 88.2 and 96 kHz is more open and relaxed, compared to their sound at 44.1 and 48 kHz. This is what I found with the Apogee unit when I reviewed it (PAR, 9/99, p. 22). With the Lucid units, the sound at 44.1 kHz was considerably closed-in and the highs, especially, for example, from a soft harpsichord in the background on one of my Dorian baroque chamber music recordings, were much less believable.

Pushing that little front panel toggle switch down a couple of times, to move from 44.1 to 88.2 kHz, was a revelation. The soundstage opened up, the sound became much easier to listen to, and that distant harpsichord started to sound like it should.

The surprise for me was that the 96 kHz sound was better than the sound at 88.2 kHz, and not by a small margin either. This was the only way I could get the Lucid units to really successfully mimic the original source. This discovery caused me some anguish - for what goes up, must come down. To resample an 88.2 kHz or 96 kHz master recording down to 44.1 for CD release purposes involves digital mathematics. The conventional wisdom is that it's easier to divide by 2 than to go down to 44.1 kHz from 96 kHz.

Summary


The bottom line here is this: For a total list price of $1,648, one can do a double sample rate recording and play back to a very high standard. And while these two Lucid boxes do not have the input and output flexibility and features of the Apogee PSX-100 or Rosetta units, they do cost considerably less. And, most importantly, their sound quality requires no apologies, especially at 96 kHz. Great job, Symetrix; I forgive you for the missing AC switches!

I'd like to thank my two Colorado-based engineers, David Rick and Greg Heimbecker, whose help was indispensable.