I usually "print" reverbs to tracks to save on CPU power, and I noticed that my mixes had the room sucked right out of the reverb. After many failed attempts at adjusting mic placement, gain staging, equalization, sub-mixing methods and reverb parameters to fix the problem I decided to see if others people were experiencing the same problems. After some internet research on the topic at Pro Sound Web, Harmony Central and Digidesign’s own User’s Conference I learned that it is the opinion of many people that neither the digital clock nor the converters in the 001 system are of a very high caliber. The good news was there is a plethora of options for aftermarket digital converter units that would work with the 001 system. Oh great, another excuse to buy something.

There seems to be a trend of diminishing returns with audio equipment, and I expected a digital converter to be no exception. My main concern was to acquire a quality device (on a home studio budget) that is high enough up the ladder so I don’t have to replace it in a few years. Too high up the ladder (like a Benchmark or Cranesong) would not be optimizing my funds, and too low would likely turn out to be a planned obsolescence. In my search, two names, Lucid and Apogee, showed up often as recommendations. I could not afford to buy both and compare, but I figured that I could do no wrong with either. I bought the Lucid (used on eBay) because it was considerably cheaper than the comparable Apogee unit. It seems to be the opinion of many people that the Lucid holds it’s own against the Apogee. I have unfortunately not been able to verify these opinions for myself, but nevertheless I feel that I made the right choice for my needs. Please read on.

The Lucid AD 9624 is a half rack-space stereo analog to digital converter. Basically it is the box that allows audio to get into the digital realm, which in my case is Pro Tools LE. On the rear of the unit are two balanced XLR jacks for its analog input. There are three different output connections that can be used simultaneously: An AES/EBU (XLR connection), a S/PDIF (coaxial connection) and a S/PDIF (TOS-LINK connection). There is also a BNC sync input connector in case if your studio already has a dedicated word clock device. The front of the unit is aesthetically pleasing with its beveled edges and brushed face. There is a C-weighted 20 segment LED input level meter for each channel. The display holds each peak for a few seconds so you have some time to view an "over." The first switch configures the unit at either a 32, 44.1, 48, 88.2 or 96 kHz sample rate (whatever your session is) and whether or not you want to use an external word clock. According to Jim Latimer of Lucid Audio, although the internal clock in the AD9624 is pretty good (very good when compared to my 001 system IMHO) hooking a dedicated word clock device such as the Lucid GENx6 to the sync input of the AD 9624 will yield superior results. The second and third switches control the bit depth (16 or 24 bit) for the digital outputs. Finally, there is an input level control for each channel, which may be used in a dual-mono or a stereo configuration via a link switch. I found that a setting of approximately 1:30 on the control matched the Lucid metering with the input metering in my software. Overall the Lucid AD9624 feels like a very solid device, and it is easy to interpret and adjust. Lucid makes a specialized rack tray for mounting, or you can use a universal tray with some double-sided foam tape. There is a companion to this unit which can be racked side-by-side called the DA 9624. That unit converts a digital signal back to an analog signal. But that is another topic (and another budget).

Hooking it up was easy: an XLR cable from the output of a mic pre to the input of the unit, and a 75 ohm RCA to RCA cable from the S/PDIF coaxial out of the Lucid to the S/PDIF coaxial input of my Digi001 system. The 75 ohm S/PDIF cable carries two channels of digital audio as well as a clock signal simultaneously. (Note: using a standard RCA audio cable is highly discouraged for this use!) I usually run my recording sessions at 24 bit and 44.1 kHz, and so I set the Lucid toggle switches accordingly. Also, I set the Lucid to be the master clock (internal clock). In my DAW software I had to configure the input/output settings to accept a S/PDIF signal as an input, and to clock from an external source (the Lucid). After creating a new track and choosing the Lucid as the input device I was now getting audio into the system! Yipee skippy!

There are two factors influencing the difference in recording quality with the Lucid. One is the improved quality of the A/D converters and the other is the superior internal clock. Tracks that are recorded through the Lucid certainly sound much better to me, but also tracks recorded through the stock Digi001 converters also improve marginally when the system is clocking off the Lucid device. I was very pleased to hear that the biggest improvement in tracking with the Lucid is the depth of the sound. Older recordings done with the stock Digi001 converters sound very two dimensional and a bit lifeless, but the Lucid recordings reveal a space and depth to the sound. For example, when listening to a pair of drum overhead recordings it is easier for me to perceive which cymbals are closer and which are farther away. Another big improvement is the accuracy of high and low frequency material. Guitars have air to them that they never had with the stock converters. Down low where the kick drum and the bass guitar are dueling it out for space, it is easier for me to hear the problematic frequencies and make adjustments. To my ears, recordings done with the stock converters sound muddy by comparison. Often times, I found myself pushing up frequencies on drum overheads above five kHz with a high shelving EQ, but with the Lucid this is usually unnecessary. To quantify the amount of improvement that adding the Lucid to my signal chain has made I would say it is as much as when I got my first quality microphone preamplifier. I have read of many people saying that the improvement is minimal, but I beg to differ. On individual tracks the difference may not be huge, but 24-32 tracks of Lucid summed together to my ears sounds much better than 24-32 tracks of Digi001 summed together. Honestly I am very surprised and impressed with the differences that this unit has made in my recordings, and I would recommend it to anyone in the market for a two-channel converter.

I have noticed an interesting situation in using this device with my system. As with all DAWs, we operators need to be aware of that dirty L word LATENCY. Well here is something that I found out: My stock Digi 001 has a latency of 0.58mS (milliseconds) on its A/D conversion. To verify this, I patched a cable from one of the outputs to one of the inputs and sent a prerecorded a piece of music through this connection to be printed on a new track. The timing difference between the two waveforms was 51 samples (or 1.16mS in my case). Dividing that in half leaves 0.58mS for A/D and 0.58mS for D/A conversion. Still with me? Now patching a cable from the Digi 001 output to the Lucid AD9624 input and repeating the test yielded a result of 73 samples. After all the math this means that it takes the Lucid 1.08mS to perform its A/D conversion.

Simply put, it takes the Lucid AD 9624 0.49mS longer than the stock Digi 001 to perform A/D conversion during a 24 bit 44.1 kHz session. These numbers will certainly change with different setups, but, with any DAW latency is a fact of life and worth investigation by the operator. The problem arises when I need to record more that two channels at the same time, such as drums. I typically send two overhead signals through the Lucid and a snare and kick drum signal through the Digi 001 converters (clocking off of the Lucid). After recording, the Lucid tracks are recorded 0.49mS later that the rest of the drum tracks. In order to preserve the proper phase content of the drum kit, I need to bump the overhead tracks back by 22 samples (roughly 0.49mS). Honestly, the difference between doing this or not is barely perceivable (but to my ears results in a clearer sounding kit), but as with anything in audio every little bit counts. I imagine that this problem will be encountered with just about any aftermarket converter, and is not unique to the Lucid unit. For those with the cash the big brother to the AD 9624, the ADA 8824, offers eight channels of simultaneous A/D and D/A conversion. Tracking exclusively through this unit would eliminate this latency mismatch.

In my opinion the best time to acquire a quality digital converter is right after the first real microphone preamplifier purchase. A new microphone, mic pre or effects unit will certainly improve some recorded tracks, but a converter upgrade will make an improvement on every track, whether it is a miced signal, a keyboard or a bass DI.

Bottom Line: The Lucid AD 9624 is a well built and great sounding analog to digital converter that can improve the quality of all of your tracks. It's extensive features allow it to be coupled with just about any digital device in the studio or the field. Street price is $750.00. Highly recommended.

Link relating to this review: Lucid

Daniel Raible likes to use his Lucid to record his band, JJ Flux.