I recently purchased a used ADC1 (non-USB). I wrote Benchmark to say how much I liked it. I got a reply asking if I wanted to demo the new ADC1 USB to verify if my old model was still up to spec! Who does that? They had no idea I had written a review of their DAC2 [Tape Op #97], yet they offered a new unit for comparison. I took them up on the offer. In a few days, I received a new, silver-faced, USB-enabled loaner.
Like most of the Benchmark line, the ADC1 USB is half-wide, which means you’ll need to sort out how you want to mount it if you’re committed to a rack. The manufacturer offers two options — a joiner plate and a custom tray. The plate is an improvement over similar designs; the female threads are inside raised metal ovals that are designed to mate with oval rack-ear holes. This snug fit reduces sagging when two units are joined in the middle. I also purchased the tray, as it provides additional support.
Although I like the aesthetics of the black-faced Benchmarks, I must admit that the brushed silver units are impressive in person. The online photos do not capture the added dimensionality of the textured metal. For those with an odd-number of half-wide units, the company offers a blank plate in matching brushed silver with an engraved logo. After seeing it close-up, I confess I would happily pay for the panel. It’s really sweet.
The ADC1 USB offers two channels capable of a maximum rate of 24-bit, 192 kHz. In addition, it has three notable features: clocking, multiple outputs, and gain staging. Benchmark’s trademarked UltraLock clocking scheme delivers quality conversion even when slaved to a suboptimal external clock. As covered in the pages of this magazine, many converters deteriorate in performance under external clocking. The best standalone clock in the world becomes irrelevant if the receiving converter’s locking system botches the signal. Unfortunately, many manufacturers skimp on PLL synchronization. Thankfully, not Benchmark. Additionally, UltraLock automatically recognizes AES/EBU, S/PDIF, Word Clock, or Super Clock formats. Settings are easily managed with an intuitive array of front-panel toggles, so I was able to get up and running sans manual. But I don’t advise skipping the instructions; there are some well-thought functions you might miss otherwise.
One of the non-obvious features provides multiple digital outputs. The ADC1 USB has a total of five digital outs: one XLR, two coaxial, one optical, and one USB. These can operate simultaneously at up to three independent sample rates. An added bonus — one of the coaxial jacks can be configured for 16-bit TPDF-dithered output. So for example, you could cut a CD-R via a 16-bit, 44.1 kHz signal to a standalone CD writer in real-time, while simultaneously recording to a DAW at 24-bit, 96 kHz. Most users will simply choose to send an AES output to a suitable DAC, but the options are there.
The analog input has two stages. The first is factory-calibrated. A toggle allows the user to select 0, +10, or +20 dB gain. The second is variable, and dual 41-detent potentiometers go from −5 to +19 dB. Thus, the effective input range of the ADC1 USB spans from −5 dB to +39 dB. At a gain setting of 0 dB, the converter will reach full-scale (0 dBFS) with a +24 dBu input level. Furthermore, the second stage can be bypassed, should a factory setting prove optimal. Just flip a switch from variable to calibrated to remove the potentiometers from the circuit.
To be finicky, engaging the pots does alter the L/R balance very slightly. In my tests, I observed 0.1–0.4 dB disparities. That might be irrelevant for most users, but for mastering, the ADC1 USB may require a little help from another gain-stage. The unit also runs a little bit hot, so having an empty rack space above it is a good idea.
The ADC1 USB is very natural sounding. What I put in, is what it captures. Should I wish to color a track, I can call upon other gear in my rack. In a mastering context, a neutral, flat-sounding converter is very desirable. The ADC1 USB has a slight amount of forgiveness in the clipping department. Momentary red flashes on the peak meters generally translate sonically without issue. Pinning the meters in the red, however, does not sound flattering or particularly musical. Offering the variable input calibrations might be optional for some manufacturers, but I appreciate the flexibility. From capturing an analog chain to conducting intake for reel-to-reels, the range of adjustment is very helpful.
If two channels are not enough, Benchmark also makes the well-regarded 16-channel ADC16, but I’m pleased as punch with this half-rack workhorse. It provides an honest representation of the input signal, is forgiving on momentary peaks, and is designed to provide years of uninterrupted service. Benchmark offers a 30-day, risk-free trial, too.