by Jackson Macinnis
Recently, Benchmark introduced its $3,995 made-in USA, ADC16 A/D converter which kicks analog-to-digital conversion up to a higher level of performance for all kinds of recording studios — especially today’s professional-grade home studio. The Benchmark ADC16 fits 16 channels of its premium converters into a single rack space — yet still manages to fit AES/EBU, ADAT, coaxial and TOSlink connectivity. It even contains an expansion port for a Firewire port DAW interface, which is how I used the ADC16.
I played a Gibson Custom Shop ’59 Les Paul, which has a fantastic warm humbucker tone. I have recorded this rig with other converters, but the Benchmark ADC16-recorded tunes played back through the DAC1USB (or even my Apogee DAC) blew them all away. I have never heard my guitar rig sound this good...
The primary A/D design is based on the stereo reference ADC1 A/D, using the excellent-performing AKM 5394 A/D stereo ICs (eight of them), as well as high-quality digital clocking and analog components throughout the audio path. Unlike the ADC1, the ADC16 utilizes synchronous conversion for seamless compatibility for all sample rates.
Benchmark also has improved the already impressive jitter reduction via its new proprietary clock-sync system, which is termed UltraLockDDS. This upgrade to the previous Ultralock technology is said to reduce audible jitter — even if using an external clock reference — and the ADC16 does it with reduced latency, which has been noted in the previous generation.
Although the ADC16 has major utility for home studios, it is also designed to work in other professional scenarios including television studios, film production and dubbing stages. The use for reference audio of this specification is endless. With its number of channels, connectivity and performance, the $4,000 price tag is a bargain!
For this review, Benchmark provided the Firewire card-equipped ADC16 as well as a DAC1USB D/A for stereo monitoring. Setting it up was fairly straight forward and not difficult at all. The Firewire option installation required the use of a Pico driver, which installed with no issues in the 8-core Xeon Apple Mac Pro that I used for the test. Once I launched Apple’s Logic and created an aggregate device I was able to use the ADC16 for my inputs and the DAC1USB for monitoring the mix down stereo outputs. Pretty darn slick setup.
I used a variety of microphones, Mogami cable and our esteemed publisher, John Gatski, loaned me his British-built ORAM 16T 16-channel analog console. As the front end to the system, this $4,000 console contains quiet, dynamic mic preamps, which are easily accessed through the direct outputs. We used a quarter-inch, balanced TRS-to DB-25 cable to get the audio from the ORAM mixer to the ADC16.
The drum kit playback of the stereo mix down (24-bit/192 kHz through the DAC1USB) was truly amazing: smooth, quiet and warm, yet very dynamic and real sounding. The Benchmark definitely had more detailed nuance (cymbal reverb tail, etc.) than when I used an Apogee multichannel converter.
The quality of the A/D output, when listening to the stereo mix down via the Benchmark DAC1USB, revealed to me one critical element: to hear the ultimate sonic detail from the ADC16, you need a DAC capable of delivering what the A/D has laid down on disc.
After listening a bit more to the impressive clarity of treble and midrange tones (cymbal decay and the hi-hat), I focused on the low end. In digital, good-sounding, low-frequency music reproduction has always been easier to eek out of the digital converters than the top end. But in the case of the Benchmark A/D conversion, I heard so much more definition than I expected in the kick. The tones were low, no inherent thinness. It was reproducing exactly what we sent it from the ORAM mic pre-amps. And isn’t that the point? Isn’t that what we strive for as recording engineers? The sound of the music as it is heard live by the studio engineer and performers. Unlike other devices that we use to color sound, the highest compliment for an A/D converter is that it has no color — no artifacts; this accurate character is exactly what I found with the Benchmark ADC16.
The key to the Benchmark's flexibility is the input/output architecture. First, the balanced analog inputs are via DB-25 connectors. Eight channels per each of its two DB-25 input banks, which means you will need your sources to have the correct output cables with DB-25 connector to interface with ADC16.
I am so impressed how real sounding these Benchmark converters are. Yes, the ORAM mic pre-amps are outstanding and contributed to the positive recording experience for this review, but without the Benchmark A/D converter in the mix, the recordings were not quite as detailed or dynamic. And just think, if you have good mics and preamps, the ADC16 gives you have this kind of recording quality using just a computer and some software in your home studio!
The last thing I recorded was an electric guitar, using a Cascade Fathead ribbon microphone as a room mic and a mic close to the Fender Vibro-King amplifier. I played a Gibson Custom Shop ’59 Les Paul, which has a fantastic warm humbucker tone. I have recorded this rig with other converters, but the Benchmark ADC16-recorded tunes played back through the DAC1USB (or even my Apogee DAC) blew them all away. There was such body and fullness of tone; I have never heard my guitar rig sound this good on tape. Oops, I mean disc.
I had no real qualms or problems with the ADC16, operationally or sonically. There was a wee bit of learning curve in the beginning to get the ADC to communicate with Logic, but a quick read of the very detailed manual had me up and running in no time.
I used the ADC16 in a home recording studio — where all levels of artists from garage bands to the well-known artists do their recording these days — and it excelled beyond my high expectations. The finest A/D conversion I have ever heard is through the ADC16. And it is easily available (for just under $4,000 of course) to those who simply want to plug a unit into a computer and make tracks as good as any world class standalone studio. Who wouldn’t want this?
The Benchmark ADC16 is versatile A/D converter with a wide selection of sample rates, output formats, and connection possibilities to normal analog inputs and/or to a DAW with an added accessory card. Measurements were made to analog inputs 1 & 2 with a reference input level of 12V rms set as 0 dBFS which was just shy of onset of clipping.
Frequency response at 0 dBFS at sample rates of 44.1, 88.2, and 192.0 kHz is shown plotted in Fig. 1. Filter shapes are such that the response is quite flat up to the onset of filter roll-off. Low frequency response was flat to below 10 Hz. An interesting and revealing measurement in digital converters is the THD+N vs. level of a 1 kHz tone in the converter output where the input ranges from 0 dBFS down to a sufficient low level to reveal the noise floor. In the case of this design, the noise floor is an impressive approximate -120 dBFS but the distortion takes quite a reduction of input level to get there – approaching 0.0001%!. This is plotted in Figure 2 for both channels and sample rates of 192.0 and 44.1 kHz. The results (not shown) for sample rates of 88.2 and 96.0 kHz were closer to the 44.1K data. The higher amount of THD+N is for the 192.0 kHz sample rate.
THD+N vs. frequency at full scale was reasonably constant over most of the audio range rising a bit in the last two octaves. This data is shown in Figure 3 for sample rates of 192 kHz (Magenta), 96.0 kHz (Red), and 44.1 kHz (Blue). The S/N ratios at the digital outputs for sample rates of 44.1, 96.0, & 192.0 kHz and in a measurement bandwidth of 20 kHz were 119 dB for all three sample rates. Dynamic range measurements for the same sample rates were also 119 dB.
Finally, for the three sample rates, quantization noise was -118 dB. Adjacent channel separation was excellent, similar in both directions, and better than 106 dB even at 20 kHz. All in all, the basic measurement parameters of the Benchmark ADC16 are in or near the top of A/D converter performance standards — numbers that we come to expect from this engineering-driven electronics company.