June 2012

Benchmark Media ADC1 USB 
Two channel 24-bit/192kHz analog-to-digital audio converter… and the art of the LP burn.
Review By Tom Lyle

  Until the archiving of vinyl, I can't remember a time when I encountered so many different opinions regarding not only the methods in which a piece of audio equipment should be used, but to which method is better than the others. The methods I'm talking about, of course, are the ways an analog signal (the majority of the time, from a turntable) is to be transferred to a computer in the form of a digital file. Naturally, I also have my opinions on these methods, and since I am the one writing this review of the Benchmark ADC1 USB and the way I use it to archive vinyl, I am going to hope that, at least for the moment one will keep an open mind as to my methodology. I'm not professing to be an expert on this or any subject, but those who have experience with burning LPs will realize that is as much of an art as well as a science. If one disagrees with my methodology (and surely there will be those that will), I hope reading this will expose those to different ways of doing things than their own. And for those that either have little or no experience with transferring a vinyl record's signal to the computer, this may serve as an introductory primer. There is hardly enough space to go into too much detail, though. But for both these new folks and especially for those with more experience with this sort of thing, this will serve above all a review of the Benchmark ADC1 USB analog-to-digital converter.

There also the matter of why one is turning a vinyl LP or single into digits in the first place.  I would hope that one would think twice before committing to a project to burn one's entire record collection to a computer. Things are changing to fast, so there is no way to guarantee that the method used is the best method, or the resolution used is the highest that will be acceptable in the future. Even if I had the time (I don't) I would not consider digitizing my entire collection. There is really no reason to, and my time is better spent listening to the records. I'll admit to a small chance that somehow I will lose my entire collection because of some sort of disaster, and even though I'm not a betting man I'd wager that this will not happen. So, I figure my records will be around for at least the rest of my life, and I might as well enjoy them by spinning them on the turntable on a killer system. Some say one should archive to preserve one's records. The act of playing my records on my turntable isn't wearing them out, as I have some records in my collection that are over fifty years old, in perfect shape, and they show no signs of deteriorating. On my system when I want to listen to vinyl I spin vinyl. My reasons for digitizing my records (other than that it is fun to do) are simple: to make CDs for the car and other places where only a CD will do, to share hi-rez versions of the fantastic sound of the vinyl with friends, to place some select records in files on the hard-drive for the music server, and to listen to them on portable devices. So, as I am burning my very difficult to replace (or at least rather expensive to do so) RCA "Living Stereo" Prokofiev Symphony No. 5conducted by Jean Martinon I am doing this more for the above reasons than anything else.

Garbage In Garbage Out
The results one gets when using the magnificent Benchmark ADC1 USB analog-to-digital converter to digitize vinyl are highly dependent on the original source. If one doesn't have a decent source to begin with, one should hardly expect a satisfactory sound at the end. One is going to need an LP in fine condition that has been subject to a recent wet/vacuum record cleaning, and a good turntable, tonearm, phono cartridge, and phono preamplifier. I have heard very good results using lesser equipment than I use, and I would never deny the enjoyment an audiophile will surely have when burning LPs, but if one's goal is to get as exact copy of the original vinyl as possible one should keep in mind that there is no doubt that these factors are going to come into play.

I clean my records with a Nitty Gritty 3 record cleaning machine, which although is a bit old,  shows no signs of age other than needing an occasional replacement of the felt strips that lines the vacuum slot, and it also needed a one-time replacement of the support and platter pad. I use Premier record cleaner on new records, which is a volatile liquid that removes the factory mold-release compounds. I then use a homemade cleaning fluid, which is mostly made from purified water after first using the Premier, and for all the "used" records that enter into my collection, or others that need a touch-up cleaning. I am currently using a Basis Debut V turntable that was updated by Basis from a Gold model. They took quite a long time to do the work, and it was quite expensive, but in the end it was worth it. I also recently upgraded the turntable's platter belt to their Revolution model, and use a Basis' reflex clamp to hold the record on the turntable platter.

The turntable's AC is plugged into its own PS Audio Power Plant AC Regenerator that provides the turntable's AC synchronous motor with a pure 60Hz sine wave for 33.3 rpm records, and an 81Hz sine wave for 45 rpm records. The tonearm is a Tri-Planar VI, a model that was built for me by the late Herb Papier, the original owner, inventor, and manufacturer of this tonearm. For a short time I was using a model VII U, which was built by his protégé and current manufacturer of Tri-Planar, Tri Mai. There are differences between the two 'arms of course. Some say that the tighter tolerances of the VII U lead to a greater transient response and greater overall resolution. Yet others have claimed that the VI, which was the last model built by Mr. Papier, also built with a high degree of precision but is more of an artisanal product, which some (including me) say has a more musical sound and is more lifelike, especially on acoustic instruments. The phono cartridge is a Lyra Kleos that I reviewed in the April 2011 issue), and the tonearm's internal wire is Discovery, which continues without a termination box, morphing into an interconnect with Cardas RCA jacks. This cable is connected to a Pass Laboratories XP-15 phono preamplifier, and the phono preamp is connected to the system's line stage via its XLR outputs with MIT interconnects.

As is fairly obvious I put a great deal of importance on the analog front end, and therefore the signal that is fed to the Benchmark ADC1 USB. While speaking to the people on the other end of the phone at Benchmark, and also mentioned in their literature, it seems that they understand that audiophiles are interested in "a sense of musical engagement that was originally present when the sounds were created" as they do that there unit is as technically proficient as possible. Benchmark uses terms such as "depth", and "images". For a company that intended that their equipment be used by studio professionals, they get it.

Guarantee
The ADC1 USB is a two-channel 192 kHz 24-bit analog-to-digital audio converter. Benchmark claims that their unit is jitter-free, using their UltraLock clock system, and a well-built analog section to guarantee this. Again, an important aspect of the Benchmark that should be considered is that the ADC1 USB is not only built for audiophile use, but for professional studios. So, although some of the features built into the ADC1 USB may never be used by an audiophile the performance of the ADC1 USB is not compromised in any way. So, even though one may not use an external clock, the ADC1 USB's sound will not degrade when slaved to this external clock. The ADC1 USB recognizes AES/EBU, S/PDIF, Word Clock, or Super Clock sources. Even better, as I mentioned the Benchmark has a well-built analog section. Benchmark claims that this aids in the transparency of the unit, and I believe them. They claim that the analog front end delivers "low-noise low-distortion high-bandwidth performance". There are precise gain and calibration controls that allow for accurate channel balance. They go on in their literature with more audiophile terminology, saying that it captures exact imaging, difficult transients, and subtle details with "stunning" realism. If this sounds as if they are talking about their DAC1 USB digital-to-analog converter that has ended up in so many audiophile's systems, including mine, one would be correct, and that only made me more excited to get started using the ADC1 USB.

Functionality
The ADC1 USB analog-to-digital converter seems like it is a more complex device than the DAC1 USB digital-to-analog converter, so much of its functionality seems as if it were designed for the professional studio, therefore many of its functions might not be used by the average home user. That's OK. Even though at first I was a bit confused by its busy front and rear panels, I was able to use the ADC1 USB to, at least I would think, its full advantage.  As digital music progresses, my needs progress, and it seems as if the ADC1 USB will be able to progress with these needs. Even if one only uses its USB outputs to the USB inputs of the computer one will hear the benefits of using this very high-quality digital-to-analog converter. Spoiler alert: I found the sound to be as sonically proficient as their DAC1 USB, and in many ways, better.

The ADC1 is able send to the computer a digital signal that is up to 192kHz and 24-bit   output. The ADC1 USB has a total of five digital outputs, one XLR, two coax, one optical, and its USB output. These can operate simultaneously at up to three independent sample rates, and if one is using this unit in a professional setting this can be quite useful, for example, one output can feed a real-time recording of a CDR in 16-bit, one output to a digital workstation at 88.2kHz/24-bit, while another output sends a signal to a digital recorder operating at 192kHz/24-bit. This is especially useful in live recording sessions when a backup must be made. The USB output has a resolution as high as 96kHz and 24-bit.

Spent
The sample rate and word lengths are set by the front panel controls, but I spent most of the review period using its USB output where the sample rate and word lengths are set by the recording software. I use a PC. I am well aware that many who edit music use Apple Mac hardware, but I've been using a PC for music since the MS-DOS era so I'm pretty entrenched in this environment, not only because of the software that I've learned to use (and purchased) over the years. I use Sony's Sound Forge 6.0, which is a bit outdated (in a world where it is common for some software companies to issue weekly updates) but I bought it before the company was purchased by Sony, when it was still called Sonic Foundry. Sony declined to participate in this review (they did not return my phone calls or emails), and the other reason I didn't use the latest version of Sound Forge, but as far as I can tell from the demo I have little need for the features in the current version. For those that would rather use free software that mimics the Sony software quite well there is the popular Audacity program. I feel that the Audacity program isn't as stable as the Sound Forge, but it will get the signal onto the computer and make the files available for editing. If one wishes to burn a CD and one uses a PC, I can think of no better than Sony's current version of CD Architect 5.2, which I have been using since the very early days of Sonic Foundry's existence.

Simplifying matters is always a good thing, especially since most of the time spent in burning an LP is the editing process. Yes, one is going to spin the LP in real time but this is when one can sit in the sweet spot and enjoy the record, since the levels are set beforehand and changing the level once the record is playing is not going to be necessary on about 99% of the records on is likely to burn.  My previous method of burning LPs involved using multifunction soundcards. I did get more than satisfactory sound from these, but a major disadvantage of using it, besides that these PCI soundcards are subject to the noisy environment of the computer, is that the input volume that is fed to the computer cannot not be set. It is determined by the gain stage of the phono preamplifier. This usually was not a problem since the volume was just about perfect with a gain setting of 66 dB on the phono preamp, but sometimes it was a bit too low, and especially on 45 rpm records it was too high.  And this pretty much ruins the sound. If the signal is too low (but not excessively so) it can be compensated for by editing the waveform on the software, and still, even with an optimum setting on the volume control of the ADC1 USB a bit of tweaking is usually necessary later on in the editing process. As I said before, if the volume is too high the signal will clip, and the resulting waveforms will end up being just about useless.

Serious
I could waste some serious space with editing examples and tips. I cannot stress strongly enough that one download a version, demo or otherwise, and try some editing for oneself. The following is a simple example of editing a waveform. No matter what method one method one uses to get the signal into the computer, the waveform will look like this when it goes into the computer, in this case a 96 kHz/24-bit version of the Mobile Fidelity Sound Labs version of The Beatles Revolver:

Here one sees the first song, "Taxman" and the beginning of the second, "Eleanor Rigby". Here, I will demonstrate how the space between the songs needs to be muted. After enlarging the portion of the screen with the quiet grooves and highlighting it, and highlighting it is just as one would do with a word processing program. Choosing the correct place to highlight can be done audibly because the program will only play the highlighted section when hitting the "play" icon.

Then one chooses mute from the edit menu, the space between the songs will then look like this:

This is hardly a Sound Forge manual, so I am describing this in a manner that is simpler than it actually is. Although the editing program is a powerful tool, is hardly rocket science, and can be mastered as one uses it. Many don't edit the final waveform as much as I do, but I've been doing this for quite a while and find it rather enjoyable to produce a final product that represents the LP as much as possible without any sonic artifacts such as record noise in the lead-in and lead-out grooves, and between songs, as illustrated above. There are many other places besides the spaces between tracks that might need editing, such as the aforementioned beginning and end of the record sides when a quick fade might be inserted, or a few crackles, which will appear as spikes in the waveform from damaged vinyl needing, which can be eliminated by "erasing" the click in the waveforms. When producing a CD in CD Architect, one must indicate track beginnings and ends, and this takes a bit of finesse that can be learned quite quickly.

Some editing programs that are purposely designed for vinyl editing have filters for eliminating noise that are extremely harmful to the transparency of the final product, so I want anyone who is reading this to promise me that it will never be used – unless the record is severely damaged and there is no chance that a replacement copy can be found. A few crackles and pops are much less annoying to me than listening to a record that has its overall sound (transparency) ruined by a filter.

But I have to emphasize again that this can be a very time consuming pursuit. On most every rock album, especially one such as The Beatles Revolver, if one wants each track to appear separately,  a separate file for each song is going to have to be made by highlighting each track and transferring to a separate screen. This could also be done, but of course with only 44.1kHZ/16-bit files, by loading the file into CD Architect, inserting track markers, burning a CD, and then transferring the CD to the hard-drive with a program such as Exact Audio Copy (a free open-source program) which will create separate track files in the format one chooses such as FLAC, .wav, or a variety of compressed formats. I've often done it this way for albums that didn't need (or deserve) a resolution higher than CD quality, or sometimes I'd make a lower resolution copy specifically for CD.

There are also programs that make it possible to connect an analog-to-digital converter such as the ADC1 USB directly to the computer, bypassing the phono preamp, where the program sets the desired RIAA curve. I have never used one of these, and I've never requested to use one, as I hear many sonic advantages to my choice of phono preamps, the Pass Labs XP-15. In my case I have a choice of either monitoring the LP's output through my system, and take the signal feed from the tape output of the preamplifier. I could have just as easily taken the feed from the phono preamplifier. I heard no difference between the two. What I did hear, though, was the major improvement in sound using the Benchmark ADC1 USB in place of the popular, but rather low cost soundcards to convert the analog signal into digital. No surprise there, really, because these units not only serve as an analog-to-digital converter, but a digital-to-analog converter. Some have other functions such as a headphone jack.

The resulting sound of the files that ended up on my computer when using the Benchmark ADC1 USB had everything that Benchmark promises in their literature and more. The most noticeable quality of the Benchmark, even in my first casual listen off-axis to one of the first files that I recorded from LP was the separation of instruments in a huge soundstage. The inner detail of the music, that enabled me to hear instruments, sounds, and voices I thought once impossible to recover, and were made evident when making recordings of LPs of even the most complex orchestral and choral music. I could continue to heap praise upon the sound of the ADC1 USB, but all this would really accomplish is me reciting audiophile-isms in regards to transparency, soundstage, frequency response, etc. The take-away is that I've never used or heard a better analog-to-digital converter, and if I ever have the opportunity to use or review another high-end converter the Benchmark has set the high standard for all other comparisons. I would post high resolution recordings of I burned using the Benchmark in my DropBox account of albums for my friends to hear, and they would report back to me that they have never heard anything close to the quality of these recordings, even when compared to "officially released" high-resolution digital downloads.

Realize
So there you have it. I realize that that this is only a brief overview of what is possible not only when burning an LP using digital editing software but of the very fine Benchmark ADC1 USB. The mastery of using the software takes hands-on use and gets better over time, but the mastery of using the Benchmark ADC1 USB is a much, much simpler. It does not require any special drivers, and when using the USB output of the unit it is as easy as just setting the left and right channel volume controls. The Benchmark ADC1 USB is a plug-and-play unit that I not only highly recommend as a tool for burning vinyl to one's computer, but as an audiophile component because of its attention to all the details that a component must have to be considered for use in an audiophile's system. I was about to say that the folks at Benchmark should win some sort of an award for creating such a fantastic component, but it will when I nominate it for Enjoy The Music 2012 Blue Note Awards. Recommend? No. It is required.

Specifications
Type: Two channel 24-bit/192kHz analog-to-digital audio converter
Analog audio Inputs
Two via Gold-Pin Neutrik female XLR
Impedance: 200 k Ohms 
Sensitivity: -15dBu to +29 dBu (at 0 dBFS)

Clock Reference Input 
Format: Auto-detect AES/EBU, Word Clock, and Super Clock (256x)
Impedance: 75 Ohms 
Sensitivity: 150 mV (AES), 200 mV (word clock), 750 mV (super clock)

Wordclock Reference Output 
Impedance: 75 Ohms
Level: 5 Vpp, 2.5 Vpp into 75 Ohms

Digital Audio Outputs
Number of digital outputs: 1 XLR main, 1 TosLink main, 1 BNC main, 1 BNC aux, 1 USB
Connectors: Gold-pin Neutrik male XLR
Number of audio channels: Two
Main output word length: 24 bits
Main output sample frequencies: 44.1, 48, 88.2, 176.4, or 192 kHz 
Aux output word lengths: 16 or 24 bits
Impedance: 110 Ohm XLR, 75 Ohm BNC
Level: 4 Vpp into 110 Ohm XLR, 1 Vpp into 75 Ohm BNC

Audio Performance
[Fs = 44.1 to 192 kHz, 20 to 20 kHz BW, 1 kHz test tone, 0 dBFS = +24 dBu (unless noted)]
SNR: A-weighted, 0 dBFS = + 8 to + 29 dBu: 121 dB
THD+N, 1 kHz at -1 dBFS: -102 dBFS, -101 dB, 0.00089%

Dimensions

Company Information
Benchmark Media Systems
203 East Hampton Place
Suite 2
Syracuse, NY 13206

Voice:(800) 262-4675 or (315) 437-6300
E-mail: sales@benchmarkmedia.com
Website: www.benchmarkmedia.com