Wavelength Audio Cosecant USB DAC
The right price and giving hope for the future.
Review By Dr. Jules L. Coleman
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  In addition to designing highly acclaimed amplifiers, Gordon Rankin — the man behind Wavelength Audio — has engineered and built high sensitivity loudspeakers, and custom guitar amplifiers. He also invests in projects that support musicians in his native Cincinnati and is an avid, if not yet accomplished, guitarist and collector of vintage guitars. Most of our e-mails over the past few months have been about vintage electric guitars, not audio gear. The creation of digital audio, in the name of "Perfect Sound Forever," may be considered by some to be against the will of the musical G-ds and a minor disturbance in the natural order.

And G-d Created Computer Audio
Like other designers during the mid to late 1980s, Rankin found himself designing DACs in the hopes of taming the shrill, hard, impenetrable, paper thin and textureless sound/characteristic of digital playback during the dark ages. In the intervening twenty years, digital audio has made substantial strides. Today, its harshest critics and skeptics (me among them) agree that contemporary digital playback is enjoyable and, at its best, quite 'musical.' Though digital playback hasn't always been a musically satisfying format, it has always been a convenient one. If anything, the convenience of the digital format has only been enhanced by the advent of computer/hard drive based systems. Such systems share at least four virtues — three of which are practical: convenience, storage, and access to music (via the Internet). None of these are virtues that bear on the quality of music playback. In contrast, the fact that computer playback systems allow for largely error-free bit-by-bit playback of musical files is. On the other hand, a computer is not a particularly hospitable environment for an audio signal. Computers are noisy and the circuits are not designed to ensure the integrity of a musical signal. In addition, a computer's soundcard rarely constitutes the state of the art in music playback.

Not Just Another Brick In The Wall
The solution to the latter problem is the use of an outboard DAC. There is no getting around the fact that computer audio has fueled a bump in the production and development of standalone digital to analog converters. There are two sorts of DACs suitable for use with computers. The first is the standard device; the second is the so-called USB DAC. In order to use a standard DAC with a computer, one must generally use an interface device that takes the computer signal from the USB port and turns it into a signal that the DAC can accept — usually through the RCA jacks. I have been fortunate enough to review two of the best of these devices, both designed by Steve Nugent for Empirical Audio. The very best digital playback I have achieved using a computer and digital interface was an Apple Laptop G4 through Nugent's offramp into the I²S input of an Empirical Audio modified Perpetual Technology DAC. While the sound quality did not equal that of the previously reviewed Reimyo CD, it was quite good in most musically important respects. It also made me a believer in the possibilities inherent in this approach to digital playback.

At this time, my reference digital playback consisted of the same laptop feeding Gordon Rankin's USB Brick DAC. I had already committed to computer-based playback on my reference system in my Connecticut home, which is where I do most of my critical listening. Digital playback on my other two systems — in my NYC apartment and my Yale Law School office — continues to be handled by standard CD players. Most of my serious listening at my home in Connecticut is vinyl based and I flirted with the idea of a true reference quality CD setup at home while reviewing the Reimyo player. Once I decided against purchasing the review sample, my mind turned from musical excellence to convenience.

Digital would never be the format employed for critical evaluation. I was jaded by my experience with the Reimyo. It was just so much better than anything heard to that point. I formed a generalization and acted on it. For my money the best digital is really a step apart from the rest, but as soon as one drops down a notch or two CD players are more similar than different. This is especially true in comparison to vinyl. If you weren't going to spend big time — and I wasn't — it was fairly easy to do quite well at a reasonable cost.

Yes, I was drawing an inference due to the modest sample (by any serious scientific standard), but it was my theory. Like a good, stubborn audio reviewer, I was sticking to it — at least until someone could convince me otherwise. If convenience were the game, then an Apple laptop would be the way to go digitally. In the end, a very satisfactory digital playback system based around the Apple Laptop came into being plus a LaCie hard drive and Wavelength Audio's Brick DAC.

I purchased the Brick after reviewing it for another publication. To my ears, the Brick represented a genuine value. It presents music in a relaxed, engaging, entirely inoffensive and non-fatiguing way. Digital playback with the Brick in my system is 'comfortable.' On the downside, the Brick has a somewhat homogenizing effect on the music. The leading edge of notes is blunted or softened, which takes a bit of life from the music. The consequent reduction in micro-dynamic shadings makes the overall picture big and robust rather than refined and nuanced.

In addition, the bottom end is a little chubby, and with the loss of dynamics the sound is experienced as a bit slow by comparison to the real thing. At its retail price south of $2,000 I judged the Brick on balance to be a value I couldn't resist. It has been my benchmark for USB-based digital playback ever since. I have been happy with it. Nevertheless, upon hearing the Empirical Audio combination it was clear to me that that the Brick could be bested by taking another approach.... A substantially costlier approach to be sure, but the improvement that the Nugent setup provided forced me to take note. 

Of Cosines And Cosecants:
Doesn't every sharp dressed man at M.I.T. wear a slide-rule?
I knew that the Brick did not represent the ceiling of USB DAC performance. Heck, it wasn't even top dog in the Wavelength product line! Desiring a better idea of the possibilities inherent in the USB approach, I called to Gordon of Wavelength Audio and asked if he would be interested in having me review the Cosecant DAC. I had heard the Cosecant in several systems before, notably in the Stereovox/Peak Consult room at January's CES in Vegas. Chris Sommovigo of Stereovox is a big fan and I was very impressed by the sound produced during the CES. Gordon agreed and a Cosecant DAC along with its external power supply and USB cable arrived within the month. I replaced the Brick with the Cosecant which has graced my reference system ever since. By the end of this month the Cosecant will no longer be the top dog in the Wavelength stable of USB DACs, though it represented the best Wavelength had to offer during the review period... and a damn fine offering it is. So good, in fact, that I bought the review piece. Indeed, I couldn't wait to do so and here's why.

First of all, whereas the Brick is a rather ordinary looking component, the Cosecant is a handsome piece of industrial design. Its low voltage 6GM8 triode tube protrudes out the top, looking a bit like a passenger in modern automobile, with an acrylic roof over his head. I am a fan of industrial design and liked the Cosecant aesthetics. Beauty is only skin deep and it wouldn't count for much if the sound wasn't up to the task at hand. Everything the Brick does the Cosecant does better; much better. Again the overall presentation is relaxed and non fatiguing. While this version of the Cosecant is not the last word in defining the leading edge of notes, it does not blunt or soften them. Though the Cosecant, like the Brick, favors the way notes develop and leave the scene over the way they enter, the relative reduction in microdynamics that I experienced with the Brick is nowhere to be found in the Cosecant. While the Cosecant does not have the punch and drive of the three times more expensive Sim Audio Andromeda currently in for review, it makes up for this ever so slight deficiency in drive with a tonal purity and balance as good as any I have heard from digital since I sent the Reimyo back to the good folks at May Audio.

Of More Technical Details...
(By editor Steven R. Rochlin)
The Wavelength Audio Cosecant USB DAC avoids the pitfalls found in single IC USB DACs and, instead, opts for multi-bit DAC IC. A single resistor is used for passive I/V conversion and this choice, according to Wavelength Audio, is "Because only a resistor can be a linear device over the entire audio band." Care is taken with the critical power supply as the outboard unit employs Linear Technologies regulators and Hexfred Rectifiers. A grand total of 22 Black Gate capacitors are in the Cosecant. Seven BGNX HIQ, seven BGN, and eight standard. Black Gates are longtime favorites of DIY'ers and can be found in some of the world's best gear. As for the tube output section, the 6GM8/ECC86 is parallel feed and has an output impedance of 600 Ohms with the choke and step down transformer being manufactured by MagneQuest.

Dr. Jules L. Coleman Continues...
There is nothing soporific about the Cosecant as it can get up and dance. I just finished playing all four disks of the Stiff Box collection and the music bounced when it was supposed to, the guitars jangled, the singers mumbled and stumbled just like I remember them doing when I listened to the same box set on the Reimyo. Horns have the right burnished tone; stand up basses display string and body in just the right combination, and the piano tone is absolutely first rate. If the defining characteristic of the Brick is comfort, the defining characteristic of the Cosecant is balance. If the three most important words in real estate are 'location,' 'location,' 'location,' then the three most important words in audio are 'balance,' 'balance' 'balance.' Tonal balance from top to bottom, balance from leading edge to decay, and dynamic balance.

The Price Is Right
The Cosecant is not perfect, but it is a great value at $3,500. There is an all silver version that comes in at $10,000 and my bet is that it improves on the Cosecant in the areas of focus, transient response and energy. The Cosecant is not the last word in any of these ways, but it is close enough for me. If I had $16,000 to spend I would have bought the Reimyo. If I had $12,000 I wouldn't hesitate for a minute to buy the Sim Audio Andromeda. These are both class leaders in CD playback and both best the Cosecant in some musically important respects, but not in all of them. The Cosecant sets the standard for tonal balance and ease. Its energy level falls below the Andromeda and it does not resolve the finest music details as well as either the Reimyo or the Andromeda do.

What it shares with both of these extraordinary machines is the fact that when you play music through it, it sounds like music. You have absolutely no sense of the machine being in the way. When matched with an appropriate computer and hard drive, a Cosecant based system comes in at one third the price of the Andromeda, and about one quarter of the price of the Reimyo. Given my budget, the price is right. More than that, it gives one hope for the future. Computer/hard drive digital playback is here to stay, and the Cosecant has made me feel a whole lot better about that fact.

Specifications
Type: Vacuum tube USB digital to analog converter with outboard power supply
Tube Compliment: 6GM8/ECC86
Frequency Response: 5Hz to 20kHz
USB Audio: 1.1 & 2.0 compliant at 32K, 44.1K and 48K at 16 bits
Output Voltage: 2.5Vac - 2.75Vac depending on tube
Dimensions: 6.5 x 6.5 x 5 (WxDxH in inches)
Warranty: 1 year parts and labor
Price: $3500 with copper wound output transformers, $10,000 with silver wound output transformers

Company Information
Wavelength Audio 
3703 Petoskey Avenue
Cincinnati, OH 45227

Phone/Fax: (513) 271-4186
Website: www.wavelengthaudio.com