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Wavelength Audio
Cosecant USB DAC
Cosecant DAC
Finally, excellent sonics from the computer!

Gordon Rankin on his new Cosecant DAC

Even though the Cosecant DAC was one of the most forward thinking ideas I ever had, I was still a little apprehensive because of all the talk concerning how poor computer audio can be. The idea came about after I saw a headline that reported CD sales down 12% while downloadable music sales were up 6000%. The light bulb finally lit. Why not make the best DAC one can find dedicated to the computer, notorious for mediocre sonics?

Basically the DAC has a single digital USB input designed for computer use with either MAC or PC. USB, unlike SPDIF, is bi-directional and therefore has error correction and buffering on both sides. Also since this interface is asynchronous, the clocking problems associated with SPDIF are abolished.

The end of Computer audio hellOn computer power up, the 2 devices negotiate services. In this case the Cosecant DAC tells the computer it can do 16 bit audio at 32K, 44.1K and 48K. Since the USB receiver only has to handle these 3 frequencies, the clocking to the DAC has almost no jitter. SPDIF actually has to be synched to the exact frequency of the transport (i.e. if the transport is working at say 44.0896K instead of 44.1K the DAC has to sync to that frequency). Therefore the jitter problems of SPDIF almost go away. So we have a zero error protocol to link the computer to the DAC and very low jitter.

The Cosecant is platform and operating system independent. In other words, any Mac or PC based computer that has USB output will be able to hook up to the Cosecant DAC without software drivers. Just select the Cosecant for Audio Output in your system preferences or control panel and you're done.

That's right you can now do any of the following:

  • Use the CD drive as a transport and play CD's.
  • Use your hard drive as a media storage unit.
  • Stream Internet audio (i.e. FM stations etc.)
  • Video audio output
  • Use the DAC as a monitor for computer recording

In designing this product I looked at many available USB Audio DAC chips. The offerings really did not excite me much as most of them where one bit Sigma-Delta units. So I stuck with the Transcendental DAC we use in our own Cosine. There was no need for the Caffeine options since jitter was so low. This DAC is basically a multibit 16 unit with passive I/V and does not have any analog or digital filtering. It also does not adhere to up/oversampling.

The tube output does filter the output in its own way and the MagneQuest transformer coupled output assures both isolation and good drive capabilities. So we use a USB receiver for this DAC to our Transcendental DAC technologies to the 6GM8/ECC86 tube with parallel feed transformer output.

How do we optimize the computer side?

First, we make sure that all the importing is done with AIFF format. This is usually a parameter in the configuration of the application you are using (i.e. preferences in Apple's iTunes). Also there are usually items in the configuration such as error reading, recovery, and buffering size. Always set the parameter for error recovery when reading audio CD's. Be sure to set the buffering to the highest setting to allow for the larger AIFF files. AIFF is lossless encoding, much like zipping an audio file. The data take in is the same as the data output.

Got your curiosity up?
More questions? Drop by Wavelength Audio

Wavelength Cardinal WE
Wavelength Audio, ltd.
3703 Petoskey Avenue
Cincinnati, Ohio 45227
(513) 271-4186 ph.vm.fax

1404 East Bristol Street Philadelphia PA 19124 USA
Voice: 215-288-4816 Fax: 215-288-4816

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