Wadia iTransport iPod Dock Gets Bit-Perfect Digital from iPods!

[audioengr]

Originally Posted by HeadphoneAddict

I wouldn't say "all I see is bigger brand names" - aside from headphones, much of electronic stuff is from companies that I never heard of in the first 45 years of my life. I believe my Apogee mini-DAC re-clocks the signal, and I thought that most up-sampling DACs do something like that. I could be wrong.

Correct, and this is one way to reduce jitter. Medium effectiveness. No upsampling DAC that I have modded is insensitive to incoming jitter, regardless of what the manufacturers claim, and I have modded at least 15 different DAC's.

As for asking about the alternatives, so I see you do support Coax S/PDIF as long as it is implemented properly. Originally it sounded like you thought it should be tossed out. I use Coax whenever possible - my DVD and CD rig uses Coax, and I invested in a good digital coax cable and DAC to minimize jitter.

Absolutely. S/PDIF coax implemented well - that means fast edge-rates and good impedance matching can be outstanding. Still not quite as good as I2S, but can be very close, depending on the CODEC hardware used.

If I understand, I2S has a separate channel for the clock signal, right?

Correct, actually two clocks. The I2S signals are typically these four:

MCLK
SCLK
SDATA
L/RCLK (actually data bit)

If it is superior, I wonder why so few sources offer that? I know Stello makes a DAC that accepts I2S and nobody can seem to provide a recommendation for source that puts out I2S.

I2S is the native interface of the D/A chip. Most DAC's must end-up with I2S before the D/A chip. There have been a number of companies that have tried to establish it as a standard, however there are usually technical flaws in the implementation. Some of my mods remove these. I list Stello as one of the DAC's that can be driven with my Off-Ramp USB converter or my Pace-Car reclocker directly with I2S. Others are Northstar 192 and Extremo, Perpetual P-3A, Audio Logic and modified Benchmark DAC-1.

Same with AES - my Apogee can accept AES but I don't know any sources that offer that as an output.

There are several computer devices that output AES, including the UD-10, the Off-Ramp, the Pace-Car and HagUSB, as well as professional sound cards, such as the Hammerfall or Lynx.

As for optical, I have not had any problems with detail and resolution or distortion that could be blamed on the optical interface increasing jitter, which are admittedly mostly my portable sources (Macbook, Sony portable CD, iRiver).

You probably have a lot of jitter and just dont know it. Most audiophiles are shocked when it is eliminated to discover what they have been missing. It's almost impossible to get good depth of soundstage without first having very low jitter IME.

Steve N.

[emmodad]

Originally Posted by audioengr

There are some companies that are leading the way in this arena and have I2S sources, reclockers and I2S input DAC's, namely Empirical Audio and soon PS Audio (announced).

Steve, non-I2S query, and just for historical perspective: not asking as a yours-vs-X product question, and it's perhaps rather innocuous / moot as this one has been out of production for years... in your research and product development testing, have you ever analyzed performance of the old Genesis Digital Lens (for those who don't know, a "reclocker" / jitter reduction unit with a plethora of digital input and output options, incl AES/EBU XLR)? They put some good emphasis on output waveform integrity, consistent clean fast output edges, etc....

Of course the product is limited to 48 kHz, but I'll mention (purely anecdotally and subjectively, of course) that I certainly perceive improvements in playback from various sources when using my (still going-strong) GDL.

Thanks for your observations.

[audioengr]

Originally Posted by emmodad

Steve, non-I2S query, and just for historical perspective: not asking as a yours-vs-X product question, and it's perhaps rather innocuous / moot as this one has been out of production for years... in your research and product development testing, have you ever analyzed performance of the old Genesis Digital Lens (for those who don't know, a "reclocker" / jitter reduction unit with a plethora of digital input and output options, incl AES/EBU XLR)? They put some good emphasis on output waveform integrity, consistent clean fast output edges, etc....

I have not seen one in person, but I know how it works. The main disadvantage is that it will eventually overflow if the playlist is long enough or the computer streaming rate is a bit high (very common). It was designed for CD's, which have limited length. The timeframe of this design makes it a bit long in the tooth. There were not many low-jitter clocks available at that time, so that is the first negative. Secondly, the logic families available at that time were also not as good as the ones available today.

I think if you can get a good buy on one, it could be beneficial. I have modded the DIP and the Big Ben for customers and these are also old technology and needed lots of mods to make them good. I think the Lens would probably be better than these, but still in need of updating to get really low jitter.

Of course the product is limited to 48 kHz

This is a limitation of course, but if you are using it with an AirPort Express or Squeezebox, no need for 96.

Steve N.