NEW - Wadia 170 iTransport

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frugal-phile™
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I think this has HUGE potential. These are the 1st guys to pay Apple for the secret codes that lets them get at the digital stream before the iPod DAC. With loosless files this should bring an iPod up close to mega-buck transports and sound quality will be limited by whatever DAC you chose. The only thing i can see it missing is an IS2 output. There might even be room inside to mount some of the diy DACs.

dave
 
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Joined 2006
Megabucks transports are slaved to the DAC clock and that's possible because they don't use S/PDIF (or they have a clock line coming from the DAC). Considering this uses an S/PDIF connection, I don't see how it can compete with these ultra-low jitter systems.
 
In regards to jitter, measurements from the 2003 Stereophile review show:

-The Miller Analyzer performs a narrowband spectral analysis of a
player's output signal, then searches for symmetrical sideband pairs
around the 11.025kHz fundamental.-

"The overall result is superbly low, at 225 picoseconds peak-peak."



of course there's a new generation of iPod out now, and they may
measure differently. If anything the Wadia and a 160GB iPod would
make a convenient playback system, that will probably sound very nice,
Although i will admit, no very DIY at all :)
 
frugal-phile™
Joined 2001
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abzug said:
225 ps is low? You must be joking, this kind of jitter reaching the DAC chip is too high even for 16 bit audio.
Even worse for 24-bit audio, where you need a fraction of a picosecond to actually achieve 24 bit resolution.

I don't know much about the nitty gritty, but i see test figures for seriously good kit measured in this range... and i don't think anyone has made any commercial product that does much better than 21 bit resolution (at least from all the actual measured results i have seen). I'd be very interested to know different.

dave
 
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Joined 2006
planet10 said:
i don't think anyone has made any commercial product that does much better than 21 bit resolution (at least from all the actual measured results i have seen).

Anagram have, with multiple DACs and noise-shaped dithering between DACs, showing about 22.5 bit linearity:

An externally hosted image should be here but it was not working when we last tested it.


On another forum jwb told me that the 0.2 ps jitter clock (from 10 Hz and up) I'm looking at is only good for 22 bits and one should use an ovenized clock for more. Of course, I don't need more so I'll stick with the cheaper clock.
 
clearly, i was just posting what John Atkinson had written in his review
of the 2003 iPod - i see no reason why he'd be joking.

If i can get a hold of one of these iTransports i'll give it a go in my system
and report back on how it sounds.

With a 160 GB ipod i could have a huge selection of music available
in a very small footprint - that's dead quiet - and easy to access...

and may sound swell to boot :)
 
moe29 said:
"The overall result is superbly low, at 225 picoseconds peak-peak."

Well you don't understand S/PDIF very well. The Stereophile measurement was made using the analog outputs of the iPod. Using an S/PDIF will necessarily add jitter due to the poor design of the interface itself. That is why two-box solutions (transport + DAC) lost popularity in recent years.
 
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Charles Hansen said:
Using an S/PDIF will necessarily add jitter due to the poor design of the interface itself.
Yes, however,
That is why two-box solutions (transport + DAC) lost popularity in recent years.
this is not necessary since one can supplement or replace S/PDIF (by adding a clock cable to the transport or using an asynchronous interface), so there's fundamentally nothing wrong with having separate transport and DAC--it's just the standard interface that's bad.
 
abzug said:
this is not necessary since one can supplement or replace S/PDIF (by adding a clock cable to the transport or using an asynchronous interface), so there's fundamentally nothing wrong with having separate transport and DAC--it's just the standard interface that's bad.

It's hard enough to add an upstream clock to a full size DAC and transport. I think it would be nearly impossible with an iPod as a transport.
 
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Joined 2006
It should be possible since the iPod is a small computer, and it's to an extent a software issue.
It's quite easy to have an asynchronous interface with a computer, and indeed there are standards for asynchronous audio specifically (as a subset within the USB Audio specification).
 
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