DAC output stage
Jun 20, 2009 at 3:37 PM Post #2 of 10
g1's DAC is a voltage out, so your scope for modification is limited. One possible idea would be a buffer with a different analog filter, but then all you're doing is changing the frequency response. Might sound better, might not...
 
Jun 20, 2009 at 5:02 PM Post #5 of 10
links to what?? they are just making suggestions based on your question
 
Jun 20, 2009 at 10:34 PM Post #6 of 10
The "output stage" of γ1 is internal to the Wolfson WM8501, and is configured to operate in the chip's high performance mode. Its output is taken directly (via DC blocking coupling caps) to the output jack. There is nothing to "upgrade".
 
Jun 20, 2009 at 10:44 PM Post #7 of 10
The WM8501 looks like a decent DAC and the integrated line driver is nice
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But it has the same -88 dB of THD of the CS4338, 24/96 DAC that is found inside my Cambridge Audio D300SE CD player, and in the newer 340A. Not quite a high-end level of distortion (my CS4398 DAC's all have much more sonic potential).
 
Jun 20, 2009 at 10:55 PM Post #8 of 10
The WM8501 datasheet quotes the THD and S/N specs for standard mode, not high performance mode. Unfortunately there is scant information in there about high performance mode, we had to contact a Wolfson engineer to learn about what it does and how to enable it. Basically, it increases the bias current through the internal output stage and provides lower noise and distortion. You can see my actual measurements at the γ1 website, in the "Specifications" section.
 
Jun 20, 2009 at 11:07 PM Post #9 of 10
Quote:

Originally Posted by hopeless /img/forum/go_quote.gif
But it has the same -88 dB of THD of the CS4338, 24/96 DAC that is found inside my Cambridge Audio D300SE CD player, and in the newer 340A. Not quite a high-end level of distortion (my CS4398 DAC's all have much more sonic potential).


Valve amplifiers have higher THD measurements than that. Still sound good? THD is not the be all and end all in performance. With the size and "DIY for general use" constraints imposed on it, it comes in the high-end. How much do you think such a well configured and designed product would go for commercially? There are a lot of cheap knockoffs on eBay, but few come up to such a high standard.
 
Jun 21, 2009 at 7:13 AM Post #10 of 10
Quote:

Originally Posted by guzzler /img/forum/go_quote.gif
Valve amplifiers have higher THD measurements than that. Still sound good? THD is not the be all and end all in performance. With the size and "DIY for general use" constraints imposed on it, it comes in the high-end. How much do you think such a well configured and designed product would go for commercially? There are a lot of cheap knockoffs on eBay, but few come up to such a high standard.


Was referring to my direct experience, where a -88 dB THD sounds "good" for sure, yet it sounds significantly inferior to a high performance DAC of today (CS4398).

In general, I think that in a DAC the THD specification is a rather precise indicator of its quality, unlike, possibly, in analog stages.
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BTW I'm not trying to knock off the y1 in any way; I've looked at the photos of it and it looks nice.


Regarding this "high performance mode", apparently it only concerns the analog line driver integrated in the chip. Of course its distortion will contribute to the total distortion indicated by the datasheet, and this seems to go in favor of the WM8501 versus my CS4338.
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