Da-capo issue (John W?)

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JohnW

JohnW

Member
Joined 2004
Hi Loris,

Yes - I'll bring you a long awaited present when we come to Europe for Christmas.

To measure the Clock, the unit must be "Locked" to a CD source (44.1kHz).

You should measure 16.9344MHz, +/- 100ppm - if its really over 17MHz then this is bad news.

Once I get back to China next we Ill take a look at a Dacapo PCB and forward other test points to Measure.

Vincent - Hi! Still around, working in China, While we are in China, most Forums are blocked - so I can only normaly access the Forums while in Europe (depending on what the Great China Firewall decides to allow).

I'm still using my Yahoo Email... Hope to catch up with you soon!

John
 
V

vincent_brient

Member
Joined 2005
vincent.brient.free.fr/main.htm
abraxalito said:
Great stuff in the FPGA. But what's the reason for using the discrete DAC - surely PCM1704 is better performance on all counts, as well as being cheaper?
Click to expand...

Well I also compared the Vishay foil R2R DAC to the PCM1704 and many others but R2R DAC sounds much better to my ears. See also MSB tech which also uses R2R ladders.
Also PCM1704 requires a I/V stage whereas R2R DAC doesn't need any analog electronics and the output buffer is optional.
 
abraxalito

abraxalito

Member
Joined 2007
Oh, so the R2R is a voltage output DAC. And you compared the PCM1704 against your DAC with what I/V conversion? I will have a detailed look at the MSB tech design - I'm ever curious about people doing discrete DACs and the figures for that look totally incredible, so I will study it very carefully. Yours looks really good except for it looks from your measurements that its rather noisier than the 1704. Do you notice the noise levels in practice?
 
V

vincent_brient

Member
Joined 2005
vincent.brient.free.fr/main.htm
abraxalito said:
Oh, so the R2R is a voltage output DAC. And you compared the PCM1704 against your DAC with what I/V conversion? I will have a detailed look at the MSB tech design - I'm ever curious about people doing discrete DACs and the figures for that look totally incredible, so I will study it very carefully. Yours looks really good except for it looks from your measurements that its rather noisier than the 1704. Do you notice the noise levels in practice?
Click to expand...

I made a quick mesurement using FFT mode instead of notch filter then FFT. If you look at MSB measurement their noise floor is very low, and I am sure they do use better resistors than I use, I have sure they don't use 48 0.01% vishay foil resistors in their mono channel module.
When listening to my DAc the listenable noise is much lower than with other DACs, that's what most testers said.
 
R

RHCD

Member
Joined 2010
John W - wondering if you have heard the Rega DAC

I've followed this thread with great interest, well, the parts about the development of your new DAC, and life in China, a place I spent a whole year a long time ago when it was very different in many ways, though still contained snakes.

Anyway, I have also been excited about Rega's upcoming DAC as I have heard and been impressed by both the Saturn and Isis. I shouldn't imagine you've had a chance to hear one yet but if you do I'd be most interested to know your opinion.

Robert
 
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