Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it.

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RE: So

Posted by Todd Krieger (A) on August 20, 2014 at 17:48:57

In Reply to: So posted by jusbe on August 19, 2014 at 01:05:05:

"I wonder what's happening in my implementation?

"I have tried to elicit more information about the transport and dac I'm using, but to no avail. All I know is this:

"The transport upsamples to 96kHz"

The transport upsamples to 96 kHz?

This is unusual for a transport.... Most transports merely send the output at the native rate. Any upsampling would take place at the DAC.

"The transport communicates with the dac via I2S"

It's supposedly a desirable link option.... But otherwise don't have much opinion of that.

"The dac, it's suggested, reclocks (is that needed with I2S?) and plugs straight into the 4x 1704U-K chips."

An upsampler is supposed to have a *very* precise output clock. (Because if it doesn't, the imprecise timing of 24/96 upsampling would result in larger noise artifacts introduced into the signal.) If it does, reclocking wouldn't gain anything.....

"Presumably, with the I2S delivery at 96kHz, not much digital filtering is needed?"

96 kHz upsampling would already filter the signal. So no additional digital filtering would be necessary. Regardless of the link used between transport and DAC. (Although at the higher rate, the bandwidth of the link becomes more critical.)

"Output stage is FET-based, balanced, class A, no negative feedback and independently powered (as is the digital stage and transport)."

If the DAC has a nice analog output stage, it deserves a cleaner conversion in front of it.........

"There is a digital filter in the dac but the manufacturers have anonymised it. (Normally the DF1704 is used with these chips - is it something else?)."

As stated earlier, if the transport upsamples to 24/96, a digital filter wouldn't be needed in the DAC.... The DAC sees a 96 kHz input, the only filtering is to attain full stopband at 48 kHz, easily attainable with analog post filtering. (The upsampling at the transport would provide full stopband at 20 to 22 kHz for the CD playback. Although the output is 96 kHz sample rate, there should be no information above 22 kHz in that signal.)

"The resulting sound is tremendously engaging and, above all, noticeably 'muscular' and resolute. It feels like the sound is sculpted in space, with no loss of tonal shading or timbre subtlety. The icing on the cake is that I consider the overall cost for the sound I have, to be, frankly cheap."

If you like how it sounds, what I stated above may not matter at all.... The only thing I will say is you might prefer a setup that does not upsample to 96 kHz......

(I might criticize a design technically, but if a listener likes how it sounds, what I say doesn't mean a thing.)

"I wish more on here could hear it."

If you're in the Phoenix, AZ area, I'd be happy to..... [-;

But I'll be honest, I've never heard a CD source that upsampled to 96 kHz that I liked.

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