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Old 22nd September 2007, 05:50 PM   #1
ctong is offline ctong  United States
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Default Pass D1 analog stage

Can the D1's I-V and output stage be used for sacd playback? The filter in D1 seems to be second order whereas sacd might require a much steeper one.
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Old 24th September 2007, 03:22 PM   #2
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One reference would be DAC datasheets that support both PCM and SACD. Checking AD1955, IT/BB1792, and CS4398 - they spec the same filter for the both modes.

Optimization maybe a difference story, but atleast the chip vendors are not recommending different analog filters pre data type.

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Old 24th September 2007, 04:17 PM   #3
ctong is offline ctong  United States
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Quote:
Originally posted by dw8083
One reference would be DAC datasheets that support both PCM and SACD. Checking AD1955, IT/BB1792, and CS4398 - they spec the same filter for the both modes.

Optimization maybe a difference story, but atleast the chip vendors are not recommending different analog filters pre data type.

-David

I see that the CS4398 datasheet specifies a 2-pole filter. But the PCM1792 datasheet shows a 3-pole filter for PCM and a 4-pole one for DSD. I wonder how to increase the filter roll-off slope of the D1 output stage.
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Old 3rd November 2007, 08:50 PM   #4
ctong is offline ctong  United States
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I experimented with my Denon 2900 by eliminating the active filter in the analog stage and changing the passive filter cut off. Now I have three passive filter with cut off frequencies of 88K, 240K, and 120k. I do not have a good spectral analyzer to look at the ultrasonic noise but the player sounds much better than before (even with sacds). Therefore, I think less aggressive filtering is just fine. I am now very attempted to try the D1 analog stage for this player. I do not have the datasheet for PCM1790. It appears to have a center current of -6mA which will push the idle current of the IV Mosfet in D1 to around 15 mA. So I guess the analog stage should work fine.
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