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Yamaha CDX-393 Review (CD Player)

I would consider replacing the DAC ceramic resonator with a proper crystal (1M res=2x caps) . That model is the poverty pack special bottom of the line plastic front panel unit- no headphone amp populated, no remote control receiver, no TOSLINK out and the crystal + caps are missing.

CDX-493 has the "upgrade":

View attachment 397707
Hi John,

Quick follow up on the above. Update performed, as you suggested, nothing else:

Yam393-006.jpg


Here is a 1kHz before the Xtal update, this is 1khz with dither:

1734693524037.png


We get 1'001.99Hz instead of 1'000.00Hz...

After the Xtal update:

1734693612367.png


We get 999.93Hz, which is indeed much better but we're not quite here.

Worth another upgrade? :)
 
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We get 999.93Hz, which is indeed much better but we're not quite here.

Worth another upgrade? :)
What does the datasheet of the xtal you ended up installing say about recommended loading? Seems 47p + 47p for C37/38 (assuming that's what you went with) is a bit too much. Do you have some other values at hand (say 22p or 33p)? You can also try just removing e.g. C38 again. A trimmer capacitor may prove handy.

Since your xtal is likely to be different from what Yamaha used, you get to play development engineer here. Either way, -70 ppm (-0.007%) is not a bad start. RF folks would not be impressed but it is plenty accurate enough for audio.
 
Hi @AnalogSteph, yes 47p and the crystal is a ROSON for which I could not find the specific data sheet. All parts were sent to me by a friend, and I did not think the crystal could have different requirements for the caps, now I know :)

So yes trimmer capacitor is probably the easiest solution to see how precise I could go with that crystal, and that'd be fun. Do you have one to recommend me? And maybe I'll change the crystal to one of those that you recommended before, so I'd know the caps values from the start.
 
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I found this online: (although it's not the same frequency this might be an indication of the correct capacitance?)


Table below from here => https://www.indiamart.com/proddetail/electronic-crystals-20103260997.html

Roson Electronic Crystals​

₹ 3.50/PieceGet Latest Price
BrandRoson
Frequency12MHz
Dimension0.447 L x 0.183 Inch W (11.35 mm x 4.65mm)
Operating Temparature- 20 to + 70 Degree Celsius
NUmber Of Teminals2 Pin
Mounting TypeThrough Hole
Load Capacitance20pF
Height0.142 Inch (3.60 mm)
Frequency Tolerance+/- 30ppm
Frequency Stability+/- 50ppm
Equivalent Series Resistance60 Ohms
 
Cool, thanks, and I'm finally not that far from Tolerance + Stability. I'm interested to do better as I learn about the topic.
 
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