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Why is PCM1704U-K a better DAC chip than PCM1704U???

post #1 of 9
Thread Starter 

http://www.ti.com/lit/ds/symlink/pcm1704.pdf

 

I find the spec in the page 2 of the above link

 

Can someone explain why the U-K version is better in layman's terms?

 

Thanks

post #2 of 9

Because it has better dynamic range and lower SNR. Chip manufacturer tend to make the same chip in very large quantity in every batch. So in every batch, there are chip that performs very well and there are chip that are just slightly off. The common practice is to test and select the one that has the best performance / spec and sells it as a premier product and remarks those lesser in quality as a lower end product for a cheaper price. So you might even find two different opamp with the same inner design where the expensive one has a better spec and a cheaper one with a lousier spec. Much like the sweetest apple get sold at higher price than the tasteless apple though they are from from the same farm and are the same species.

post #3 of 9
Thread Starter 

Thanks for your reply. What do you mean by "better dynamic range"? Can you tell me which number to look for in the spec page?

 

According to the spec page, they all have the same S to N ratio. So that's not a plus for U-K, right?

post #4 of 9

It is all in the 2nd page, spec.

 

Take the typical number:

 

THD-N (Vo=OdB): PCM1704U - 0.0025% | PCM1704U-K - 0.0008% (lower the better)

THD-N (Vo=-20dB): PCM1704U - 0.008% | PCM1704U-K - 0.006% (lower the better)

Dynamic Range: PCM1704U - 110dB | PCM1704U-K - 112dB (higher the better)

 

Yes, SNR is the same, but other than that U-K seems to be better on THD and dynamic range.

post #5 of 9
Thread Starter 
Quote:
Originally Posted by ClieOS View Post

It is all in the 2nd page, spec.

 

Take the typical number:

 

THD-N (Vo=OdB): PCM1704U - 0.0025% | PCM1704U-K - 0.0008% (lower the better)

THD-N (Vo=-20dB): PCM1704U - 0.008% | PCM1704U-K - 0.006% (lower the better)

Dynamic Range: PCM1704U - 110dB | PCM1704U-K - 112dB (higher the better)

 

Yes, SNR is the same, but other than that U-K seems to be better on THD and dynamic range.


Thanks for your reply. What is dynamic range in sound? I only know dynamic range in photography....

 

post #6 of 9

Dynamic range is the ratio between the biggest possible undistorted signal and the noise floor, I think.

post #7 of 9

^^^

Yup.

However, I really wouldn't recommend choosing any products based on chip specs. The devil's in the implementation.

post #8 of 9

 

Quote:
Originally Posted by umvue View Post


Thanks for your reply. What is dynamic range in sound? I only know dynamic range in photography....

 


Its the same thing, only with sound instead of light. 

 

post #9 of 9
Thread Starter 

Thanks for your replies. I think I understand now.beerchug.gif

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