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Contradiction! CD player has lower TDH than its chip

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Posted on February 27, 2017 at 16:19:45
dave789
Audiophile

Posts: 472
Joined: September 21, 2001
Creek Destiny 2 CD Player has CS4396 DAC chip.

The THD+N spec of CS4396 chip is -100dB, in terms of percentage,

0.001%.

However, the CD player containing that DAC chip is spec'ed better:

0.0008%

 

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RE: Contradiction! CD player has lower TDH than its chip, posted on February 27, 2017 at 16:51:53
knewton
Audiophile

Posts: 459
Location: Mid-Atlantic/Northeast
Joined: May 18, 2010
Don't be too surprised. I can think of at least two reasons why that lower figure might be accurate.

1) The DAC chip's datasheet distortion spec. is likely a maximum limit for a given chip to be considered acceptable. It's a conservative figure intended to help ensure a high yield of acceptable chips, and is not the center of distribution. Otherwise, there could be frequent product returns for devices not meeting the data sheet spec. As a consequence, actual distortion produced by the vast majority, of not all, of chips would be less than that specified in the data sheet. Possibly, significantly less.

2) Should the DAC chip and the CD player circuitry each exhibit even order distortion having complementary symmetry, that distortion will tend to cancel, potentially resulting in an net lower distortion total together than each do separately.

So, those distortion figures aren't necessarily contradictory.
_
Ken Newton

 

RE: Contradiction! CD player has lower TDH than its chip, posted on February 27, 2017 at 19:44:20
Thorsten
Manufacturer

Posts: 4171
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
Hi,

First, the Datasheet numbers are obtained using the precise circuit given in the Datasheet and/or implemented on the Evaluation Board. The datasheet and associated schematics/evaluation circuits illustrate the IC manufacturers system used to characterise the IC and give you a platform that will allow you to replicate the IC manufacturer's results reliably, they are not prophetic words set in stone that shall never be altered or challenged.

An actual design, by an actual designers is likely to have variations for many reasons. A poor designer or one with specific design objectives may fail to attain the Datasheet stated DAC IC Performance, while another who may be especially capable or one with specific design objectives may exceed the Datasheet stated DAC IC performance, often quite significantly.

Second, the difference you note is fairly small. Just a slightly cleaner clock than found on the CS4396 Eval Board may cause this sort of variation.

Ciao T

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?

 

RE: Contradiction! CD player has lower TDH than its chip, posted on February 28, 2017 at 13:58:47
fantja
Audiophile

Posts: 10033
Location: Alabama
Joined: September 11, 2010
Dave-

this is a very good cd player. On spec, look into the signal to noise (S/N) ratio for best outcome.

 

RE: They could be Lying ?, posted on March 1, 2017 at 14:59:17
bare
Audiophile

Posts: 524
Joined: April 14, 2009
Nawww that's Never happened before.. has it?

 

RE: They could be Lying ?, posted on March 1, 2017 at 15:07:54
knewton
Audiophile

Posts: 459
Location: Mid-Atlantic/Northeast
Joined: May 18, 2010
Why suppose that they are lying?
_
Ken Newton

 

Michael Creek - unlikely, posted on March 1, 2017 at 18:20:01
Thorsten
Manufacturer

Posts: 4171
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
Hi,

I had the occasion to run into the Gentleman behind Creek Audio a few times strictly socially. He appeared to me a straight shooter.

So I will grant an innocent mistake as possible (just as much as it may be just better design than the Chip makers Evaluation Board), but an outright lie...?

And if you are going to lie, then the difference between 0.001% and 0.0008% seems not significant enough (to me anyway - it's 2dB so 100dB vs. 102dB) to risk some smartypants catching you out and going: "But the datasheet says the chip can only do 0.001%".

Now if the datasheet says 0.001% and someone using the chip (and only one chip)claims 0.0001% - then we may suggest that something is not kosher.

Though depending on the context, even that may not be impossible, I have seen similar levels of improvements from using multiple chips correctly applied (which is not dumb "stacking").

Ciao T

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?

 

Hi-Fi World measurement, posted on March 2, 2017 at 18:33:54
dave789
Audiophile

Posts: 472
Joined: September 21, 2001
I do not know well about the measurement conditions, but this is what I see.

Hi-Fi World 2011 02

CREEK DESTINY 2 1,400

Distortion (%)
0dB 0.0005
-6dB 0.0007
-60dB 0.18
-80dB 4.2

 

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