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Topic: Upsampling to avoid de-emphasis? (Read 4172 times) previous topic - next topic

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  • amiti
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Upsampling to avoid de-emphasis?
Hello,

My sound card Juli@ uses ak4358 DAC which applies digital De-emphasis for 32, 44.1 & 48kHz sampling rates.

Is it a good idea to upsample 44.1khz files in order to avoid this?

  • DVDdoug
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Upsampling to avoid de-emphasis?
Reply #1
I'm not exactly sure what that means...  De-emphasis is normally used to flatten frequency response when there has been pre-emphasis (boosting high frequencies on the recording).  It's used on analog tape and on FM radio.      Pre-emphasis is rare on digital recordings, although it is allowed on CDs and CD players will  automatically add de-emphasis when needed.

Digital audio is always (or should always be) low-pass filtered to prevent alaising during analog-to-digital conversion and to "reconstruct" the analog waveform during digital-to-analog conversion.

Quote
Is it a good idea to upsample 44.1khz files in order to avoid this?
Upsampling is sort-of like copying a VHS tape to Blu-Ray.    It does not improve quality, and in fact there is a teeny-tiny loss of quality (hopefully unnoticeable) in any conversion.
  • Last Edit: 23 May, 2012, 12:34:25 PM by DVDdoug

  • amiti
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Upsampling to avoid de-emphasis?
Reply #2
I saw in the DAC chip specifications page de-emphasis applied only for 32 , 44.1 and 48 Khz samplerates. I know upsampling is usually useless but if by increasing the sample rate I will bypass this de-emphasis filter - maybe it would be worth the tiny loss.

  • pdq
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Upsampling to avoid de-emphasis?
Reply #3
According to the data sheet a de-emphasis filter is available at those sample rates if the applications calls for it. Otherwise it can simply be left disabled.

  • lvqcl
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  • Developer
Upsampling to avoid de-emphasis?
Reply #4
I'm sure that this function is optional and is off by default.

  • amiti
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Upsampling to avoid de-emphasis?
Reply #5
OK , thank you for the help.

  • Wombat
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Upsampling to avoid de-emphasis?
Reply #6
I donĀ“t know if reading datasheets is necessary when using an already build design
The chip applies de-emphasis when a register is set to do so. If this chip is used in a CD Player and the inserted CD shows a pre-emphasis flag the internal logic of the CD-Player sets the de-emphasis register and the DAC applies it. Otherwise it stays off all the time.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!