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?
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.
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.
I saw in the DAC chip specifications page (http://www.asahi-kasei.co.jp/akm/en/product/ak4358/ak4358.html) 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.
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.
I'm sure that this function is optional and is off by default.
OK , thank you for the help.
I don´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.