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Digital Drive: Re: Erroneous Stuff... by Todd Krieger

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Re: Erroneous Stuff...

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"You're right - if you use a brickwall-type analog post filter with an upsampler, you don't get any benefit in the area of phase distortion. However, the over/upsampler allows you to use a gentler low pass filter."

True, but the "gradual filter" is only applied *after* the upsampler applies its **own** filter to the signal. (It can be either by the DAC chip running at 96 or 192 kHz, or by an external analog filter.) And the filter in the upsampler is the same brickwall filter used in the vast majority of DACs. (The digital output from the upsampler then has the "time smear" element in the signal, before the "gradual filter" is applied.) The author of the paper erroneously claims the upsampler *itself* uses a gradual filter. (Maybe if Wadia would ever make a proprietary 44-to-96 upsampler, it would implement such a filter.)


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Topic - upsampling article - solidgore 08:08:38 08/22/03 ( 47)