Synchronous up-sampling vs native
August 07, 2016 06:29PM
I was reading the descriptions for the Avarice and the discontinued Vanity module and was curious about this:

"Oversampling‘s purpose is to dramatically simplify the design of the analogue post-DAC filter by performing the hard work in the digital domain instead of analogue domain. Not many people are aware that 8x oversampling filters are integrated within nearly every DAC in existence and that these converters do not in fact operate at 44.1kHz when replaying CD, but at a much higher „Oversampled“ rate. So why do we need extra upsampling when we already have oversampling already integrated within our DAC? The reason is simply a question of quality. Unfortunately, the performance of common oversampling filters range from mediocre to poor. We found this to be one of the main factors for the commonly perceived 'digital' sound - lack of sound stage and depth, with an unnatural “busy“ feel.
The 2x Upsampling performed by our Zero Alias Filter practically substitute the first stage of DAC's own oversampling filter – from an audio quality perspective, the most influential one. We've experienced a dramatic improvement in overall sound quality on various DAC’s featuring currently the best oversampling filters available. In fact we shouldn't even be surprised considering what we know about those filters, nonetheless the difference our Zero Alias Filters made impressed us."

The current VanityHD output opts for native resolution rather than the 2x upsampling option in the original Vanity and the 4x option in the Avarice. Is it felt that the benefits of a "bit-perfect" signal at native resolution outweigh the benefits of by-passing the DAC's 1st filter stage via upsampling? Does the answer depend upon how the signal is processed/filtered within the DAC? Thanks.

Edited 2 time(s). Last edit at 08/08/2016 02:49AM by Mjay71.
Re: Synchronous up-sampling vs native
August 11, 2016 10:12AM
Hi Mjay71,
Thank you for your question.
Correctly implemented external upsampling and bypassing the DAC's internal filters is indeed always beneficial in terms of audio quality. The original Vanity and the Avarice was aimed to do this job on two channel stereo audio. The VanityHD is a different story and its primary purpose is to de-jitter the digital audio signals and do format conversions (DSD->PCM or DSD->DoP). All that for 8 channels in total. If we had the resources (given by the used FPGA) to add 8 high quality PCM oversampling filters we would definitely do that, but the FPGA is already utilized to the max with the current set of features. Hope it answered your question.

Re: Synchronous up-sampling vs native
August 11, 2016 02:22PM
Thank you, Pavel.
As I'm only interested in 2-channel audio at the time, perhaps looking for an existing original Vanity module would give me the best results? Maybe that's not an option, however, since I am looking to fit an oppo 103, which is not listed in the models the vanity fits.

For 2 channel and DSD-PCM, are there advantages to the HD in terms of clocking/jitter and/or buffering, etc over the original module?

Thanks again for your help.

Edited 1 time(s). Last edit at 08/11/2016 02:34PM by Mjay71.
Re: Synchronous up-sampling vs native
August 12, 2016 08:51PM
Hi Mjay71,
First of all the original Vanity module is obsolete and we don't manufacture it any more. We had to tailor the firmware for every single player model, the installation was too complicated (soldering and drilling the back panel), etc.
The feature set of the HD board is nicely ballanced to give the best results for most common applications. It handles all PCM sampling rates, DSD via DoP and proprietary DSD to PCM. All of that packed with a nice clean clock from the Buffer Locked Loop de-jittering circuit. And you can install it yourself smiling smiley. The benefit of the BLL on the HD board IMO outweighs the upsampling feature of the original module.
From the development and manufacturing perspective there is very small difference between stereo and 8-channel operation, so the multi-channel feature is actually a small benefit that comes for free.

Edited 1 time(s). Last edit at 08/13/2016 01:35PM by AP.
Re: Synchronous up-sampling vs native
August 13, 2016 12:50AM
Thank you, Pavel. I pulled the trigger on an HD board. Can't wait to instal and hear it!
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