HQPlayer: when to use DSD5 and DSD7 shapers

[Samuel T Cogley]

Apologies if this has been covered before and I missed it.  If so, please delete this thread and point me in the direction of the discussion.

 

Having spent considerable time trying different shapers (and filters) in HQPlayer, I think my brain understands how DSD5 and DSD7 can sound different.  But I'd be very hard pressed to put it in words.

 

To quote the HQP4 manual:

 

Quote

Fifth order modulators are more suitable for DACs that have simple analog reconstruction filters. Seventh order modulators provide better technical performance, but also put more demands on the DAC's analog reconstruction filter. Typically this means that fifth order modulators suit DACs that have one switching element while seventh order modulators have potential for better performance on DACs that have multi-element switching arrays. DSD* modulators are fixed configuration ones while ASDM* modulators are adaptive in various ways based on source signal.

 

Are there examples of DACs with "simple analog reconstruction filters" and ones with "multi-element switching arrays"?  Again, I just try different ones until I arrive at one that I most like.  And I've noticed that I lean toward DSD5 for some DACs and DSD7 for others.

 

Please understand, I'm not looking for a fixed rule of "use shaper X with DAC A", etc.  I'm just trying to understand the underlying tech better.

 

[Miska]

On 12/18/2019 at 12:09 AM, Samuel T Cogley said:

Are there examples of DACs with "simple analog reconstruction filters" and ones with "multi-element switching arrays"?  Again, I just try different ones until I arrive at one that I most like.  And I've noticed that I lean toward DSD5 for some DACs and DSD7 for others.

 

This aspect matters more at lower DSD rates, such as DSD64 and DSD128, and less at higher rates like DSD256+.

 

For SDM, the D/A conversion stage itself is usually a filter, which could be called also a "mixed domain filter" since it is right on the boundary between digital and analog. And then there's another analog filter following the DAC chip that is supposed to complete the reconstruction.

 

ESS Sabre is one example of chip that doesn't have much filter on it's own for DSD, although when married with a typical external analog filter it reaches DSD/SACD specification. It is as DAC a multi-element array, but it is not utilized as a filter for DSD conversion.

 

While if you look at chips like TI/BB and AKM, or discrete implementations, they are usually configured as a filter and reach steeper attenuation than required by the DSD spec.

 

Order of the modulator tells how steeply the ultrasonic noise increases. Higher orders put more demand on the analog filters, although for example ASDM7 is tuned to be still gentle in the most critical areas.