Digital Filtering

M

Mr Peabody

Well-known member
Joined
Nov 19, 2013
Messages
3,326
Location
St. Louis, MO, USA
My DAC provides 3 filters. In reading about them and trying to find information I found it a bit confusing, no place really broke down what I was looking for. So feel free to correct me if I'm wrong, a source would be appreciated, remember I'm in the "Show-Me" state.

There's talk of this ringing but not much explanation. Supposedly, some are sensitive to it. I believe I'm one of those unless it's just the difference in what the filter does.

I have a "fast" filter which is a quick roll off and I believe this causes pre and post ringing but very linear and less distortion.

A "slow" filter where the high frequency cutoff slope is slow but no ringing.

Then there's a "minimal phase" filter with only post ringing. I don't know what is meant by minimal phase, the other two seem to have to do with how steep the cutoff slope is.

Unfortunately, no switching on the fly. I found the DAC set to "fast". It sounds good like that. I set it to "slow" and immediately liked that better. I haven't tried the other one yet but from what I hear with the "slow" I think I'm set. I didn't realize anything was wrong when I listened to "fast" but when "slow" is engaged it's just easier to listen to. Some may call It more analog. I find it less piercing, lack of a better word. All the detail is there, it's just easier to take in and sounds more natural.

Any experience with filters on your gear or knowledge to share?
 
there is a good explanation of digital filtering (interpolation algorithms for oversampling) in the manual for the t+a dac 8 dsd -- see link below, page 55 -- which might be of general interest for those with other dacs.

i much prefer the pure bezier interpolator / filter and agree with their qualitative description of the sound... "This process delivers a perfect reconstruction of the original music signal. It exhibits no pre- or post-echoes of any kind, and does not add coloration or timing errors to the original signal. In sonic terms this method offers an impressive blend of naturalness, good dynamics and accuracy."

...YMMV

https://www.ta-hifi.de/wp-content/uploads/um_dac_8_dsd_222_de_en.pdf
 
aKnyght said:
there is a good explanation of digital filtering (interpolation algorithms for oversampling) in the manual for the t+a dac 8 dsd -- see link below, page 55 -- which might be of general interest for those with other dacs.

i much prefer the pure bezier interpolator / filter and agree with their qualitative description of the sound... "This process delivers a perfect reconstruction of the original music signal. It exhibits no pre- or post-echoes of any kind, and does not add coloration or timing errors to the original signal. In sonic terms this method offers an impressive blend of naturalness, good dynamics and accuracy."

...YMMV

https://www.ta-hifi.de/wp-content/uploads/um_dac_8_dsd_222_de_en.pdf
Click to expand...

Thanks for sharing. I own that DAC but never bothered to read that far into the manual. Indeed a Good explanation of differences between filters.

Many of the older DACs do not give you the option of using different filters.
 
Listen to percussive instruments when you try minimum phase. See if you like it better or not - some people do, some people don't.
 
Here are a couple of cheat sheets I used when I had my Esoteric K-01X. The first describes filters in AKM's latest chips and the second is one I edited because it's specific to the K-01X but has Esoteric's additional description of those particular filters. Maybe the descriptions apply to your filters, as well.


attachment.php

attachment.php
 

Attachments

  • AKM FILTER DESCRIPTION.jpg
    AKM FILTER DESCRIPTION.jpg
    270 KB · Views: 43
  • Esoteric Filter Description copy.jpg
    Esoteric Filter Description copy.jpg
    397.2 KB · Views: 43
I use HQPlayer. They have many filters available. Some HQP filters require a lot of computer power (much more than what typical DACs have). From memory, the developer recomnends certain filters based on the type of music (classical, jazz, etc.). In any event, I think others have provided good links to articles that hopefully will answer your questions. Good luck!
 
Interesting you mention percussion. First, if the filtering has to do with removing trash above 20kHz, how does it effect lower frequencies that would shape percussion, unless maybe leading edges. One of the blog articles below mentions MQA uses a slow filter and removes ringing. If this is so, I xperienced what you mention at a demo. The first track, a Dunky Trio, I liked MQA, it allowed me to hear more melody or more musicality to the track, more beauty. The next track had a crescendo, without MQA I felt like I almost was jolted out of my chir. With MQA the crescendo was less violent.

I've yet to try the Minimal Phase where it removes pre-ringing t allows post ringing.

wklie said:
Listen to percussive instruments when you try minimum phase. See if you like it better or not - some people do, some people don't.
Click to expand...
 
Although I appreciate the articles and he does describe what the filters do, I don't like him trying to convince me I am not hearing a difference. I had a T+A CDP that had filters and I admit the differences were subtle. However, the filters on the 526 I can easily hear a difference.

What I hear in the filter he says he likes, the steep roll off that provides flattest response, is sort of a glare or brightness. I can turn up the music louder on slow filter without ringing due to that brightness removed. With ringing it does seem to bring a bit more excitement to the presentation.

What's puzzling, slow filter is supposedly adding distortion but it's easier to listen to and I can seemingly hear into the music more due to that ringing removed.

As I stated in Peter's post, I haven't tried the Minimal Phase, which removes pre-ring but allows post ring yet. The manual said it's best for strings which led me to belief it's polite but that may not be the case.

Anatta said:
http://archimago.blogspot.com/2016/07/musings-digital-interpolation-filters.html

http://archimago.blogspot.com/2018/01/audiophile-myth-260-detestable-digital.html
Click to expand...
 
You must log in or register to reply here.
Back
Top