Filter brewing for the Soekris R2R - Page 15 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st February 2015, 12:46 PM   #141
leehan is offline leehan  United Kingdom
diyAudio Member
 
Join Date: Jun 2010
Location: Kent, UK
Quote:
Originally Posted by lehmanhill View Post
Leehan, please document the filter.
rePhase file attached.

Used a low noise floor windowing and adjusted centering for IP as suggested by Pos, otherwise nothing special.

EDIT: Also used same roll off values for LP and MP.

IP filter you mentioned has similar tradeoff (higher stopband floor). I hope somebody actually tests this for image attenuation and other criteria. I don't have any means to do so and time to set up one at the moment.

I'm testing the filter with mostly small band acoustic and electric music with plenty of acoustic or electric bass, drummers using cymbals a lot, clean guitars, female vocals, brass instruments, piano and electric keyboards and synths. Not tested with heavy guitars yet. And still too much albums to listen for a final verdict...

Of course, this verdict will be for my system and ears Very excited that people are sharing and testing these.

Cheers.

Last edited by leehan; 21st February 2015 at 01:00 PM.
  Reply With Quote
Old 21st February 2015, 02:45 PM   #142
Can you say Audio?
diyAudio Member
 
Join Date: Aug 2011
Location: Aurora, Colorado
I'll chime in; I'm finding MB2b very pleasant.
  Reply With Quote
Old 21st February 2015, 03:29 PM   #143
leehan is offline leehan  United Kingdom
diyAudio Member
 
Join Date: Jun 2010
Location: Kent, UK
Quote:
Originally Posted by TNT View Post
Wating for your assesment of MB2b.
Strangely my dac doesn't lock with MB2b.skr...?

"Assessment" is an overstatement
  Reply With Quote
Old 21st February 2015, 04:22 PM   #144
soekris is offline soekris  Denmark
diyAudio Member
 
Join Date: Jun 2009
Quote:
Originally Posted by MisterRogers View Post
I'll chime in; I'm finding MB2b very pleasant.
Interesting, as:

MB2b: dam1021,44100,2,1,1016,1

is not a valid option. Maybe it result in something close to non oversampled, but I have no clue....
__________________
Søren
  Reply With Quote
Old 21st February 2015, 04:31 PM   #145
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
I was aiming for 2x oversampling - ok?

How would I achive this?

What are the valid options for these params?

//
  Reply With Quote
Old 21st February 2015, 04:41 PM   #146
Can you say Audio?
diyAudio Member
 
Join Date: Aug 2011
Location: Aurora, Colorado
Yes - very interesting.
  Reply With Quote
Old 21st February 2015, 04:47 PM   #147
zfe is offline zfe
diyAudio Member
 
Join Date: Dec 2014
Quote:
Originally Posted by TNT View Post
I was aiming for 2x oversampling - ok?

How would I achive this?

What are the valid options for these params?

//
What do you consider as 2x oversampling here, 1 -> 11110000?
If yes, convolute your filer, with the filter having four times 1 as taps and stay formally with 8 x oversampling.
  Reply With Quote
Old 21st February 2015, 05:07 PM   #148
leehan is offline leehan  United Kingdom
diyAudio Member
 
Join Date: Jun 2010
Location: Kent, UK
Default Why IP for 44kHz sources.

OK, a post explaining my interest in IP filters. Statements are based on scientific claims. They may help somebody beginning their journey on this thread. My conclusion may be BS.

1. We distinguish timbre of different instruments mainly by "attack" of the sound envelope. Daniel Levitin mentions (1) a research where test subjects had difficulty distinguishing piano from guitar when attack portion of the sound was removed. Too long pre-ringing may affect attack of the envelope negatively. This eliminates maximum phase filters and warns about linear phase (LP).

2. We are more sensitive to pre-masking than post-masking in a phenomenon called temporal masking (2). This means we can tolerate more post-ringing than pre-ringing. This gives minimum phase (MP) and advantage over LP.

3. Duration of ringing is affected by the steepness of the roll-off curve. Longer durations affect items 1 and 2, and also transients negatively (3). A slow-roll off is desirable for shorter ringing. But as everybody knows DA artifacts also need to be attenuated. By how much? This should depend on person's hearing and listening environment (headphones, speakers, acoustic treatment, etc.). Although there should be a limit to this since we share the same evolutionary hearing system. Also manufacturers that adverise use of slow roll off filters are likely to deal with this after the dac by other means. We don't have them on dam1021, so we need to deal with this by filters. This implies using filters with steep-ish roll off and with low stopband floor. Unfortunately, too much post-ringing caused by this type filters may also render MP only filter undesirable.

4. We are trying to get best out of 44.1kHz sources. This will always be a compromise. There are many publications about benefits of high sample rate (both processing and hearing wise). I have to settle on a filter and move on.

5. [Non-scientific] Different types of filters said to perform better for different types of music and recording environment. My personal interest is to settle on one that is true to the timbre of instruments as much as possible, then transients, and finally headphone listening.

Hence my preference of IP for 44.1kHz as an optimisation between pre and post ringing given the necessary roll-off steepness. I also found the phase related experiment I mentioned earlier useful.

For the IP filter I'm using at the moment, I will try to bring down the stopband floor lower to at least -80dB at Nyquist while keeping ringing around 1ms.

Cheers.

PS: When configuring a filter for higher sample rates than 44.1kHz, is it just a matter of using correct number of taps Soren stated? Do we need any other adjustment to the filter itself? Thanks.

(1): Daniel J. Levitin, This is Your Brain on Music: Understanding a Human Obsession
(2): Auditory masking - Wikipedia, the free encyclopedia
(3): Music and the Human Ear
  Reply With Quote
Old 21st February 2015, 05:39 PM   #149
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
Quote:
Originally Posted by zfe View Post
What do you consider as 2x oversampling here, 1 -> 11110000?
If yes, convolute your filer, with the filter having four times 1 as taps and stay formally with 8 x oversampling.
No but 1->10 as it works with 0 instertions - and 88khz. But what Sören say, it seems undefined

I wonder in which dimension?

//
  Reply With Quote
Old 21st February 2015, 05:42 PM   #150
Eldam is offline Eldam  France
diyAudio Member
 
Join Date: Sep 2012
Location: France
Maybe some info to pick here about digital filters ?

I don't like too much this webzine think it's biased, but mostly here in this review the Chord engineer is talking about him HUGOTT DAC and some choice about digital filters strategy : too complicate for me ! Maybe could help, dunno ! 6moons audioreviews: Chord Hugo TT
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Soekris 's DAC implementations Eldam Digital Line Level 1031 19th February 2017 10:38 AM
Sold: Soekris DAM1021 R2R DAC Eldam Swap Meet 6 6th February 2015 08:23 AM
24-bit R2R DAC using miltiple 16/18/20-bit R2R chips Marek Digital Source 21 1st April 2011 10:05 PM
project brewing in my head, challenging, but seem like a good way to try new concepts lemans23 Multi-Way 26 11th October 2005 01:29 PM


New To Site? Need Help?

All times are GMT. The time now is 07:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki