Filter brewing for the Soekris R2R - Page 6 - 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 16th February 2015, 09:10 AM   #51
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Blog Entries: 1
Quote:
Originally Posted by pos View Post
Ok so those filters are basically brickwall filters (so called "windowed sinc"), using 3 different windowing algorithm.
This is the simplest possible LP filter design you can do with FIR.
The final shape (steepness and ripples "floor") is dictated by the chosen window.
Similar design to what Soren originally did use, but with more taps which allows for steeper slopes with the same ripples floor...

Attached is an example you can play with (choose different windowing algorithms and generate to see the resulting curve, and also maybe change the filter frequency).
Those that work well in this context are Nuttall, Blackman-Nuttall, and Blackman-Harris.
I don't have Taylor and Chebychev windows in rephase so cannot try these, but I can add them for the next version.

Funny thing is that people wanted a shallower slope and no preringing, but now the steepest linear-phase (ie tons of preringing) filter is preferred
Thanks pos!

Of course measuring and listening are two different things It was partly to see what was happening on the outputs and how close it matched the filter curves.

I still like the slow roll-off / little ringing better for listening.

cheers
Paul
  Reply With Quote
Old 16th February 2015, 09:13 AM   #52
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Blog Entries: 1
Quote:
Originally Posted by TNT View Post
If you experience loss of output level, one possible reason could be that you did not change the "numbercoefficients" parameter implying that not the whole filter is executing. Sören to confirm that this would be the consequence...

-- Format:
-- signature, samplerate, interpolationrate, type, numbercoefficients, multiplier

//
All the filters are done at 1015 with the following header...

Code:
dam1021,44100,8,1,1015,8
Input FIR, 44.1 Khz Samplerate, 0-19 Khz +- 1.83 db, 24 Khz -7.84db
It's more likely related to the slow roll-off in the HF.
The white noise was fairly close, but the 19kHz tone was down, and this is where the slow roll-off is starting to bite.
Checked the response of the filter - it's -3dB at 19kHz.

Last edited by spzzzzkt; 16th February 2015 at 09:22 AM.
  Reply With Quote
Old 16th February 2015, 09:20 AM   #53
pos is online now pos  Europe
diyAudio Member
 
pos's Avatar
 
Join Date: Feb 2008
Location: Paris
Paul, talking about listening tests how does the NOS mode sound?
TotalDAC users seems to be happy with this kind of configuration...
__________________
2016-12-08: rePhase 1.2.0 | JBL M2 crossover settings
  Reply With Quote
Old 16th February 2015, 09:45 AM   #54
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Blog Entries: 1
Quote:
Originally Posted by pos View Post
Paul, talking about listening tests how does the NOS mode sound?
TotalDAC users seems to be happy with this kind of configuration...
I haven't had a serious listen but I'll give the NOS another run in the day or so.
The filters seem to be piling up, so it's hard to know where to go next.
  Reply With Quote
Old 16th February 2015, 12:03 PM   #55
soekris is offline soekris  Denmark
diyAudio Member
 
Join Date: Jun 2009
Quote:
Originally Posted by TNT View Post
If you experience loss of output level, one possible reason could be that you did not change the "numbercoefficients" parameter implying that not the whole filter is executing. Sören to confirm that this would be the consequence...

-- Format:
-- signature, samplerate, interpolationrate, type, numbercoefficients, multiplier

//
As I said, there isn't much error checking on filter tools, parameters have to match or consequences varies between subtle differences, to strange sound to no sound....
__________________
Søren
  Reply With Quote
Old 16th February 2015, 12:10 PM   #56
Eldam is offline Eldam  France
diyAudio Member
 
Join Date: Sep 2012
Location: France
TotalDac is not 100% NOS, my understanding is Vincent made a FIR filter beginning in the high frequencies above 16 K hz iirc and staying NOS below : some basic descriptions in him commercial site!
  Reply With Quote
Old 16th February 2015, 12:43 PM   #57
pos is online now pos  Europe
diyAudio Member
 
pos's Avatar
 
Join Date: Feb 2008
Location: Paris
I might be wrong but I think it is a normal NOS design and the "natural" rolloff (~-3dB at 20kHz) is compensated using a small FIR EQ to get ~0dB at 20kHz.
By the way this EQ in linear-phase, which shows on the square response.
__________________
2016-12-08: rePhase 1.2.0 | JBL M2 crossover settings
  Reply With Quote
Old 16th February 2015, 12:55 PM   #58
Eldam is offline Eldam  France
diyAudio Member
 
Join Date: Sep 2012
Location: France
Yeap it sounds like that when I read him commercial website... sure you have a better understanding than me as I don't understand absolutly nothing to those digital filters .

The tube filter has a great sucess, certainly adding a descent repartition between harmonics with odds ones : so numeric re tailored analogic somewhere at the output !... with my simple words !
  Reply With Quote
Old 16th February 2015, 02:11 PM   #59
diyAudio Member
 
Join Date: Jun 2006
With an active stage following the DAC incorporating a low pass filter seems it could be useful to remove that capacitor on the output of the DAC.

Could not possibly be one of the better dielectrics. Especially if one is duplicating the job with a subsequent circuit!

Either a capacitor based filter or transformer coupling of the line stage should be able to make a much better filter than what is given.
__________________
Rick McInnis
  Reply With Quote
Old 16th February 2015, 04:51 PM   #60
mkc is online now mkc  Denmark
diyAudio Member
 
Join Date: Jun 2002
Location: Denmark
I Read somewhere that Charles Hansen wrote that Ayre upsamples 16x. This is likely for 44,1 KHz. Also, the analog stage contains 2 filters, which can be seen on various pictures on the web.

Mogens
  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 1038 20th April 2017 05:30 PM
Sold: Soekris DAM1021 R2R DAC Eldam Swap Meet 6 6th February 2015 07:23 AM
24-bit R2R DAC using miltiple 16/18/20-bit R2R chips Marek Digital Source 21 1st April 2011 09:05 PM
project brewing in my head, challenging, but seem like a good way to try new concepts lemans23 Multi-Way 26 11th October 2005 12:29 PM


New To Site? Need Help?

All times are GMT. The time now is 06:45 AM.


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