Go Back   Home > Forums > > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Vendor's Bazaar Commercial Vendors large & small hawking their wares

Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
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 May 2018, 05:58 PM   #7331
manniraj is offline manniraj  India
diyAudio Member
 
Join Date: Nov 2012
Quote:
Originally Posted by arnd13 View Post
Soekris firmware is 1.06 or greater with normal filters?
I have recently upgraded the firmware to 1.19 and set the filter to "Soft".
  Reply With Quote
Old 21st May 2018, 08:38 PM   #7332
oliv44 is offline oliv44  France
diyAudio Member
 
Join Date: Oct 2012
???
how can we know if ours filters are "normal" or not ?
  Reply With Quote
Old 21st May 2018, 10:33 PM   #7333
arnd13 is offline arnd13  Germany
diyAudio Member
 
Join Date: Nov 2015
If you use the filters provided by Soekris, than the filters are normal.
There are also customized filter to find, but they are not provided by Soekris.
  Reply With Quote
Old 22nd May 2018, 08:09 PM   #7334
zfe is offline zfe
diyAudio Member
 
Join Date: Dec 2014
Here again an indication that the frequency tracking of the FIFO of the DAM has some ... ahm ... room for improvement.
My conclusion of the reasoning below is that there is need to add some (preferably fast) damping.

The first image is the long term recording of a 96Hz square wave (upper track the source, lower track the recording).
SQ-DAM-unst-1.jpg
In the recording you see oscillation of a period of about two minutes.
This comes from the differences in the magnitude of the overshot (the following second image zoomed in as illustration) due to a phase shift the location of the flank of the square wave moves in the sample (the ADC is oversampling, we see the result of the low-pass filter + decimation).
SQ-DAM-det.jpg

I think the phase shift comes from how the FIFO frequency tracking is performed. Assume the input signal is perfect (no jitter). The start frequency of the DAM (I have the impression it uses some memorised value to start from) can be slightly different from the actual signal frequency, the tracking adjust the frequency towards the signal, but it will overshot the aimed frequency and then track in the other direction and so on.

If I stop the signal and start it again it seems that the DAM starts with the frequency where it stopped before. So with some try and error you can get as start frequency, more or less, the right value and a recording without (noticeable) oscillation and this will survive start and stops until you change the sample frequency - then the whole game starts again.
So some damping in the tracking is needed to prevent this oscillation - especially if the input signal is very good.
SQ-DAM-stable.jpg

I do not claim that the oscillation has audible effects but it is "wrong".

The recording was made with the RTX6001 analyser, which has a good clock. The signal for the DAM came from the RTX6001 by SPDIF.

The low frequency oscillation her is something different from the oscillation due to slightly different clock speeds when using a USB interface with its own clock for the signal for the DAM. This I reported here. This oscillation has much shorter period and is gone if you use the SPDIF of the analyzer, and thus the clock of the analyzer, as source.
  Reply With Quote
Old 22nd May 2018, 09:35 PM   #7335
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
Nice find zfe! Keep up the good job.

As I understand the algo, what one should see is a possible jump/skip at the most every appr. 2 minutes (the filtering time). Between the adjustment, the whole D/A process should be firmly locked to an unaltered oscillator.

//
__________________
More distortion to the people!
  Reply With Quote
Old 26th May 2018, 12:40 PM   #7336
inMotion is offline inMotion  Germany
diyAudio Member
 
Join Date: May 2013
Default Lower output level with NOS filter?

Hi Soekris,

I put the DAM1021 (Rev 5) into operation and ported the original NEWNOS filter to the new firmware and uploaded it. Compared to my old DAM1021 Rev 1 with NewNOS filter, the available output level is estimated to be 3-5 dB lower than before (single ended output). This has a very negative effect on kernel streaming with digital volume control, as I have to connect an additional preamplifier stage to drive low-efficiency speakers (in this case Celestion SL600). How can this be explained?
By the way - sound quality with Rev 5 and new firmware is very good.
  Reply With Quote
Old 26th May 2018, 01:39 PM   #7337
soekris is offline soekris  Denmark
diyAudio Member
 
Join Date: Jun 2009
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Quote:
Originally Posted by inMotion View Post
Hi Soekris,

I put the DAM1021 (Rev 5) into operation and ported the original NEWNOS filter to the new firmware and uploaded it. Compared to my old DAM1021 Rev 1 with NewNOS filter, the available output level is estimated to be 3-5 dB lower than before (single ended output). This has a very negative effect on kernel streaming with digital volume control, as I have to connect an additional preamplifier stage to drive low-efficiency speakers (in this case Celestion SL600). How can this be explained?
By the way - sound quality with Rev 5 and new firmware is very good.
The new 1.20 firmware and 4K filters have zero at -2 dB, the dam1021 then add 1 dB gain, resulting in zero at -1 dB with 1 dB margin, ie when volume level is set to 0 then it's 1.26V rms output at resistor network, about 1.9V at buffered single ended and 3.8V buffered balanced.

I have no idea how your filters are designed and what it have at zero level. Look at the filter file source for details.
__________________
Søren
  Reply With Quote
Old 26th May 2018, 02:42 PM   #7338
zfe is offline zfe
diyAudio Member
 
Join Date: Dec 2014
Do you say that there is some change in the level, with the new firmware, aside of the FIR1 filter multiplicators (which are about 1.7dB lower in the new firmware)?
  Reply With Quote
Old 26th May 2018, 08:30 PM   #7339
soekris is offline soekris  Denmark
diyAudio Member
 
Join Date: Jun 2009
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Quote:
Originally Posted by zfe View Post
Do you say that there is some change in the level, with the new firmware, aside of the FIR1 filter multiplicators (which are about 1.7dB lower in the new firmware)?
Yes, the soft butterworth FIR1 filter needed lower gain to keep the coefficients below 1.00, and I wanted to keep all filters at the same level, so I settled for -2 dB in the FIR1 filters, see filter file for details. To compensate a little, I added 1 db gain later on by firmware.
__________________
Søren
  Reply With Quote
Old 27th May 2018, 07:44 AM   #7340
zfe is offline zfe
diyAudio Member
 
Join Date: Dec 2014
Is this 1dB gain just done by an implicit 1dB offset of the volume control?
  Reply With Quote

Reply


Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KhzHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
e18 DAC - 8 channels at 32bit /384 kHz exa065 exaDevices 30 29th June 2012 05:11 PM
384 Khz DAC? SunRa Digital Source 8 1st October 2009 11:14 PM
24 bit/192 kHz via USB? gentlevoice Everything Else 3 22nd December 2008 06:24 AM
sign magnitude DAC Bernhard Digital Source 0 30th January 2007 01:40 PM
24 bit / 192 kHz Tube DAC questions Overlord Digital Source 4 29th April 2003 05:14 PM


New To Site? Need Help?

All times are GMT. The time now is 07:05 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki