Up-sampling in Gigawork DAC - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

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 22nd March 2012, 02:47 AM   #1
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Default Up-sampling in Gigawork DAC

A few weeks ago I bought on eBay the latest Lars Audio Gigawork Balanced USB DAC W/ Headphone amplifier “DAC-2 BL” (version LM-DAC7 V3.2), based on the features and specs announced in the ebay’s ad. In description and in pictures provided it showed up-sampling module with CS8421. When I received the actual DAC, I have examined it and found that this module is missing, and instead there are four jumpers installed. I contacted the seller and he told me that this version goes without up-sampling and should work fine (it is). Make it short, I got the missing module from the seller, installed it, and it sounds fine as well with that module. At least, I cannot tell a difference, specially taken in account that the DAC is completely new and may require some burning.

So, I have two questions (sorry, I know, it was discussed thousand times):
1. Do I need up-sampling or not? I tried to read through hundreds of pages in some threads here and couldn’t get a straight answer.
2. Is there somewhere (on ebay?) a DIY module that could be plugged into this DAC to show a sampling rate of the input signal?
Any input is highly appreciated. I don’t mean to start a new long discussion, a link to the post where those questions are clarified would be sufficient.
  Reply With Quote
Old 22nd March 2012, 11:45 AM   #2
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
The way those ASRC cips do the upsampling is not very... usefull. Especially if your source (transport) has a decent quality with low jitter.
Practically they don't bring up significant improvements of the sound quality, some say that even they mudd up the sound. So probably, what you hear is real...
Technically the upsampling process in those cips is simplistic, crude, due to the lack of processing power and buffer memory. The "correct" way to do it is using dedicated audio DSP cips (processors with sufficient speed and memory). DSP-way it is done in some high-end players, receivers.

What IC did you receive on the module, the CS8421?

Last edited by SoNic_real_one; 22nd March 2012 at 11:49 AM.
  Reply With Quote
Old 22nd March 2012, 04:02 PM   #3
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Quote:
Originally Posted by SoNic_real_one View Post

What IC did you receive on the module, the CS8421?
Yes, and idea was to feed that DAC with the best signal possible.
  Reply With Quote
Old 22nd March 2012, 05:49 PM   #4
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
Well, then feed it with native 24/96 signals
I did listen the ASRC made by TI and AD and was not happy with the results. AD was marginally better, but maybe was just my imagination. I still have to hear a CS one, but the principle of operation is not different from the others. No buffer for jitter reduction, single stage digital PLL loop, ROM coeficients used to guess the next sample...

Alpha Processing by Denon, RLSIII by Harman Kardon, ATF by Anagram Technologies/Cambridge Audio, Hi-bit Legato Link by Pioneer are several better sounding up-sampling methods. All done via DSP.

Alternative would be upsampling done in PC - foobar2000 has a couple of add-on modules to do that. I like (and use) the one based on SOX code.

Last edited by SoNic_real_one; 22nd March 2012 at 05:52 PM.
  Reply With Quote
Old 22nd March 2012, 11:18 PM   #5
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Quote:
Originally Posted by SoNic_real_one View Post
Well, then feed it with native 24/96 signals
............
Alternative would be upsampling done in PC - foobar2000 has a couple of add-on modules to do that. I like (and use) the one based on SOX code.
That is another question: Where one could get those, specially titles that you like and not that are offered for free.

I am afraid that the most of the 24/96 files offered are result of the PC after-processing, as you noted.

Even more questionable look to me "high-res" LP rips. Why would I need them if I have Technics SP-10MK2 next to my DAC?
  Reply With Quote
Old 22nd March 2012, 11:44 PM   #6
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
Why? So you don't scratch away your LP discs and eat up your diamond tip... You would need a very good sound card (ADC) to do that conversion. Like E-MU class...
For testing, to see if your system can even reveal the hi-res, you can try free files from here: High Resolution Music DOWNLOAD services .:. FLAC in free TEST BENCH
  Reply With Quote
Old 23rd March 2012, 07:38 PM   #7
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Thank you, Sonic, for a link. Good selection for the tests.
But again, if original source is SACD, my Denon 3910 does pretty good job playing it. It would be nice to have the real 24/192 source.

Anyway, back to the topic. Right now I more interested to get the best from the red book cd. For that task considering the current chipset (receiver CS8416, DAC PCM1798 and Up sample rate converter CS8421), what would be in theory the better option: with up-sampling or without it?
  Reply With Quote
Old 23rd March 2012, 10:09 PM   #8
diyAudio Member
 
Join Date: Jan 2008
Location: Virginia
PCM1798 is a good DAC. So it might not make a difference in the end.
I didn't listen the CS8421 ASRC, maybe you can do some A-B comparations. It also depends of the final amp/speaker/headphones if you can detect small differences.
  Reply With Quote
Old 24th March 2012, 02:44 AM   #9
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Quote:
Originally Posted by SoNic_real_one View Post
PCM1798 is a good DAC. So it might not make a difference in the end.
I didn't listen the CS8421 ASRC, maybe you can do some A-B comparations. It also depends of the final amp/speaker/headphones if you can detect small differences.
My test setting to play CD is decent:
Denon 3910 -> optical -> Gigawork DAC Balanced ->balanced bypass Classe SST-600 -> Bryston 4B-ST -> Thiel 3.6

I cannot see any difference between using CS8421 or not. At the same time the sound is tiny bit inferior to what I can get using Rotel RCD-950 analog RCA -> Classe, but better than one from my other CD players, including Denon 3910.

Now, here is a problem: after downloading 24/192 material I have discovered that my DAC does not play it. All previous sample files I used were 24/96
  Reply With Quote
Old 24th March 2012, 05:44 AM   #10
mishak is offline mishak  United States
diyAudio Member
 
Join Date: Mar 2007
Location: Chicago
Correction, Gigawork DAC does process 24/192 file if I feed it directly from PC foobar2000 player via USB, but apparently none of mine stand alone hardware media players could output that signal correctly.
  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
Help needed on Gigawork DAC !!! nick974 Digital Line Level 11 17th April 2012 10:13 PM
Gigawork 24/192 dac comparable with Benchmark dac ? ashok Digital Source 18 28th July 2011 02:12 AM
Anyone finished a Gigawork DAC? fastasulike Digital Line Level 20 5th May 2011 10:09 PM
Gigawork CS4398 DAC +... McCrackers Swap Meet 5 30th December 2010 08:30 PM
Gigawork DAC board MFranzen Swap Meet 0 30th December 2010 01:05 AM


New To Site? Need Help?

All times are GMT. The time now is 11:32 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2