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

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

Weird Asynchronous Sample Rate Converter Behavior
Weird Asynchronous Sample Rate Converter Behavior
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
Thread Tools Search this Thread
Old 23rd May 2010, 12:54 AM   #1
stokessd is offline stokessd  United States
diyAudio Member
stokessd's Avatar
Join Date: Nov 2002
Location: Grantham, NH
Default Weird Asynchronous Sample Rate Converter Behavior

I just build a DAC based on a CS8416, a CS8421, and a CS4398. I poured over the data sheets and set everything up thusly:

Receiver output: Left justified
Sample Rate Converter: 24.5760MHz crystal, 256Fs output for 96KHz resampling rate, input left justified (up to 32 bits in), output left justified 24bits out.
DAC: left justified (up to 24 bits in), double speed mode.

All chips are in hardware mode with appropriate setting resistors.

The DAC played music reasonably well, but on loud female vocals it sounded a bit broken up. And when I look at the output on the scope sine waves look like triangle waves with rounded tops and bottoms. I checked square wave response and 0dB response and everything looked good, except for the weird sine waves. I tried all sorts of DAC modes, and double checked all my clocks etc. I didn't grab data from the ASR chip and try to decode it myself.

While I was troubleshooting, I reduced the ASR output from 24bits out to 20 bits out, and everything is perfect now. The DAC chip data sheet says it accepts 24 bit data, the ASR chip says it's happy to send 24 bit data but something funky was happening that I can't explain.

The one thing I didn't try was to switch from left justified data ll the way through to I2S format.

Another piece of evidence is an FFT of the DAC output with a pure sine wave input shows better performance with the DAC jumpers set for single speed (no deemphasis mode). The second order harmonic just peeks up in double speed, but is gone in single speed mode. Do I have a hinky DAC chip, I'm stumped.

Does anybody have any ideas? I'm stumped, but the DAC sounds amazingly good in 20 bit mode.

  Reply With Quote


Weird Asynchronous Sample Rate Converter BehaviorHide 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
Asynchronous Sample Rate Conversion werewolf Digital Source 122 18th December 2009 07:10 AM
FS: SRC2496 Behringer Sample rate converter gypsielectro Swap Meet 1 11th July 2006 06:18 AM
Sample rate converter with fixed output frequency Michele Spinolo Digital Source 1 20th November 2004 04:11 AM

New To Site? Need Help?

All times are GMT. The time now is 01:15 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio