Trying to build a DAC, very very confused - 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 28th May 2013, 03:16 AM   #1
diyAudio Member
 
krfkeith's Avatar
 
Join Date: Sep 2011
Default Trying to build a DAC, very very confused

Alright so I've settled on using the WM8741 for a DIY DAC. Now, I'm not entirely sure what I'm going to use as a source, but I know that the audio will be decoded and spit out by the MCU as an I2S stream. Basically, what I'm confused about is the talk of things like FIFOs, isolates, and a bunch of other stuff that I forget. What I want to know is this: how do I get the I2S stream from the source to the WM8741 most reliably? I assume I'm going to need an external clock to combat jitter, do I need a separate one for each sampling rate? Is there anything else that I am missing?
  Reply With Quote
Old 28th May 2013, 02:09 PM   #2
diyAudio Member
 
Join Date: Feb 2013
Good source is XMOS, USB to I2S.

Example : Xmos 384kHz High Quality USB to I2S PCB with Ultralow Noise 6 5UV Regulator | eBay

Use twisted pair of wire - 4 pairs, 8 wires - so each signal have a ground return next to it. It is reliable and good, if under 10cm.

Or use u.fl cable for each pair.

Isolator can stop noise from source so the sound is better. You can add later.

FiFO can store and re-clock data so the sound is better. You can add later.

External clock depends on the DAC design and other device that add later.
__________________
  Reply With Quote
Old 28th May 2013, 04:34 PM   #3
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
fifo doesnt store anything, technically its a buffer, it only stores (while it fills) till the buffer is half full, before it starts outputting, after its turned off everything vanishes.

Despite much web space, advertising and text enlisted to promote an improvement, an external clock by itself will not improve anything and will not combat jitter, on the contrary it will add jitter vs onboard, unless:

• it is of significantly higher quality than the onboard clock
• it is able to be mounted reasonably close to the DAC chip (10cm max, preferably much less)
• it is able to be connected by impedance controlled 50Ω connections
• it is supplied with a very low noise power regulator

I recommend Amanero over the Xmos for USB->i2s input without a second thought.

MCU spitting out i2s/PCM? erm... sounds like youve got your wires crossed so to speak. Generally an MCU refers to a microcontroller used to control the operation of other components, rather than doing anything by itself; some devices will have an on-chip MCU, but thats not the norm.
  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
Confused noob: Need a USB DAC munce31 Digital Line Level 4 19th November 2012 09:54 PM
Confused about port length on planning my first subwoofer build JDawg Subwoofers 8 26th January 2012 05:47 PM
confused about -3.5db @20k on nos dac build hbc Digital Line Level 22 2nd March 2011 12:36 PM
PC based audio to amplifier via DAC - confused? racedirector PC Based 7 10th September 2010 02:17 AM
Confused about USB/DAC choice. danrgleason Solid State 2 5th December 2009 12:58 AM


New To Site? Need Help?

All times are GMT. The time now is 12:09 AM.


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