DAC info - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, 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 18th September 2003, 02:02 PM   #1
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Default DAC info

Can anyone point me in the right direction as to how to build a DAC or what is required to use say BB PCM1794 or Wolfson8740 chips.

I have in mind using one chip per channel like highlighted on TI for the PCM1738.

The input will be from a computers SBlive digi out SPDIF. So I assume I will need a converter chip such as the DIR1703, or like MWP's post a USB interface. I do want to use the DSP onboard the SBlive so maybe the USB isnt an option.

Is using one of these chips quite simple appart from the surface mount bit, which shouldnt be a problem.

Do you need to set the chip into different sampling frequencies or will it just decode anything you throw into it.

I have tried looking at the TI site for papers on using these chips but not really found anthing.

Cheers Matt.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 18th September 2003, 04:36 PM   #2
MWP is offline MWP  Australia
diyAudio Member
 
Join Date: Oct 2002
Location: Adelaide, South Australia
Hmmm... my favorite movie.
I just happen to be listening to the 5th element sound track at the moment

USB interface does act like a complete sound card, so it would bypass the SBLives DSP.

Im wondering why you want to go to the extra trouble of using the PCM1794 when you are just using it with a SBLive... it will let the DAC down.

The PCM1794 datasheet is here:
http://www-s.ti.com/sc/ds/pcm1794.pdf

Itll have details on everything you need to know.

AFAIK it requires a microcontroller to setup the internal registers.
  Reply With Quote
Old 18th September 2003, 06:56 PM   #3
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
OK well I use the computer as my music player. Now I intend on using the DSP as a tool to design loudspeakers along with some CAD software, the DSP allowing me to try different xover frequencies then CADing to make the final design with a passive xover. For listening Ill use the USB if it sounds better then the SB because I want this to be as good quality as possible.

Now I have read the data sheet and assimilated as much info as my very limited digital knowledge will let me understand.

Now as far as I can see the DAC will require a clock and then something to control it.

From what I understand to make what I want work I will need the USB chip and the SPDIF chip and ofcourse the DACs.
Then the USB will output a SPDIF signal and I will then switch between the two (USB and externall SPDIF in) using a switch. After which the SPDIF chip will convert the SPDIF into data for the DAC.
These two chips are configured to work in their respectable ways. Now the sample frequency is controlled by the 6 dip switches and then the LED's light up in combinations to highlight which one is active. OK now the DAC receives data from the SPDIF chip which selects its sample frequncy, input data and clocks the DAC to the SPDIF chip. Then the DAC is set to the mode its intended to be used in and everything works. Oversimplification tho

Is this accurate or am I way off the mark. Im interested in all aspects of audio and am trying to learn about digi. I would like to design or half design and use other peoples ideas or projects as a way to learn. I know how to build things so making one of the simple non sampling TDA's wouldnt really teach me about DAC's more then how to make a PCB and solder bits in place which I can already do.

Setting things "high and low" is this like an on or off signal from a logic gate??

Cheers for any help Matt.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 18th September 2003, 07:00 PM   #4
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
I didnt see that last bit on your post Afaik microcontroller sounds hard

Ill look at the differences in the PCM1794 and PCM1730 and see.
From reading the data sheet I cant say I have seen it say it needs one, maybe it does between the lines, its just I dont know what half the lines mean

again cheers for any help.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 18th September 2003, 07:26 PM   #5
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
and again I just looked at the USB interface do they make a 24bit 96 version or is 16bit 48 the best, is this the limit of USB and I suppose that the digi out on the card wouldnt be as good as the USB anyway.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 19th September 2003, 03:23 AM   #6
MWP is offline MWP  Australia
diyAudio Member
 
Join Date: Oct 2002
Location: Adelaide, South Australia
Quote:
Originally posted by 5th element
and again I just looked at the USB interface do they make a 24bit 96 version or is 16bit 48 the best, is this the limit of USB and I suppose that the digi out on the card wouldnt be as good as the USB anyway.
48khz 16bit is max until they make a USB2 part (we are hoping...).

The SPDIF out on the USB part should be very good quality as its not resampled.
  Reply With Quote
Old 19th September 2003, 11:54 AM   #7
diyAudio Member
 
Join Date: Oct 2001
Location: .
You can definitely get 24/96 from USB and probably 24/192. However it is not handed to you on a plate, unlike 16/48 with the PCM2906.

ray.
  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
Need info on my Onkyo, can't find any info anywhere. gixxierific Digital Source 0 19th April 2009 03:49 PM
How to get cathode bias info from grid bias info? leadbelly Tubes / Valves 8 14th August 2008 04:40 PM
need info for Zen-XA amp space2000 Pass Labs 5 20th June 2008 03:33 AM
Info ?? lpd Solid State 1 16th August 2006 10:54 PM


New To Site? Need Help?

All times are GMT. The time now is 09:19 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