Multibit DAC core boards coupled with I2S-PCM driver board - 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 26th September 2013, 09:47 AM   #1
vzs is offline vzs  Europe
diyAudio Member
 
Join Date: Dec 2005
Location: Cluj-Napoca, Romania
Default Multibit DAC core boards coupled with I2S-PCM driver board

Since the I2S-PCM driver board is soon to be released the idea came up to create some bare DAC boards that could be coupled with.

The concept is a core board for multibit DACs, with keeping anything else such as digital front end, I/V, power supply external. To reduce the complexity and cost each DAC will have its own core board with same size and same interface, so it can become a standard part in the system.

Why only a core board with everything else external?
- to let us easily swap the DAC
- most of us already have different breeds of power supplies
- some may have an I/V but want to try out others. Would be nice to continue this idea for different I/Vs as well.

There were some starting ideas about this board:
- 2 layers (if mostly possible)
- options for stereo / balanced / dual mono configurations - this means it has to hold 2x stereo DACs or 4x mono DACs

Open questions (that comes to my mind):
- size of the board
- how to integrate it with other components
- power supply options
- I/V options

Once we decide about the questions, volunteers are needed to design the PCB and/or prototype and test it. I'm offering to design, prototype and test the AD1865 DAC and later on the PCM1704.

L.E. Policies for better readability: since this thread is dedicated for multiple core boards let's use the Title of a post to differentiate between subjects, like this:
- Core Board: posts related to standardization of the core board and _not_ specific DACs related: e.g. size of the core board, connector placement, etc
- AD1865: related to this DAC
- TDA1541:....

Regards,
Zsolt

Last edited by vzs; 26th September 2013 at 01:20 PM.
  Reply With Quote
Old 26th September 2013, 10:11 AM   #2
Marek is offline Marek  Poland
diyAudio Member
 
Join Date: Apr 2003
Location: Katowice
Great idea, can't wait for AD1865/2 and PCM63 and PCM1704 boards!

Please think about allowing use of 3-pin local shunt regulators on daughter boards with optional bypass.
  Reply With Quote
Old 26th September 2013, 10:46 AM   #3
noizas is offline noizas  Lithuania
diyAudio Member
 
Join Date: May 2009
Location: Vilnius, Lithuania
Default TDA1541A core PCB

Quote:
Originally Posted by vzs View Post
Since the I2S-PCM driver board is soon to be released the idea came up to create some bare DAC boards that could be coupled with.

The concept is a core board, with keeping anything else such as digital front end, I/V, power supply external. To reduce the complexity and cost each DAC will have its own core board with same size and same interface, so it can become a standard part in the system.

There were some starting ideas about this board:
- 2 layers (if mostly possible)
- option for balanced / dual mono configuration - this means it has to hold 2x stereo DACs or 4x mono DACs

Open questions (that comes to my mind):
- size of the board
- how to integrate it with other components
- power supply options
- I/V options

Once we decide about the questions, volunteers are needed to design the PCB and/or prototype and test it. I'm offering my help in designing, prototyping and testing the AD1865 DAC and then the PCM1704.

Zsolt
Hi Zsolt,

I have no software to design any kind of schematics for PCB creation (last time I used PCAD almost twenty years ago ), but will gladly participate here.

Some ideas about what should be included on core board for TDA1541:
1. Socket or sockets for TDA1541A (depends on board size, but about it later).
2. Surrounding components:
2.1 U.FL and/or alternative connectors and 3.3V attenuators for LE, BCK, DATA_L, DATA_R signals;
2.2 SMD capacitor for oscillator (polystyrene or better COG/NPO) SMD 1208. I still do not understand how free running DEM oscillator by John (ecdesigns) can work succesfully with such wide range of sampling frequencies (44,1 kHz to almost 400kHz), so here is an open question - is it better than text book 470 - 680 pF capacitor?
2.3 connectors for all three power supply lines (per one TDA1541);
2.4. HF filtering SMD 1206 size capacitors on all power lines, placed nearby pins of TDA1541.
2.5 decoupling capacitors on power lines - in case we still have space for it : I think it is not bad idea to have the opportunity to use 100 - 220 uF OSCONs pin type, however it solely depends on power solution in certain DIY project - I'm not sure in case of use Salas shunt regulators (placed nearby core PCB) such power decoupling capacitors would help.
2.6 famous decoupling capacitors. I would place those right under TDA1541A on topside and/or downside of PCB as 1206 size SMD, making shortest way from those 14 capacitors to digital ground (pin 14). 1206 size solder pads would let us experiment with a lot of different types capacitors - whatever everyone needs (X7R, FCA alcylic or COG/NPO). You can also use here 1210 size capacitors, soldering those on side less than 1.8mm, for example 1uF FCA1210C105M-G2.
2.6 Jumper or at least soldering pads for selecting TDA1541 mode (pin 27 to DGND or pin 26 or pin 28) - not sure is it really needed if we are going use that PCB with Ian's FIFO and PCM converter - in offset binary simultaneous mode, but anyway...
2.7 on analog outputs - as minimum we need place for I/U resistor, as maximum - I/U resistor and CSS for 2mA injection to every output.

I guess or, better say, dream , that using all components SMD type, except TDA1541 itself and analog output parts, would allow to fit balanced set of two TDA1541 on double sided PCB 80x70mm (size of FIFO without clock board).

On the other hand, 80x60mm core PCB for ONE TDA1541 allows to make unbalanced stereo set (one board) or balanced set by two PCB (stacking one over another). Also not bad really.


Best regards
Saulius
  Reply With Quote
Old 26th September 2013, 01:15 PM   #4
vzs is offline vzs  Europe
diyAudio Member
 
Join Date: Dec 2005
Location: Cluj-Napoca, Romania
Default Core Board

The main idea is that all DAC boards will share the same size and have the same connectors to be easily replaceable.

Data input: all output connectors of I2S-PCM driver board: 10pin PH2.0 + all U-FL connectors.

PSU input: highly differs between multibit DACs but I think +0- for analog side and +0- for digital side covers all: so 2 x 3pin connectors.

Output: Since we have dual-mono/balanced then 4 x 2pin connectors.

Size and placement: we have from 20pin SOIC (PCM1704) to 28pin DIP (PCM63) everything. If we want to stick to the dual-mono/balanced setup for most common multibit DACs we have to be able to accommodate the largest footprint needed 4 x 28DIP. Maybe the size of FIFO-Clock board would be enough and this board could be placed alongside FIFO-Clock board...
  Reply With Quote
Old 26th September 2013, 01:25 PM   #5
vzs is offline vzs  Europe
diyAudio Member
 
Join Date: Dec 2005
Location: Cluj-Napoca, Romania
Default AD1865

A first schematics attempt for the AD1865 core board.
Once we agree upon the size/shape of the board will start to design the PCB for it.
Attached Files
File Type: pdf DACore_AD1865_v0.1.pdf (232.8 KB, 140 views)
  Reply With Quote
Old 26th September 2013, 01:43 PM   #6
tubo is offline tubo  Philippines
diyAudio Member
 
Join Date: Apr 2007
Location: Mundelein, Illinois
Looking forward to ad1865 core board.
  Reply With Quote
Old 26th September 2013, 02:03 PM   #7
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
My vote for PCM1704.
  Reply With Quote
Old 26th September 2013, 03:29 PM   #8
noizas is offline noizas  Lithuania
diyAudio Member
 
Join Date: May 2009
Location: Vilnius, Lithuania
Default Core Board

Please take into account that if you are going to have possibility for direct replacement (cold swap) of one DAC core board by another DAC core board, you need "standartise" all inputs and outputs of each core board, including approximate position of sockets (cabling issue).
So, not only sockets, but also supply voltages and analog signal type (I or U) and level of signal should be matched on certain pin of certain connector...
That means you can not use 2x3pin connectors for power supply, as you wrote. You need so many pins in each connector, how many supply voltages you have per whole list of DACs !
Else you have no desired task solved - "cold swap" would lead to malfunction at least, damage at worst.

Concerning size of core board: I would not plan core board for 4xDIP28 set - it would be not enough space on 132x80mm board (FIFO+clock).
Please look photos of PCM63 in Rotel RCD-991 in Lukasz site: Rotel CD with tubes .

Length of one PCM63 is about 35mm (DIP28) - for scaling right on monitor

Those two PCM63 with surroundings (without capacitors for opamps) need at least 80x100mm area .
And this is without any sockets and MSB adjustment circuitry ( I see no trimmers in photos).
And actually without I/U conversion (no opamps - remember "standartised" level of output).
I guess, even complete usage of SMD components for surrounding would not allow to squeeze almost in same size area double set of parts.

So, take maximum FIFO "compatible" size, let say your mentioned 132x80mm board (FIFO+clock) and try to put here maximum 2 of DIP28 DAC chips.


Saulius
  Reply With Quote
Old 26th September 2013, 04:33 PM   #9
vzs is offline vzs  Europe
diyAudio Member
 
Join Date: Dec 2005
Location: Cluj-Napoca, Romania
Default Core Board

Quote:
Originally Posted by noizas View Post
Please take into account that if you are going to have possibility for direct replacement (cold swap) of one DAC core board by another DAC core board, you need "standartise" all inputs and outputs of each core board, including approximate position of sockets (cabling issue).
So, not only sockets, but also supply voltages and analog signal type (I or U) and level of signal should be matched on certain pin of certain connector...

That means you can not use 2x3pin connectors for power supply, as you wrote. You need so many pins in each connector, how many supply voltages you have per whole list of DACs !
Else you have no desired task solved - "cold swap" would lead to malfunction at least, damage at worst.
I would like to have same position of input/output sockets for all boards.

The idea is to have all PSU and I/V external - so the board should have current output _without offset_. Core boards with DACs that have offset like TDA1541 will have to take care about this by using a current source to null out the offset. As far as the current output level is concerned it will be between +-1mA to +-2mA (AD1865, AD1862, PCM1702/4, PCM58, PCM63, TDA1541) - double that for dual mono.

Good you brought up this direct replacement (cold swaping) issue: up to now I didn't thought about directly replacing one board with another _without adjusting the power supplies_. I thought when replacing e.g. AD1865 with AD1862 the user will consciously take care that analog voltage should be +-12V and when switching back to AD1865 he/she will change it +-5V - indeed it's easy to shoot yourself in foot this way.
So there are two possibilities:
1. Have only 2x3pin connectors but switching will need attention - power supply adjustment/change is needed
2. Have as many power connectors as many different DAC needs...

I would certainly choose #1 for simplicity and let the gravity of switching boards to the user.

Quote:
Originally Posted by noizas View Post
Concerning size of core board: I would not plan core board for 4xDIP28 set - it would be not enough space on 132x80mm board (FIFO+clock).
Please look photos of PCM63 in Rotel RCD-991 in Lukasz site: Rotel CD with tubes .

Length of one PCM63 is about 35mm (DIP28) - for scaling right on monitor

Those two PCM63 with surroundings (without capacitors for opamps) need at least 80x100mm area .
And this is without any sockets and MSB adjustment circuitry ( I see no trimmers in photos).
And actually without I/U conversion (no opamps - remember "standartised" level of output).
I guess, even complete usage of SMD components for surrounding would not allow to squeeze almost in same size area double set of parts.

So, take maximum FIFO "compatible" size, let say your mentioned 132x80mm board (FIFO+clock) and try to put here maximum 2 of DIP28 DAC chips.
Saulius
Will check this tonight...

Thanks!
Zsolt

Last edited by vzs; 26th September 2013 at 04:58 PM.
  Reply With Quote
Old 26th September 2013, 06:06 PM   #10
diyAudio Member
 
iancanada's Avatar
 
Join Date: Dec 2009
Location: Toronto
Quote:
Originally Posted by vzs View Post
A first schematics attempt for the AD1865 core board.
Once we agree upon the size/shape of the board will start to design the PCB for it.
vzs has already confirmed the schematics of AD1865 DAC core board by himself. I'll take care of the PCB design and prototyping. We are open for more suggestions.

Ian
__________________
Ian GBV - I2S to PCM converter board & FIFO KIT
http://www.diyaudio.com/forums/group...ml#post3662743
  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
Drive NOS AD1865/62,PCM1704/02/63,TDA1541 from FIFO: Universal I2S-PCM driver board iancanada Digital Line Level 697 13th September 2014 03:36 PM
DAC with LVDS I2S input + LVDS I2S Driver Harmonic Distortion Digital Source 4 23rd June 2014 06:53 AM
a new multibit DAC chip Arda technologies AT1401 Shinja Digital Line Level 77 20th January 2014 02:22 PM
WTT: Complete Pass D1 (v3 rebuild) multibit DAC tritosine Swap Meet 2 22nd May 2013 10:15 PM
Is the PCM-61 Dac are I2S or EIAJ data input ? gaetan8888 Digital Source 2 7th August 2007 05:08 PM


New To Site? Need Help?

All times are GMT. The time now is 01:37 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