I2S and Analog Output problem of CDPRO2


2008-01-17 8:55 pm
Hi All,

I have two strange problems when I try to make my CDPRO2 alive.
I bought the CDPRO2 from Singapore some months ago and have tried to make a direct connection from I2S pin of CDPRO2 to TDA1541A.

Problem 1: I2S Problem
I've made a double layer pcb NOS Dual DAC TDA1541A from Torben like this one ; http://bygselvhifi.dk/images/nosdac/nosdacdac.jpg

Also I've set the DAC mode of CDPRO2 to default (I2S - FS mode) using DSA interface provided by CDM12 Controller from http://www.diyparadise.com/cdm12controller.html

Then I've made direct connection from CDPRO2 ==> TDA1541A like this:

Pin1: MISC ==> Not Connected
Pin2: SCLK ==> Pin3: BCK
Pin3: WCLK ==> Pin1: LE/WS
Pin4: DATA ==> Pin2: DATA L/DATA
Pin5: GND ==> Ground star of DAC PCB
Pin6: V4 ==> Not Connected

When I measure the voltage of all pins of TDA1541A using DMM then I found all voltages are correct as Lesha's measurement. (http://users.podolsk.ru/boga/DAC.html) but when I measure the frequency of pin1 and pin2, pin4 of TDA1541A also using the same DMM (I have no oscilloscope) then I found :
- Pin1 = LE/WS ==> 44,1 kHz
- Pin2 = BCK ==> 0
- Pin4 = DATA R ==> 0

Then I remove the connection and try to measure the frequency of SCLK directly from CDPRO2 (while it's still running) but I found "0 kHz also". I've measured nothing. :confused:

Problem 2: Analog Output Problem
After failed in the firts attempt using I2S directly from CDPRO2 then I try to make a direct connection between analog output of CDPRO2 to my tube preamp and tube power amp but only dead silent. I've tried to measure the voltage of analog output of CDPRO2 using also the same DMM but there is nothing happen. :headbash:

Now I can only hear the CDPRO2 singing is using its AES/EBU SPDIF output port connected to TDA1545A Monica2 DAC. She sings beautiful indeed but my target is to make direct connection from its I2S to TDA1541A Dual Balanced DAC.

After some searchings in this forum then I have conclusions but still need helps from you guys to enlighten me about this problems:

1) Is it normal to find that there is no frequency measurement in pin SCLK of CDPRO2?
2) How could I know that the I2S of CDPRO2 damaged?
3) Is it normal fo find that analog output of CDPRO2 also gives nothing?
4) I've read DSA INTERFACE BUS PROTOCOL from daisy laser and there is feature of "Switch internal DAC on/off (shadow register 7)" in the page 34 of http://www.daisy-laser.com/products/CD/modules/CDPro2/P10501_dsa.pdf but I don't know the way to do it. Could somebody enlighten me about this feature?
5) Is it possible by coincident I've switched the internal DAC to be off? How could I re-enable it?

I know the best way to measure is using oscilloscope but I don't have any :( and some suggestions from all of friends here will be very appreciate. :worship:
Thank you.


- ims -
Check your pin arrangement on the tda1541a chip

My schematic says:

1 - LE/WS
2 - Bck
3 - Data L
4 - Data R

Pin 4 (data R) terminates into trace leading to pin 2 (Bck)

FWIW, my dac has 3, 10 ohm resistors in series with pin 1, 2 and 3 and pin 4 terminates into the trace going into pin 2 on the "dac side" of the 10R. Not sure of significance though.

For a pic of this see


"TDA1541A Dac PCB" tab (I have twin dac chips and the bottom one in the pic shows the correct pin arrangement)


2008-01-17 8:55 pm
Typo error

Thanks riotubes,

Yes, it's my mistake, just typo error. The right connection I have done is:

Pin1: MISC ==> Not Connected
Pin2: SCLK ==> Pin2: BCK
Pin3: WCLK ==> Pin1: LE/WS
Pin4: DATA ==> Pin3: DATA L/DATA
Pin5: GND ==> Ground star of DAC PCB
Pin6: V4 ==> Not Connected

I attach the pictures of the connection.

I've read some people also uses 22R..100R series with the 3 pins od I2S as a damping resistors suppresses signal overshoot / ringing http://www.diyaudio.com/forums/showthread.php?postid=1421501#post1421501.

TDA1541 Info in this forum also says this is for reducing the groud-bound effect http://www.diyaudio.com/forums/showthread.php?postid=788596#post788596

BTW, do you have measure the frequency of pin2 (SCK or BCK)? Please tell me what you got?




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2008-01-17 8:55 pm
Internal DAC sometimes singing

Since I am a novice diyer, I asked some suggestions from other diyers. I did their suggestions:

- For the internal dac; I reduce the cable and now 10 cm long. Connect the cable to preamp and power amp. First silent but sometime just singing for a moment, silent again dan singing for a moment again.

- Cannot use DMM to measure frequency of SCLK. DMM ranges only 5-125 kHz. Should use oscilloscope which I don't have any oscilloscope right now :(
So I should postpone this suggestion, maybe later time when I have a chance to use it.

Hope any diyers of this forum who has similar experience about that internal dac behaviour could share your experiences.

Any suggestions from you guys would be very appreciated.



2008-01-17 8:55 pm
Onboard DAC is singing now

Tonight I have to try some suggestions from you guys via this forum as well as by emails and onboard DAC is singing now.

She's just singing beautifully.

The problem is the power supply. Should give proper attention in this area. I gave independent board ps using simple LM317 at 9 VDC and 5 VDC to CDPro2. But unfortunately I only tapped the transformer at 0-9VAC to feed the 9VDC so after loading it with CDPro2, the psu voltage drop to 7.72VDC. After changing the tap to 0-12VAC then the onboard DAC singing nice. It just that simple solution.

Thank you for guys and now I will try to make the external DAC using dual TDA1541A singing also.

I've tried to measure the DC voltage with DMM instead of oscilloscope. I found that the SCLK, WCK give 1.652 VDC and DATA give various level of voltage related to signal from CDPRO. I measured at 0 Volt at CDPRO full stop and various between 0 to 1.25 VDC while CDPRO singing. Thanks for your suggestion, Spencer. :worship:

I hope that I2S port will running smoothly with TDA1541A tomorrow.



2008-01-17 8:55 pm
All output ports of CDPRO is running well now

Dear All,

I want to confirm that ALL outputs of CDPRO2 which I bought from AHFartaudio are running well now.
I just made the I2S port also working with Dual Balanced TDA1541A DAC. She is singing nice.

I've made a simple civ to the schematic of Torben DAC as attached file.
Although the gain is not perfect but it's working for my preamp and power amp.

Since I have only little experience to use tube design then I plan to use D1 IV stage for that DAC instead of tube. Maybe sometime I can use the tubes.

Thanks for many suggestions which I have received via this forum as well as emails, especially for Alessandro Galavotti, Spencer, riotubes, Yeo, CK Kok and also Robert (AHFartaudio). Many thanks for your supports, guys.

Now, I should make a planning for IV stage as well as the chassis.

Hope this thread could give something to the newbie diyers like me.

- ims -


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