NOS Dac noise when changing tracks

[carlosfm]

I made a board to put inside my Philips CD650 with two paralleled TDA1543 dacs, and OPA627 op-amps.
BTW, at least with op-amps, two TDA1543s sound much better to me than only one. It's one on top of the other (the top one is bypassed too).
I've got the I2S signals from the TDA7210.
For now I'm impressed with the sound, but there's some noise when hitting play or changing tracks.
I can hear the music starting to play for less than a second, then pause and the it starts.
I know that the TDA7220 internally mutes, but as I want NOS, I've got the I2S signals from the TDA7210.
Is there a way around this?
Thanks in advance.

P.S. I don't have the TDA7220 datasheet, I can't find it anywhere , so I don't know if you can get NOS I2S from it.
I don't want 4x OS...

 

[Bricolo]

here's the datasheet:

http://www.geocities.com/audiograde/semi.html

 

[guido]

Put a gate into the dataline, so you can "mute" it by making it low towards the dac.

Then take the signal from microprocessor to 7220 or mutingtransitors to trigger that gate so dataline goes low.

End of rubbish.

(still have to do that on mine, have to admit. So no details yet...

GuidoB

 

[carlosfm]

Thanks for the link, Bricolo.
Google doesn't go there.
Yes, it's SAA, not TDA...

Hey Guido, nice idea, show us when it's done.😉
BTW, I've sent you a private mail, but that's not needed anymore.😉

 

[Elso Kwak]

For now I'm impressed with the sound, but there's some noise when hitting play or changing tracks.
I can hear the music starting to play for less than a second, then pause and the it starts.
I know that the TDA7220 internally mutes, but as I want NOS, I've got the I2S signals from the TDA7210.
Is there a way around this?
Thanks in advance.

P.S. I don't have the TDA7220 datasheet, I can't find it anywhere , so I don't know if you can get NOS I2S from it.
I don't want 4x OS...

Hi,

To restore muting just connect (wire "D") pin 23 of the SAA7220 to
pin 11 of the SAA7210.
That's all.
For muting schematic take a look at last picture on :
http://members.xoom.virgilio.it/_XOOM/hi_fi/com.htm
Hope this helps, courtesy of Marco Amboldi.

Datasheet of SAA7220 also on Marco's site.

 

[Bricolo]

Re: Re: NOS Dac noise when changing tracks

Hi,

To restore muting just connect (wire "D") pin 23 of the SAA7220 to
pin 11 of the SAA7210.
That's all.
For muting schematic take a look at last picture on :
http://members.xoom.virgilio.it/_XOOM/hi_fi/com.htm
Hope this helps, courtesy of Marco Amboldi.

Datasheet of SAA7220 also on Marco's site.

He wants NOS, so no 7220

 

[Elso Kwak]

Re: Re: Re: NOS Dac noise when changing tracks

He wants NOS, so no 7220

Bricolo,
If you have a look at the schematic you will see that this even works with a SAA7220 removed from the circuit.
Marco Amboldi' s NON-OS mod is to cut tracks on the PCB and to install jumper wires. I just remove the SAA7220.
The muting mod works in both cases.
See also:
http://members.xoom.virgilio.it/hi_fi/cd960.htm
and
http://members.xoom.virgilio.it/hi_fi/com.htm
I also installed the muting mod in my own CD650 and I can tell you it works!
😎

 

[carlosfm]

Hi Elso, nice to see you here.
Yesterday I looked again to the 650 schematic and I also think the solution is there.
The uP has a muting pin that intercepts the Data that goes to the TDA1541.
But your solution is really simple.
Thanks for the information Elso.

Bricolo, I downloaded the SAA7220 datasheet from the link you posted and the 3rd zip file is not ok...
I can't extract page 14.
Does anyone has page 14?

 

[Elso Kwak]

Muting Trick

But your solution is really simple.
Thanks for the information Elso.

Hi carlosfm,
I got it from Marco Amboldi. Cudo's for him!😉

 

[carlosfm]

I've got the complete SAA7220 datasheet in PDF format.
Google with this:
"SAA7220 pdf".

 

[Bricolo]

Re: Re: Re: Re: NOS Dac noise when changing tracks

Bricolo,
If you have a look at the schematic you will see that this even works with a SAA7220 removed from the circuit.
Marco Amboldi' s NON-OS mod is to cut tracks on the PCB and to install jumper wires. I just remove the SAA7220.
The muting mod works in both cases.
See also:
http://members.xoom.virgilio.it/hi_fi/cd960.htm
and
http://members.xoom.virgilio.it/hi_fi/com.htm
I also installed the muting mod in my own CD650 and I can tell you it works!
😎

In fact, this tweak connects the 7210/7310's mute output to the bases of the muting transistors. Am I right?

If I am, how can I fix the same problem, but on a self made nos dac (with I2S, and TDA DAC), that of course hasn't muting transistors


PS: Elso, I got the Horowitz & Hill from my university's library. Time for learning 😉
I'll try to finish reading chapter 2 this evening (it's already late 🙁 ), I like the book, things are soo clearly explained

 

[Elso Kwak]

Re: Re: Re: Re: Re: NOS Dac noise when changing tracks

In fact, this tweak connects the 7210/7310's mute output to the bases of the muting transistors. Am I right?

Bricolo, no you are not right. No muting transistors are involved. [In fact I removed all muting transistors]. Muting comes from the servo panel, that is connected to pin 23 or pad of SAA7210 and goes straight to the pin 11 of the SAA7210. Pin 11 of the digital signal processor is a muting-in connection.
So the muting is done in the digital signal processor before the NON-OS DAC.

In my Philips CD931 I did not experience this muting problem when taking off I2S signals for my NON-OS DAC: [SAA7310]->[74HC125]->[TDA1543]->[OPA604]->[discrete ouputbuffer].


😎

 

[carlosfm]

Re: Re: Re: Re: Re: Re: NOS Dac noise when changing tracks

Bricolo, no you are not right. No muting transistors are involved. [In fact I removed all muting transistors]. Muting comes from the servo panel, that is connected to pin 23 or pad of SAA7210 and goes straight to the pin 11 of the SAA7210. Pin 11 of the digital signal processor is a muting-in connection.
So the muting is done in the digital signal processor before the NON-OS DAC.

In my Philips CD931 I did not experience this muting problem when taking off I2S signals for my NON-OS DAC: [SAA7310]->[74HC125]->[TDA1543]->[OPA604]->[discrete ouputbuffer].
😎

Yeeeeeeeeeeeesssssssssssssssss!!!
Hey Elso, the trick works wonders.
I made it yesterday at night, and it's beautiful.
I don't have the muting transistors too, that's one of the first things I remove.😉
Now I have the internal TDA1541 in NOS mode (and muting😀 ) and my board with TDA1543 in nos mode (and muting too😀 ).
Gotta A-B that thing.😎
Gotta buy you a beer, man.

 

[Bricolo]

Re: Re: Re: Re: Re: Re: NOS Dac noise when changing tracks

Bricolo, no you are not right. No muting transistors are involved. [In fact I removed all muting transistors]. Muting comes from the servo panel, that is connected to pin 23 or pad of SAA7210 and goes straight to the pin 11 of the SAA7210. Pin 11 of the digital signal processor is a muting-in connection.
So the muting is done in the digital signal processor before the NON-OS DAC.

In my Philips CD931 I did not experience this muting problem when taking off I2S signals for my NON-OS DAC: [SAA7310]->[74HC125]->[TDA1543]->[OPA604]->[discrete ouputbuffer].


😎

OK,


And how is the whole thing connected before any mod?

Decoder to 7220 mute in, and after?

 

[carlosfm]

Bricolo,

Read the link that Elso posted, it's all there.
For muting, just connect pin 23 of SAA7220 to pin 11 of SAA7210.
That's it.