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Old 29th September 2003, 12:29 PM   #1
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Unhappy NOS Dac noise when changing tracks

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...
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Old 29th September 2003, 03:01 PM   #2
Bricolo is offline Bricolo  France
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here's the datasheet:

http://www.geocities.com/audiograde/semi.html
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Old 29th September 2003, 03:18 PM   #3
guido is offline guido  Netherlands
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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...

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Old 29th September 2003, 03:56 PM   #4
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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.
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Old 29th September 2003, 04:48 PM   #5
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Lightbulb Re: NOS Dac noise when changing tracks

Quote:
Originally posted by carlosfm

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.
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Old 29th September 2003, 07:43 PM   #6
Bricolo is offline Bricolo  France
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Default Re: Re: NOS Dac noise when changing tracks

Quote:
Originally posted by Elso Kwak


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
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Old 30th September 2003, 06:53 AM   #7
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Cool Re: Re: Re: NOS Dac noise when changing tracks

Quote:
Originally posted by Bricolo



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!
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Old 30th September 2003, 07:56 AM   #8
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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?
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Old 30th September 2003, 08:03 AM   #9
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Default Muting Trick

Quote:
Originally posted by carlosfm
But your solution is really simple.
Thanks for the information Elso.

Hi carlosfm,
I got it from Marco Amboldi. Cudo's for him!
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Old 30th September 2003, 11:32 AM   #10
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I've got the complete SAA7220 datasheet in PDF format.
Google with this:
"SAA7220 pdf".
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