DAC with TDA1541A noisy

[muzeau]

Hi dear all,

This is my first post after populating a board DAC with OS and NOS TDA1541A. And I have a problem. I started by testing mode OS and a noise occurs when the music plays, even lower. Some regular clics. I managed to swap mode NOS and the sound seems more or less clean it depends on the op amps, but no clicks.
I bought two TDA1541A, for 1 the seller stated NOS type for this TDA. The second stated nothing but his DAC is also noisy in the same manner. My question is: Is it possible to find TDA1541 which operate well only in NOS mode?

[muzeau]

In other words, is it possible that people are selling tda1541 who are unable oversampling ?

[pilli]

What chip is doing the oversampling?


_

[muzeau]

The chip doing the oversampling is SAA7220 P/C, the recommanded chip is SAA7220 P/B. Possibly this one that make noise ?

[UV101]

NOS = New Old Stock in retail terms
NOS = Non over sampling when used without an over sampling chip

All TDA1541A and Non A are non oversampling. In most cases it its the SAA7220P that does oversampling with this chip.

The oversampling chip sits on the I2S bus between the SPDIF (in a DAC) or the Decoder chip (CD Player) and the DAC chip.

i.e. Over sampling DAC
SPDIF -> Oversampling chip(SAA7220P) -> DAC(TDA1541A)
NOS DAC
SPDIF -> DAC

There is a problem elsewhere causing noise!

[Fidelity Audio]

When working on tda based players i've found bad grounds can cause pops, clicks and static noises on the analogue.

Brent

[Joris]

Originally Posted by muzeau

The chip doing the oversampling is SAA7220 P/C, the recommanded chip is SAA7220 P/B. Possibly this one that make noise ?

I thought the SAA7220P/C was used in digital broadcasting tuners, it should not be able to accept data from cd. Where did you get the SAA from?

[muzeau]

Hello Joris,
I bought this model at the sole French distributor who sold. At this moment I do not think this little diference have an impact. I ordered the Model B in China ... and I'll let you know the results of change.

Thanks

[UV101]

You should try to bypass the chip to test.

Its is effectively the NOS mod

remove the chip and bend pins 1,2,3,15,16&18 out striaght so they do not go through the holes on the pcb. Refit the chip.

On the PCB, link pin 1 to 18 (word select in to word select out)
pin 2 to 16 (clock in to clock out)
pin 3 to 15 (Data in to Data out)

In the full nOS mod, there are other things to do like move the xtal direct to the decoder chip and connect through the mute functions (you can then fully remove the SAA7220) but connected as abouve will test to see if its the SAA7220P/C that is giving you the issues. If you still have the noise, the problem is elsewhere.

Her is a picture of the same mod on my CD50.



Ian

[muzeau]

After removing the SAA7220P/C, the clicks remains !!! After I removed the clock chip 74HC4040 no sound (no music no clicks). After putting the CS8414 in master mode the music came back and no clicks. Conclusion the clicks apear with the clock enabled and the receiver in slave mode.

Anybody understand that ?

Do not ask me to stay in NOS I want test in both modes.

Best regards