33.8688 TCXO Reclocking = noise !?

canvas · 7th June 2008, 03:00 AM

Hello everyone,

I tried to reclock the DIR's WCK,BCK,DOR,DOL from a 74HC574. At first, the sound was excellent, but it only last for an hour before the strange noise came in right channel. This noise will getting worse and worse, the only way to get rid of it is to shutdown the CD transporter and DAC for a while and turn on. Some people suggest AC logics, so I tried another 74AC374 but no help at all. 74AC374, on the other hand, only work for 30 minutes before the noise came in. Does anyone ever encounter this problem?

John Delmo · 7th June 2008, 07:25 AM

interesting. : )

kevinkr · 7th June 2008, 10:09 PM

Take a look at your layout, do you have a scope? How is the decoupling on your flip-flop and how does the I2S path differ right to left channel? Something drifting out of spec as the unit warms up?

Incidentally VHC series logic is what is recommended these days for best sound.

Do not mix 3.3V logic and 5V logic without proper level translation. VHC incidentally should work fine on either rail voltage, but again pay attention to the output voltage of your clock source and what the digital path in your cd player expects to see.

Possible damage occurred when you did the mod? Does it work ok with no reclocking?

canvas · 8th June 2008, 02:05 AM

Thanks Kevin,

I guess I found the problem, but I am not sure if that is the real cause. I put my DAC and 6 MOS regulators all in one chassis. This DAC is placed above the my class A amplifier, so the DAC gets hot easily. I am now placing the DAC above CD transporter, and it has been working flawlessly over 12 hours. I guess the TCXO + 74HC574 is sensitive to temperature.

Po-Ting

kevinkr · 8th June 2008, 02:09 PM

Quote:

Originally posted by canvas
Thanks Kevin,

I guess I found the problem, but I am not sure if that is the real cause. I put my DAC and 6 MOS regulators all in one chassis. This DAC is placed above the my class A amplifier, so the DAC gets hot easily. I am now placing the DAC above CD transporter, and it has been working flawlessly over 12 hours. I guess the TCXO + 74HC574 is sensitive to temperature.

Po-Ting

Hi Po-Ting,
That is as likely an explanation as any. Hopefully that is all it was.

7th June 2008, 03:00 AM	#1
canvas diyAudio Member Join Date: Nov 2003 Location: Taiwan	33.8688 TCXO Reclocking = noise !? Hello everyone, I tried to reclock the DIR's WCK,BCK,DOR,DOL from a 74HC574. At first, the sound was excellent, but it only last for an hour before the strange noise came in right channel. This noise will getting worse and worse, the only way to get rid of it is to shutdown the CD transporter and DAC for a while and turn on. Some people suggest AC logics, so I tried another 74AC374 but no help at all. 74AC374, on the other hand, only work for 30 minutes before the noise came in. Does anyone ever encounter this problem?

7th June 2008, 10:09 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Take a look at your layout, do you have a scope? How is the decoupling on your flip-flop and how does the I2S path differ right to left channel? Something drifting out of spec as the unit warms up? Incidentally VHC series logic is what is recommended these days for best sound. Do not mix 3.3V logic and 5V logic without proper level translation. VHC incidentally should work fine on either rail voltage, but again pay attention to the output voltage of your clock source and what the digital path in your cd player expects to see. Possible damage occurred when you did the mod? Does it work ok with no reclocking? __________________ "Extraordinary claims require extraordinary evidence." - Carl Sagan

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7th June 2008, 07:25 AM	#2
John Delmo diyAudio Member Join Date: May 2008	interesting. : )

8th June 2008, 02:05 AM	#4
canvas diyAudio Member Join Date: Nov 2003 Location: Taiwan	Thanks Kevin, I guess I found the problem, but I am not sure if that is the real cause. I put my DAC and 6 MOS regulators all in one chassis. This DAC is placed above the my class A amplifier, so the DAC gets hot easily. I am now placing the DAC above CD transporter, and it has been working flawlessly over 12 hours. I guess the TCXO + 74HC574 is sensitive to temperature. Po-Ting