Inverting data line ?

Bernhard · 16th May 2005, 03:03 PM

Hi,

there was a thread about using balanced TDA1541A in a way so that PSU ripple and noise will cancel.
One data line should be inverted and if the negative output is subtracted from the positive, signals add while noise and ripple cancel.

Please correct me if I am wrong.

Now how to invert the digital signal ?
Look at a COB DAC.
If just the data line is inverted instead of BPZ we get -1 LSB while +FS becomes -FS and -FS becomes +FS.

If after inversion, one is added, BPZ becomes BPZ, but +FS becomes -FS +1 LSB and -FS gets overflow and will be -FS because +FS + 1LSB is not possible .

What is better ????

philbyx · 16th May 2005, 04:14 PM

Hello,

As we say here in France, you are discovering the sugared water

All the balanced Dac (with two dacs by channel) are fed by data for one, and /data for the other one.
There is effectively 1 bit offset, because of two's complement on the inverted channel, but it doesn't matter.

Look at this schematic in the post.
http://www.diyaudio.com/forums/showt...767#post554767
It's a ad1865, but the principle is the same

Philippe

rfbrw · 16th May 2005, 04:30 PM

This topic has been flogged to death. see here
'Chibi' phase inverting mod.

16th May 2005, 03:03 PM	#1
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Inverting data line ? Hi, there was a thread about using balanced TDA1541A in a way so that PSU ripple and noise will cancel. One data line should be inverted and if the negative output is subtracted from the positive, signals add while noise and ripple cancel. Please correct me if I am wrong. Now how to invert the digital signal ? Look at a COB DAC. If just the data line is inverted instead of BPZ we get -1 LSB while +FS becomes -FS and -FS becomes +FS. If after inversion, one is added, BPZ becomes BPZ, but +FS becomes -FS +1 LSB and -FS gets overflow and will be -FS because +FS + 1LSB is not possible . What is better ????

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16th May 2005, 04:14 PM	#2
philbyx diyAudio Member Join Date: Mar 2004 Location: near Paris	Hello, As we say here in France, you are discovering the sugared water All the balanced Dac (with two dacs by channel) are fed by data for one, and /data for the other one. There is effectively 1 bit offset, because of two's complement on the inverted channel, but it doesn't matter. Look at this schematic in the post. http://www.diyaudio.com/forums/showt...767#post554767 It's a ad1865, but the principle is the same Philippe

16th May 2005, 04:30 PM	#3
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	This topic has been flogged to death. see here 'Chibi' phase inverting mod.

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