Do I really need any DC output capacitor between a DAC chip and the low pass filter ?

ygg-it · 4th April 2011, 04:45 PM

A part of the "amplified DC security issue", can I DC couple a PCM1710 DAC directly to the low pass opamps filter?

Can I get rid of all DC coupling capacitors in the CD player (after the DAC) if I know that my amplifier has an DC input CAP?

Are we lowering the distortion in this way?

Thanks

rsdio · 5th April 2011, 01:17 AM

A low pass filter does not remove DC, but a high pass filter would.

You can remove DC coupling capacitors in between your CD player and amplifier, but any circuits in the middle will need to be examined to determine whether the bipolar power supply rails have enough voltage range to support any DC offset that might occur.

oshifis · 6th April 2011, 01:41 PM

If there is an input selector and a volume control between the CD player and the power amplifier, it is better to not letting DC on them - they will create noise.

qusp · 7th April 2011, 12:16 AM

and make certain low leakage caps are used or dc will build up on the input to the opamps until it overrides the rails. yes dc on any pot is bad!! in your description without any output caps, if dc build up in the dac and you connect it to the amp, a dc transient will be unleashed that will probably pass the cap via leakage

4th April 2011, 04:45 PM	#1
ygg-it diyAudio Member Join Date: Feb 2008	Do I really need any DC output capacitor between a DAC chip and the low pass filter ? A part of the "amplified DC security issue", can I DC couple a PCM1710 DAC directly to the low pass opamps filter? Can I get rid of all DC coupling capacitors in the CD player (after the DAC) if I know that my amplifier has an DC input CAP? Are we lowering the distortion in this way? Thanks

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5th April 2011, 01:17 AM	#2
rsdio diyAudio Member Join Date: Feb 2008 Location: Seattle	A low pass filter does not remove DC, but a high pass filter would. You can remove DC coupling capacitors in between your CD player and amplifier, but any circuits in the middle will need to be examined to determine whether the bipolar power supply rails have enough voltage range to support any DC offset that might occur.

6th April 2011, 01:41 PM	#3
oshifis diyAudio Member Join Date: Mar 2004 Location: Budapest, Hungary	If there is an input selector and a volume control between the CD player and the power amplifier, it is better to not letting DC on them - they will create noise.

7th April 2011, 12:16 AM	#4
qusp Sometimes a square peg fits a round hole just fine diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	and make certain low leakage caps are used or dc will build up on the input to the opamps until it overrides the rails. yes dc on any pot is bad!! in your description without any output caps, if dc build up in the dac and you connect it to the amp, a dc transient will be unleashed that will probably pass the cap via leakage

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