Question about DC offset from source.

theAnonymous1 · 12th November 2006, 12:02 PM

I have an Entech 203.2 DAC that uses an OPA2134PA for its output.(this isn't a question about anything digital)

This DAC has no DC on its output until a low frequency signal is passed through it. Starting at around 40hz or so some 20-40mv of offset starts to show up. I have the DAC DC coupled to my amp and at lower frequencies and high enough volume my amp will go into protection.

I have little experience with opamps or even electronics in general, so I need some help trying to figure out what would cause this.

Thanks.

AndrewT · 12th November 2006, 07:07 PM

Hi,
it is not a power amp problem.
It does not appear to be an opamp problem.

That only leaves a digital problem.

I assume you do not want to fit DC blocking caps around the opamp and before the power amp.

If you avoid the LF content, does the DC output offset stay stable and low?

theAnonymous1 · 12th November 2006, 08:07 PM

Hi Andrew, thanks for the response.

I would like to avoid DC blocking caps as I am really enjoying the sound without them.

With any other frequency above 40-50hz the measured DC is very low, around 1mV.

I've tried two different digital sources going through the DAC and they both produce the same results.

12th November 2006, 12:02 PM	#1
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	Question about DC offset from source. I have an Entech 203.2 DAC that uses an OPA2134PA for its output.(this isn't a question about anything digital) This DAC has no DC on its output until a low frequency signal is passed through it. Starting at around 40hz or so some 20-40mv of offset starts to show up. I have the DAC DC coupled to my amp and at lower frequencies and high enough volume my amp will go into protection. I have little experience with opamps or even electronics in general, so I need some help trying to figure out what would cause this. Thanks.

12th November 2006, 07:07 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, it is not a power amp problem. It does not appear to be an opamp problem. That only leaves a digital problem. I assume you do not want to fit DC blocking caps around the opamp and before the power amp. If you avoid the LF content, does the DC output offset stay stable and low? __________________ regards Andrew T.

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12th November 2006, 08:07 PM	#3
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	Hi Andrew, thanks for the response. I would like to avoid DC blocking caps as I am really enjoying the sound without them. With any other frequency above 40-50hz the measured DC is very low, around 1mV. I've tried two different digital sources going through the DAC and they both produce the same results.

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