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-   -   what happens if DC blocking capacitors is removed (http://www.diyaudio.com/forums/chip-amps/223039-what-happens-if-dc-blocking-capacitors-removed.html)

rhythmsandy 7th November 2012 06:01 AM

what happens if DC blocking capacitors is removed
 
what happens if we take out the dc blocking capacitor since i really dont want to spend on the Mundorf but would like to take off the input cap but what happens if we remove it the dc enters into the amp and blows up?

palstanturhin 7th November 2012 06:08 AM

You can leave it if you are sure there is no DC present at the output...

sofaspud 7th November 2012 06:29 AM

The input cap is part of a high-pass filter. Removing it extends the input response to DC. The DC will enter the amp and be amplified.

AndrewT 7th November 2012 11:49 AM

Yes, the DC gets through to the load.

And the non blocking of DC at the input opens up the input to errors that affect the input offset current and input offset voltage of the amplifier, i.e. the amp will not work as intended by the designer.

If you don't know this then you should not be considering this modification.
You are behaving like a foolish child, who has no appreciation of danger and takes risks because they have no previous experience to fall back on. The not so foolish child listens to their parents.

rhythmsandy 7th November 2012 02:39 PM

I agree Andrew thank you for the input as i didnt knew thought to take out the capacitor and see how it behaves but eventually it needs experience which i dont have now if somebody asks me the same question i have the answer thank you...

Conrad Hoffman 7th November 2012 04:39 PM

“Good judgement is the result of experience and experience the result of bad judgement.” Twain

The learning process can be painful to experienced onlookers, as in electronics it often results in damaged and destroyed components. Still, if I had never messed anything up, I wouldn't know what I know today.

Fast Eddie D 7th November 2012 04:51 PM

Quote:

Originally Posted by AndrewT (Post 3231961)
Yes, the DC gets through to the load.

And the non blocking of DC at the input opens up the input to errors that affect the input offset current and input offset voltage of the amplifier, i.e. the amp will not work as intended by the designer.

If you don't know this then you should not be considering this modification.
You are behaving like a foolish child, who has no appreciation of danger and takes risks because they have no previous experience to fall back on. The not so foolish child listens to their parents.

Yes Andrew, I am of the school of thought that extending response to DC is quite foolish, and I do not understand the panacea surrounding it.

I think it is equally foolish to elimate the capacitor from the feedback network. Doing so will cause DC offset with "real world" signals (not test signals).

Oh those evil capacitors. I cannot stress enough that a properly designed circuit will not exhibit degraded performance with the inclusion of these two capacitors.

sreten 7th November 2012 05:19 PM

Hi,

You can leave out the input capacitor as long as you
are sure the output driving it has a coupling capacitor.

(The same applies in reverse for omitting output caps.)

rgds, sreten.

Mihkus 7th November 2012 06:03 PM

What? you will have very loud mains noise in ur woovhers.

lehmanhill 7th November 2012 06:21 PM

I agree that working without a DC blocking cap is not advised.

The other thing, you didn't say which amp design you are working with. If it is one of the MyRef series, then the collected wisdom is that removing the cap also hurts bass response due to an interaction with the 318 opamp. Other designs, the interaction won't be a problem.

If you don't want to spring for the Mundorf in question, then look around for other, less expensive alternatives. Try one of the cheap Russian caps. Depending on the value needed, you could try a Sprague Orange Drop or any number of metalized polypro caps.


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