Opening the new DacMagic???? - Page 47

ClefChef · 3rd July 2012, 10:34 PM

Well, the transformer sums up signals from both opamps, + and - signals. The immediate improvement in the sound is in the bass level and articulation - no more muddiness.

aptsys · 4th July 2012, 05:47 PM

Quote:

Originally Posted by ClefChef

Removed C17 and C18 from digital inputs 1 and 2 (we absolutely don't need capacitance there)
removed C269 and C264, those are HF filtering caps - snip snip.

Why did you deem it necessary to remove these? Have you thought about what function they perform?

No offense, but it looks more like you've selected a few components randomly which won't stop it working for no reason.

ClefChef · 4th July 2012, 06:16 PM

Quote:

Originally Posted by aptsys

Why did you deem it necessary to remove these? Have you thought about what function they perform?

No offense, but it looks more like you've selected a few components randomly which won't stop it working for no reason.

No offence taken...I know exactly what function those caps perform, they should not be there.

Those caps on digital inputs were probably put to filter out HF noise. Problem is that they also add to cable capacitance that would cause an "overshoot" of square digital signal.
Those caps on analog outputs were put to filter out HF noise as well, that is already done by signal processing components up the signal chain.

ClefChef · 4th July 2012, 07:09 PM

...my mistake, caps on digital inputs add to cable capacitance and cause signal not to "overshoot" but to become "saw-tooth".

stormsonic · 4th July 2012, 09:05 PM

Quote:

Originally Posted by aptsys

Why did you deem it necessary to remove these? Have you thought about what function they perform?

Take a look at the picture. They are screwing up the signal.

aptsys · 09:12 AM

Quote:

Originally Posted by stormsonic

Take a look at the picture. They are screwing up the signal.

Interesting - is that the digital input? Do you have the before and afters? They shouldn't really be affecting the signal like that as the -3dB point is way above any SPDIF frequency, and more intended for radio and mobile phone interference suppression.

stormsonic · 5th July 2012, 10:57 AM

yes, digital input with 100pF cap to ground. And bellow is picture with 100pF cap removed.
Stop thinking in "audio analog signal", flip switch to "RF signal integrity mode"

aptsys · 5th July 2012, 11:55 AM

Where did you have the scope probe? At the input to the mux, and was the mux set to that input?

marce · 5th July 2012, 12:12 PM

Digital signal integrity

stormsonic · 5th July 2012, 05:24 PM

yes, it should be: Digital signal integrity.
But there is clock embedded into signal and must be extrapolated, therefore I intentionally wrote down "RF signal integrity"

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3rd July 2012, 10:34 PM	#461
ClefChef diyAudio Member Join Date: Sep 2011	Well, the transformer sums up signals from both opamps, + and - signals. The immediate improvement in the sound is in the bass level and articulation - no more muddiness.

4th July 2012, 07:09 PM	#464
ClefChef diyAudio Member Join Date: Sep 2011	...my mistake, caps on digital inputs add to cable capacitance and cause signal not to "overshoot" but to become "saw-tooth".

5th July 2012, 11:55 AM	#468
aptsys diyAudio Member Join Date: Jan 2010	Where did you have the scope probe? At the input to the mux, and was the mux set to that input?

5th July 2012, 12:12 PM	#469
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	Digital signal integrity

5th July 2012, 05:24 PM	#470
stormsonic diyAudio Member Join Date: Aug 2008	yes, it should be: Digital signal integrity. But there is clock embedded into signal and must be extrapolated, therefore I intentionally wrote down "RF signal integrity"