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Old 2nd November 2014, 09:00 PM   #21
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Quote:
Originally Posted by mcluxun View Post
Do I need 3.3v on other pins: 7, 10 and 11.
Just on the pin 10, pin 9 is the other 3V3 pin, but it is not connected. Note the non-standard pin numbering on the Amanero connector! So pin 10 is the top-left pin (you can see trace on the solder side goes to C1).

Quote:
And for SCJ1 I should short 1 and 2?
Yes... This makes the DSDEN signal control latch-enable on the 595. So when there is no DSD data, output latches are in high-impedance state.
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Old 4th November 2014, 02:20 AM   #22
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mcluxun, sorry for my memory about R1, I never set it to 1K when I check it just now.
The gain was by value=432r of R806, Sounds really great but loudness still not enough.
When I try to chang R1 to 1K from 500r, distortion can be heard.15K/32=468.75r, 8K/32=250r you know. So set the gain on output stage is the right way.
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Old 4th November 2014, 07:45 AM   #23
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I didn't get any notable increase in distortion by setting R1 to 1K. 2nd harmonic in the output is around -80 dB and higher order harmonics at lower levels. Increased level at the intermediate stages increases distortion a little since it is relative to level, but also increases SNR.

Reason why I changed my mind for this is that at 0-point half of the latches are on, thus 15K/16=937.5 and 8K/16=500. So on average, the source is half of the total resistance.

You can of course also change gain by placing suitable resistor at R806/R816 which are there, but marked "NI" (Not Installed) for that reason.
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Old 4th November 2014, 10:11 AM   #24
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Sorry for my word expression. The source impedance is 468.75r on full range and the source current is 10.67mA p-p, mapped to R1 should be 10.67V p-p if R1 is 1K, gain=-2.13. Sounds seems been clipping distortion. Perhaps this is 'a case' on my side.
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Old 5th November 2014, 03:50 AM   #25
mcluxun is offline mcluxun  United States
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To make it easier I ve actually shorted the relay.

Right now I'm still getting very loud noise. Any hint where should I start looking?
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Old 10th November 2014, 10:48 PM   #26
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Quote:
Originally Posted by LeonBernieniv View Post
Sorry for my word expression. The source impedance is 468.75r on full range and the source current is 10.67mA p-p, mapped to R1 should be 10.67V p-p if R1 is 1K, gain=-2.13. Sounds seems been clipping distortion. Perhaps this is 'a case' on my side.
It shouldn't ever have more than about 75% of the elements in same state, otherwise the input signal is illegal...
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Old 10th November 2014, 11:01 PM   #27
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Quote:
Originally Posted by mcluxun View Post
To make it easier I ve actually shorted the relay.

Right now I'm still getting very loud noise. Any hint where should I start looking?
It would be good to verify the wiring if you are not using Amanero input board...

Of course supply voltages for all chips, check that the enable line at shift registers is stable so that the latches stay enabled. Scope or logic analyzer on bit clock and data lines at the shift register end. If you have spectrum analyzer, then checking out the output at resistor network.

This design should be pretty simple to debug even with just plain scope, since there's just one clock and two data lines...
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Old 27th November 2014, 03:41 AM   #28
mcluxun is offline mcluxun  United States
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Quote:
Originally Posted by Signalyst View Post
It would be good to verify the wiring if you are not using Amanero input board...

Of course supply voltages for all chips, check that the enable line at shift registers is stable so that the latches stay enabled. Scope or logic analyzer on bit clock and data lines at the shift register end. If you have spectrum analyzer, then checking out the output at resistor network.

This design should be pretty simple to debug even with just plain scope, since there's just one clock and two data lines...
So embarrassing.... it's a grounding issue.
here's the 1k sine wave
Click the image to open in full size.
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Old 27th November 2014, 06:44 AM   #29
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Good tool! I am very interested to see what will happen after this:
Attached Images
File Type: png Screenshot23.png (299.7 KB, 591 views)
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Old 27th November 2014, 09:13 PM   #30
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Quote:
Originally Posted by LeonBernieniv View Post
Good tool! I am very interested to see what will happen after this:
In this picture there is still missing PSU feed for IC1/IC2 that is normally coming from the Amanero +3.3V output...

I tried to make a clarifying picture:
Click the image to open in full size.

(the DSC1 PSU board has suitable 3.3V output for the purpose)
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