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Chip Amps Amplifiers based on integrated circuits

My_Ref Fremen Edition - Build thread and tutorial
My_Ref Fremen Edition - Build thread and tutorial
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Old 10th December 2018, 11:55 AM   #4071
Joseph K is offline Joseph K  Hungary
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I'm afraid there could be a misunderstanding here..
As far as I remember Dario always told: connect PGND to the case.

Now, seriously: even without loop braker - you could do a test. Just connect PGND with and then without PE connection. Without is only a temporary, transitorial test, not stable solution.

Ciao, George
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Old 10th December 2018, 12:48 PM   #4072
Luca72c is offline Luca72c
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That's true, and ground lift is suggested by Dario himself too, in the build tutorial you can find in the project google drive repository

Last edited by Luca72c; 10th December 2018 at 12:51 PM.
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Old 10th December 2018, 04:33 PM   #4073
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition - Build thread and tutorial
Quote:
Originally Posted by wilco87 View Post
Problem is there's a lot of hum from both channels in the integrated one, probably a ground loop I cant find.
(...)
Is the mass from cinch to IN (myref gnd) and from volume to IN (on myref gnd) correct? Took that connection from the audiocreative integrated chipamp. DIY LM3886 Chipamp

See attached photos for drawing of the spaghetti mix of red wires. Still need to clean that up...

You have two ground paths, I would remove the ground wire that goes from My_Ref boards input GND to the ground bus on RCA inputs.


Also shielding (the missing of) and not twisted wires coudl have a (big) role.


Quote:
Originally Posted by wilco87 View Post
Removed all the wires, selector and volume: Just the boards and output. Stil humming. I will remove the boards from the case and report back.

Wait! Did you short boards inputs during this test?


Unless connected to signal ground via a source or a preamp the amp will hum, it is absolutely normal.


The amp should be silent when connected to a source/preamp or with shorted inputs.


If with shorted inputs the amp is not silent you can:
  • double check heatsink grounding
  • rotate transformers until hum disappear
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Last edited by ClaveFremen; 10th December 2018 at 04:47 PM.
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Old 10th December 2018, 07:50 PM   #4074
Luca72c is offline Luca72c
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Quote:
Originally Posted by ClaveFremen View Post
You have two ground paths, I would remove the ground wire that goes from My_Ref boards input GND to the ground bus on RCA inputs.

?
Then were would Myref boards (and pot) connect to input GNDs?
Maybe i didn't understand well what you wrote...
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Old Today, 05:58 AM   #4075
freegianmaria is offline freegianmaria  Italy
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Ok, little confusion to me.
Only 3 question:
1) PGND must be connected to the ground or not?
2) The heatsink must be isolated from the ground or not?
3)The - of signal audio must is connected to the ground?
Thank you very much to anyone reply me.
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