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Old 10 December 2021, 23:29   #14
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Join Date: Jun 2010
Location: PL
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Originally Posted by ugrnm View Post
But that should be fine for pro line level, no? Vpp of pro line level is <3.5V.
Issue is not in level but in inability to isolate analog circuitry from digital part as they share same power line - unless Paula has embedded some fancy circuitry to provide true reference current/voltage to DAC's then you will have lot of unwanted sounds from digital circuitry on analog signal out lines.

Originally Posted by ugrnm View Post
Hmmm, starting with R309, which ferrite bead value would you recommend then?
Something like

Highest possible impedance, maximum DC resistance bellow 1 Ohm, not sure about accurate Paula power consumption but i think ferrite bead should allow current not less than 500mA, ferrite bead tailored for rather low/standard frequencies...
Anyway even randomly selected ferrite bead will be probably better than resistor (strange that Amiga guys didn't selected ferrite bead instead 1 Ohm resistors - this can be explained by relatively new idea of ferrite bead and perhaps underestimation for signal quality expectations) - there is famous application note from linear technology (now owned by analog devices) - last page says everything important about ferrite beads - "megahurts to minihurts converter" this very good description for this small component capabilities.

Also avoid MLCC capacitors as most of them is piezoelectric and may produce audible interference's.
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