Amiga 600 Audio Mods

Some notes taken while trying to improve audio quality and signal levels on an Amiga 600.

Op-Amp replacement

Ref: https://www.amigawiki.org/doku.php?id=en:parts:tl082_tl084

Before:

At the exit of C334:

Vpp 1/R + 2/R 5.64-5.68
Vpp 1/R 3.12-3.16
Vpp 2/R 3.08-3.12

At the exit of C324:

Vpp 0/L + 3/L 5.84-5.88
Vpp 0/L 3.04-3.08
Vpp 3/L 3.24-3.28

After:

At the exit of C334:

Vpp 1/R + 2/R 5.80
Vpp 1/R 3.28
Vpp 2/R 3.32

At the exit of C324:

Vpp 0/L + 3/L 6.06
Vpp 0/L 3.26
Vpp 3/L 3.46

Replacing some the SMD caps and resistors of the audio circuit

At the exit of CN3

   Vpp 1/R + 2/R 1.66-1.68
   Vpp 1/R 1.00-1.02
   Vpp 2/R 1.00-1.02

At the exit of CN4

   Vpp 0/L + 3/L 1.74-1.76
   Vpp 0/L 0.98-1.00
   Vpp 3/L 1.04-1.06

Pro line level

Vrmspro = 1.228V Vrmscons = 0.3162V

Vrms = 1.9V at C334/C324 Vrms = 0.495V at CN3/CN4

Ferrite bead

Vin 4.958V

Vout 4.783V