Amiga 1200 Rev 1A Distorted Audio Output - Part 4 (Final)

This is the final instalment of my quest to get nice sounding audio out of an Amiga A1200 Rev 1A.

Here is the same mod file captured at 0dB with the following modifications:

R331 changed to 680R
R321 changed to 680R
C331 changed to 6800pF
C321 changed to 6800pF
R335 changed to 360R
R325 changed to 360R
R345 changed to 680R

(R335 and R325 are on the bottom side of the board)

These modifications are the same as Commodore implemented between the Rev 1 and Rev 2 boards according to the schematics I have.

For comparison with previous posts, here's the 1kHz sound test with the LED filter disabled (jaggies) and enabled (smooth)...

The audio output sounds about perfect to me and I'm more than satisfied with the result.  It does appear the changes Commodore specified for the Rev 2 board onwards were well engineered.

The output level is still a little higher than the A600 (Rev 1.5 board) and could perhaps be lowered just slightly (say changing R331 and R321 to ~600R).  Also, with the optional (LED) filter switched off there's noticeably more aliasing present than on the A600.  However, I think these slight differences give the A1200 its own characteristic sound verses the other models and I rather like it.

In theory this machine should sound the same as a stock Rev 2 board but I don't have one to compare with.

That's the end of this mod.  Thanks for reading!