Do you have a working one that you can measure?
No, I only have a picture of the board.
Based on the picture I have, I was able to identify two capacitors. One is marked A3 (1nF), the other A2(100pF).
The one with A2 is used in the output LPF of the sound IC. The other A3 in the input LPF as C5 in the above circuit.
If I interpret the capacitor values only on their optical appearance, the resulting cut-off frequency is 21685Hz.
I was looking around the internet and found a service manual from Sony. They used the same IC for Dolby Surround.
The cut-off frequency of the Sony circuit is something about 9773Hz.