Hi Ti,
According to AIC3268 datasheet, the max input level is 0.5Vrms per input. For differential input, it is up to 1Vrms.
If I want to handle the differential signal with +4dBu level (professional line level, comes from audio mixer, microphone preamp...etc).
+4dBu is about 1.228Vrms so the divider network is necessary!
I am new to audio hardware circuit design. Please help me check:
(1) Use the divider network to half the differential input voltage, enlarge the maximum voltage to 2Vrms.
In Figure 111. Analog Input Connection With Resistor Divider Network of datasheet, R1 || R2 << Req
Could you suggest me the resistor value R1, R2 of the divider?
(2) Is it any risk for divider to handle +4dBu signal for long time? The audio quality is OK?
(3) BTW, use the 1 Vrms as our differential input maximum voltage and limit audio source output(use audio mixer gain control to lower audio etc.) or use the divider up to 2Vrms. which is better?
I think lower the audio source gain may decrease the SNR in audio mixer and cause the bad quality. Could you give some suggestions?
Thank you!
BR,
Steven