ProtoDAC TDA1387 X8 project

[v12nut]

The cap value can be 4.7 to 10uF for 10kOhm impedence, typical for solid state line stage. Tube stages can have impedence of 50k-100k. This affects the calculation.

High pass filter calculator

10K impedence and 10uF gives a corner frequency of 1.5915Hz. You want any phase shifts from the filter to be far away from the audio band. With 20Hz, that is usually 10Hz as a rule of thumb with audiophile designs. 6.8uF is 2.3405 Hz. 4.7uF is 3.386Hz. Well within that limit.

For 50K impendence for a tube preamp, 1uF gives a corner frequency of 3.183Hz. 100k is 1.5915Hz with 1uF.

Thank you, useful info.