Hello.

I have been working on an audio switch, using a 4053, and have breadboarded my design so far. One of the problems I am having is that none of the low frequency is passing through the IC.

I have attached a simplified version below. Basically. Line level comes in, and a high pass filter filters out the existing DC. I then add in my VBias, and run it through the switch. On the other side I have another high pass filter on the other side.

What I think my problem is, is that I have a problem with my math. The formula f=1/(2piCR) should calculate the cutoff frequency, which I know I want to keep much lower than 20hz.

I have two theory's of what is wrong.

a) because I have two resistors on each high pass filter, is 1/R=1/R1+1/R2?, or

b) Is it actually 1/R = 1/R1+1/R2+1/R3+1/R4, or

c) Am I completely wrong.

I know the practical answer is just increase the capacitors and resistor values until it sounds good, but I would like to understand my error.