Ok. I know just enough to be dangerous, with that said, what is wrong with my formula. I'm not going to bug Papa Pass again, so educate me please.
ACA Amp with 10k input impedance. Here is email with help from Jom at diy
Hi Jon,
The input impedance will be a little bit more than 10K, but that’s a good figure
for a thumbnail calculation. If you put 4.7 uF in series with the RCA, you should
get pretty close to 80 Hz, however as the cap gets bigger, the frequency goes
down, not up.
Your formula would be 1/RC = 6.3 * F
where R is in ohms, C is in Farads, and F is frequency.
I think it will work fine.
best, np
From: Jon Parkhurst
Sent: Thursday, April 30, 2015 7:14 AM
To: Pass Nelson
I need to create a passive inline rca filter for an ACA.
6V6 suggested there would be an issue if I did that?
There is 68K from input positive to almost ground, and 1K from that node to ground, making about 70K. Start with that as an assumption.
BUT, the 10K and 10uF in series is going to maybe screw up a passive filter in front of it... so at this point I a past my understanding, have to punt and suggest that you should ask Nelson. He usually replies to simple questions in a day or two.
Can I calculate for 10K input and do 5 uF for 80 hz first order
7uF for 110
8.5 for 135 etc.
159155/10000*cap=FReq
Thanks
Jon