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Posted
53 minutes ago, Pars said:

It looks like the NC pins of the relay on the board are floating. I wonder if tying these to ground would take care of it?

If that were the case though, I'd get thump on headphones too, no? No thump with headphones or speakers, just the sub. Common denominator is the sub out is only thing that has a reference to PS Gnd.

Voltage divider for the sub out is: +out > 10k > 1k to PS Gnd. Sub out taken from junction of 10k and 1k. 

Posted

Can anyone help me? Some resistors in the schematic are 600R and 680R, while the 1.22 Gerber file is 300R and 600R. Some resistors are 4.2K and 50K, while the schematic is 1.9K and 25K. Which is the correct resistor value, and where can I find the latest CFA3 schematics? If I only keep SS, do I not need to populate the 4.2K and 600PF CAPs? Thanks

Posted

600 or 680 can be used. 680 will be slightly higher front end gain

300 is correct

4.2k is just higher gain than 1.9k

I don't remember what the 50k and 25k are -- SS feedback resistors? if so also just higher vs lower gain

If only using SS, it's possible you can eliminate the 4.2k, as long as there is still another resistor in parallel with it. what you would do is measure the gain with and without the SS feedback resistors, and choose values so you have ~6dB less gain with the SS feedback resistors installed

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