Hi BillL001
Let me try to explain.
>1. In your previous post you mentioned that the C-48 capacitor (at the edge of the amp board) serves as a time delay for U5 power swith chip,
No. The Solder Jumper add constand +5V st. by supply in the U5 LM324 opamp pin 4 all the time.
C48 do not sit on the U5 main supply supply. C48 is only a side cap in the curcuit for the timedelay shutdown. So the size of this cap have aorund +3.6 volt across it. And is slowly drops over the ~15-20min. You can check who long time it takes before is shutdown the +/-62Volt Supplys for the amp part.
>this made me wonder the following: what if we use a higher rated cap for this capacitor, from 100uF and 20V, changing it to 500uF or 10uF, and maybe 50V, so that when the power to the capacity was cut off by other part of the circuit, there is still enough power left in the capacitor to power the U5 chip, would that prolong the power to the chip so that its power will not get cut off? If this can keep the chip powered, we maybe able to take off that jumper, and just let this capacitor keep the sub going when it plays low frequencies or playing high volumes, and will not be shut off. Do you think this could be a fix for the power dopping problem? In other words, since capacitors can provide a delay in power being switched off, would increase its power saving rating be able to keep the power on long enough?
The value in voltage don't change anything. There will never be above +5volt on the C48 caps.
Changing the uF will only change the delay time. If you ad a 10uF its only takes 1/10 of the time before if shutsdown and if you do it 500uf it takes 5 times longer than org. 5x 15-20min before the sub close down.
But if you take a volt meter and messure on C48 you will see then you add a signal to the sub it's rise in voltage, but as soon there are no signal detected the voltage drops right away to 3.6volt and will keep falling, untill a signal is again added to the signal input. Then the cap is again at full voltage, and discharge down from there when no signal added to the sub.
Hope i don't confused you with this description.
2. I noticed that sometimes when I just power on the sub, the sub produces some continuous knocking or ticking sound from its cone - see below video:
Ihave not seen this on my sub's. I can see on the video the cone to jumping. Could be a DC on the speaker. But i would expect its a cap problem, making the DC jump in the circuit. Don't know if you have a osc. scope, but then i would try to follow the signal way to find there the noise comes from. You can't see it with a norm. volt meter. i Osc. scope is needed to error search. But try with the caps in the EQ section first or replace all caps if you dont have access to a osc. scope.
Good error Search 🙂