effects from coupling capacitors in audio circuits

[perazaroberto2]

It is the most intelligent explanation I've seen in my life, rustic, but very intelligent teaching. thank you very much!.

[vibra64]

Great video. Can you tell me what is that white looking gel on your breadboard?

[radiofun232]

@vibra64 It is transparent silicon kit, used to fix the capacitors to the borad. It has good properties for isolating electronic circuits.

[teflondon91]

What happens when you use really big caps in the like 10,000uf? I have seen in some HIFI amps they use multiple caps of different values on the output of a tube stage... here is an example of what I am speaking about: tubecad.com/2009/10/11/srpp+%2­0mosfet.png

[radiofun232]

There is a difference between the output and the input of an amplifier. On the output (non electrostatic amp.) a current has to drive a low impedance load, let us say a 4-32 Ohm coil. This means a "heavy" current, this can only be supplied via a high value capacitor (1000 uF-10000 uF), capacitive reactance. On the input all audio frequencies are delivered to a 3-4K (bipolar transistor amp input) or 500K-1M (triode tube amp input) stage. The coupl. cap. can be less if so.

[teflondon91]

@radiofun232 Did you see the 3 caps in parallel on the ouput what method is used here?

[radiofun232]

@teflondon91 cannot find the link to a mosfet circuit on this website.

[teflondon91]

Hello Mr. Tillman, I wanted someone to do this! I found a very interesting paper you might want to check out also: tech.juaneda.com/en/articles/e­lectrolyticcapacitors.html

[teflondon91]

@teflondon91 he kept the same value but just varied the capacitor type and material.

[radiofun232]

@teflondon91 Thanks, I am gonna search and read it.

[radiofun232]

@teflondon91 As far as I could see these capacitors are used as power supply capacitors, connected to the bridge rectifier. They are used to keep the hum level low without using a stabilizing circuit with a transistor.

[radiofun232]

@teflondon91 I saw today it was a test for supply capacitors, that is why he used the resistor. So far so good.