[tabacaru]

Hey all,
 
Just had two quick questions about the virtual ground circuit used in the CMOY headphone amp that you seasoned veterans may know how to answer.
 
1. What are the caps used for? Is it to provide more current?
 
2. Why are the values for the resistors/caps chosen to be 220uf/4.7kohm respectively?
 
Thanks for your input!

 

[Avro_Arrow]

Quick answers...
 
1. Yes
 
2. No special reason. (they can be different values within a reasonable range)

 

[Soymilk]

if you want to do some reading, here: http://tangentsoft.net/elec/vgrounds.html goes over all the stuff in detail.

 

[tabacaru]

I have read over that, I just couldn't find any specifics on the actual values of the caps/resistors as well as how the input caps provide more current. (There is only one line that says something along the lines of, "we need caps to provide more current").

 

[Avro_Arrow]

Think of it like this...the resistors represent a tap filling up a bucket.
The bucket stores water until it is needed and the bucket can empty
very fast, much faster than the tap that is filling it. As long as the tap
can refill the bucket between uses it will never run out.
 
The resistors are chosen based on the average draw of the op amp
you are using. Using resistor values too high just wastes power from
your battery. You want the value to be as small as possible and still
have enough power for your op amp. The Capacitor store energy
so the op amp can provide bursts of energy for things like drum
hits and bass notes. Bigger caps provide more energy for a longer
time.
 
That was a pretty non-techinical explanation but I hope it helped...