value capacitors deviate

[widea]

Hi,



What should be 470nF input capacitors of my headphone amp seem to be 461nF for one channel and 492nF for the other channel. That is a deviation of 1,9% and 4.6%.


I measured the values of the capacitors already soldered on the board but without active components.



Are these errors to be expected because I measured them in the circuit?


And, would this be audible?


Or are these value errors a property of capacitors in general?



Regards,


Cor

 

[Mooly]

While measuring in circuit could generate errors, the variation you are seeing is well within normal tolerances which typically could be 10% or even 20% of the marked value.

There should be no audible difference caused by this.

 

[widea]

Thanks!

 

[coolnose]

If you have more than 2 of the beforementionned capacitors you could have measured / matched them before soldering them in, otherwise I agree on the tolerences quoted by Mooly. If yiu can hear it, you're in trouble

 

[widea]

If you have more than 2 of the beforementionned capacitors you could have measured / matched them before soldering them in, otherwise I agree on the tolerences quoted by Mooly. If yiu can hear it, you're in trouble

Haha you're probably right.
At first I was afraid I overheated one of the capacitors while soldering it in. It did not go as fast as I would like.
So I thought maybe the value could change because of the prolonged high temperature. And therefor I measured them while in circuit.

 

[kodabmx]

Most caps will have the tolerance marked on the body. If it's not marked it's usually 20%.