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Measuring impedance of headphone jack of a receiver

post #1 of 4
Thread Starter 

I have vintage receiver and I get hissing with low impedance phones.  I really want to measure the impedance so that I can determine how much attenuation I need.  Is there any clever method to do that?  Can I make something to adjust the headphone jack impedance?  In order to lower the output impedance I can put a smaller impedance attenuator in parallel right?  That would most likely get rid of the hissing?


Edited by High_Q - 5/27/10 at 12:41pm
post #2 of 4

the attenuator is on the input of the circuit generally, not the output. you could add a buffer to the output and this would lower the output impedance

post #3 of 4
Thread Starter 

Quote:

Originally Posted by qusp View Post

the attenuator is on the input of the circuit generally, not the output. you could add a buffer to the output and this would lower the output impedance

What I want is something at the output to have the headphones to appear to have more impedance(an attenuator, which are just resistors). I also don't want to modify the receiver's internals, and looking for a easier solution than adding buffers.  Forget the comment about the resistors in parallel because that would just increase the signal power to the headphones, which I do not want for headphones that have high sensitivity that is outputting hissing.  What I think I really need is resistor in series to plug into the output of the receiver, but I want to get a general Idea of the output impedance.  How would you measure that?  Is it difficult because its an active component?


Edited by High_Q - 5/27/10 at 10:23pm
post #4 of 4

How to measure output impedance http://electra-print.com/techblog.php?blogid=1

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