[roymail]

I have an old SS amp that I'd like to know the input impedance but have no manual, and can't find any info online.  The only thing I have is a volt/ohm meter.  Is there some way I can measure the impedance?

Appreciate any advice... thanks! 

[jtwrace]

What's the model and brand?  We may be able to help.   

[Speedskater]

If you put:
"Measuring Input and Output Impedance" into a search engine, you will come up with pages like the one below:
www.sengpielaudio.com/calculator-InputOutputImpedance.htm

Basically what you do is input a test tone through a variable resistor while measuring the output voltage. When the output voltage is reduced to 1/2 of the no resistor value, the adjusted resistors value is equal to the input resistance.

[Steve]

If you put:
"Measuring Input and Output Impedance" into a search engine, you will come up with pages like the one below:
www.sengpielaudio.com/calculator-InputOutputImpedance.htm

Basically what you do is input a test tone through a variable resistor while measuring the output voltage. When the output voltage is reduced to 1/2 of the no resistor value, the adjusted resistors value is equal to the input resistance.

Nice post speedskater.

If one has a scope may I also add changing the frequency of the test tone, esp to high frequencies. The input capacitance of the active device may affect the input Z to some degree. Would be interesting to compare input Z of different brands/models.

Hope this helps.

[roymail]

Never mind... that's way more than I bargained for.  Since I don't have a pay grade, it's more than that, too!   

Thanks anyway!   

[timind]

Never mind... that's way more than I bargained for.  Since I don't have a pay grade, it's more than that, too!   

Thanks anyway!   

Still, someone may have a spec sheet if you post the model.

[Steve]

Never mind... that's way more than I bargained for.  Since I don't have a pay grade, it's more than that, too!   

Thanks anyway!   

I understand. Maybe check more for spec sheet. 

For others more technically minded, one could just use 60 or 120hz input and measure as Speedskater mentions. I believe Radio shack has some high resistance pots.

Cheers.