Well, finished the frequency vs impedance plot. Was a lot easier when I went and picked up a 50k pot to use as the variable resistance. The results make sense given the high frequency drop out as by 10khz the input impedance is down to 770ohms which is less than double the output impedance of the CD player. The high frequency drop out starts around 3Khz when the input impedance is 3500ohms.
Not in properly designed transformers.
Your curve indicates about 10nF capacitance in parallel with the input.
No wonder the high frequencies are attenuated.
Your curve indicates about 10nF capacitance in parallel with the input.
No wonder the high frequencies are attenuated.
I suppose it could also indicate that the way I'm measuring the input impedance is wrong.
Does the fact that there's no attenuation(at least until past 10KHz) with a 100ohm output impedance make sense with my measurements?
What I'm doing is outputting a sine wave through the input at a given frequency then setting the output voltage on the pre-amp to 1v via the volume control and then leaving it fixed. Then I add a variable resistance between the source and the pre-amp until the 1v output is cut to 0.500v and then measure the resistance which cut the output signal in half. From what I gathered online that should equal the input impedance at that frequency since that would mean the voltage was being split evenly between the input impedance and resistance I've added to the source.
I do get the same result no matter where the volume control or input voltage is set at so it remains constant independent of those factors which seemed to lend weight to it being the correct reading.
I'd just like to re-iterate my appreciation for your help. Most of this is new to me and I'm trying to learn a lot in a short period of time.
Does the fact that there's no attenuation(at least until past 10KHz) with a 100ohm output impedance make sense with my measurements?
What I'm doing is outputting a sine wave through the input at a given frequency then setting the output voltage on the pre-amp to 1v via the volume control and then leaving it fixed. Then I add a variable resistance between the source and the pre-amp until the 1v output is cut to 0.500v and then measure the resistance which cut the output signal in half. From what I gathered online that should equal the input impedance at that frequency since that would mean the voltage was being split evenly between the input impedance and resistance I've added to the source.
I do get the same result no matter where the volume control or input voltage is set at so it remains constant independent of those factors which seemed to lend weight to it being the correct reading.
I'd just like to re-iterate my appreciation for your help. Most of this is new to me and I'm trying to learn a lot in a short period of time.