The Beast of Infinity Damping Factor 
Just measured my speaker cables using 4 wire Keithley Bench Meter.
Resistance is between 5mOhms and 10mOhms.
Adjusted Amp output impedance to get Negative 5 mOhms for near infinite damping.
Hahaha
I will do distortion measurements on Monday and tweak it the way I want.
I have a very small amount of overshoot on square wave but no ringing, I will fix this tonight most likely.
Simulated results are a little off from reality with regards to circuit gain, this is most likely because Id of Jfets is actually higher than the jfets used in simulation resulting in less voltage gain from the first stage.
Just measured my speaker cables using 4 wire Keithley Bench Meter.
Resistance is between 5mOhms and 10mOhms.
Adjusted Amp output impedance to get Negative 5 mOhms for near infinite damping.
Hahaha
I will do distortion measurements on Monday and tweak it the way I want.
I have a very small amount of overshoot on square wave but no ringing, I will fix this tonight most likely.
Simulated results are a little off from reality with regards to circuit gain, this is most likely because Id of Jfets is actually higher than the jfets used in simulation resulting in less voltage gain from the first stage.
square is sissy
I can speed it back up.
I will see where I can get it too before it starts over shooting.
I'm enjoying the idea of the very keen audio folk measuring their speaker cables in prep for the ultimate F7 build.
Contact Resistance
Today I was reminded how much I hate non-soldered electrical joints.
I have a Fluke 289 multimeter (not cheap), I have been noticing the resistance measurement slowly creeping up (over a couple of years) when taking a zero measurement, it had creeped up to over 2 Ohms.
Visually the leads looked fine, and the probes looked shiny new.
I honestly thought the meter had gone out of calibration or was faulty.
Anyway today I decided to clean the probes with p800 SiC paper and IPA after cleaning the contact surfaces, the zero measurement went from 2.3 Ohms to 0.11 Ohms.
Oxides and crap build up on surfaces and many oxides are not even visable to the eye. This is another example of why non-soldered joints are not good for my mental health. Hahahaha
I would have assumed Fluke to use something better for the price they charge eg gold plated.
Today I was reminded how much I hate non-soldered electrical joints.
I have a Fluke 289 multimeter (not cheap), I have been noticing the resistance measurement slowly creeping up (over a couple of years) when taking a zero measurement, it had creeped up to over 2 Ohms.
Visually the leads looked fine, and the probes looked shiny new.
I honestly thought the meter had gone out of calibration or was faulty.
Anyway today I decided to clean the probes with p800 SiC paper and IPA after cleaning the contact surfaces, the zero measurement went from 2.3 Ohms to 0.11 Ohms.
Oxides and crap build up on surfaces and many oxides are not even visable to the eye. This is another example of why non-soldered joints are not good for my mental health. Hahahaha
I would have assumed Fluke to use something better for the price they charge eg gold plated.
Very first measurement at the original setting of 5/15 Ohms.
Distortion is 0.17%, around SIT3 levels.
2nd harmonic is -46dB and Third harmonic is -61dB, and virtually nothing else.
Hope to get it to around 0.07 to 0.1%, but maybe I will actually prefer it higher.
I will try some other jfet source resistance settings.
I have throne away 6dB in negative feedback to get the damping factor where I want it so that probably explains the higher values of distortion.
Distortion is 0.17%, around SIT3 levels.
2nd harmonic is -46dB and Third harmonic is -61dB, and virtually nothing else.
Hope to get it to around 0.07 to 0.1%, but maybe I will actually prefer it higher.
I will try some other jfet source resistance settings.
I have throne away 6dB in negative feedback to get the damping factor where I want it so that probably explains the higher values of distortion.
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