Tony L
Administrator
Just for clarity if anyone is playing along at home: when I said I had the pots set by ear to 29-30 Ohm (this value measured with the pots out of circuit when I was swapping them over) this is between the wiper (VR1) and the pin that connects to the 4R7 resistor.
PS I accept acoustic measurement in a perfectly controlled condition is of great value, it is just far harder to do in reality as moving the mic just a cm in any direction or getting the speaker a degree or two difference in axis (getting a round JR149 perfectly square on the stand) often impacts the plot more that the thing one is trying to measure! Ears seem far more useful unless one has an anechoic chamber to hand! In my close near-field listening setup leaving the mic in position between changes would just impede the listening space too much, it would inevitably get knocked out of position. I’ll do a measurement right at the end of this process once I’m happy.