Have a few newer SP1 microphones I a going to install prototype circuits in. Before taking them apart I tried one.
The JFET is a XG https://groupdiy.com/index.php?topic=67291.msg854256#msg854256 like in the 890.
One I measured had a 0.2mV difference between emitters.
Capsule voltage is 50VDC measured with a 10meg input R meter at the cap at the second diode DC to DC section.
Do not know what series SMD ceramic caps are being used.
The JFET is a XG https://groupdiy.com/index.php?topic=67291.msg854256#msg854256 like in the 890.
One I measured had a 0.2mV difference between emitters.
Capsule voltage is 50VDC measured with a 10meg input R meter at the cap at the second diode DC to DC section.
Do not know what series SMD ceramic caps are being used.
