D 104 microphone elements

[John W. King]

I have several D 104 microphones and some sound better than others. One
of them once utilized a pre-amp that someone took out of the circuit by
by-passing it. It sounds very poor and has very low output. My question
is whether anyone has any reliable information whether ALL Astatic D104
microphone elements are the same or whether those microphones with
pre-amps get a different element...thus the poor audio quality and low
output when the pre-amp is disabled. If you have extensive experience
with D 104 microphones, I will appreciate information and proven
suggestions for better sound from the microphones for use with solid
state and tube rigs. Thanks and 73, John, K5PGW