Circuit Analysis of Neve 1073 Preamp (BA 283)

The famous Neve Class A recording series modules such as the 1066, 1073, and 1272 all used a similar gain building block like the BA283.

 This circuit consists of two stages of amplification on a single printed circuit board with an input voltage gain stage and a line driver output stage.

The BA283 are connected with EQ, filters and fader inserted between them in the case of the channel amplifier modules such as the Neve 1073 or directly connected with just a level control or an external fader between the two stages in the case of the Neve 1272.


Note that the Neve L01166 output transformer is an integral part of the second stage of the BA 283 circuit and DC is supplied to the collectors of the 2nd BC 184C transistor and the 2N3055 output transistor through its primary winding. The BA283 input stage would normally have an input transformer such as a Neve 10468 connected directly to it (pin U being the input) in the case of a 1272 or by way of an input sensitivity or gain switch in the case of a 1073. It's interesting to note that many people feel that the sound of the Neve class A modules is in large part due to the transformers themselves ("The sound's in the iron"). By the way, the BA283 operates on a single +24 volt DC supply.

BA 283 Pinout

U : First Stage Input Pin
S : Connect to pin U in series with a 15K to 18K ohm resistor.
T :First Stage Gain Adjust Pin
V : First Stage Ground Pin
P : First Stage Output Pin
N : Fisrt Stage Power Pin
J : Second Stage Ground Pin
A : Connect to B- (power supply common).
K : Second stage gain adjustment pin. Connect in series with an 80uf or larger capacitor to pin J with a resistor from the table below to increase gain
L : Second Stage Input Pin
M : Second Stage Power Pin
B : Connect to L01166 output transformer pin 1
F : Unbalanced output