1. Improve The HF Response in 1066/1073 or equivalent Channel Amps

Here is a little experiment that you can experiment on your early Neve Channel Amplifiers to improve the high frequency response when the EQ is selected. Although in EQ "out" the modules are flat within 0.5dB from 20Hz to 20Khz, if the EQ is selected the high frequency response will drop down to around –4dB at 20KHz! The reason for this is that the two inverting EQ stages on the BA184/284 printed circuit board have roll off capacitors scattered liberally around the first transistors (presumably around the time that the modules were first destined to work in close proximity to broadcast transmitters). The result, quite frankly, is a roll off that is a little too steep! The value of the 47pF collector/base capacitor should either be reduced to around 10pF. . . or even removed altogether. The result of this simple mod is a response, EQ "in", that is flat well beyond 20KHz.

Also, look at the small polystyrene capacitors linking pin C to E and K to M. These should be 470pF and 180pF but I have found modules with larger values. These also roll off the high frequency and should not be larger than these values.

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