Souffle sur le Fader des Aigus

Hi Verne,
Hiss is usually a result of the internal noise of the input transistors
amplified by the total electrical gain and then correspondingly
transduced by the loudspeaker.
It is not usually associated with a lack of shielding which causes
mostly hum and/or a buzing sound.
A malfunctioning circuit externally driven by a powerful radiating
source of electromagnetic energy (like the antenna of a radio
transmitter) can oscillate at a high frequency and produce large
amounts of hiss and possibly other sounds, but this is usualy easy to
identify by moving the circuit to change its proximity with possible
interferences. I assume you're referring to the usual type of white
noise encountered in high gain situations.
No amount of shielding will lower the hiss of a preamp. I suggest using
expanders or noise gates to reduce the apparent noise floor.
It's possible to lower the noise level in the preamp by changing the
IC's.
Those which are of the low-noie type are usually much more power
hungry. For example, the TLE2064's can be changed to TLE2074 for a 10dB noise reduction, however, the batery life will be reduced from 200 hours to about 50 hours. It's a matter of operational priorities.

Best regards,

RMC

Ou alors cet Aop oscille parce qu'il est mal découplé. Vous pouvez toujours essayer de rajouter un condensateur quelconque entre + et - pour voir si ça change quelque chose.