All mixers are repaired with original semiconductors. No ecg or nte generic replacements are used. We believe that the generics are close, but do not fall within the specified range of operation designed by the project engineers. We do offer low noise N5332 operational amplifier replacements that exceed most N4558 original designs for an additional cost. Serviceable controls and faders are treated with maintenance solutions and all questionable connections are re-soldered. Powered mixers go through additional procedures outlined in solid state amplifiers.Contact us today to get started!