Aug 23rd, 2015
It seems people are constantly asking about modifying machines by changing out op amps. Most recently on a TNE 7000 Noise Reduction unit which we do modify (see Services section) but not by changing out the op amps for more updated, better paper-rated versions. Ironically, “better” op amps will actually work worse in the circuit due to the need for correct DC offset and time phase, delay required at 4 stage all pass filter. In fact, the incorrect op amp running in the circuit will ruin the FET/switch of the high filter operation. What I am changing is the way and how the circuit can switch out the transients more inaudibly. This is done by installing precise calibratin trimmers and more clever filters at the FET switching. Also, a special circuit which gain rides the possible ticks so as not to fool the click suppression. I spent about 6 months picking the circuit apart to reduce the modification to about 8 parts. The modification is $140 plus the cost to return ship. I have done many of these mods and everyone has been impressed with the results.
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