DSP board on Stage 100 and Acoustasonic are identical except for an amp specific programmable U4.
Stage 100:
TP 26 (input to DSP) is about 50% ampliltude of Acoustasonic TP33.
Noise is present at TP27 (output of DSP)but is about 60% lower than Acoustasonic R53 and looks to be of higher frequency. Signal output looks to be 3 times higher.
Noise mostly gone at TP28 (after first op amp stage).
So it looks like the noise may be inherent to the DSP stage and may be the result of U4 programming. i.e. Not much can be done about it.
So I am thinking about possibly reducing the relative noise level of the entire amp by reducing the gain set for U10-A by increasing R53 and R54. This will reduce the effects overall which might be a good thing. I am not sure if this will change the filter network.
Any thoughts out there? What resistances would be reasonable?
Stage 100:
TP 26 (input to DSP) is about 50% ampliltude of Acoustasonic TP33.
Noise is present at TP27 (output of DSP)but is about 60% lower than Acoustasonic R53 and looks to be of higher frequency. Signal output looks to be 3 times higher.
Noise mostly gone at TP28 (after first op amp stage).
So it looks like the noise may be inherent to the DSP stage and may be the result of U4 programming. i.e. Not much can be done about it.
So I am thinking about possibly reducing the relative noise level of the entire amp by reducing the gain set for U10-A by increasing R53 and R54. This will reduce the effects overall which might be a good thing. I am not sure if this will change the filter network.
Any thoughts out there? What resistances would be reasonable?
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