The simple signal path:
mic - pleiades transformer - pleiades preamp (1 stage)
sounds great but there is no peak control at all so when it is connected to a DAC things get tough.
mic - pleiades transformer - pleiades pre (1 stage) - pleiades 1 stage) sounds much better with tubes (a 12AU7 double triode 12V battery powered or 2 k117 pleiades jFET stages.They produce .euphoric distortion, 3nd harmonic, gentle peak limiting etc.
Cascading a third stage the distortion becomes apparent.
So in the 2nd K117 stage the 47uf source bypass capacitor was replaced with 68nf (to treble boost) and the drain resistor of the 3rd stage was shunt with 68nf to high cut. It sounded nice and strong and looking at the oscilloscope on could clearly see while hearing nasty harmonics disappear ( waveform rounded by adding the shunt capacitor!
Next step is to do the same by clipping a magnetic material (eg a pleiades transformer simulating the saturation in a tape recorder). Since the pleiades filter operates on constant current like a tape head all frequencies could be peak limited.
mic - pleiades transformer - pleiades preamp (1 stage)
sounds great but there is no peak control at all so when it is connected to a DAC things get tough.
mic - pleiades transformer - pleiades pre (1 stage) - pleiades 1 stage) sounds much better with tubes (a 12AU7 double triode 12V battery powered or 2 k117 pleiades jFET stages.They produce .euphoric distortion, 3nd harmonic, gentle peak limiting etc.
Cascading a third stage the distortion becomes apparent.
So in the 2nd K117 stage the 47uf source bypass capacitor was replaced with 68nf (to treble boost) and the drain resistor of the 3rd stage was shunt with 68nf to high cut. It sounded nice and strong and looking at the oscilloscope on could clearly see while hearing nasty harmonics disappear ( waveform rounded by adding the shunt capacitor!
Next step is to do the same by clipping a magnetic material (eg a pleiades transformer simulating the saturation in a tape recorder). Since the pleiades filter operates on constant current like a tape head all frequencies could be peak limited.
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