Hi All,
Thought I'd pipe in here with some perspective. The LDR3000T is indeed NOT a passive preamp although it does employ our V25 LDR preamp controller/attenuator which is the heart of our current line of passive preamps. Downstream there's a zero-low gain active linestage with a tube input/gain (voltage amplifier) stage followed by a discrete solid state JFET buffer (current amplifier) output stage. We run the tube deliberately zero to low (+6 dB) gain running at a slack plate voltage of only 42 volts. The input stage is direct coupled (no cap) but the output stage does employ a DC blocking output coupling cap. By keeping the plate voltage low we can use the same voltage to run the class A buffer output stage. Some or all of the above tends to illicit cries of heresy and blasphemer from certain orthodox tubies. The active linestage is a second generation derivative of a similar circuit used for the past 2 years in our TBP.V1 Tube Preamp Buffer which has been very well received by our customers. heresy notwithstanding. I make no claims about this design being purely original first-of-kind work but the devil is truly in the details. The overall synergy produces a remarkably pleasing sound that I personally find very enjoyable and satisfying. We think other folks will as well.
Cheers,
Morten
Thought I'd pipe in here with some perspective. The LDR3000T is indeed NOT a passive preamp although it does employ our V25 LDR preamp controller/attenuator which is the heart of our current line of passive preamps. Downstream there's a zero-low gain active linestage with a tube input/gain (voltage amplifier) stage followed by a discrete solid state JFET buffer (current amplifier) output stage. We run the tube deliberately zero to low (+6 dB) gain running at a slack plate voltage of only 42 volts. The input stage is direct coupled (no cap) but the output stage does employ a DC blocking output coupling cap. By keeping the plate voltage low we can use the same voltage to run the class A buffer output stage. Some or all of the above tends to illicit cries of heresy and blasphemer from certain orthodox tubies. The active linestage is a second generation derivative of a similar circuit used for the past 2 years in our TBP.V1 Tube Preamp Buffer which has been very well received by our customers. heresy notwithstanding. I make no claims about this design being purely original first-of-kind work but the devil is truly in the details. The overall synergy produces a remarkably pleasing sound that I personally find very enjoyable and satisfying. We think other folks will as well.
Cheers,
Morten