Hi All Glass Audio fans
The name of this thread may come over as contrived. Classic preamps were made for mono sources with weak output signals, so a classic preamp for modern sources will really be a modern preamp? With "classic" I mean the presentation and circuit will hark back to the days of open transformers and tube rectifiers; but yes, it will be stereo.
For years I have been searching for the ultimate preamp design. On late Mr Valve's recommendation I initially built an 6SN7 SRPP and it worked wonderfully. But the gain was too high. The Aikido Cathode Follower also came out great, but the input cap bothered me (for no specific reason, I just like the sound of circuits with minimal capacitors in the signal path).
I noticed that a trader in high end audio used a 6SN7 preamp to demonstrate solid state power amps. It was a plain triode grounded cathode voltage amplifier with zener diode regulation in the power supply. I realized that a plain resistor loaded triode actually might be best, after all :thinking: The problem was the high gain.
Since I have been looking at the Plate Follower. It is a plate loaded triode (grounded cathode) amplifier but you can adjust the gain by applying local negative feedback. You can also tune the input impedance and use the Miller effect to roll off very high frequencies (typically all those DAC noise and RF above 100kHz).
The circuit is similar to this one, except different component values:
This will be available as a kit, soon, with tube rectification and selectable source inputs. As a matter of fact, one of these will be built at a workshop in Gauteng next month.
If there is any interest, I'll post some photos of the prototype and the schematic :O0:
The name of this thread may come over as contrived. Classic preamps were made for mono sources with weak output signals, so a classic preamp for modern sources will really be a modern preamp? With "classic" I mean the presentation and circuit will hark back to the days of open transformers and tube rectifiers; but yes, it will be stereo.
For years I have been searching for the ultimate preamp design. On late Mr Valve's recommendation I initially built an 6SN7 SRPP and it worked wonderfully. But the gain was too high. The Aikido Cathode Follower also came out great, but the input cap bothered me (for no specific reason, I just like the sound of circuits with minimal capacitors in the signal path).
I noticed that a trader in high end audio used a 6SN7 preamp to demonstrate solid state power amps. It was a plain triode grounded cathode voltage amplifier with zener diode regulation in the power supply. I realized that a plain resistor loaded triode actually might be best, after all :thinking: The problem was the high gain.
Since I have been looking at the Plate Follower. It is a plate loaded triode (grounded cathode) amplifier but you can adjust the gain by applying local negative feedback. You can also tune the input impedance and use the Miller effect to roll off very high frequencies (typically all those DAC noise and RF above 100kHz).
The circuit is similar to this one, except different component values:
This will be available as a kit, soon, with tube rectification and selectable source inputs. As a matter of fact, one of these will be built at a workshop in Gauteng next month.
If there is any interest, I'll post some photos of the prototype and the schematic :O0:
