Do you think that adding two more chokes in the power supply and running the PS for each tube separatly is a good idea?
https://www.dhtrob.com/schemas/Gallery/PowerAmps/2A3%20or%2045%20SE%20PSU.GIF
https://www.dhtrob.com/schemas/Gallery/PowerAmps/2A3 or 45 SE AMP.GIF
https://www.dhtrob.com/schemas/Gallery/PowerAmps/2A3%20or%2045%20SE%20PSU.GIF
https://www.dhtrob.com/schemas/Gallery/PowerAmps/2A3 or 45 SE AMP.GIF
futurum21,
The first link does not work.
Chokes:
There is more than one way to make a good power supply.
Chokes are heavy, expensive, sprays magnetic fields that can be picked up by the output transformers, takes up space, has to be kept far from output transformers, the rotation angle has to be oriented to reduce hum pickup to the output transformers.
Capacitors are less expensive, do not spray magnetic fields, take less space.
Choke input filter makes the B+ secondary run cooler, tube rectifiers run cooler, reduces the transient current, versus Capacitor input filters (Chokes less problems with hum ground loops, and less problems with hash ground loops).
But Choke input filters output DCV that is 0.9 x B+ secondary voltage, and cap input filters output DCV that is 1.414 x B+ secondary voltage. So choke input filters require 1.57 x more B+ secondary voltage to get the same DC voltage out.
The 2A3/45 schematic:
With no 6SN7 bypass cap, the gain is too low, and it will not drive the 2A3 or 45 to full output power, unless you have a very large signal voltage in.
The typical full scale output voltage of a CD player, 2.1Vrms (3V peak) will not give full power out of that amplifier.
The parallel 6SN7 should have individual 1200 Ohm self bias resistors, with individual 100uF bypass caps across them, for each cathode (do not connect the cathodes together.
That will make for good current sharing of the two 6SN7 triodes.
And the bypass caps will significantly increase the gain, which will allow for more output power when the amp is driven from a CD player.
The first link does not work.
Chokes:
There is more than one way to make a good power supply.
Chokes are heavy, expensive, sprays magnetic fields that can be picked up by the output transformers, takes up space, has to be kept far from output transformers, the rotation angle has to be oriented to reduce hum pickup to the output transformers.
Capacitors are less expensive, do not spray magnetic fields, take less space.
Choke input filter makes the B+ secondary run cooler, tube rectifiers run cooler, reduces the transient current, versus Capacitor input filters (Chokes less problems with hum ground loops, and less problems with hash ground loops).
But Choke input filters output DCV that is 0.9 x B+ secondary voltage, and cap input filters output DCV that is 1.414 x B+ secondary voltage. So choke input filters require 1.57 x more B+ secondary voltage to get the same DC voltage out.
The 2A3/45 schematic:
With no 6SN7 bypass cap, the gain is too low, and it will not drive the 2A3 or 45 to full output power, unless you have a very large signal voltage in.
The typical full scale output voltage of a CD player, 2.1Vrms (3V peak) will not give full power out of that amplifier.
The parallel 6SN7 should have individual 1200 Ohm self bias resistors, with individual 100uF bypass caps across them, for each cathode (do not connect the cathodes together.
That will make for good current sharing of the two 6SN7 triodes.
And the bypass caps will significantly increase the gain, which will allow for more output power when the amp is driven from a CD player.
Last edited: