Different SUPPLY configurations:

Tube type

Primary connections

Secondary connections

Typ. bias point

Ideal supply

KT66/807/PX25

P1+P2=230V@40Hz
or
P1//P2=115V@40Hz
P3-4: NC or pre-amp

S1-2: power tube heating (>6.3V/2.6/1.9/2.6A)
S3-4: driver tube heating (>6.3V/1.2A)
S5-6: NC
S7-8: FW-supply (>2X430VDC/0.15A)

62.5mA@400V
Pa=25W

438VDC

KT88/6550/300B

P1+P2=230V@40Hz
or
P1//P2=115V@40Hz
P3-4: NC or pre-amp

S1-2: power tube heating (>6.3V/3.2/3.2A)
S3-4: driver tube heating (>6.3V/1.2A)
S5-6: 300B heating: (>5V/2.4A)
S7-8: FW-supply (<2X430VDC/0.22A)

100mA@400V
Pa=40W

443/480VDC

6C33/1H
One heater/tube

(P1+P2)//(P3+P4)
=230V@40Hz
or
P1//P2//P3//P4
=115V@40Hz

S1-2: power tube heating (<6.3V/6.6A)
S3-4: driver tube heating (>6.3V/1.2A)
S5-6: NC
S7-8: FW-supply (<2X430VDC/0.32A)

150mA@300V
Pa=45W

395VDC

6C33/2H
One UNI/channel

(P1+P2)//(P3+P4)
=230V@40Hz
or
P1//P2//P3//P4
=115V@40Hz

S1//2//3: power tube heating (<6.3V/13.2A)
S3: driver tube heating (>6.3V/1.2A)
S5-6: NC
S7//8: FW-supply (<430VDC/0.42A)

200mA@300V
Pa=60W

410VDC

845
One UNI/channel

(P1+P2)//(P3+P4)
=230V@40Hz
or
P1//P2//P3//P4
=115V@40Hz

S1-2: NC
S3-4: driver tube heating (>6.3V/1.2A)
S5+6: power tube heating (<10V/6.4A)
S7+8: FW-supply (>860VDC/0.17A)

75mA@840V
Pa=65W

960VDC

845
Power enhanced
One UNI/channel

P1+P2=230V@40Hz
or
P1//P2=115V@40Hz
P3+P4=added to S7+8

S1-2: NC
S3-4: driver tube heating (>6.3V/1.2A)
S5+6: power tube heating (<10V/6.4A)
S7+8+P3+P4: FW-supply (>1100VDC/0.17A)

100mA@1kV
Pa=100W

1100VDC

Typical suggested Universal Transformer Supply usage. Heater and supply voltages are estimated only and the fact that heater voltages may vary within as much as +/-10% has been taken into consideration and noted. Driving circuit is always supposed to be swing-modified Williamson push-pull 6SN7 drive. Use of 6SL7 drive may have to be considered if input level or feedback is high.

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