R120 SE Stereo Amplifier MK2
.

The work of this R120 amplifier is my 2nd challenge.
This time I used SRPP in voltage amplifier section with ECC35.

About R120
Schematics
Measurement result

R120MK2_front-2.jpg Front view

R120MK2_top.jpg Top view

R120MK2_rear.jpg Rear view

R120MK2_inside.jpg inside

About R120
R120 is indirect-heat valve that was developed by French Philips in 1950s.
R120 is the valve of the character that resemble well with 2A3,
but it has a transparent high tone as a characteristic.

R120typical operation (A1 Single)
Ef (V)If (A)Ep (V)Ip (mA) Eg (V)rp (K.ohm )RL (K.ohm) Wo (W)
6.31.4525060-35 0.842.53.5

There are 2 kinds in R120:-as plane plate, mesh plate.
I tried both, and I confirmed a subtle difference in tone between each one.
Plainly speaking, mesh is soft and plane is clear.

R120MK2_RT.jpg R120MK2_SB.jpg
RT R120
mesh plate 		SB R120
plane plate

Schematics
R120MK2SRPPsch.gif
R120MK2PSsch.gif

Measurement result
R120MK2_I-O.gif
R120MK2_THD.gif
R120MK2_FR.gif

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