Jas-Audio BRAVO 2.3SE - Manual (Page 8)

Procedures of bias adjustment for Bravo 2.3SE 6C33 SET Integrated Amplifier
1) Switch off the power and make sure all the tubes are correctly inserted, then turn the V1 &
V2 adjust points to the far end by anti-clockwise. Set the voltage meter into to 10V DC
voltage position, plug in the black pen into the rear black(-) blinding post
2) Switch on the power and wait about 1 minute for warming up the gear.
3) Use the red pen to measure the test points V1 & V2 as the voltage should not exceed 1.3V,
if the voltage of each testing point is checked to be too high than 13V then must be turned
off the power immediately and to replace for the faulty tube.
4) Turn slowly clockwise with a screwdriver to turn the adjust point V1 by using the voltage
meter’s red pen to measure Test point V1 (Noted : ensure the testing pen & testing point
are being well connected) until the meter display to 1.2V. then to set the V2 Test point by
the voltage meter until display 1.2V as well.
5) 5 minutes later, repeat Step 4 again but to set both of the adjust points of V1 & V2 to 1.3V
(current about 130MA as it is best working stage of Bravo 2.3SE’s 6C33 tubes, and as the
current stage will be going up after few minutes of warming up).
6) Again, after10-15 minutes, repeat the Step 5 to check the V1 & V2 are at 13V as the
working current stage would be varied after longer period of music playing.
Caution :
(1) After the adjustment procedures of the tubes that to be labeled as V1, V2 and hence those
6C33C tubes must be inserted to the right V1 / V2 positions.
(2) The Bravo 2.3SE (including other kinds of tube amplifiers) is advised to set the volume in
lower listening within the first 10-15 minutes while switching on, as the tube amplifier would be
damaged in high output level without fully warm up. Especially for the 6C33 tube’s anode is a
metal casting, very thick and heavy so that its warming up time is longer than other tubes.
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V2 Test
V2 adjust point
V1 Test