Manley 50 WATT MONOBLOCK AMPLIFIER Owner'S Manual Download Page 6

BIAS PROCEDURES

The Manley 50 Watt Amplfier is a fixed bias system that requires very little attention.  If you wish to
adjust or check the bias, complete the following steps. For this procedure you will need a multimeter
to read millivolts (less than 2 volt range) and a small flat screwdriver.

1.

Looking at the front section of the top plate of the amplifier, you can see 4 red tip jacks and 1

black tip jack.  To measure the current draw of each output tube place the positive probe (red) into
the red tip jack for the tube you wish to measure and the negative probe (black) in the black
(GROUND) tip jack and set the meter to read 'millivolts'.

2.

Each of the four (4) output tubes can have its own bias adjusted by altering its own bias

adjust pot. The numbering sequence for the 4 output tubes runs from left to right, as do the
corresponding tip jacks (measurement points).   The bias adjust pots are located on the top side of
the amplifier, therefore it will be NOT be necessary to remove the bottom cover to changing the
bias. They also read left to right.

3.

The first step to setting the bias is to turn on the amplifier and insure that there is zero signal

input.  Also, leave your loadspeakers connected as these provide an ideal load on the output.  Never
operate your amplifiers without a suitable load  or speakers attatched. It is recommended that you
leave the amplifier on long enough to ensure that the tubes have reached their stable current draw.

5.

Set your meter to read VOLTS DC. You will be measuring less than 1 volt so set your meter

for a low range if it is not an autoranging meter. Place the probes in the first red tip jack (negative
probes remains in the black tip jack for whole biasing procedure) and adjust the first bias trim pot
located on the left side top deck of the amplifier until you measure approx. 200 mVDC (0.2VDC).
Since you are measuring across a 10 ohm cathode resistor, this would correspond to a 20 mA bias
current.

6.

If you are unable to bring the bias voltage down to 200 mV on any tube then we recommend

that the tube be carefully watched or replaced.

7.

Follow step five with the remaining tubes.  Once they are all set, your amplifier should be in

perfect operation.

Summary of Contents for 50 WATT MONOBLOCK AMPLIFIER

Page 1: ...MANLEY LABORATORIES INC OWNER SMANUAL MANLEY 50 WATT MONOBLOCK AMPLIFIER Manley Laboratories Inc 13880 Magnolia Ave Chino CA 91710 tel 909 627 4256 fax 909 628 2482...

Page 2: ...CONTENTS INTRODUCTION 3 MAINS CONNECTIONS 4 CONNECTINGYOURAMPLIFIER 5 BIAS PROCEDURES 6 OPERATIONAL NOTES 7 SPECIFICATIONS 8 WARRANTY 9 WARRANTY REGISTRATION 10 SECTION PAGE...

Page 3: ...with ample ventilation Allow a minimum of 2 inches of clearance on the top and sides of the amplifier such that a constant flow of air can flow throughout the ventilation openings We also recommend th...

Page 4: ...E NEUTRAL terminal BROWN LIVE terminal As the colors of the wires in the mains lead may not correspond with the colored marking identifying the terminals in your plug proceed as follows The wire which...

Page 5: ...cable to the black binding post See diagram 2 Ensure that the other end of the cable is connected correctly to the speaker Tighten the binding posts by hand If you use a nut driver 3 8 do not over tig...

Page 6: ...r to changing the bias They also read left to right 3 The first step to setting the bias is to turn on the amplifier and insure that there is zero signal input Also leave your loadspeakers connected a...

Page 7: ...PECIAL NOTE The Manley 50 Watt Monoblocks are equipped with a voltage change over switch located under the bottom cover Insure that this switch is set at 110 if your mains voltage is 100 110 120 or 12...

Page 8: ...5 dB 20 Hz 20 KHz Input Sensitivity 460 mV Input Impedance 100 KOhm Load Impedance 5 Ohm Factory preset for 5 Ohm S N Ratio 350W 80 dB Power Consumption 100 Watts Quiescent 168 Watts Full Power Mains...

Page 9: ...atories productfailstomeettheabovewarranty thenthepurchaser ssole remedyshallbetoreturntheproducttoManleyLaboratories wherethedefectwillberepaired without charge for parts and labor The product will t...

Page 10: ...RIAL No ______________________ PURCHASE DATE ______________ SUPPLIER ______________________ PLEASE DETACH THIS PORTION AND SEND IT TO MANLEY LABORATORIES MODEL ____________________ SERIAL No _________...

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