TUBES

The input tubes in this amplifier were chosen for their specific performance characteristics. These tubes should last several years or many thousands of hours. We can only guarantee the performance of this unit when used with input tubes supplied by Quicksilver.

Quicksilver ships the V4 Amplifiers with matched KT88 output tubes but the V4 can use a variety of output tubes. The output tubes do not need to be matched, however matched tubes can provide better performance.

Output tubes will need to be replaced periodically. When a degradation in sound occurs, the fuse blows repeatedly, or the tubes will not hold their bias anymore it is time for new output tubes. We recommend purchasing tubes from Quicksilver Audio or your dealer and we recommend keeping extra fuses and an extra output tube on hand.

OUTPUT TUBE BIAS SETTING

Output tube bias should be set immediately when new tubes are put in; then again in 15 minutes; and periodically the first few times of using the amplifiers. After that the bias should be checked monthly.

Recommended bias is 40 ma and maximum bias for each tube type is as follows:

EL34

40ma

KT77

40ma

6L6

45ma

6550

50ma

KT88

55ma

Bias controls are behind each tube. To check the bias push in the button for the tube you want to check and note the reading on the meter. Each tube corresponds to the black button nearest it. The amp may sound a little better with higher than 40 ma bias on some speakers and lower than 40 ma bias on others.

To adjust the bias you will need a slot-head screwdriver. Adjust by turning clockwise to increase bias; counterclockwise to decrease bias. Do this for each of the four output tubes. Actual bias is shown on the bias meter. The V4 can use a variety of output tubes. Remember that bias set above

the recommended values will wear out your tubes prematurely.

If you depress two or more buttons at the same time the meter averages the readings of the tubes, so your meter will not be damaged. Tube biases should be checked individually.

WARNING

This device has very high internal voltages. Never operate with the bottom removed!

Never operate your amplifers with the speakers disconnected.

To prolong the life of your amplifiers, never turn them off and then on within a short period of time (45 seconds.)

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Manfrotto V4 manual Tubes, Output Tube Bias Setting