ALLNIC AUDIO A-2000 MK3 Owner's Manual - Page 8

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OPERATION

When the power is on, the current meters on the top plate of the chassis will illuminate. From this point on,

operation is straight-forward. When you are finished listening, turn off your A-2000 MK3's power first; then, turn

off your preamplifier and sources.

the speakers as the amplifier's relays turn off. Though this sound is harmless to speakers, some users may prefer

not to hear it. To avoid the sound, simply switch the A-2000 MK3 to pentode (beam tetrode) mode prior to

turning it off (see the "On-the-Fly Triode/Pentode Switching section below).

In the case of any failure, please contact your Allnic dealer for assistance.

"ON-THE-FLY" PENTODE/TRIODE SWITCHING

You can use the Pentode/Triode "Mode Selector" button at any time during operation to switch back and forth

from Pentode to Triode operation. Press the mode selector button on the left side of the front panel down to

have the A-2000 MK3 operate in Triode mode; press the button again so it is in the raised position to have the A-

2000 MK3 operate in Pentode mode (See Figure 5).

THE CURRENT METERS

The illuminated meters on the chassis' top plate indicate the current supply to each of the four KT170 gain tubes in

the A-2000 MK3 (See Figure 6). There is one current meter for each channel's pair of KT170 power tubes. These are

switched between tubes in each pair by using the small switch between and to the outside of each KT170 pair. There

are also a potentiometer (yellow bias control screw) and a fuse for each KT170.

After soft-start and sufficient warm up of the A-2000 MK3, the needle of each current meter should be centered

between the two parallel lines on the meter face. Any error of current supply to or failure of a KT170 tube is

indicated by the needle on the KT170 tube's respective meter moving out this position and even a small distance out

from between these two parallel lines. Re-centering the needle between the lines on the meter face to achieve

proper bias may be required from time to time. See below.

TUBES AND TUBE BIAS

The A-2000 MK3 Stereo Power amplifier uses the following tubes:

• Four (4) x KT170

• Four (4) x 6S4

• Two (2) x 5654

Because of the individual bias for each KT170, it is not necessary to use a matched quad of these power tubes in the

A-2000 MK3.

As mentioned above, there is a switch on the top plate of the chassis between and to the outside of each of the left

and right channel pairs of KT170s (See Figure 6). Flipping the switch toward the rear of the chassis sets the meter to

read the rear KT170 for that channel. Flipping the switch toward the front of the chassis sets the meter for the front

KT170 for that channel. As noted above, the needle of the meter should always be centered between the two

parallel lines in the center of the meter. The position of the needle should be the same for all four KT170s. You may

adjust the needle's position by turning the relevant yellow potentiometer screw clockwise or counter-clockwise

using an appropriately bladed screwdriver. The position of the needle between the lines will alter the sound.

If the A-2000 MK3 is in triode mode at turn-off, it will produce a sound through