Palmer CAB 212 G12A OB Manuel D'utilisation page 9

You may use either of the sockets as an input.
NOTE
Never use both sockets as inputs (i.e. do not connect two amps or speaker
outputs to this cabinet). This can damage the amplifier(s) and speaker.
CONNECTING A SECOND CABINET
The two sockets are wired in parallel. This means you can connect a sec-
ond cabinet to this cabinet. When connecting a second cabinet, make sure
the impedances of both cabinets are Identical. Because the sockets are
wired in parallel, the resulting impedance will be halved.
Example: The first Palmer cabinet has an impedance of 8 Ohms. The Second
cabinet must also have an overall impedance of 8 Ohms. Connect the second
cabinet to one of the sockets of the first cabinet. The overall impedance
that the amp now "sees" is 4 Ohms.
NOTE
Ideally the power handling of both cabinets should be similar. If the
power handling of the cabinets is similar or the same, then you can add
them. I.e. Two cabinets with a power handling of 75W each can handle 150W
when linked together.
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