User Manual

18. Preamp Out - Plug in here to send your sound

to an external bass amp or power amp without a

simulation of a mic'd cabinet. (HD400 & HD750 only)

19. Extension Speaker Output (LD400Pro only)

Only use an 8 Ohm Speaker cabinet when using the

Extension Speaker Output.

20. Speaker Outs (HD400 & HD750 only) -

Only use a 4 Ohm speaker cabinet when running in

mono. Only use 8 Ohm speaker cabinets when feeding

a pair. Warning! Do not plug two 4 Ohm cabinets

into either the HD400 or HD750 as it can result in

damage to the amplifier.

Using Neutrik Speakon Output Connections

The LD400 Pro, HD400 & HD750 all feature Neutrik

Speakon NL4 series high current twist-lock speaker

output connections. These are used instead of standard

1/4-inch unbalanced speaker jacks to provide superior

and safe coupling characteristics with professional grade

bass guitar cabinets like the Line 6 LowDown 410

cabinet.

Pins 1+ and 1- are used so that a standard two conductor

Speakon-to-Speakon cable can be used, or a two

conductor Speakon-to-1/4-inch adapter.

Warning! If a Speakon-to-1/4-inch adaptor must be

used, we recommend that the power amp be OFF when

plugging the amplifier to a standard 1/4-inch cabinet

input jack to prevent any risk of shock.

Warning! Do not use a Speakon Cable labeled

“BRIDGE MODE” with the HD400 or HD750. This

can cause damage to the amp.

Additional outputs of the HD400, LD400 Pro & HD750.

PARALLEL SPEAKER OUTPUTS

MINIMUM 4 OHM OUTPUT AT 400 WATTS

CONNECT

8 Ohm pair

4 Ohm single

ONLY

PRE

OUT

UNBALANCED

EXTENSION

SPEAKER

OUTPUT

MINIMUM 8 OHM LOAD