Mesa/Boogie Bass 400 Plus Operating Instructions page 3

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The Effects Return jack can also be used to plug directly into the 400's power section. The

Master can regulate sensitivity, and the Graphic EQ will be functional. If you wish to use

only the preamp section of your Bass 400, you can use the Effects Send jack as a preamp

output; be sure to set the Effects Blend at 10 and the Master to 0. This will prevent signal

from driving the power section, so running the amp without a speaker or load resistor will

be OK.

SPEAKER JACKS

Two 8-ohm, two 4-ohm and 2-ohm speaker jacks are provided on the Bass 400 Plus. The

amp will produce its full power at all of these impedances, provided that the total

impedance of your speaker cabinets is matched to the output(s) used. (Slight mismatches

are not a major problem, but they will cause slightly lower output and may shorten tube

life.) When using more than one speaker cabinet, remember that the total load impedance

goes down as more cabinets are connected. For example, if you use one 8-ohm speaker

cabinet, use one of the 8-ohm jacks. But if you use two 8-ohm cabinets, they will be

operating in parallel and the total load will be 4 ohms. Therefore, plug each cabinet into a

4-ohm jack. If you want to use two 2x15 cabinets where each cabinet is rated at 4 ohms

(which is how Boogie 2X15's are wired), connect both cabinets to the 2-ohm Jacks

provided.

SLAVE LEVEL, SLAVE OUTPUT

The Slave system is an adjustable Direct Output that can be used to feed a mixing board

or another power amplifier. The signal is taken right from the output transformer where the

tone is best and loading problems are avoided. When using the Slave, be sure to first get

the desired sound on the Bass 400 with the Slave Level at zero. Then turn up the Slave

Level until the proper output level is achieved.

600-OHM BALANCED OUTPUT

A three-pin male XLR jack is provided for connecting to the balanced 600ohm

transformer. Again, the signal is taken from the speaker jack for best results. This output

has a fixed level of about 2 volts peak-to-peak (when the Bass 400 is at clipping level). It

is therefore suitable for either "mic" or "line" inputs on a mixer, although line-level would

be preferable. When using either the Slave or the Balanced XLR output, it is important

that a speaker (or suitable load resistor) be used.

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