Tube Preamp Stage: Two dual triode vacuum tubes are used in
the preamp stage for warm and powerful sound reproduction.
Speaker-level Input: High-level inputs can be used when the
source device doesn't have preamp-level outputs. The same RCA inputs on the amp
are used for either speaker-level or line-level connections. When a speaker-level
signal is used, speaker wire-to-RCA adapters are needed (item number
136XDCLR2S, sold separately) and the Input Select switches should be set to high.
2-Ohm Stable: In stereo mode (powering four speakers) the
amplifier is stable down to 2-ohms. The 2-ohm output is 160 Watts RMS x 4
Bridgeable: The E 400 can be bridged to two channels, outputting
320 Watts x 2-channels into 4 ohms. You can also wire the E 400 in three channel
mode, bridging half the amp and running the other half in stereo (110 Watts RMS x
2 channels plus 320 Watts x 1-channel).
Protection Circuitry: The E 400 offers four protection circuits:
short circuit (or too low an impedance on the outputs), thermal overload, over voltage,
and under voltage.
4-Channel: The amplifier is divided into two sections, channels
1/2 and channels 3/4. Each pair of channels has independent gain, crossover, and
input level controls.
Crossover: The built-in crossovers have three position switches
to select the crossover operation as high-pass, full-range, or low-pass. The crossover
points are continuously variable from 40 to 250 Hz.
Input Select: The input level control is switchable; set to
Low when connecting line level input signals and to High when connecting speaker
Gain: The rotary gain controls are continuously variable from
0.4 volts to 6.0 volts to match the source signal.
Power: The power and ground inputs are set-screw terminals;
they will accept bare wire up to 2-gauge (HELIX recommends 4-gauge minimum) and
are tightened/loosened with the included 5mm Allen wrench.
Remote: The remote turn-on input is a set screw terminal; it
will accept bare wire up to 8-gauge and is tightened/loosened with the included
2.5mm Allen wrench.
Speaker Outputs: The speakers connect to four pair of set-screw
terminals; they accept bare wire up to 8-gauge and are tightened/loosened with the
included 2.5mm Allen wrench.
Signal Input: Two pair of stereo RCA jacks connect to the output
signal from the head unit. The RCA jacks will accept line level signals, or speaker
level signals (requires speaker wire to RCA adapters, sold separately).
Fuse: The amp is protected by three 25-amp ATO-type fuses.
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