Lab systems 400B User manual

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PRODUCT INFORMATION AND INSTRUCTION MANUAL
INTRODUCTION AND OVERVIEW:
The Labsystems 400B has been specifically designed for the modern bassist that
requires a high performance bass head in a compact easy to handle package without sacrificing
quality or reliability. We at Labsystems feel that up until the introduction of the 400B, this goal
had not been achieved by other manufacturers; compromise had always taken precedent and
reliability had been less than perfect. With the introduction of the 400B these problems are now
overcome.
Years of development and refinement have gone into the Labsystems unique preamp
design, which features radical pre shaping eq. to give you a great starting sound, with the front
panel equalisation controls set flat. From here the tonal possibilities are endless, with carefully
chosen centre frequencies on the equalisation and voicing controls, and massive amounts of cut
and boost available on each of the controls. The separate variable voicing controls give you
added flexibility in addition to the normal equalisation with radical changes in mid and high
frequencies, tailored over a broader spectrum.
On board compression is also standard on the 400B, incorporating Labsystems unique
bass detection circuitry. Sophisticated frequency filtration networks process the signal for
threshold sensing eliminating over compression of the lower notes. What this means in sonic
terms is the ultimate slap and pull sounds; the transient response of the bottom end retained,
whilst smoothing out the top end to eliminate that harshness, often heard with today's aggressive
bass techniques. The overall amount of compression is of course adjustable to your taste, or if
desired can be fully bi-passed.
Attenuation is also catered for in the form of a 10dB pad switch on the front panel,
allowing you to use basses with either active or passive pickups, whilst still maintaining correct
gain integrity to drive the preamp stage to the optimum.
A 600 ohm balanced D.I. output is provided, which is taken post eq., so you can be
assured the sound you are getting out front is the same as your stage sound, the way you want
it to sound. An effects loop is also provided, to allow you to correctly interface with the vast array
of signal processing devices available to the modern bass player.
Power output is achieved by the legendary Labsystems M4 modular mosfet output
module, this same module having been used extensively in our entire product range for many
years now with reliability un-surpassed and un-rivalled in other products. Current limiting
incorporated into the module provides a high degree of protection against speaker impedance
mismatch and short circuit, a common killer of "other" output stages. Also built into the 400B are
protection circuits for over voltage and spike suppression.
The 400B utilises a toroidal power transformer, and high grade capacitors to achieve a
power supply light in weight, low in noise, but heavy on performance, with adequate reserves to
deliver high speed voltage swing necessary for the transient attack demanded by the bassist of
the nineties.

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