Instruction manual

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delivering over 1000 watts into 8 ohms. Please ensure that the Amplifier is switched
off before changing the bridge switch position.
Throughout the design, the component quality has been chosen to suit the job being
performed (there has been no attempt to over specify components for marketing
reasons), and ensure that the amplifier can be built at the lowest cost commensurate
with the extremely high performance for which it was designed, and operate reliably
over a long period. Please complete the registration card with your details and return
the completed card to us in Bristol. In the unlikely event of a failure, we are here to
rectify the fault and speedily return the amplifier after soak testing to you. Happy
listening.
Instructions for use
Although the amplifier barely gets warm, it needs sufficient space around it for air to
circulate and prevent a build up of heat. The amplifier heat sink is the central part of
the rear panel between the speaker terminals, which you can readily feel for
temperature.
Power is supplied to the amplifier via an IEC socket on the rear panel. There is a push
button next to the IEC socket to turn the power on and off. When powered on, the
amplifier can be put into “standby” using a cable from the matching Alner Hamblin
SP400 preamp, which connects to the 2.5mm socket on the rear panel. In standby, the
blue led on the front panel is dimmed.
The Amplifier has been designed with a defined power up sequence: -
1, At Switch On a Current Limiter is in circuit to reduce Inrush Current surges to
prevent mains Line fuses blowing, and also reduce the audible “thung” noise in the
transformer due to the Initial magnetizing current.
2, After approximately 2 seconds the Limiter is switched out of circuit, and the low
voltage supplies are applied to the Amplifier, which enable the Input circuitry and
Output stages. The Amplifier then enters a self-test routine, which checks the supply
lines and various other circuit functions, e.g. Output offset voltage.
3, If all of the above tests pass then after a further 2 seconds the Amplifier is enabled,
and full operation is possible.
The Amplifier has protection circuits, which shut down the Output stage if a short
circuit or low Impedance is sensed on the Output terminals. Further, the Amplifier
will shut down if there is an abnormally high level of High Frequencies present on the
Output terminals, and also if the Amplifier is driven with high input levels with no
load (Loudspeaker) connected.
To reset the Amplifier after a shutdown, turn the Amplifier off with the mains switch
on the Rear panel, wait for approximately 4 seconds and then switch back on again. If
the Amplifier repeatedly shuts down, ensure that the Input level is at a minimum and