Neumann.Berlin KH 810 - Page 34

32 | KH 810/870
Analog
output card
The analog output card has seven channels of 4th order 80 Hz high pass filtering and a level control
for each of these channels. Following this, there are seven electronically balanced output stages,
whose signal is present at the sockets OUTPUT | LEFT/RIGHT BACK, LEFT/RIGHT SURROUND, LEFT,
CENTER and RIGHT. All outputs (main channels and sum) have protective circuits to avoid power on/
o noises: the outputs switch on after a short delay when mains power is applied and mute instanta-
neously when mains power is removed.
If you select the corresponding mode, there is also 80 Hz high pass filtering and summing of the LFE
channel to the left and right outputs (more details can be found in the section “Boosting the LFE chan-
nel and adjusting the LFE mode” on page 20).
The socket OUTPUT | SUM 0 allows you to connect additional subwoofers. There is no volume control
on this output as volume control is performed locally in each subwoofer.
Crossover Using 4
th
order filters, the crossover divides the input signal of each channel into two bands for repro-
duction by the subwoofer or the main loudspeakers. The crossover frequency is fixed at 80 Hz for all
the main channels and can be bypassed when required. This frequency was chosen to balance the
conflicting requirements of having a high crossover frequency to relieve the main loudspeakers of of
their low frequency duties thereby reducing distortion, and of the need to have a low crossover fre-
quency to minimize the chances of localizing the subwoofer thereby giving greater flexibility when
placing the subwoofer in the room. In addition, by choosing 80 Hz, there is a compatibility with the
replay conditions commonly found in consumer products.
Driver(s) Long throw, ecient, low distortion drivers ensure a clean sound quality even at high replay levels.
The drivers are loaded by the internal volume of the cabinet and are magnetically shielded for use
next to CRT screens and magnetic storage media.
LFE channel “Low Frequency Eects” (Dolby) or “Low Frequency Enhancement” (dts). The LFE channel has a lim-
ited bandwidth. Because of the limited frequency range of the LFE channel, it is referred to as “.1”
when describing, for example, a 5.1 system. The designation “LFE channel” always refers to the source
and not to the loudspeakers.
Power
amplifier(s)
The high eciency power amplifiers of the KH 810/870 minimize power dissipation and are run in
bridged mode to minimize distortion.
Protection
system
An extensive protection system prevents damage to the subwoofer if high signal levels are applied to
the input. The LED POWER ON E flashes when the protection system is active. In this case, reduce the
input signal level. If this happens regularly, use a larger subwoofer with a higher SPL output or add
more subwoofers to the system to increase the LF headroom.
The protection system consists of thermal and peak limiters for the amplifier(s) and thermal modeling
of the driver(s). The protection system is not a compressor, it is designed to protect the subwoofer
from damage. The protection system cannot protect against sustained abuse of the loudspeaker sys-
tem, i.e. playing the subwoofer for long periods of time with the LED POWER ONE flashing. Please
avoid consistent abuse of the subwoofer to not aect the long service life of the product.
Remote
switch-on/
switch-o
A 12 V DC trigger voltage allows you to remotely switch the subwoofer on and o without having to
use the switch MAINS POWER 5. This can be useful in a large installation where the whole room is
powered up using a single switch. The devices are switched on using a time-delay to prevent high
starting current peaks. The trigger voltage switches the subwoofer’s electronics completely on and
o, so the startup time is subject to the same on/o muting delays as if the subwoofer had been
switched on and o using the switch MAINS POWER 5.
EN