Koch LB120-II - Handbuch (Seite 5)

[8] PHONES OUTPUT : Provided for the connection of a set of headphones. The signal is frequency compensated
in order to simulate the sound of a guitar speaker or speaker cabinet [10 ‘silent practising'].
NOTE: a set of normal quality headphones will often give the best results. High quality headphones may sound
shrill with distortion sounds as a result of their extended high frequency response.
[9] PHONES VOLUME : Controls the volume of the headphones.
[10] POWER ATTENUATOR SECTION : Your guitar speaker(s) or speaker cabinet [7 'two cabinets'] can be
connected to one of these six output jacks each providing a different level of output power. It is not possible to use
more than one output simultaneously.
NOTE: the label in the upper right-hand corner must match with the total load/impedance of your speaker(s) or
speaker cabinet(s). This means for example that an 8 ohms version of the LB120 (8 ohms label) may only be used
either with one 8 ohm speaker or speaker cabinet, or with two 16 ohm speakers or cabinets (total load/impedance
is 8 ohms) [7 'two cabinets'].
100% - this OUTPUT jack is directly linked to the input jack [11] and provides no power attenuation.
40% - the use of this output jack reduces the guitar amplifier's output power to 40%. This means, for example, that
if an amp delivers 100 watts into the input jack [11], only 40% of it (= 40 watts) is delivered to the speaker cabinet.
So, a 100W amp is now turned into a 40W amp, a 50W amp into a 20W amp, etc.
15% - the use of this output jack reduces the amp's output power to 15%.
5% - the use of this output jack reduces the amp's output power to 5%.
2% - the use of this output jack the amp's output power to 2%.
1% - the use of this output jack the amp's output power to 1%.
NOTE: for silent recording or practising the LB120-II can be used as a Dummy Load. This means that you don't
have to connect any speaker(s) or speaker cabinet(s) to the LB120-II.
[11] FROM GUITAR AMP'S SPEAKER OUTPUT : This INPUT jack must be connected to the SPEAKER
OUTPUT JACK of your guitar amplifier.
ALWAYS USE THE INCLUDED CABLE OR A SPECIAL JACK-TO-JACK SPEAKER CABLE AND NEVER USE A
GUITAR CABLE!
NOTE: the number on the ohmage label in the upper right hand corner must match with the impedance of the
speaker output of your guitar amplifier. This means for example that an 8 ohms LB120-II must always be
connected to the 8 ohms speaker output of your guitar amplifier.
[12] FAN POWER SUPPLY : This connector provides an input for an external power supply (not included) which
can activate the internal cooling fan.
If the LB120-II is used under normal circumstances, fan cooling is not neccessary.
If the LB120-II is built-in in a 19" rack housing or if the LB12-II gets really hot during operation, fan cooling must be
activated by connecting an external power supply. The LB120-II will accept any standard mains adapter with a 2.1
mm female plug and a DC voltage between 6 and 12 Volts / >250mA. Fan speed depends on the adapters output
voltage: 6 Volts for LOW speed, 9 Volts for NORMAL speed, 12 Volts for HIGH speed. Please mind to connect the
of "+" and "-" correctly.
RACK MOUNTING
The LB120-II LOADBOX is housed in a stainless steel, half 19' wide and 2U(nits) high housing. Two LB120-II units
can be mounted next to each other in a 1U high standard 19" rack support.
NOTE: A 2U high standard 19" rack support may be used only if its side panels do not block the fan openings of
the LB120-II.
Two M3 bolts + rings are supplied for mounting the LB120-II on a standard 19" rack support. The LB120-II has two
M3 nuts in the bottem plate that correspond with standard holes in the bottem plate of the 19" rack support. Before
mounting remove the four rubber feet.
If one or two LB120-II LOADBOXES are built-in in a 19" rack mount housing, the internal fan(s) must be activated
during operation. See [12].