Krell Industries KAV 3250 - Manual (Page 15)

14 Krell KAV–2250 and KAV–3250
Troubleshooting System Noise
When you mix and match high-performance audio components, each with its own
ground potential, a low frequency hum may occur in one or all loudspeakers. If this
happens when you place the amplifier into your system, follow these simple
troubleshooting steps:
1. Check that all input and output connections are of sound construction.
2. With the amplifier off, remove all the interconnect cables, then turn the amplifier
on. If the hum disappears, turn the amplifier off and reinsert one of the
interconnect cables. Turn the amplifier back on.
3. If the hum reappears with the interconnect cable reinserted, the cable may need
to be replaced. Turn the amplifier off and connect a different interconnect cable to
the same location. Turn the amplifier back on.
4. If the hum disappears with the interconnect cable reinserted, that cable most
likely is sound.
5. Turn the amplifier off, disconnect the interconnect cable, and re-connect one of
the other interconnect cables.
6. Repeat steps 3 through 5 until you have checked each interconnect cable
individually.
7. If all the interconnect cables appear to be sound, and if you still have hum, you
may be experiencing a ground loop. Please contact your authorized Krell dealer,
distributor, or Krell for suggestions on how to eliminate it.
Krell KAV–2250 and KAV–3250 11
Connecting the Amplifier to Your System
INPUT AND OUTPUT CONNECTIONS
The amplifier is equipped with balanced and single-ended inputs.
Krell recommends using balanced interconnect cables. Balanced interconnect cables
not only can minimize sonic loss but are also immune to induced noise, especially with
installations using long cables. Balanced connections have 6 dB more gain than single-
ended connections. When level matching is critical, please keep this gain value in mind.
The amplifier is shipped with shorting pins in the XLR inputs. These pins should remain
in the XLR inputs if the amplifier is operating in the single-ended mode. When the
shorting pin is inserted, pins 1 (lower left) and 3 (top) are shorted together. Remove the
shorting pins to connect the amplifier for balanced operation.
The XLR pin configuration is described below:
Pin 1 Shield (ground)
Pin 2 Non-inverting (hot) (0°)
Pin 3 Inverting (cold) (180°)
Follow these steps to connect the amplifier to your system.
1. Make sure all power sources and components are off before connecting inputs and
outputs.
2. Neatly organize the wiring between the amplifier and all system components.
Separate AC wires from audio cables to prevent hum or other unwanted noise from
being introduced into the system.
3. Connect the interconnect cables from your output device to the amplifier inputs using
the balanced or single-ended inputs located on the back panel: (4) and (6) on the
KAV–2250 or (5) and (7) on the KAV–3250. The balanced inputs use three-pin XLR
connectors; the single-ended inputs use RCA connectors.
IMPORTANT
Use only one input to each amplifier channel at a time.