User Manual

KH 120 | 15

If a video delay compensation has already been made, add the time-of-ﬂ ight di erence

(here: 0.4 ms) to the setting already made.

Example

Video delay compensation on loudspeaker A: 2 x 40 ms/frame

Desired time-of ﬂ ight compensation for loudspeaker A: 0.4 ms

Time-of-ﬂ ight compensation: 80.4 ms

This delay value can be made with these switch settings: 3 x 25.6 ms, 2 x 1.6 ms, 4 x 0.1 ms.

The latency of the analog-to-digital and digital-to-analog converters should be

taken into account when using the DELAY rotary switches E for time-of-ﬂ ight com-

pensation. For the digital-to-analog conversion (input signal via digital connector),

the latency is dependent on the sample rate (values can be seen in the Speciﬁ ca-

tions table on page 18). The analog-to-digital-to-analog conversion (input sig-

nal via analog connector) is ﬁ xed at 0.54 ms.

For time-of-ﬂ ight compensation delay, calculate the desired delay value then sub-

tract the appropriate latency depending on the input signal and sample rate, and

then set the needed additional delay using the delay switches on the back panel.

Example:

Distance compensation for 1 m: 1 m / 344 m/s = 2.91 ms: 2.91ms

Digital input signal, sample rate: 48 kHz, latency: 0.85 ms

2.06 ms

Delay settings:

0 x 25.6 ms, 1 x 1.6 ms, 5 x 0.1 ms

(equals 2.1 ms, which is the nearest value)

For video delay compensation, converter latency can be ignored as it is insigniﬁ -

cant compared to long video signal delays.

To help with choosing a delay setting there is a set of lookup tables at the end of

this operating manual. Also Neumann has made a delay calculator which is avail-

able at www.neumann.com.

KH 120 D

Activating ground lift

If there is humming or buzzing noise coming from the loudspeaker, ﬁ rst search for the cause of

the noise:

Disconnect all input and output signal cables from the loudspeaker.

If the noise goes away, it is probably coming from the audio source or source cabling.

It might be possible to eliminate the noise by disconnecting the ground from the input signals

(activating ground lift).

To activate ground lift:

Reconnect the signal cables and set the DIP switch [4] (“Ground lift”)5 to “Lift”.

This internally disconnects pin 1 of the ANALOG INPUT socket (XLR)6 from the loudspeak-

er’s chassis ground (see diagram “Pin assignment of the XLR socket” on page 9).

For safety reasons, the electronics chassis ground is always connected to the mains

power earth pin.