Violectric DHA V590² Pro Headphone Amplifier, Preamp, and DAC User Manual
Page 7
7
General GROUND-LIFT Jumper
( Accessible from the inside. Mind the SECURITY INSTRUCTIONS):
Ex-works this jumper is set to the LIFT position.
The internal ground potential is “lifted” by means of this jumper.
As a result, the interconnection for DC voltages and lower frequencies (< 150 Hz) will be cut.
Higher frequencies will be bled off to earth potential through the RC filter. The LIFT position is
helpful in case of hum or jitter caused by different ground/earth potentials. Of course, full electrical
protection is granted as the case is always connected to ground/earth potential!
See page 31 "Jumper Settings" for details.
Unfortunately, there is no general recommendation how to solve hum and jitter problems - or even
minimize them. The best way to succeed is to check different options! In case of balanced cables, it
should always be verified if the shield of the cable is connected to the shell of the XLR connector.
The shell is ALWAYS connected to earth potential when the connector is inserted!
Concerning ANALOGUE inputs and outputs, the relationship between ground and earth may be
modified. Electrical safety is always ensured since the earth conductor is permanently
connected to the enclosure!
XLR GROUD-LIFT Jumper
( Accessible from the inside. Mind the SECURITY INSTRUCTIONS):
G(ROUND): Ex-works all jumpers are set to "G" (ground) position.
Pin 1 is connected to the internal ground reference.
High frequency interference is deflected to the case via a 100 nF capacitor.
L(IFT):
The interconnection between Pin 1 and ground is open. High frequency interference is
deflected to the case via a 100 nF capacitor. This jumper position is specifically useful
if the unit is equipped with audio-transformers!
C(ASE):
Pin 1 is connected to the case, the 100 nF capacitor is bridged. This jumper position
may be varied together with the General GROUND-LIFT jumper.
Please note that with jumpers not in the ex-works position
EMC emission might occur,
for which the user is responsible only!
So, only change these settings when you know what you are doing!