15
SPLITSWITCH
FUNCTION
"STEREO"
Both outputs are working in
normal stereo operation.
"SPLIT"
The left channel is output to both
earpieces of the headphone
connected to the left socket.
The right channel is output to both
earpieces of the headphone
connected to the right socket.
This operation mode is to be
preferred when mono signals are
fed to the inputs.
THE ADDITIONAL AMPLIFIER
OUTPUTS
The stereo signal from the amplifers is present
also on the back mounted “AMP A/B STEREO
OUT” sockets. These sockets may be used e.
g. to supply remote headphone connectors.
ABOUT OUTPUT POWER,
OPERATIONAL RELIABILITY,
PROTECTING FUNCTIONS
It is strange to say that just a “simple” product
like a headphone amplifier needs increased
efforts in circuitry to preserve its functionality.
Basically it is made to deliver only small
portions of power to small sonic transducers.
However these transducers feature impedan-
ces between 8 and 600 ohms which must be
handled. Further F399 offers connecting
facilities for up to 8 headphones on the
frontpanel. If these are 8-ohm types, the
resulting impedance is 1 ohm - which is not far
from a short circuit !!
Different headphones offer various sensitivities
and multiple load limits which have to be
considered to satisfy the majority of users.
Last but not least each time a phone jack is
inserted, the system is shorted due to the
desing of the jacks !
To align PHONE-AMP F399 preferably best to
different headphones, the the overall gain two
times. This was described earlier.
Unfavorable operating conditions are displayed
by flashing LEDs.
We differentiate between:
CLIP
The amplitude of every single stereo amplifier
is monitored independently of the operating
voltage. When the amplitude reaches approx.
–3 dB of the maximum, the “CLIP/TEMP”-LED
starts flashing to show that distortions may
appear on the outputs.
This operating condition should be avoided by
limiting the volume of the dedicated amplifiers.
TEMP
The temperature of every single amplifier is
monitored. The “CLIP/TEMP”-LED visualizes
the activation of the temperature protection.It is
also audible as the amplifier is shut off during
temperature protection !
This operating condition should be avoided by
limiting the volume of the dedicated amplifier or
by reducing the load by unplugging head-
phones.
