7.3.2 Headroom, sensitivity and VPL / Gain
settings
The input amplifier and limiter system is designed
to accommodate extremes of performance. Typi-
cally, exceeding maximum input by much as +10 dB
will only result in a 1% increase in distortion. The
following schematics illustrate how the adjustable
VPL and Gain circuitry affect input sensitivity and
output power.
The tables to the left of the drawing below show input
sensitivity for a FP 13000 with a 2 ohm load and
195 Vpeak (max.) and 54 Vpeak (min.) respectively
for the eight different gain stages between +23 dB
and +44 dB. The resulting output power is displayed
in dBu, Vrms and watts in the tables to the far right.
Complete input sensitivity tables for all VPL and Gain
settings for all FP+ Series models can be found at
www.labgruppen.com.
The headroom available through the input stage to
the clip limiter is shown by the dotted lines as +10
dB at 195 V peak and +16.1 dB at 54 V peak. These
lines illustrate the additional signal level that can be
accepted at the input before any significant distortion
will appear at the input stage.
If you use the level potentiometer in the
signal chain to reduce the level by an amount
greater than the headroom relative to input
sensitivity, AND you drive the amplifier
to clip level, you are in danger of clipping the input
stage before the current or voltage peak limiters are
activated.
When bridging two channels, you must
add +6 dB to the input sensitivity to achieve
maximum output voltage due to the
automatic -6 dB gain compensation
inserted by the amplifier.
7 OPERATION AND PERFORMANCE
FP 13000 VPL and GAIN settings
Gain set to:
(DIP-switches)
+ 44 dB
+ 41 dB
+ 38 dB
+ 35 dB
+ 32 dB
+ 29 dB
+ 26 dB
+ 23 dB
Voltage Peak
Limiter set to:
(DIP-switches)
195 V
peak
170 V
peak
140 V
peak
116 V
peak
100 V
peak
80 V
peak
66 V
peak
54 V
peak
Input
sensitivity
dBu / V
rms
1,0 / 0,87
4,0 / 1,23
7,0 / 1,7
10,0 / 2,5
13,0 / 3,5
16,0 / 4,9
19,0 / 6,9
22,0 / 9,8
Hard/Soft switch
Gain select switches
Front panel
potentiometer
Dynamic
Gain reduction
VPL select switches
Class TD
Voltage Clip sensing
Current clip sensing
Monitoring Level
Temperature
Fault/Warning
Control Mute
+ 10 dB headroom to clip
relative to input sensitivity *)
Output
power
dBu / V
rms
45,0 / 138
43,8 / 120
42,1 / 99
40,5 / 82
39,2 / 71
37,3 / 57
35,6 / 47
33,9 / 38
Gain set to:
(DIP-switches)
+ 44 dB
+ 41 dB
+ 38 dB
+ 35 dB
+ 32 dB
+ 29 dB
+ 26 dB
+ 23 dB
Input
sensitivity
dBu / V
rms
-10,1 / 0,24
-7,1 / 0,34
-4,1 / 0,5
-1,1 / 0,7
1,9 / 1,0
4,9 / 1,4
7,9 / 1,9
10,9, / 2,7
+ 16,1 dB headroom to clip
relative to input sensitivity*)
VPL set to 54 V
PEAK
VPL set to 195 V
PEAK
Input Amplifier
Level Control Clip Limiter Voltage Peak Limiter
Output Power Amplifier
*) Headrom limited to +5dB at Gain set to +23 dB at Max. VPL
Complete tables for all VPL
settings can be found at:
www.labgruppen.com
Output Power
@ 2 Ohm
Watt
6.500 W
6.500 W
4.970 W
3.540 W
2.550 W
1.850 W
1.330 W
960 W
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