Benchmark HPA4 - Page 41

Instruction Manual for HPA4 with 1.0.X Firmware – REV B Page 41
Graph 10 - FFT Idle Channel Noise - Balanced In to Balanced Out
The HPA4 is an exceptionally quiet line amplifier. This allows it to be inserted between a
Benchmark DAC3 and an AHB2 power amplifier without degrading the noise performance of the
system. This same line stage is used in front of the THX-888 headphone amplifier. The line stage
provides volume control without degrading the performance of the headphone amplifier.
Notes:
• The scale on the left (dBr A) is dB relative to +28 dBu. This is the maximum input and
output level supported by the HPA4 line stage.
• The scale on the right (dBr B) is dB relative to +22 dBu. This is the input level required to
drive an external AHB2 power amplifier to full output power. It is also the level required to
drive the internal THX-888 to full output power.
• Balanced inputs to balanced line outputs, volume control set at 0 dB.
Audio Precision
07/13/18 15:49:14
FFT_Idle_Unity_Gain_Bal_Bal.at27
ColorSweep
Trace Line Style
Thick Data Axis
Comment Source 2
1
2 Green
Solid 4 Fft.Ch.1 Ampl Left
Left Line Output : 1.00000 =Swr.Ch. A Input
1
3
Green Solid 4 Fft.Ch.1 Ampl Right
: 1.00000 =Swr.Ch. A Input
2
2 Red Solid 4 Fft.Ch.1 Ampl Left Right Line Output
: 2.00000 =Swr.Ch. A Input
2
3
Red
Solid 4
Fft.Ch.1 Ampl Right
: 2.00000 =Swr.Ch. A Input
3
2 Yellow
Solid 4
Fft.Ch.1 Ampl Left Mono Line Output
: 3.00000 =Swr.Ch. A Input
3 3
Yellow Solid 4
Fft.Ch.1 Ampl Right : 3.00000 =Swr.Ch. A Input
-180
+0
-170
-160
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
B
-190
+0
-180
-170
-160
-150
-140
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
2.5k 47.5k 5k 7.5k 10k 12.5k 15k 17.5k 20k 22.5k 25k
27.5k
30k
32.5k
35k 37.5k 40k 42.5k 45k
Hz