PRE420 Instruction Manual – rev. E
Page 24
THD Spectrum at 1 KHz
Audio Precision
02/21/07 09:43:49
1 kHz FFT at 60 dB Gain, Output Level = +24 dBu, 0 dBr = +24 dBu
Color
Sweep
Trace
Line Style
Thick
Data
Axis
Comment
Cursor1
Cursor2
1
1
Red
Solid
4
Fft.Ch.2 Ampl
Left
*-111.404 dBr A
*-122.747 dBr A
-150
-100
-148
-146
-144
-142
-140
-138
-136
-134
-132
-130
-128
-126
-124
-122
-120
-118
-116
-114
-112
-110
-108
-106
-104
-102
d
B
r
A
-150
-100
-148
-146
-144
-142
-140
-138
-136
-134
-132
-130
-128
-126
-124
-122
-120
-118
-116
-114
-112
-110
-108
-106
-104
-102
-111.404
-122.747
d
B
r
A
2k
20k
4k
6k
8k
10k
12k
14k
16k
18k
2.00513k
3.00537k
Hz
dx=1.00024 kHz
dy=-11.343 dB
The above FFT plot shows that the PRE420 has very little harmonic distortion. The 1 kHz test tone
is notched out with a THD analyzer to improve the resolution of the test. Distortion is exceptionally
low. 2
nd
-harmonic distortion measures better than -111 dB. 3
rd
-harmonic distortion measures
better than -122 dB. Note the absence of higher-order harmonics.
