Specifications

TEST RESULTS
28 | Australian Hi-Fi
0.08%, increasing to 10.29% at 50-watts,
under the test conditions noted earlier.
The spectrograms show the output
spectrum of the Stingray with a 1kHz
test signal at 1-watt and 25-watts into
4Ω and 8Ω loads. At one watt, the second-
harmonic distortion component rises
from –60dB (0.1%) when driving
8Ω loads to –50dB (0.3%) when driving
4Ω loads. The third harmonic increases
only slightly, from around –78dB (0.01%)
to –70dB (0.03%). The sidebands visible
around the fundamental and harmonics
are caused by the Stingray’s power
supply. They’re even more obvious on
the spectrograms showing distortion at
25-watts. Look at the 4Ω graph and you
can see the second, third and fourth
harmonic distortion components are all
very high at around –43dB, –45dB and
–50dB respectively. At –43dB, the second
harmonic is 0.7% distortion. The levels
of the first three harmonic distortion
components are slightly lower when the
amplifier is driving an 8Ω load, but not
by much. Perhaps more importantly,
two of the higher-order distortion
components, the 5th and 6th, are also
prominent at around –70dB and –80dB,
with their relative level switching with
the load.
Square wave testing revealed a peak
in the amplifier’s frequency response at
around 95kHz that was responsible for
the considerable ripple across the 10kHz
waveform and is also visible on the 1kHz
square wave. The considerable tilt on
the 100Hz square wave is indicative of
the limitations of the amplifier’s low-
frequency performance, as noted in the
frequency response tests. The ‘bending’
of the flat tops and bottoms of this square
wave is caused by the low-frequency
phase shift also mentioned previously.
Although it, too, shows the effect of the
peak in the high-frequency response,
the square wave showing the Stingray’s
performance into a highly capacitative
load (2µF across 8Ω) is otherwise
excellent, showing good stability.
Steve Holding
10kHz Square Wave (8Ω resistive load)
1kHz Square Wave (8Ω//2µF capacitive load)
er er
Manley Laboratories Stingray Valve Integrated Amplifier
Manley Laboratories Stingray Integrated Valve Power Amplifier -
Power Output using 5 ohm tap (Ultra Linear Outputs Mode)
No of
Channels
Load (Ω) 20Hz
(watts)
20Hz
(dBW)
1kHz
(watts)
1kHz
(dBW)
20kHz
(watts)
20kHz
(dBW)
1 8Ω 24 13.8 31 14.9 24 13.8
2 8Ω 24 13.8 31 14.9 24 13.8
1 4Ω 28 14.5 30 14.9 20 13.0
2 4Ω 28 14.5 30 14.9 20 13.0
1 2Ω 28 14.5 30 14.9 20 13.0
2 2Ω 28 14.5 30 14.9 20 13.0
Manley Laboratories Stingray Integrated Valve Power Amplifier. Serial Number: MST477
Test Measured Result Units/Comment
Frequency Response @ 1 watt 10Hz–53kHz –1dB
Frequency Response @ 1 watt 4.7Hz–72kHz –3dB
Channel Separation 68/69/52 (20Hz/1kHz/20kHz)
Channel Balance 0.4029dB @ 1kHz
Interchannel Phase 8.4/0.01/4.8 deg (20Hz/1k/20k)
THD+N 0.08% / 10.29% 1 watt/rated o/p
S/N Ratio (unweighted/weighted) 67dB/79dB dB re 1 watt output
S/N Ratio (unweighted/weighted) 68dB/80dB dB re rated output
Input Sensitivity (CD input) 43mV/238mV (1 watt/rated o/p)
100Hz Square Wave (8Ω resistive load)
1kHz Square Wave (8Ω resistive load)
ManleylabHFSep06.indd 28 22/01/2009 1:56:27 PM