Linn Klimax Twin
Stereo Amplifier: Measurements
All amplifier measurements are performed
independently by BHK Labs. Please click to learn
more about how we test amplifiers there. All measurement data and graphical
information displayed below are the property of SoundStage! and Schneider
Publishing Inc. Reproduction in any format is not permitted.
- Measurements were made with 120V AC line voltage.
- Power output and distortion plotted with both channels
- Test signal applied to unbalanced inputs unless otherwise
- Gain: 27.1x, 28.7dB.
- Output noise, 8-ohm load, unbalanced input, 1k-ohm input
termination: wideband 0.348mV, -78.2dBW; A weighted 0.056mV, -94.1dBW.
- Output noise, 8-ohm load, balanced input, 600-ohm input
termination: wideband 0.220mV, -82.2dBW; A weighted 0.035mV, -98.2dBW.
- AC line current draw at idle: 0.67A; AC line current draw in
- Output impedance at 50Hz: 0.08 ohms.
- This amplifier does not invert polarity.
Power output with 1kHz test signal
- 8-ohm load at 1% THD: 118W
- 4-ohm load at 1% THD: 212W
The Linn Klimax 500 Twin design utilizes a switching power
supply, and hence allows for the attractive compact form it takes. It appears that Linn
has done their homework regarding shielding and managing the potential radiation and
corruption from the power-supply switching action. Although I could see some switching
noise in the low-power distortion readings, it was way down there in the neighborhood of
the 1mV level.
Measurements shown were made through the unbalanced inputs.
Most results were essentially the same through the balanced inputs with the exception of
the output noise, which was lower using the balanced inputs as the balanced gain is about
6dB lower than the unbalanced input gain. Chart 1 shows the frequency response of the amp
with varying loads from an open circuit down to a 4-ohm value. This amp's output impedance
is low enough to not bother with plotting the NHT dummy-speaker-load response as the
variation would be only of the order of +/- 0.1dB. Chart 2 illustrates how total harmonic
distortion plus noise versus power varies for 1kHz and SMPTE IM test signals and amplifier
output load. As can be seen, attainable power is greater for the 4-ohm load as is usual
for most power amplifiers. Total harmonic distortion plus noise as a function of frequency
at several different power levels is plotted in Chart 3. In this plot, the 1W level is
dominated by switching noise, which is within the 80kHz measurement bandwidth used for the
chart. Damping factor versus frequency is shown in Chart 4. A spectrum of the harmonic
distortion and noise residue for a 1kHz test-signal frequency, 10W output level, and 4-ohm
loading is plotted in Chart 5. The amount of AC line harmonics are admirably low and there
is no hum modulation of some of the signal harmonics as have been seen in quite a few
other amplifiers measured.
- Frequency Response of Output Voltage as a Function of Output Loading
Magenta line: open circuit
Red line: 8-ohm load
Blue line: 4-ohm load
|Chart 2 - Distortion as a Function
of Power Output and Output Loading
(line up at 10W to determine lines)
Top line: 4-ohm SMPTE IM
Second line: 8-ohm SMPTE IM
Third line: 4-ohm THD+N
Bottom line: 8-ohm THD+N
|Chart 3 - Distortion
as a Function of Power Output and Frequency
8-ohm output loading
Green line: 1W
Cyan line: 10W
Blue line: 30W
Red line: 100W
|Chart 4 - Damping Factor
as a Function of Frequency
Damping factor = output impedance divided into 8
|Chart 5 - Distortion and
1kHz signal at 10W into an 4-ohm load