Linn Klimax 500 Solo monoblock power amplifier Measurements

Sidebar 3: Measurements

A full set of measurements of the Linn Klimax was made using its balanced input, with selected measurements repeated in unbalanced mode where noted.

Following its 1/3-power, one-hour preconditioning test, the Klimax's chassis was barely warm. The input impedance measured 7.7k ohms (8.2k ohms unbalanced). The output impedance measured a minuscule 0.043 ohms at 1kHz, increasing to 0.071 ohms at 20kHz, both assessed by measuring the voltage rise when an 8 ohm load was open-circuited. Using 4 ohm loads, this increased by a maximum of 0.01 ohm at 20kHz, to 0.081 ohm. Voltage gain into 8 ohms measured 22.3dB balanced and 28.6dB unbalanced. The signal/noise ratio ref. 1W into 8 ohms measured 96dB over a 22Hz-22kHz bandwidth, 88.4dB from 10Hz to 50kHz, and 98.8dB A-weighted. The corresponding unbalanced figures were 91dB, 83.5dB, and 93.8dB, respectively. The Klimax is noninverting when driven from its positive, unbalanced input; at the balanced, XLR input terminal, pin 2 is positive. DC offset measured a low 1.2mV.

Fig.1 shows the Klimax's frequency response. Only the balanced result is shown; the unbalanced is virtually identical. Apart from the relatively common degree of high-frequency rolloff, there is little to comment on here. The response into a simulated loudspeaker load differs little from the response into a pure resistance, which is characteristic of an amplifier with a low output impedance. The 10kHz squarewave response (fig.2) exhibits a good risetime, with a softened leading edge (very common among even the best amplifiers) and no overshoot or ringing. The 1kHz squarewave response, not shown, is nearly ideal.

Fig.1 Linn Klimax 500 Solo, frequency response at (from top to bottom): 2.828V into simulated loudspeaker load, 8 ohms, and 4 ohms (1dB/vertical div.).

Fig.2 Linn Klimax 500 Solo, small-signal 10kHz squarewave into 8 ohms.

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