Electrocompaniet AW 300 M Mono Amplifier Measurements

Link: reviewed by Phil Gold on SoundStage! Ultra on September 15, 2024

General information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The Electrocompaniet AW 300 M was conditioned for 1 hour at 1/8th full rated power (~35W into 8 ohms) before any measurements were taken. All measurements were taken using a 120V/20A dedicated circuit.

The AW 300 M is a one-channel amplifier with one balanced (XLR) input and two sets of speaker-level outputs. An input of 305mVrms was required to achieve the reference 10W into 8 ohms.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency-response measurements utilized a DC to 1MHz input bandwidth.

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Electrocompaniet for the AW 300 M compared directly against our own. The published specifications are sourced from Electrocompaniet’s website, either directly or from the manual available for download, or a combination thereof. Assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz:

* 327k ohms per differential input

Our primary measurements revealed the following (unless specified, assume a 1kHz sinewave at 305mVrms at the input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the AW 300 M was able to sustain about 532W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (34.2W) for five seconds, for five continuous minutes without inducing a fault or the initiation of a protective circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the sides and top of the AW 300 M were slightly warm to the touch.

Frequency response (8-ohm loading)

In our frequency-response (relative to 1kHz) plot above, measured across the speaker outputs at 10W into 8 ohms, the AW 300 M exhibits a near-flat frequency response across the audioband (0/-0.1dB at 20Hz/20kHz). The AW 300 M appears to be DC-coupled, as it is perfectly flat down to 5Hz. The -3dB point is at 200kHz.

Phase response (8-ohm loading)

Above is the phase-response plot from 20Hz to 20kHz for the balanced line-level input, measured across the speaker outputs at 10W into 8 ohms. The AW 300 M does not invert polarity and exhibits, at worst, only -10 degrees of phase shift at 20kHz, due to its extended bandwidth.

RMS level vs. frequency vs. load impedance (1W, one channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 10Hz to 100kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we find the maximum deviation between an 4-ohm load and no-load to be around 0.02dB up to 2kHz. Beyond 2kHz, the deviations are as high as 0.07dB at 20kHz. This is an indication of a very high damping factor, or low output impedance. With a real speaker, the deviations from 20Hz to 2kHz were roughly the same (0.02dB) from 20Hz to 10kHz.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the output into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue plot is at 1W output into 8 ohms, purple at 10W, and pink is near the rated power (260W). The 1W and 10W data are close (within 5dB from 20Hz to 2kHz and 10dB up to 20kHz), with the 1W data outperforming the 10W data and ranging from 0.0003% from 20Hz to 2kHz, then up to 0.001% at 20kHz. The 260W THD data are higher but still very low, ranging from 0.003% from 20Hz to 2kHz, then up to 0.02% at 20kHz.

THD ratio (unweighted) vs. output power at 1kHz into 8, 4, and 2 ohms

The chart above shows THD ratios measured at the output of the AW 300 M as a function of output power for the analog line-level input for an 8-ohm load (blue), 4-ohm load (purple), and 2-ohm load (pink). The 8-ohm data ranged from 0.001% at 50mW, down to 0.0003% from 1-2W, then up to 0.002% at the “knee,” at roughly 250W. The 4-ohm data ranged from 0.0015% at 50mW, down to 0.0005% from 0.5-2W, then up to 0.003% at the “knee,” at roughly 420W. The 2-ohm data ranged from 0.002% at 50mW, down to 0.001% from 0.2-4W, then up to 0.01% at the “knee,” at roughly 700W. The 1% THD marks were reached at 289/515/814W into 8/4/2 ohms.

THD+N ratio (unweighted) vs. output power at 1kHz into 8, 4, and 2 ohms

The chart above shows THD+N ratios measured at the output of the AW 300 M as a function of output power for the analog line-level input for an 8-ohm load (blue), 4-ohm load (purple), and 2-ohm load (pink). The 8-ohm data ranged from 0.01% at 50mW, down to a low of 0.0007% from 10-50W, then up to the “knee.” The 4-ohm data ranged from 0.015% at 50mW, down to a low of 0.001% from 20-100W, then up to the “knee.” The 2-ohm data ranged from 0.02% at 50mW, down to a low of 0.002% from 5-10W, then up to the “knee.”

THD ratio (unweighted) vs. frequency at 8, 4 and 2 ohms

The chart above shows THD ratios measured at the output of the AW 300 M as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yielded roughly 50W at the output into 8 ohms (blue), 100W into 4 ohms (purple), and 200W into 2 ohms (pink). The 8-ohm data ranged from 0.0007-8% at 20-1kHz, then up to 0.005% at 20kHz. The 4-ohm THD data ranged from 0.0009% at 20Hz to 1kHz, then up to 0.007% at 20kHz. The 2-ohm data yielded a steady climb from 0.0015% at 20Hz up to nearly 0.02% at 20kHz.  This shows that the AW 300 M is perfectly stable into 2-ohms, with low THD ratios even at 200W.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers

The chart above shows THD ratios measured at the output of the AW 300 M as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). At very low frequencies, the two-way speaker yielded the highest THD ratios (0.02%). In the all-important 300Hz to 5kHz range, THD ratios into all three loads were extremely close, hovering around the 0.0002-0.0003% level. At the highest frequencies, the three-way speaker yielded the highest THD ratios (0.005% at 20kHz).

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the AW 300 M as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kH, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load are fairly consistent, from 0.0003 to 0.0005% across the sweep. The results were higher into real speakers, ranging from 0.0005% to 0.003%.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers

The chart above shows IMD ratios measured at the output of the AW 300 M as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input in stereo mode. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load remained constant between 0.001% and 0.002%. All three plots are essentially identical and constant at 0.002%.

FFT spectrum – 1kHz (line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at -110dBrA and -115dBrA, or 0.0003% and 0.0002%. Other signal harmonics can be seen but below the extremely low -135dBrA level, or 0.00002%, level. There are power-supply noise-related harmonics, but these are below the -125dBrA level, or 0.00006%. This is a clean FFT result.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most dominant (non-signal) peaks are again the signal’s second (100Hz) and third (150Hz) harmonics at -110dBrA and -115dBrA, or 0.0003% and 0.0002%. There are power-supply noise-related harmonics, but these are below the -125dBrA level, or 0.00006%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at the very low -120dBrA, or 0.0001%, level, while the third-order modulation products, at 17kHz and 20kHz, are a little higher at -115dBrA, or 0.0002%.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the AW 300 M with the APx 32-tone signal applied to the input. The combined amplitude of the 32 tones is the 0dBrA reference, corresponding to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are below the very low -130dBrA, or 0.00003%, level.

Square-wave response (10kHz)

Above is the 10kHz squarewave response using the balanced analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the AW 300 M’s slew-rate performance. Rather, it should be seen as a qualitative representation of the AW 300 M’s relatively wide bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we see a very clean result, with no ringing in the corners and only very mild softening.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We find very high damping factor values, from 600-700 from 20Hz to 2kHz. Above 2kHz, there is a dip in damping factor, reaching 250 at 20kHz. This is a very strong damping factor result.

Diego Estan
Electronics Measurement Specialist