Yamaha A-S3200 Integrated Amplifier Measurements

Link: reviewed by Roger Kanno on SoundStage! Hi-Fi on January 1, 2021

General information

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

The A-S3200 was conditioned for 30 minutes at 10W (8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The A-S3200 offers four sets of line-level unbalanced (RCA) inputs, two sets of balanced (XLR) line-level inputs, one phono input with selectable moving-magnet (MM) and moving-coil (MC) options, a set of fixed line-level RCA outputs, a set of variable RCA pre-outs, and two pairs of speaker outputs (A and B). Based on the accuracy of the left/right channel matching (see table below) and 0.5dB volume-step resolution, I determined that the A-S3200’s volume knob is not a potentiometer in the signal path, but rather provides digital control over a proprietary or integrated analog-domain volume circuit. The balance and tone-control knobs were left in the center positions, and the speaker selection switch was left on “A.” There are also two small toggle switches behind the unit for the balanced inputs, one to invert polarity (it was left on Normal), and one to provide 6dB of attenuation (it was left on Bypass).

I attempted to optimize the volume position to achieve the best signal-to-noise (SNR) and THD+N measurements at the speaker-level outputs (8 ohms). I found very little differences with the volume at various positions (for the same output voltage). Most measurements were made with the volume set to unity gain for the preamplifier (about 12 o’clock), as measured at the pre-outputs. At this volume position, to achieve 10W into 8 ohms, 242mVrms was required at the balanced line-level input and 4/0.25mVrms at the phono input (MM/MC settings). I also found no appreciable differences in THD+N values between the balanced and single ended line-level inputs, and both yielded the same gain.

Volume-control accuracy (measured at speaker outputs): left-right channel tracking

Published specifications vs. our primary measurements

The tables below summarize our primary measurements performed on the A-S3200. Here we can compare directly against Yamaha’s own published specifications for the A-S3200, which are stated as follows:

• Rated output power (20Hz to 20kHz, 0.07% THD): 100W into 8 ohms, 150W into 4 ohms
• Dynamic power: 120W into 8 ohms, 200W into 4ohms, 300W into 2 ohms
• Maximum effective output power (1kHz, 10% THD): 130W into 8ohms, 210W into 4 ohms
• Damping factor: >250 (8 ohms)
• Input sensitivity (1kHz, 100W/8-ohm): MC: 150uVrms, MM: 3.5mVrms, CD/BAL: 200mVrms
• Input impedance: MC: 60 ohms, MM: 47k ohms, CD: 47k ohms, BAL: 100k ohms
• Overload margin: MM: 20dB, MC: 12dB
• Headphone jack rated output power (1kHz, 32 ohms, 0.2% THD): 50mW (measured: 47mW)
• Frequency response: 5Hz to 100kHz (+0/-3dB), 20Hz to 20kHz (+0/-0.3dB)
• Deviation from RIAA: MM/MC +/-0.5dB
• THD+N (phono): MC to Line Out (ref 1.2Vrms): 0.02%, MM to Line Out (ref 1.2Vrms): 0.005% (measured: MC: <0.015%, MM: <0.001%)
• THD+N: CD/BAL to speaker out (50W/8-ohm): 0.035%
• Signal-to-noise ratio (A-weighted): MC: 90dB, MM: 96dB, CD: 110dB, BAL: 114dB
• Residual noise (A-weighted): 33uVrms
• Channel separation (1/10kHz): MC: 66/77dB, MM: 90/77dB, CD/BAL: 74/54dB

Our primary measurements revealed the following using the balanced line-level inputs (unless specified, assume a 1kHz sinewave, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth): 

Our primary measurements revealed the following using the phono-level inputs (MM, unless specified, assume a 1kHz sinewave, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth): 

Our primary measurements revealed the following using the phono-level inputs (MC, unless specified; assume a 1kHz sinewave, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth):

Yamaha’s power output claims of 100/150W into 8/4 ohms were corroborated with our maximum (1% THD+N) measurements of 102/169W into 8/4 ohms, during which time our line AC voltage never dipped below 123VAC. Yamaha’s claim of 120W of dynamic power into 8 ohms is difficult to corroborate, as they have not defined the term or the level of THD. However, their claim of effective maximum power of 130/210W into 8/4 ohms at 10% THD can be verified. Under these conditions, we measured 121/202W into 8/4 ohms, again with our line AC voltage dipping to a low of 123VAC.

The clipping headroom result of 0.086dB, defined as the ratio of max power over rated power into 8 ohms, is low. Nonetheless, the Yamaha was able to sustain 170W into 4 ohms using an 80 Hz tone for 500ms, alternating with a signal at -10dB of the peak (17.0W) for 5 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 top of the A-S3200 was warm to the touch, but not hot enough to cause discomfort.

Yamaha’s claim of a damping factor of 250 was corroborated with our measurements of 289/291 (L/R) at 1kHz (see graphs below for damping factor versus frequency).

Yamaha’s input sensitivity claims (volume at maximum) were verified, where we measured 190/3/0.18mVrms (BAL/MM/MC), which are very close to Yamaha’s 200/3.5/0.15Vrms specs. Our input impedance measurements were also very close to Yamaha’s specs of 60/47k/100k ohms for MC/MM/BAL, with our measured values of 70/46k/83k ohms. Our measured output impedance for the pre-outs was on the high side, with 1480 ohms, but Yamaha did not provide this spec.

Yamaha’s maximum input signals for the phono input of 2/50mVrms (MC/MM), which we converted to overload margins at 12/20dB (MC/MM), were corroborated and bettered with our 16/20dB measurements.

Yamaha’s THD+N (A-weighted) claims for the phono input of 0.02/0.005% (MC/MM), referenced to 1.2Vrms at the line outputs, were also corroborated, where we measured 0.015/0.001%. The THD+N values found in our tables above for the phono input are measured at 10W across an 8-ohm load at the speaker outputs, and therefore show higher THD+N values. The claim of 0.035% THD+N (A-weighted) measured with the line-level inputs at 50W (8-ohms) at the speaker outputs was corroborated, where we found 0.0099% (10W), and also measured roughly the same THD+N values at 50W.

We found one (MC) of Yamaha’s SNR claims (A-weighted) to be on the high side compared to our own measurements, although it’s not clear if for the phono inputs, the SNR values are referenced to the line-out like with the THD+N values, or the speaker outputs at the rated power of 100W. Our SNR values are referenced to 100W at 8 ohms. Yamaha has claimed 90/96/114dB (MC/MM/BAL), where we measured 76/98/113dB.

Yamaha’s residual noise value of 33uVrms (A-weighted) could not be corroborated, as we measured a still very low 85/65uVrms (L/R) at the speaker outputs for the balanced line-level input. The channel separation (or crosstalk) claims (1/10kHz) of 66/77dB, 90/77dB, 74/54dB (MC/MM/BAL) were either conservatively low, or a bit high as compared to our own worst-case measurements of 56/55dB, 78/75dB, 110/93dB.

Our primary measurements revealed the following using the balanced line-level inputs at the headphone output (unless specified, assume a 1kHz sinewave, 2Vrms output, 300 ohms loading, 10Hz to 90kHz bandwidth, gain set to “0”): 

Here, Yamaha only provided one spec of 50nW into 32 ohms at 0.2% THD. This value was validated by our measured 47mW under the same conditions.

Frequency response (8-ohm loading, line-level input)

In our measured frequency response plot above, the A-S3200 is perfectly flat within the audioband (20Hz to 20kHz) for the line-level input. These data corroborate Yamaha’s claims of 5Hz to 100kHz (+0/-3dB) and 20Hz to 20kHz (+0/-0.3dB) for the line-level input. The A-S3200 is at about -0.1dB at 5Hz, and -3dB at about 150kHz. The A-S3200 can be considered a high-bandwidth audio device. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so perfectly overlap, indicating that the two channels are ideally matched.

Frequency response (8-ohm loading, phono input)

The plot above shows left- and right-channel frequency response for the phono input (MM and MC behaved the same), and shows a maximum deviation of +0.5dB from flat within the audio band. What is shown is the deviation from the RIAA curve, where the input signal sweep is EQd with an inverted RIAA curve supplied by Audio Precision (i.e., no deviation would yield a flat line at 0dB). This corroborates Yamaha’s claim of a worst-case RIAA deviation of +/-0.5dB.

Frequency response (8-ohm loading, treble and bass controls at minimum and maximum settings, line-level input)

Above are two frequency response plots for the balanced line-level input, measured at 10W (8-ohm) at the speaker outputs, with the treble/balance controls set at both minimum and maximum. They show that the A-S3200 will provide a maximum gain/cut of approximately 9dB at 20Hz, and a maximum gain/cut of approximately 8dB at 20kHz.

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

The plot above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the balanced line-level input swept from 5Hz to 100kHz. The blue line is into an 8-ohm load, the purple line is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can found here), and the cyan line is no load connected.

This plot is the same test but the chart has been zoomed in on the y-axis to highlight differences. Here we find that there’s a total deviation of less than 0.1dB in the flat portion of the curve, which is an indication of a high damping factor, or low output impedance. At the frequency extremes (20Hz and 20kHz), the spread is close to the same. The maximum variation in RMS level when a real speaker was used as a load is very small, deviating by about 0.05dB within the flat portion of the curve (20Hz to 10kHz), with the lowest RMS level, which would correspond to the lowest impedance point for the load, exhibited around 200Hz, and the highest RMS level, which would correspond to the highest impedance point for the load, at around 2-3kHz.

Phase response (line-level input)

Above is the phase response plot from 20Hz to 20kHz for the balanced line-level input. The A-S3200 does not invert polarity on the line-level input, and the plot shows very little phase shift, with a worst case of just under +20 degrees at 20kHz.

Phase response (phono input)

Above is the phase response plot from 20Hz to 20kHz for the phono input (blue/red traces for the MM setting, purple/green traces for the MC setting) from 20Hz to 20kHz. With the MC setting, polarity appears to be reversed, as there is an almost 180 degree difference between the MM and MC phase plots. For the phono input, since the RIAA equalization curve must be implemented, which ranges from +19.9dB (20Hz) to -32.6dB (90kHz), phase shift at the output is inevitable. Here we find a worst case -50 degrees at 200Hz and 5kHz for the MM setting, with the MC setting following roughly the same trend, but with an extra 180 degrees of phase shift (i.e., just above -250 degrees at 200Hz and 5kHz.

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 (20Hz to 20kHz) for a sinewave stimulus at the balanced line-level input. The blue and red plots are for left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at the full rated power of 100W. The power was varied using the volume control. At 1W and 10W, the THD values are quite close, with the 1W figures slightly outperforming the 10W figures by about 2-3dB. The general trend of the lower THD figures from 20Hz to 1kHz (between 0.005% and 0.007%), with higher figures at frequencies above 1kHz (0.02% to 0.025% at 20kHz), was consistent for both the 1W and 10W data. The 100W data shows considerably higher THD values, and a 5dB disparity between channels. In general, the THD values hovered between 0.2% to 0.5% at 100W, and decreased down to between 0.1% to 0.2% at 20kHz.

THD ratio (unweighted) vs. frequency at 10W (phono input)

This is a THD ratio as a function of frequency plot for the phono input measured across an 8-ohm load at 10W. The blue/red traces represent the MM setting, the purple and green the MC setting. The input sweep is EQ’d with an inverted RIAA curve. The THD values vary from about 0.05% at 20Hz, down to about 0.007% from 200Hz to 1kHz for the MM setting, then up to about 0.03% at 20kHz. The MC setting performed considerable worse at lower frequencies (20Hz to 1kHz), with large fluctiations; between about 0.6% and 0.01%. Above 1kHz, both MM and MC settings yielded very close THD values.

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

The plot above shows THD ratios measured at the output of the A-S3200 as a function of output power for the balanced line level-input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). The 4-ohm data shows consistently higher THD values compared to the 8-ohm data (about a 5dB difference). At the 50mW level, THD values measured around 0.002% (8 ohms) and 0.004% (4 ohms), rising up to around 0.006% at 10W to 90W for the 8-ohm data, and 0.01% for the 4-ohm data. The “knee” in the 8-ohm data occurs at around 90W, hitting the 1% THD mark just above the rated output of 100W (102W). For the 4-ohm data, the “knee” occurs near 150W, hitting the 1% THD mark at 169W.

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

The plot above shows THD+N ratios measured at the output of the A-S3200 as a function of output power for the balanced line level-input, for an 8 ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). The 4-ohm data shows consistently slightly higher THD+N values compared to the 8-ohm data (about a 5dB difference). At the 50mW level, THD+N values measured around 0.03% (8 ohms) and 0.04% (4 ohms), dipping down to around 0.007% at 30 to 90W for the 8-ohm data, and 0.01% for the 4-ohm data from 50 to about 150W.

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

The chart above shows THD ratios measured at the output of the A-S3200 as a function of load (8/4/2 ohms) for a constant input voltage that yields 10W at the output into 8 ohms (and roughly 20W into 4 ohms and 40W into 2 ohms) for the balanced line-level input. The 8-ohm load is the blue trace, the 4-ohm load the purple trace, and the 2-ohm load the pink trace. We find increasing levels of THD from 8 to 4 ohms, with about a 5dB difference, and almost no degradation in THD performance between 4 and 2 ohms. Overall, even with a 2 ohms load at roughly 40W, THD values ranged from 0.015% at 20Hz to just above 0.04% at 20kHz.

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 line-level input. We see that the signal’s second harmonic, at 2kHz, is at -100/-110dBrA (L/R), while the third harmonic, at 3kHz, is higher, at -85dBrA.  The fifth harmonic is at -100dBrA, and the other harmonics measured lower. Below 1kHz, we see noise artifacts, with the 60Hz peak due to power-supply noise just above (R) and below (L) -110dBrA, and the 120Hz peak at -100dBrA. The third order harmonic at 180Hz is still quite predominant, at just below -100dBrA.

FFT spectrum – 1kHz (MM phono input)

Shown above is the FFT for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the phono input with MM selected. The odd signal harmonics dominate, with the 3kHz peak sitting at -85dBrA, and the 5kHz peak just above -100dBrA. The highest peak from power-supply noise for the MM setting is at the third harmonic (180Hz), reaching almost -70dBrA for the right channel, and -85dBrA for the left channel. Again, the odd-harmonic (i.e., 180, 300, 420Hz, . . .) noise peaks are the ones that dominate the FFT, and can be found both below and above 1kHz.

FFT spectrum – 1kHz (MC phono input)

Shown above is the FFT for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the phono input with MC selected. The odd harmonics from the 60Hz peak (i.e., 180, 300, 420Hz, . . .) dominate the entire FFT spectrum, with the left channel yielding slightly higher results. At 180Hz, the peak is nearing -50dBrA. Even the 2kHz peak (second harmonic of 1kHz signal), at around -85dBrA, is drowned out by the 33rd 60Hz harmonic (1980Hz) peak at around -80dBrA.

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 line-level input. The X axis is zoomed in from 40 Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant harmonic peak is that of the signal’s third harmonic (150Hz) at about -85dBrA. The signal second harmonic (100Hz), the noise second (120Hz) and third harmonic (180Hz), are all around -100dBrA.

FFT spectrum – 50Hz (MM phono 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 phono input with MM selected. The most predominant harmonic peak is noise signal’s third harmonic (180Hz) at about -85/-75dBrA (L/R). The most predominant signal harmonic peak is the third harmonic (150Hz) at -85dBrA.

FFT spectrum – 50Hz (MC phono 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 phono input with MC selected. The most predominant harmonic peak is the noise signal’s third harmonic (180Hz) at about -50dBrA. The most predominant signal harmonic peak is the third harmonic (150Hz) at -85dBrA, barely peaking above the noise floor.

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

Shown above is an FFT of the intermodulation (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8 ohm load at 10W for the balanced 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 -100/-115dBrA (L/R), while the third-order modulation products, at 17kHz and 20kHz are much higher, at around -85dBrA.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MM phono input)

Shown above is an FFT of the intermodulation (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the phono input with MM selected. Here we find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100/-105dBrA (L/R), and smaller in magnitude than the harmonic peaks from the noise signal surrounding it. The third-order modulation products, at 17kHz and 20kHz dominate, at around -85dBrA.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MC phono input)

Shown above is an FFT of the intermodulation (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8 ohm load at 10W for the phono input with MC selected. Here we find that the second-order modulation product (i.e., the difference signal of 1kHz) is just above -70dBrA (L/R), and very close in magnitude to the odd harmonic peaks from the noise signal surrounding it. The third-order modulation products, at 17kHz and 20kHz dominate, at around -85dBrA.

Square-wave response (10kHz)

Above is the 10kHz squarewave response using the balanced 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 Yamaha’s slew-rate performance. Rather, it should be seen as a qualitative representation of its extended 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. The A-S3200’s reproduction of the 10kHz squarewave can be considered clean, with sharp edges devoid of undershoot and overshoot.

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

The final plot above is the damping factor as a function of frequency. Both channels show a general trend of a higher damping factor at lower frequencies, and lower damping factor at higher frequencies, with roughly a factor of 2x difference at 30Hz compared to 20kHz. Both channels’ damping factors tracked very closely, with a peak value just over 300 at around 30Hz, and a low value around 150 at 20kHz.

Diego Estan
Electronics Measurement Specialist