Cyrus Audio i9-XR Integrated Amplifier-DAC Measurements

Link: reviewed by Roger Kanno on SoundStage! Hi-Fi on September 1, 2022

General Information

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

The i9-XR was conditioned for 1 hour at 1/8th full rated power (~8W into 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 Cyrus does not provide a power rating into 8 ohms, only into 6 ohms (91W), which is unusual. If we assume a constant output voltage, 91 watts translates to 68 watts into 8 ohms. This is precisely the output power level where we found, through our measurements, the transition (i.e., the “knee”) from low distortion to high distortion to be. For the purposes of these measurements, the assumed rated output power into 8 ohms is 68 watts.

The i9-XR offers four unbalanced line-level analog inputs (RCA), one unbalanced moving-magnet (MM) phono input (RCA), two coaxial S/PDIF digital (RCA), two optical S/PDIF (TosLink), one USB digital input, one pair of line-level pre-outs (RCA), one pair of fixed line-level outs (RCA), and two sets of speaker level outputs. On the rear of the unit is a 1/8″ TRS headphone output. For the purposes of these measurements, the following inputs were evaluated: digital coaxial, as well as the analog line-level and MM unbalanced inputs.

Most measurements were made with a standard 2Vrms line-level analog input, 5mVrms MM input, and 0dBFS digital input. The signal-to-noise ratio (SNR) measurements were made with the same input signal values, but with the volume set to achieve the rated output power of 68W (8 ohms). For comparison, on the line-level input, an SNR measurement was also made with the volume at maximum, where only 0.223Vrms was required to achieve 68W into 8ohms.

The i9-XR also offers seven digital filters: Apodizing, Hybrid, Brick-Wall, Steep Linear, Gentle Linear, Steep Minimum, and Gentle Minimum. For some of our measurements (e.g., impulse response, frequency response at 16/44.1), all seven filters were evaluated; however, when not otherwise stated, the default filter was Apoziding, because this is the filter Roger Kanno, the reviewer of the product, used.

Based on the accuracy and non-repeatable results at various volume levels of the left/right channel matching (see table below), the i9-XR volume control is likely operating in the analog domain, but is digitally controlled. The volume control offers a total range of -79dB to 0dB on the display, which measured from -38dB to +40.4dB between the line-level analog input and the speaker outputs, in increments of 1dB.

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

Published specifications vs. our primary measurements

Cyrus only publishes two audio measurement related specifications: 91W into 6 ohms for the speaker-level output and 138mW (at 0.1% THD) into 16 ohms for the headphone output. Both of these impedances are somewhat non-standard, and, therefore, we were unable to directly verify these specs. However, based on our results into 8 ohms (77W at 1% THD, speaker output) and 32 ohms (84mW at 1% THD, headphone output), and the very low output impedances at both outputs, we can infer that the i9-XR meets Cyrus’s specifications.

Our primary measurements revealed the following using the line-level analog input and digital coaxial input (unless specified, assume a 1kHz sine wave at 2Vrms or 0dBFS, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth):

For the continuous dynamic power test, the i9-XR was able to sustain 130W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (13W) for 5 seconds, for 5 continuous minutes without inducing a shutdown or protection circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the top of the i9-XR was very warm to the touch, enough to cause pain after a few seconds.

Our primary measurements revealed the following using the phono-level input, MM configuration (unless specified, assume a 1kHz 5mVrms sinewave input, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth):

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sine wave, 1Vrms output, 300 ohms loading, 10Hz to 90kHz bandwidth):

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

In our measured frequency-response chart above, the i9-XR is perfectly flat within the audioband (20Hz to 20kHz). At the extremes the i9-XR is at 0dB at 5Hz, and -0.25dB at 20kHz. The high-frequency -3dB point is a 67kHz. 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 they perfectly overlap, indicating that the two channels are ideally matched.

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

Above are the phase response plots from 20Hz to 20kHz for the line level input, measured across the speaker outputs at 10W into 8 ohms. The i9-XR does not invert polarity and exhibits, at worst, less than 20 degrees (at 20Hz) of phase shift within the audioband.

Frequency response vs. input type (analog and 16/44.1, 24/96, and 24/192 inputs with 8-ohm loading, left channel only)

The chart above shows the i9-XR frequency response as a function of input type measured across the speaker outputs at 10W into 8 ohms. The green trace is the same analog input data from the previous graph. The blue trace is for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial digital input, and the purple trace is for a 24/96 dithered digital input signal from 5Hz to 48kHz, while the pink trace is for a 24/192 dithered digital input signal from 5Hz to 96kHz. The analog input shows a slightly more extended frequency response at high frequencies compared to the 24/192 input. The 16/44.1 data exhibits brick-wall-type filtering, with a -3dB point at 20.2kHz. The 24/96 and 24/192 kHz data yielded -3dB points at 43.7kHz and 57.3kHz, respectively. All sample rates, as well as the analog input are at roughly -0.3dB at 20kHz, and at 0dB at 5Hz.

Frequency response vs. filter type (Apodizing, Hybrid, and Brick-Wall filters; 16/44.1 input with 8-ohm loading; left channel only)

The chart above shows the i9-XR’s frequency response as a function of filter type measured across the speaker outputs at 10W into 8 ohms for a 16/44.1 dithered digital input signal from 5Hz to 22kHz using the coaxial digital input. The red trace is for the Apodizing filter, the purple trace the Hybrid filter, and the green trace the Brick-Wall filter. Both the Apodizing and Brick-Wall filter exhibit brick-wall-type behavior around 20kHz, while the hybrid filter yields a more gentle attenuation slope. The Hybrid filter is at -3dB at roughly 19kHz. The Apodizing filter exhibits some rippling in the amplitude response at high frequencies.

Frequency response vs. filter type (Steep Linear, Gentle Linear, Steep Minimum, Gentle Minimum; 16/44.1 input with 8-ohm loading; left channel only)

The chart above shows the i9-XR’s frequency response as a function of filter type measured across the speaker outputs at 10W into 8 ohms for a 16/44.1 dithered digital input signal from 5Hz to 22kHz using the coaxial digital input. The red trace is for the Steep Linear filter, the purple trace the Gentle Linear filter, the green trace the Steep Minimum filter, and the pink trace the Gentle Minimum filter. Both the Steep Linear and Steep Minimum filters exhibit brick-wall-type behavior around 20kHz, while the Gentle Linear and Gentle Minimum filters yield a gentler attenuation slope, with -3dB points at roughly 20kHz.

Phase response vs. filter type (Apodizing, Hybrid, and Brick-Wall filters; 16/44.1 input with 8-ohm loading; left channel only)

Above are the phase response plots from 20Hz to 20kHz for the coaxial digital input at 16/44.1, measured across the speaker outputs at 10W into 8 ohms. The red plot is for the Apodizing filter, the purple plot for the Hybrid filter, and the green plot for the Brick-Wall filter. The Apodizing and Brick-wall filters exhibit the same phase characteristics, so their lines overlap, with just over 40 degrees of phase shift at 20kHz. The Hybrid filter yields almost 100 degrees of phase shift at 16kHz or so, then -30 degrees at 20kHz.

Phase response vs. filter type (Steep Linear, Gentle Linear, Steep Minimum, Gentle Minimum; 16/44.1 input with 8-ohm loading; left channel only)

Above are the phase-response plots from 20Hz to 20kHz for the coaxial digital input at 16/44.1, measured across the speaker outputs at 10W into 8 ohms. The red plot is for the Steep Linear filter, the purple plot for the Gentle Linear filter, the green plot for the Steep Minimum filter, and the pink plot for the Gentle Minimum filter. The Steep Linear filter is very similar in phase response as the Apodizing and Brick-Wall filters above, with just over 40 degrees of phase shift at 20kHz. The Gentle Linear filter exhibits the most phase shift, at just over 140 degrees at 20kHz. The Steep and Gentle Minimum filters have similar phase responses to the Hybrid filter above, with peaks at roughly 14kHz of 100 and 50 degrees of phase shift, respectively. At 20kHz, both filters show -20 degrees of phase shift.

Frequency response (8-ohm loading, MM phono input)

The chart above shows the frequency response for the MM phono input. What is shown is the deviation from the RIAA curve, where the input signal sweep is EQ’d with an inverted RIAA curve supplied by Audio Precision (i.e., zero deviation would yield a flat line at 0dB). We see a maximum deviation of about +0.4dB at 20kHz (right channel), from 20Hz to 20kHz. The worst-case channel deviation is between about 5kHz to 10kHz, at about 0.25dB.

Phase response (MM input)

Above is the phase response plot from 20Hz to 20kHz for the MM phono input, measured across the speaker outputs at 10W into 8 ohms. The i9-XR does not invert polarity. 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 of about -60 degrees at 200Hz and 5kHz, and +20 degrees at 20Hz.

Digital linearity (16/44.1 and 24/96 data)

The chart above shows the results of a linearity test for the coaxial digital input for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the line-level fixed outputs of the i9-XR for a 2Vrms (at 0dBFS) output signal. The digital input is swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output is analyzed by the APx555. The ideal response would be a straight flat line at 0dB. Both data were essentially perfect as of -100dBFS down to 0dBFS. At -120dBFS, the 16/44.1 data were about +3dB above reference, while the 24/96 data were essentially perfect. This is a very a good linearity test result.  We extended the range . . .

. . . and found that the 24/96 data were only at +2.5dB at -140dB. Predictably, at -140dBFS, the 16/44.1 were overshooting by over 10dB.

Impulse response (24/44.1 data; Apodizing, Hybrid, Brick-Wall filters)

The graph above shows the impulse responses for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of the i9-XR. The blue plot is for the Apodizing filter, the purple plot for the Hybrid filter, and the orange plot is the Brick-Wall filter. The Apodizing filter and Brick-Wall filters have typical symmetrical sinc function responses, while the hybrid filter minimizes pre-ringing.

Impulse response (24/44.1 data; Steep Linear, Gentle Linear, Steep Minimum filters)

The graph above shows the impulse responses for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of the i9-XR. The blue plot is for the Steep Linear filter, the purple plot for the Gentle Linear filter, and the orange plot is the Steep Minimum filter. The Steep linear filter and Gentle linear filters have symmetrical sinc function responses, although there is far less pre- and post-ringing behavior with the Gentle Linear filter. The Steep Minimum exhibits no pre-ringing, but has significant post-ringing.

Impulse response (24/44.1 data; Apodizing, Hybrid, Brick-Wall filters)

The graph above shows the impulse response for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of the i9-XR. The pink plot is for the Gentle Minimum filter. Of all the filters, this is the one with the least amount of pre- (none at all) and post-ringing behavior.

J-Test (coaxial)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line- level pre-outs of the i9-XR. J-Test was developed by Julian Dunn in the 1990s. It is a test signal—specifically a -3dBFS undithered 12kHz square wave sampled (in this case) at 48kHz (24 bits). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz square wave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sine wave (the main peak). In addition, an undithered 250Hz squarewave at -144dBFS is mixed with the signal. This test file causes the 22 least significant bits to constantly toggle, which produces strong jitter spectral components at the 250Hz rate and its odd harmonics. The test file shows how susceptible the DAC and delivery interface are to jitter, which would manifest as peaks above the noise floor at 500Hz intervals (e.g., 250Hz, 750Hz, 1250Hz, etc.). Note that the alternating peaks are in the test file itself, but at levels of -144dBrA and below.  The test file can also be used in conjunction with artificially injected sine-wave jitter by the Audio Precision, to show how well the DAC rejects jitter.

The coaxial input (the optical input yielded the same FFT) exhibits a fairly elevated noise floor; however, no peaks can be in the audioband above the noise floor other than a single peak at nearly 20kHz at -100dBrA. This appears to be a reasonably good J-Test result, indicating that the i9-XR DAC likely has good jitter immunity. However, further investigation is warranted by injecting artificial jitter.

J-Test with 500ns of injected jitter (coaxial)

Both the coaxial and optical inputs (with the same results) were also tested for jitter immunity by injecting artificial sine-wave jitter at 2kHz, which would manifest as sidebands at 10kHz and 14kHz without any jitter rejection. Jitter immunity proved very good, with visible sidebands appearing at a low -120dBrA only when a very high 500ns of jitter level was injected.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Apodizing filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Apodizing filter. There is a sharp roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA. The main 25kHz alias peak is just below -100dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Hybrid filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Hybrid filter. There is a sharp roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA. The main 25kHz alias peak at -110dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Brick-Wall filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Brick-Wall filter. There is a sharp roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA. The main 25kHz alias peak is at -105dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Steep Linear filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Steep Linear filter. There is a sharp roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA. The main 25kHz alias peak is at -115dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Gentle Linear filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Gentle Linear filter. There is a soft roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA, and a mirrored aliasing peak at 13.2kHz, just above -110dBrA. The main 25kHz alias peak is just above -30dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Steep Minimum filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Steep Minimum filter. There is a sharp roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA. The main 25kHz alias peak is at -110dBrA.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input, Gentle Minimum filter)

The plot above shows a fast Fourier transform (FFT) of the i9-XR’s line-level fixed outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sine wave at 0dBFS (2Vrms) fed to the coaxial digital input, sampled at 16/44.1, using the Gentle Minimum filter. There is a soft roll-off above 20kHz in the white-noise spectrum. There is a broad noise peak within the audioband at around 8kHz, just above -120dBrA, and a mirrored aliasing peak at 13.2kHz, at -115dBrA. The main 25kHz alias peak is at -35dBrA.

RMS level vs. frequency vs. load impedance (1W, left 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 5Hz 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 can see a maximum deviation within the audioband of about 0.03dB from 4 ohms to no load, which is an indication of a high damping factor, or low output impedance. The maximum variation in RMS level when a real speaker was used is even less, deviating by about 0.02dB within the flat portion of the curve (20Hz to 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 for a sine-wave stimulus at the analog 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 62W. The power was varied using the volume control. Between 20 and 50Hz, THD ratios are similar, between 0.001-0.0015%, at all power levels. Above 50Hz, THD ratios are lowest at 62W, ranging from 0.001% up to 0.03% at 20kHz. At 10W, THD ratios ranged from 0.001% up to 0.04% at 20kHz, and at 1W, from 0.0015% up to 0.1% at 20kHz.

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

The chart above shows THD ratios as a function of frequency plots for the MM phono input measured across an 8-ohm load at 10W. The input sweep is EQ’d with an inverted RIAA curve. The THD values vary from around 0.03% at 20Hz, down to 0.002% at 200-300kHz, then up to 0.04% at 20kHz.

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

The chart above shows THD ratios measured at the output of the i9-XR as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right channels) and a 4-ohm load (purple/green for left/right channels). The 8-ohm data yielded THD ratios about 2-3dB lower than the 4-ohm data. Into 8 ohms, THD ratios ranged from 0.05% at 50mW, down to 0.0025% at the “knee” at 68W. Into 4 ohms, THD ratios ranged from 0.07% at 50mW down to 0.003/0.004% (left/right) at the “knee” just past 100W. The 1% THD values are reached at 77W (8 ohm) and 122W (4 ohm).

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

The chart above shows THD+N ratios measured at the output of the i9-XR as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right channels) and a 4-ohm load (purple/green for left/right channels). The 8-ohm data yielded THD+N ratios about 2-3dB lower than the 4-ohm data. Into 8 ohms, THD+N ratios ranged from just below 0.1% at 50mW, down to 0.004% at the “knee” at 68W. Into 4 ohms, THD ratios ranged from just above 0.1% at 50mW down to 0.005% at the “knee” just past 100W. 

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 i9-XR as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 5W at the output into 8 ohms (and roughly 10W into 4 ohms, and 20W into 2 ohms) for the analog 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 essentially the same THD values into 8 and 4 ohms, ranging from 0.001% at 20Hz, up to 0.05% at 20kHz. Into 2 ohms, THD ratios are higher, ranging from 0.015% at 20Hz to 0.04% at 20kHz.

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

The chart above shows THD ratios measured at the output of the i9-XR 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). From 50Hz to 20kHz, all THD data are identical. At 20Hz, the 2-way Focal yielded tne highest THD ratios at 0.02%, while the 3-way yielded 0.002%, just above the 0.001% measured across the ressitive 8-ohm load. Overall, the i9-XR THD behavior into various loads is constant and commendable.

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

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the i9-XR 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 is used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, 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). All three results are essentially the same, with IMD ratios from 0.01% at 2.5kHz, up to 0.1% at 20kHz.

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

The chart above shows IMD ratios measured at the output of the i9-XR 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 SMPTE IMD method is 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). Here we find differences between the three loads. The dummy 8-ohm load yielded the lowest results—roughly 0.006% from 40Hz to 250Hz. The two-way Focal yielded IMD results between 0.008% and 0.02%, while the three-way Paradigm yielded results between 0.015% and as high as 0.05%.

FFT spectrum – 1kHz (line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sine-wave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level input. We find the odd signal harmonics (i.e., 3kHz, 5kHz, 7kHz, 9kHz, etc.) dominating at around -95dBrA, or 0.002%, while the even-order harmonics (i.e., 2kHz, 4kHz, 6kHz, 8kHz, etc.) are lower, between -100dBrA, or 0.001%, down to below -120dBrA, or 0.0001%. On the left side of the main signal peak, we find the harmonics of the fundamental 60Hz peak (i.e., 120Hz, 180Hz, 240Hz, etc.), due to power-supply noise, at about -110dBrA, or 0.0003%, down to -120dBrA, or 0.0001%.

FFT spectrum – 1kHz (digital input, 16/44.1 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sine-wave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 16/44.1. Except for the second signal harmonic (2kHz) reaching -90dBrA, or 0.003%, the signal and noise distortion peaks are very similar to the FFT for the analog input above.

FFT spectrum – 1kHz (digital input, 24/96 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sine-wave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 24/96. The FFT spectrum is nearly identical within the audioband to the 16/44.1 FFT above.

FFT spectrum – 1kHz (digital input, 16/44.1 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 16/44.1 input sine-wave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, while signal and noise harmonics within the audioband are non-existent above the noise floor.

FFT spectrum – 1kHz (digital input, 24/96 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 24/96 input sine-wave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. The FFT spectrum is nearly identical within the audioband to the 16/44.1 FFT above.

FFT spectrum – 1kHz (MM phono input)

Shown above is the FFT for a 1kHz input sine-wave stimulus, measured at the output across an 8-ohm load at 10W for the MM phono input. We find the odd signal harmonics (i.e., 3kHz, 5kHz, 7kHz, 9kHz, etc.) dominating at around -95dBrA, or 0.002%, while the even order harmonics (i.e., 2kHz, 4kHz, 6kHz, 8kHz, etc.) are lower, between -100dBrA, or 0.001%, down to below -120dBrA, or 0.0001%. On the left side of the main signal peak, we find the fundamental 60Hz peak and its harmonics (i.e., 120Hz, 180Hz, 240Hz, etc.), due to power-supply noise, at about -75dBrA, or 0.02%, down to around -110dBrA, or 0.0003%.  

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sine-wave stimulus measured at the output across an 8-ohm load at 10W for the 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 second signal harmonic (100Hz) dominates at -105dBrA, or 0.006%, but even and odd signal harmonics at lower levels can be seen throughout. We also see the 60Hz power-supply related peaks at -115dBrA, or 0.0002%, and below.

FFT spectrum – 50Hz (MM phono input)

Shown above is the FFT for a 50Hz input sine-wave stimulus measured at the output across an 8-ohm load at 10W for the MM phono 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 predominant (non-signal) peak is from the 60Hz power-supply fundamental and its third harmonic (180Hz) at -75dBrA, or 0.02%. The second-order signal peak at 100Hz is at -90dBrA, or 0.003%.

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 sine-wave stimulus tone measured at the output across an 8-ohm load at 10W for the 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 -105dBrA, or 0.0006%. The third-order modulation products, at 17kHz and 20kHz, are around -85dBrA, or 0.006%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 16/44.1)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sine-wave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 16/44.1. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -105dBrA, or 0.0006%. The third-order modulation products, at 17kHz and 20kHz, are around -85dBrA, or 0.006%. We also see the main aliased peaks at 25.1kHz and 26.1kHz around -30 to 45dBrA due to the 44.1kHz sample rate (e.g., 44.1kHz-19kHz = 25.1kHz).

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 24/96)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sine-wave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 24/96. The FFT spectrum is nearly identical within the audioband to the 16/44.1 FFT above.

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

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sine-wave stimulus tone measured at the output across an 8-ohm load at 10W for the MM phono input. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at around -95dBrA, or 0.002%, while the third-order modulation products, at 17kHz and 20kHz, are around -85dBrA, or 0.006%.

Square-wave response (10kHz)

Above is the 10kHz square-wave response using the 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 i9-XR’s slew-rate performance. Rather, it should be seen as a qualitative representation of the i9-XR’s extended bandwidth. An ideal square wave can be represented as the sum of a sine wave 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. Here we can see a clean square-wave reproduction, with only slight rounding in the corners and no ringing.

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

The final graph above is the damping factor as a function of frequency. The left channel varies from around 760 down to 460 (20kHz), while the right channel varies from around 680 down to 450 (20kHz).

Diego Estan
Electronics Measurement Specialist