Lyngdorf Audio TDAI-2210 Streaming Integrated Amplifier Measurements

Link: reviewed by Roger Kanno on SoundStage! Hi-Fi on May 1, 2026

General Information

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

The Lyngdorf Audio TDAI‑2210 was conditioned for 1 hour at 1/8th full rated power (~13W 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 TDAI‑2210 offers five sets of line-level analog inputs (four RCA, one XLR), one phono input (MM only), three digital coaxial (RCA) inputs, one digital optical (TosLink) input, one USB digital input, left/right pre-outs and sub-outs, one set of speaker level outputs and one headphone output over 1/8″ TRS connector. Bluetooth and streaming connectivity are also offered. For the purposes of these measurements, the following inputs were evaluated: digital coaxial, analog (XLR) line-level and phono, as well as the headphone output.

Most measurements were made with a 2Vrms line-level analog input and 0dBFS digital input. The signal-to-noise (SNR) measurements were made with the default input signal values but with the volume set to achieve the rated output power of 105W into 8 ohms. For comparison, on the line-level input, a SNR measurement was also made with the volume at maximum. The TDAI‑2210 offers a speaker limiter function, which was left off, and a subsonic filter, which was also left off, though frequency plots can be found herein showing its effect.

Based on the accuracy and repeatability of the left/right volume channel matching (see table below), the TDAI‑2210 volume control is operating in the digital domain. The TDAI‑2210 overall volume range is from -78dB to +38dB (line-level input, speaker output). It offers 1200 0.1dB volume steps. Due to the  TDAI‑2210’s digital amplifier technology, which exhibits excessive noise above 20kHz, our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements including FFTs and THD versus frequency (20Hz to 6kHz). Frequency response measurements utilize a DC to 1 MHz input bandwidth.

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

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Lyngdorf Audio for the TDAI‑2210 compared directly against our own. The published specifications are sourced from Lyngdorf’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth was extended to 1MHz, assume, unless otherwise stated, 10W into 8ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the line-level analog input and digital coaxial input (unless specified, assume a 1kHz sinewave at 2Vrms or 0dBFS, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the TDAI‑2210 was able to sustain 295W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (16.1W) for 5 seconds, for 5 continuous minutes without inducing the fault protection circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the top and sides of the TDAI‑2210 were only slightly warm to the touch.

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 22.4kHz bandwidth):

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sinewave, 2Vrms input/output, 300 ohms loading, 10Hz to 22.4kHz bandwidth):

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

In our frequency response plots above (relative to 1kHz), measured across the speaker outputs at 10W into 8 ohms, the blue/red traces are with speaker limiter off, and purple/green with speaker limiter on. With the speaker limiter engaged, there is a steep roll-off below 30Hz—the -3dB point is at roughly 18Hz. Without the limiter, the TDAI‑2210 is only -0.1dB at 20Hz. At high frequencies, the TDAI‑2210 is up almost 1dB at 20kHz, with a continuous rise peaking at +2.5dB at 40kHz. This is, however, speaker-load dependent. Into 4 ohms, there is a dip at high frequencies (about -0.5dB at 20kHz). 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.

Frequency response (8-ohms loading, line-level analog input, ADC on)

Above is a frequency plot showing the sub-outs (purple/green, relative to 20Hz)) and the main speaker outputs (blue/red, relative to 1kHz) configured with a 120Hz crossover point. We find the two plots converging at -6dB at 120Hz.

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 TDAI‑2210 digitizes the analog inputs, and therefore exhibits excessive phase shift (-17000 degrees at 20kHz) when including the timing delays of the ADC process.

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

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, showing only excess phase shift by removing the ADC timing delays. The TDAI‑2210 yielded only about +25 degrees of phase shift at 20Hz, and 0 degrees at 20kHz.

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 relatively flat response from 20Hz to 20kHz, and worst-case channel-to-channel deviations of roughly 0.1dB at 3kHz to 20kHz. There is also a 0.3-0.4dB dip in the response between 3kHz and 10kHz.

Phase response (MM input, excess)

Above is the excess phase response plot from 20Hz to 20kHz for the MM phono input, measured across the speaker outputs at 10W into 8 ohms. The TDAI‑2210 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 +70 degrees at 20Hz and -10 degrees at 6-8kHz.

Frequency response vs. input type (8-ohm loading, left channel only)

The chart above shows the TDAI‑2210’s frequency response (relative to 1kHz) as a function of input type measured across the speaker outputs at 10W into 8 ohms. The two green traces are the same analog input data from the speaker-level frequency-response graph above. The blue and red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial input, the purple and green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and the pink and orange traces are for a 24/192 dithered digital input signal. At low frequencies, all signals yielded the same response. The extra attenuation for the digital signals is due to the analyzer’s 10Hz high-pass filter that required activation to deal with excessive noise with DC coupling. The -3dB points are: 21kHz for the 16/44.1 data; 46kHz for the 24/96, 24/192, and analog data.

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 pre-outputs of the TDAI‑2210, where 0dBFS was set to yield 2Vrms. For this test, 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. The 24/96 data were at +0.5/-1dB at -120dBFS, while the 16/44.1 data were +2/+1dB at -120dBFS.

Intersample headroom (+3dB 11.025kHz sinewave at 24/44.1 at -3/-1.5/0dBFS) — PASS

The chart above shows the results of an intersample headroom test for the coaxial digital input, measured at the line-level pre-outputs of the TDAI‑2210, where a standard 0dBFS sinewave was set to yield 2Vrms (2.83Vp or 5.66Vpp). For this test, the DAC is fed a test file consisting of a 11.025kHz sinewave sampled at 24/44.1 at +3.01dB. This is achieved without digital clipping by using a sinewave at exactly one quarter the sample rate, completely avoiding sampling at the peaks and troughs of the waveform. The test file is then run through the DAC at -3, -1.5, and 0dBFS (purple/green/orange plots). A DAC with built-in headroom will be able to reconstruct all three sinewaves cleanly with no distortion, with the highest amplitude sinewave at 4Vp (3.01dB above the standard 2.83Vp for a 0dBFS input signal). A DAC without built-in headroom will show significant clipping (up to ~10% THD) when the test file is fed at -1.5 and 0dBFS. The DAC in the TDAI‑2210 passed this test.

Intersample headroom (+3dB 11.025kHz sinewave at 24/44.1 at -3/-1.5/0dBFS) — ICC disabled

The chart above shows the results of an intersample headroom test for the coaxial digital input, measured at the line-level pre-outputs of the TDAI‑2210, where a standard 0dBFS sinewave was set to yield 2Vrms (2.83Vp or 5.66Vpp), but this time with the Intersample Clipping Correction (ICC) feature in the TDAI-1120 disabled. The DAC is fed a test file consisting of a 11.025kHz sinewave sampled at 24/44.1 at +3.01dB. This is achieved without digital clipping by using a sinewave at exactly one quarter the sample rate, completely avoiding sampling at the peaks and troughs of the waveform. The test file is then run through the DAC at -3, -1.5 and 0dBFS (purple/green/orange plots). Without the ICC feature, the -1.5 and 0dBFS sinewaves show significant clipping.

Impulse response (24/44.1 data)

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 TDAI‑2210. We see a typical symmetrical sinc function response.

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-outputs of the TDAI‑2210 where 0dBFS is set to 2Vrms. J-Test was developed by Julian Dunn the 1990s. It is a test signal—specifically, a -3dBFS undithered 12kHz squarewave sampled (in this case) at 48kHz (24 bits). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz squarewave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sinewave (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 sinewave jitter by the Audio Precision, to show how well the DAC rejects jitter.

Here we see an average J-Test result, with several peaks in the audioband, ranging from -125dBFS down to -150dBFS.

J-Test (optical)

The chart above shows the results of the J-Test test for the optical digital input measured at the line-level pre-outputs of the TDAI‑2210. The optical input yielded similar results compared to the coaxial input.

J-Test (coaxial, 10ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line- level output of the TDAI‑2210, with an additional 10ns of 2kHz sinewave jitter injected by the APx555. The telltale peaks at 10kHz and 12kHz are not present in the spectrum.

J-Test (coaxial, 100ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line level output of the A25, with an additional 100ns of 2kHz sinewave jitter injected by the APx555. The telltale peaks at 10kHz and 12kHz are still not present in the spectrum. This is an indication that despite the less than pristine J-Test result, jitter immunity in the TDAI‑2210 DAC should be robust.

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

The chart above shows a fast Fourier transform (FFT) of the TDAI‑2210’s line-level pre-outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1. The steep roll-off around 20kHz in the white-noise spectrum shows the filter is of the brickwall-type variety. There are a few very low-level aliased image peaks within the audioband at the -125dBrA and below level. The primary aliasing signal at 25kHz is highly suppressed at -120dBrA, while the second and third distortion harmonics (38.2, 57.3kHz) of the 19.1kHz tone are higher at -100dBrA.

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 50kHz. 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 see that the deviations between no load and 4 ohms are not insignificant at roughly 0.8dB (2.6dB at 20kHz). This is a poor result and an indication of a high output impedance, or low damping factor, especially at high frequencies. With a real speaker load, deviations measured lower at roughly 0.4dB.

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

The chart above shows THD ratios at the speaker-level outputs into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue and red plots are for the left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 105W. The power was varied using the TDAI‑2210 volume control. The 10W THD ratios were the lowest, with a constant  0.005-0.006% across the sweep. The 1W THD ratios were higher and relatively flat across the sweep, right around 0.01%. At 105W, THD ratios ranged from 0.015% at lower frequencies (25Hz to 100Hz), then down to 0.005% up to 6kHz.

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. For this test, the input sweep is EQ’d with an inverted RIAA curve. The THD values for the MM configuration vary from around 0.02% (20Hz) down to 0.005% from 60Hz to 6kHz.

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

The chart above shows THD ratios measured at the speaker-level outputs of the TDAI‑2210 as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD ratios into 4 and 8 ohms are remarkably close (within 2-3dB). They range from 0.01% at 50mW, down to 0.005% in the 5 to 100W range. The “knee” into 8 ohms can be found just past the rated output power of 105W, while the 4-ohm “knee” can be seen right around the rated power output of 210W. The 1% THD marks were hit at 135W and 264W into 8 and 4 ohms.

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

The chart above shows THD+N ratios measured at the speaker-level outputs of the TDAI‑2210 as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD+N ratios into 4 and 8 ohms are remarkably close (within 2-3dB). They range from 0.1% at 50mW, down to 0.005% in the 30 to 100W range.

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 TDAI‑2210 as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 20W at the output into 8 ohms (and roughly 40W into 4 ohms, and 80W 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 a roughly 5-10dB increase in THD from 8 to 4 ohms, and less than 5dB between 4 and 2 ohms. These ranged from roughly 0.005% into 8 ohms, 0.01% into 4 ohms, and 0.02% into 2 ohms. All three traces are fairly constant across the frequency sweep.

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 TDAI‑2210 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). Generally, THD ratios were similar across all three loads, except between 20 and 50Hz, where the two-way speaker yielded higher values (0.15% at 20Hz). From 50Hz to 6kHz, the resistive dummy load yielded a constant 0.01%, while the speaker load results ranged from 0.01 to 0.02%.

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 TDAI‑2210 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 2.5kHz 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). We find a constant 0.02% for the resistive load, and a range of 0.01% to 0.07% for the speaker loads.

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 TDAI‑2210 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 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). We find very similar IMD ratios into all three loads, 0.04% from 40Hz to 250Hz, 0.03% from 300Hz to 500Hz, and 0.006% from 500Hz to 1kHz.

FFT spectrum – 1kHz (XLR 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 analog line-level XLR input. We see that the signal’s second, third, fourth, sixth, and eighth (2/3/4/6/8kHz) harmonics dominate at -95dBrA, or 0.002%. The fifth, seventh, ninth, and eleventh (5/7/9/11kHz) harmonics are around the -105dBrA, or 0.0006%, level. On the right side of the signal peak, we find no power-supply-related noise peaks.

FFT spectrum – 1kHz (RCA 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 analog line-level RCA input. We see effectively the same FFT compared to the XLR input above.

FFT spectrum – 1kHz (MM phono 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 analog phono MM input. We see that the signal’s second, third, fourth, sixth, and eighth (2/3/4/6/8kHz) harmonics dominate at -95dBrA, or 0.002%. The fifth, seventh, ninth, and eleventh (5/7/9/11kHz) harmonics are around the -105dBrA, or 0.0006%, level. On the right side of the signal peak, we find two dominant power-supply-related noise peaks at 60Hz (-80dBrA, or 0.01%) and 180Hz (-85dBrA, or 0.006%).

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

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 coaxial digital input, sampled at 16/44.1. The signal harmonics are similar in amplitude compared to the line-level analog FFTs above, with the exception of the 3rd (3kHz) harmonic, which dominates at -80dBrA, or 0.01%. As with the line-level analog FFTs, there are no power-supply-related noise peaks on the left side of the signal peak.

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

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 coaxial digital input, sampled at 24/96. We see essentially the same result as with 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 sinewave 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, with no signal harmonics above the -135dBrA 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 sinewave 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, and a single signal harmonic at 2kHz just barely above the -140dBrA noise floor.

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 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. We see that the signal’s even-ordered harmonics (100/200/300/400Hz) dominate at roughly -90dBrA, or 0.003%. The odd-ordered harmonics  (150/250/350Hz) are lower at around the -100 to -110dBrA, or 0.001-0.0003%, level. There are no power-supply-related noise peaks.

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 MM phono 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 (non-signal) peak is the 60Hz fundamental power-supply noise peak at -80dBrA, or 0.01%. The highest signal harmonic is at 100Hz, 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 sinewave 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 -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are just above the -90dBrA, or 0.003%, level.

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

Shown above is the FFT of the speaker-level output of the TDAI‑2210 with the APx 32-tone signal applied to the analog input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at and below the low -125dBrA, or 0.00006%, level.

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 sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 16/44.1 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are just above the -85dBrA, or 0.006%, level.

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 sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 24/96 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are just above the -85dBrA, or 0.006%, level.

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 sinewave 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 -80dBrA, or 0.01%, while the third-order modulation products, at 17kHz and 20kHz, are lower at just above -90dBrA, or 0.003%.

Squarewave response (10kHz)

Above is the 10kHz squarewave 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 TDAI‑2210’s slew-rate performance. Rather, it should be seen as a qualitative representation of the TDAI‑2210’s low bandwidth. An ideal squarewave 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. In this case, we find a very poor representation of a squarewave, plus the high frequency oscillator (400Hz) in the switching amplifier riding on top of the waveform.

Squarewave response (10kHz, 250kHz bandwidth)

Above is the same 10kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms, but with a restricted analyzer input bandwidth of 250kHz to filter out the 400kHz oscillator. Once again, due to the TDAI‑2210’s low bandwidth, we find a very poor representation of a squarewave.

Squarewave response (10kHz, 250kHz bandwidth)

Above is the 1kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms, with a restricted analyzer input bandwidth of 250kHz to filter out the 400kHz oscillator. Here we find a cleaner squarewave shape, but an abundance of noise in the plateaus due the rise in the noise floor at above 30kHz.

FFT spectrum of 400kHz switching frequency relative to a 1kHz tone

The TDAI‑2210’s class-D amplifier relies on a switching oscillator to convert the input signal to a pulse-width modulated (PWM) squarewave (on/off) signal before sending the signal through a low-pass filter to generate an output signal. The TDAI‑2210 oscillator switches at a rate of about 400kHz, and this graph plots a wide bandwidth FFT spectrum of the amplifier’s output at 10W into 8 ohms as it’s fed a 1kHz sinewave. We can see that the 400kHz peak is quite evident, and at -20dBrA. There are also two peaks at 800kHz and 1.2MHz (the second and third harmonic of the 400kHz peak), at -50/-60dBrA. In addition, there is a rise in the noise floor above 30kHz, peaking at -60dBrA. Those peaks—the fundamental and its harmonics—are direct results of the switching oscillators in the TDAI‑2210 amp modules. The noise around those very-high-frequency signals are in the signal, but all that noise is far above the audioband—and therefore inaudible—and so high in frequency that any loudspeaker the amplifier is driving should filter it all out anyway.

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

The final graph above is the damping factor as a function of frequency. We can see here a constant damping factor of around 80 from 20Hz to 2kHz. The damping factor then dips to a low of 10 at 20kHz.

Diego Estan
Electronics Measurement Specialist