Link: reviewed by Dennis Burger *SoundStage! Access* on December 1, 2021

**General Information**

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

The TA1 was conditioned for 1 hour at 1/8th full rated power (~7.5W 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 TA1 offers two line-level analog inputs (RCA); one pair of phono RCA inputs, configurable for moving magnet (MM) or moving coil (MC); one pair of RCA pre-amp outputs (full-range or high-pass at 90Hz); RCA 2.1 preamp outputs with subwoofer channel (90Hz crossover); one coaxial (RCA) and one optical (TosLink) digital input; one USB digital input; Bluetooth connectivity; two pairs of speaker-level outputs (left and right channels); and one headphone output using a 1/8″ TRS connector. For the purposes of these measurements, the following inputs were evaluated: coaxial, analog line-level, and phono (RCA, MM and MC).

Most measurements were made with a 2Vrms line-level analog input, 5mVrms MM input, 0.5mVrms MC input, and 0dBFS digital input. The volume control is variable from 0 to 80. The following volume settings yielded 10W into 8 ohms: 52 for analog line-level and digital, 67.5 for MM, and 66.5 for MC. 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 60W. For comparison, on the line-level input, a SNR measurement was also made with the volume at maximum, where only 0.192Vrms was required to achieve 60W into 8 ohms.

Based on the high accuracy of the left/right volume channel matching (see table below), the TA1 volume control is likely digitally controlled in the analog domain. The TA1 offers 0.5dB volume steps ranging from 0 to 80. Overall range is -38.4dB to +41.2dB (line-level input, speaker output).

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

Volume position | Channel deviation |

0.5 | 0.035dB |

10 | 0.04dB |

30 | 0.049dB |

50 | 0.024dB |

60 | 0.026dB |

70 | 0.037dB |

80 | 0.01dB |

**Published specifications vs. our primary measurements**

The table below summarizes the measurements published by Emotiva for the TA1 compared directly against our own. The published specifications are sourced from Emotiva’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 is set at its maximum (DC to 1MHz), assume, unless otherwise stated, 10W into 8ohms and a measurement input bandwidth of 10Hz to 90kHz, and the worst-case measured result between the left and right channels.

Parameter | Manufacturer | SoundStage! Lab |

Amplifier rated output power into 8 ohms (0.5% THD) | 60W | 62.5W |

Amplifier rated output power into 4 ohms (0.5% THD) | 100W | 89W |

THD (60W, 20Hz-20kHz, 8 ohms) | <0.02% | <0.02% (40Hz - 7kHz) |

Frequency response (analog line-level in, speaker out) | 20Hz-20kHz (±0.15dB) | 20Hz-20kHz (-0.09,-0.3dB) |

Frequency response (analog line-level, speaker out) | 5Hz-80kHz (0, -1.8dB) | 5Hz-80kHz (-0.8,-1.6dB) |

Signal-to-noise ratio (speaker out, 60W, A-weighted) | 116dB | 107.6dB |

Maximum output level (pre-out) | 4Vrms | 4.5Vrms |

Frequency response (analog line-level in, pre-out) | 5Hz-50kHz (±0.04dB) | 5Hz-50kHz (-0.06,+0.001dB) |

THD+N (analaog line-level in, pre-out @ 1kHz, 1Vrms, A-weighted) | <0.001% | <0.0017% |

IMD (analog line-level in, pre-out, SMPTE) | <0.004% | <0.0048% |

Signal-to-noise ratio (analog line-level in, pre-out 4V, A-weighted) | >120dB | 119.3dB |

Crosstalk (analog line-level in, pre-out 1V, 10kHz) | <90dB | 97.1dB |

THD+N (MM in, pre-out @ 1kHz, 1Vrms, A-weighted) | <0.015% | <0.03% |

THD+N (MC in, pre-out @ 1kHz, 1Vrms, A-weighted) | <0.06% | <0.07% |

Gain (MM, pre-out max vol) | 44dB | 36.1dB |

Gain (MC, pre-out max vol) | 55dB | 57.2dB |

Signal-to-noise ratio (MM ref 5 mV in, 60W, A-weighted) | >78dB | 82.6dB |

Signal-to-noise ratio (MC ref 0.5 mV in, 60W, A-weighted) | >58dB | 62.0dB |

Frequency response (digital in, pre-out, 16/44.1) | 5Hz-20kHz (±0.15dB) | 5Hz-20kHz (-0.06,-0.3dB) |

Frequency response (digital in, pre-out, 24/192) | 5Hz-80kHz (±0.25dB) | 5Hz-80kHz (-0.06,-3.6dB) |

THD+N (digital in, pre-out @ 1kHz, 1Vrms, A-weighted) | <0.003% | <0.005% |

IMD (digital in, pre-out, SMPTE) | <0.007% | <0.009% |

Signal-to-noise ratio (digital in 24/96, pre-out 4V, A-weighted) | >110dB | 112.9dB |

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 90kHz bandwidth):

Parameter | Left channel | Right channel |

Maximum output power into 8 ohms (1% THD+N, unweighted) | 62.5W | 62.5W |

Maximum output power into 4 ohms (1% THD+N, unweighted) | 89W | 89W |

Continuous dynamic power test (5 minutes, both channels driven) | passed | passed |

Crosstalk, one channel driven (10kHz) | -56.5dB | -60.8dB |

Damping factor | 190 | 209 |

Clipping no-load output voltage (instantaneous power into 8 ohms) | 28Vrms (98W) | 28Vrms (98W) |

DC offset | <-18mV | <-21mV |

Gain (pre-out) | 11.9dB | 11.9dB |

Gain (maximum volume) | 41.2dB | 41.2dB |

IMD ratio (18kHz + 19kHz stimulus tones) | <-72dB | <-73dB |

Input impedance (line input, RCA) | 14.2k ohms | 14.2k ohms |

Input sensitivity (for rated power, maximum volume) | 192mVrms | 192mVrms |

Noise level (A-weighted) | <84uVrms | <81uVrms |

Noise level (unweighted) | <263uVrms | <302uVrms |

Output Impedance (pre-out) | 1.5 ohms | 1.7 ohms |

Signal-to-noise ratio (full power, A-weighted, 2Vrms in) | 107.6dB | 107.6dB |

Signal-to-noise ratio (full power, unweighted, 2Vrms in) | 98.2dB | 96.8dB |

Signal-to-noise ratio (full power, A-weighted, max volume) | 99.1dB | 98.9dB |

Dynamic range (full power, A-weighted, digital 24/96) | 107.5dB | 107.5dB |

Dynamic range (full power, A-weighted, digital 16/44.1) | 95.7dB | 95.7dB |

THD ratio (unweighted) | <0.0055% | <0.0024% |

THD ratio (unweighted, digital 24/96) | <0.007% | <0.004% |

THD ratio (unweighted, digital 16/44.1) | <0.006% | <0.002% |

THD+N ratio (A-weighted) | <0.0062% | <0.0028% |

THD+N ratio (A-weighted, digital 24/96) | <0.0066% | <0.0028% |

THD+N ratio (A-weighted, digital 16/44.1) | <0.0068% | <0.0031% |

THD+N ratio (unweighted) | <0.0062% | <0.0042% |

Minimum observed line AC voltage | 123.5 VAC | 123.5 VAC |

For the continuous dynamic power test, the TA1 was able to sustain 88W into 4 ohms (1% THD) using an 80Hz tone for 500ms, alternating with a signal at -10 dBof the peak (8.8W) for 5 seconds, for 5 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 TA1 was warm to the touch, but did not cause discomfort 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 90kHz bandwidth):

Parameter | Left channel | Right channel |

Crosstalk, one channel driven (10kHz) | -56.6dB | -59.2dB |

DC offset | <-20mV | <-20mV |

Gain (default phono preamplifier) | 36.2dB | 36.1dB |

IMD ratio (18kHz and 19 kHz stimulus tones) | <-50dB | <-50dB |

IMD ratio (3kHz and 4kHz stimulus tones) | <-52dB | <-52dB |

Input impedance | 32.4k ohms | 32.3k ohms |

Input sensitivity (to max power with max volume) | 2.95Vrms | 2.95Vrms |

Noise level (A-weighted) | <0.9mVrms | <0.9mVrms |

Noise level (unweighted) | <3.7mVrms | <3.7mVrms |

Overload margin (relative 5mVrms input, 1kHz) | 23.9dB | 23.9dB |

Signal-to-noise ratio (full rated power, A-weighted) | 82.6dB | 82.6dB |

Signal-to-noise ratio (full rated power, unweighted) | 76.6dB | 76.6dB |

THD (unweighted) | <0.028% | <0.027% |

THD+N (A-weighted) | <0.038% | <0.037% |

THD+N (unweighted) | <0.055% | <0.053% |

Our primary measurements revealed the following using the phono-level input, MC configuration (unless specified, assume a 1kHz 0.5mVrms sinewave input, 10W output, 8-ohm loading, 10Hz to 90kHz bandwidth):

Parameter | Left channel | Right channel |

Crosstalk, one channel driven (10kHz) | -56.4dB | -49.8dB |

DC offset | <-20mV | <-20mV |

Gain (default phono preamplifier) | 57.2dB | 57.2dB |

IMD ratio (18kHz and 19 kHz stimulus tones) | <-50dB | <-50dB |

IMD ratio (3kHz and 4kHz stimulus tones) | <-52dB | <-52dB |

Input impedance | 124.5 ohms | 124.4 ohms |

Input sensitivity (to max power with max volume) | 262uVrms | 262uVrms |

Noise level (A-weighted) | <10mVrms | <9mVrms |

Noise level (unweighted) | <35mVrms | <35mVrms |

Overload margin (relative 0.5mVrms input, 1kHz) | 22.8dB | 22.8dB |

Signal-to-noise ratio (full rated power, A-weighted) | 62.0dB | 62.2dB |

Signal-to-noise ratio (full rated power, unweighted) | 56.8dB | 57.2dB |

THD (unweighted) | <0.032% | <0.032% |

THD+N (A-weighted) | <0.11% | <0.11% |

THD+N (unweighted) | <0.4% | <0.4% |

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sinewave, 2Vrms output, 300 ohms loading, 10Hz to 90kHz bandwidth):

Parameter | Left channel | Right channel |

Maximum output power into 600 ohms (1% THD+N, unweighted) | 72mW | 72mW |

Maximum output power into 300 ohms (1% THD+N, unweighted) | 107mW | 107mW |

Maximum output power into 32 ohms (1% THD+N, unweighted) | 83mW | 85mW |

Gain | 21.5dB | 21.5dB |

Output impedance | 95.6 ohms | 95.9 ohms |

Noise level (A-weighted) | <7.4uVrms | <12.1uVrms |

Noise level (unweighted) | <67uVrms | <219uVrms |

Signal-to-noise ratio (A-weighted, ref. max output voltage) | 117.5dB | 113.3dB |

Signal-to-noise ratio (unweighted, ref. max output voltage) | 98.5dB | 88.2dB |

THD ratio (unweighted) | <0.0014% | <0.0015% |

THD+N ratio (A-weighted) | <0.0017% | <0.0019% |

THD+N ratio (unweighted) | <0.0044% | <0.0138% |

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

In our frequency response plots above, measured across the speaker outputs at 10W into 8 ohms, the blue and red (left/right channels) traces are for the full-range output, while purple and green represents output with the 90Hz high-pass filter enabled. Full-range, the TA1 is nearly flat within the audioband (20Hz to 20kHz). At the frequency extremes, the TA1 is -0.09dB down at 20Hz and -0.3dB down at 20Hz. These data do not quite corroborate Emotiva’s claim of 20Hz to 20kHz (+/-0.15dB). Emotiva’s claim of -1.8dB at 80kHz, was not corroborated, as we measured –3.3dB at 80kHz. With the high-pass filter engaged, the -3dB point is at 90Hz, and the slope of the filter is 12dB/octave. There are two curious observations to be made with the high-pass filter. The first is a 1dB bump at around 170Hz, and the second is a reduced high-frequency extension compared to the full-range output, with a -3dB point around 45kHz, compared to roughly 80kHz without the high-pass filter enabled.

**Frequency response (8-ohm loading, line-level input, bass and treble controls)**

Above is a frequency response plot measured at the speaker-level outputs into 8 ohms, with the bass and treble controls set to maximum (blue/red plots) and minimum (purple/green plots). We see that for the bass control, the +/-10dB controls of the TA1 yielded measured results of nearly +/-11dB at 20Hz. The treble controls yielded about +9dB, and just shy of -10dB at 20kHz.

**Frequency response (2.1-channel preamplifier outputs)**

Above is a frequency response plot measured at the line-level 2.1 pre-outs, where the high-pass output is relative to 1kHz, and the subwoofer low-pass output is relative to 20Hz. We see that the -3dB point is at 90kHz, as advertised. While the high-pass filtered output exhibits a slope of 12dB/octave, the subwoofer low-pass filtered output exhibits a slope of 6dB/octave. The same 1dB bump at 170Hz is seen here for the high-pass filtered pre-output, as is seen above at the speaker-level outputs with the high-pass filter enabled. High-frequency extension on the pre-outs is not limited, and is essentially flat out to 80kHz.

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

Above is the phase response plot from 20Hz to 20kHz for the line-level input, measured across the speaker outputs at 10W into 8 ohms. The tone controls were not engaged. The TA1 does not invert polarity and exhibits, at worst, 20 degrees (at 20kHz) of phase shift within the audioband.

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

The chart above shows the TA1’s 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 16bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial 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 16/44.1 data exhibits brick-wall-type filtering, with a -3dB at 21kHz. The 24/96 and 24/192 kHz data yielded -3dB points at 44.3kHz and 48.7kHz respectively. These data do not corroborate Emotiva’s claim of 5Hz-80kHz (±0.25dB) for a 24/192 digital input.

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

The chart above shows the frequency response for the phono input (MM configuration) with maximum deviations of about -0.4/+0.5dB (20Hz/20kHz) from 20Hz to 20kHz. 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).

**Frequency response (8-ohm loading, MC phono input)**

The chart above shows the frequency response for the phono input (MC configuration), with maximum deviations of about -4.0/+0.4dB (20Hz/200Hz) from 20Hz to 20kHz.

**Phase response (MM input)**

Above is the phase response plot from 20Hz to 20kHz for the phono input (MM configuration), measured across the speaker outputs at 10W into 8 ohms. The TA1 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.

**Phase response (MC input)**

Above is the phase response plot from 20Hz to 20kHz for the phono input (MC configuration), measured across the speaker outputs at 10W into 8 ohms. The TA1 does not invert polarity. Here we find a worst case of about +40 degrees at 20Hz and -60 degrees at 200Hz and 5kHz.

**Digital linearity (24/44.1 data, filters 1-7)**

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 output of the TA1. 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. The 24/96 input data yielded near perfect results all the way down to -120dBFS, while the 16/44.1 input data were perfect from -110dBFS to 0dBFS. At -120dBFS, the 16/44.1 data were only +2.5dB (left) and +4dB (right) above reference.

**Impulse response (16/44.1 data)**

The graph above shows the impulse response for the TA1, fed to the coaxial digital input, measured at the line-level output. Emotiva’s filter implementation appears to minimize pre-ringing.

**J-Test (coaxial)**

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line level output of the SA30. The J-Test 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.

The coaxial input exhibits low-level peaks in the audioband, at -115dBrA and below. This is a good J-Test result, indicating that TA1 DAC should yield good jitter immunity.

**J-Test (optical)**

The chart above shows the results of the J-Test test for the optical digital input measured at the line level output of the SA30. The optical input exhibits low-level peaks in the audioband, at -110dBrA and below. This result is not quite as good as the was seen with the coaxial input.

**J-Test with 10ns of injected jitter (coaxial)**

Both the coaxial and optical inputs were also tested for jitter immunity by injecting artificial jitter sinewave jitter at 2kHz, which would manifest as sidebands at 10kHz and 14kHz without any jitter rejection. Despite the TA1’s good J-test results, jitter immunity proved quite poor in this test, showing clear sidebands at -70dBrA with only 10ns of injected jitter. Shown is the coaxial input result, but the optical input yielded the same result.

**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 TA1’s line-level output with white noise at -4 dBFS (blue/red), and a 19.1kHz 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 behavior of the TA1’s reconstruction filter. Only one small aliased image within the audioband, at about -110dBrA, at around 4kHz can be seen. The primary aliasing signal at 25kHz is just below -90dBrA, while the second and third distortion harmonics (38.2, 57.3kHz) of the 19.1kHz tone are at -80 and -70dBrA.

**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 find that there’s a total deviation of about 0.1 dB from no-load to 4-ohms, 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 as a load is less, deviating by just over 0.08dB 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 2kHz.

**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 and red plots are for left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 60W. The power was varied using the volume control. At 1W, the left channel outperformed the right channel by about 5dB, whereas at 10W, the opposite was observed, with the right channel outperforming the left channel by nearly 10dB from 20Hz to 1kHz. At the lower power levels, THD values were low, between 0.002% and 0.02% at 20kHz. At the rated 60W, THD values were as high as 0.3% at 20Hz, then down to 0.01% between 40Hz and 2kHz, then up to 0.03% at 20kHz. These data do not quite corroborate Emotiva’s claim of less than 0.02% at 60W from 20Hz to 20kHz.

**THD ratio (unweighted) vs. frequency at 10W (MM and MC phono inputs)**

The chart above shows THD ratios as a function of frequency plot for the phono input measured across an 8 ohms load at 10W. The MM configuration is shown in blue/red (left/right channels), and MC in purple/green (left/right channels). The input sweep is EQ’d with an inverted RIAA curve. The THD values for the MM configuration vary from around 0.1% (20Hz) down to 0.05% (1kHz), then up to 0.07% (3kHz to 20kHz). The MC THD values essentially tracked the MM values at 100Hz and above. Below 100Hz, MC THD values were higher, reaching 0.4% at 20Hz.

**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 TA1 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 ohms load (purple/green for left/right channels). The 8-ohm data generally outperformed the 4-ohm data by 5dB for the left channel, with the 8-ohm data showing a relatively flat response at 0.006-0.007% up to 20W, then up to 0.01% at the “knee” just past 50W, then hitting the 1% THD mark just past 60W. The right channel clearly outperformed the left channel into 8-ohms, by as much as 12dB or so at 5W. The right channel into 4 ohms outperformed the left by about 5dB on average, yielding around 0.005-0.007% through most of the power range, but displayed some up and down trending between 3 and 80W. The “knee” for the 4-ohm data is at around 80W, hitting the 1% THD mark around 90W.

**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 TA1 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). Overall, THD+N values for the 8-ohm load before the “knee” ranged from around 0.05% (50mW) down to about 0.005%. The 4-ohm data was similar, but 2-5 dB worse.

**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 TA1 as a function of load (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 increasing levels of THD from 8 to 4 to 2 ohms, with about a 5dB increase each time the load is halved, except at 20kHz, where the 8- and 4-ohm data merge. Overall, even with a 2-ohm load at roughly 20W, THD values were low and constant at roughly 0.02% across the audioband. Given that the TA1 is not specified to drive 2-ohm loads, these results are admirable.

**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 analog line-level input. We see that the signal’s second harmonic, at 2kHz, is at -85/-100dBrA (left/right), or 0.006/0.001%, and around -95dBrA (left/right), or 0.002%, at the third harmonic (3kHz). Several higher order signal harmonics can be seen beyond 3kHz in decreasing amplitude. The right channel outperformed the left channel at the even-order signal harmonics (2, 4, 6kHz, etc.). Below 1kHz, we see the power-supply fundamental (60Hz) at around -110/-120dBRa (left/right), or 0.0003/0.0001%, the second harmonic (120Hz) at nearly -100dBrA, or 0.001%, and several higher-order noise harmonics at lower amplitudes.

**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. Signal and power-supply noise harmonics are very similar to the analog input FFT above, but for a slightly higher noise floor due to the 16-bit dynamic range limitation.

**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. Signal and power-supply noise harmonics are very similar to the analog input FFT above, expect for a higher third signal harmonic (3kHz) amplitude compared to both the 16/44.1 and analog input, at around -90dBrA, or 0.003%.

**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, and minor power-supply related noise peaks below -110dBrA, or 0.0003%.

**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 minor power-supply related noise peaks below -110dBrA, or 0.0003%.

**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, configured for MM. We see the second (2kHz) and third (3kHz) signal harmonics dominating at around -85/-100dBrA (left/right), or 0.006/0.001%, and at -80dBrA, or 0.01%. The most significant power-supply related noise peaks can be seen at 60Hz and 180Hz at -70dBrA, or 0.03%.

**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, configured for MC. We see the third (3kHz) signal harmonic dominating at around -75dBrA, or 0.02%, followed by the fifth harmonic (5kHz) at just below -80dBrA, or 0.01%. The most significant power-supply related noise peaks can be seen at 60Hz and 180Hz at -50dBrA, or 0.3%.

**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. The most predominant (non-signal) peaks are that of the signal’s second (100Hz), third (150Hz), and fourth (200Hz) harmonic, at between -90dBrA, or 0.003%, and -100dBrA, or 0.001%. Even-order signal harmonics are worse for the left channel, showing clear peaks at 200, 300, 400, 500, 600Hz, etc. The most significant power-supply related peak is at the second harmonic at 120Hz, at -105dBrA, or 0.0006%.

**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 (MM configuration). 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 signal’s third harmonic (150Hz) at -70dBrA, or 0.03%, while the power-supply fundamental (60Hz) and third harmonic (180Hz) reach almost the same level.

**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 (MC configuration). 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 power-supply noise, both from the fundamental (60Hz) and third harmonic (180Hz), at just below -50dBrA, or 0.3%. The third signal harmonic (150Hz) is at -65dBrA, or 0.06%.

**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 -90/100dBRA (left/right), or 0.003/0.001%, while 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 (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. We find that the second-order modulation product (*i.e.*, the difference signal of 1kHz) is at -90/100dBRA (left/right), or 0.003/0.001%, while the third-order modulation products, at 17kHz and 20kHz, are higher than for the analog input at -70dBrA, or 0.03%.

**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. We find that the second-order modulation product (*i.e.*, the difference signal of 1kHz) is at -90/100dBRA (left/right), or 0.003/0.001%, while the third-order modulation products, at 17kHz and 20kHz, are higher than for the analog input at -70dBrA, or 0.03%.

**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 phono input configured for MM. We find that the second-order modulation product (*i.e.*, the difference signal of 1kHz) is at -90/100dBRA (left/right), or 0.003/0.001%, while the third-order modulation products, at 17kHz and 20kHz, are higher than for the line-level analog input at roughly -65dBrA, or 0.06%.

**Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MC 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 phono input configured for MC. We find that the second-order modulation product (*i.e.*, the difference signal of 1kHz) is at around -90dBrA, or 0.003%, while the third-order modulation products, at 17kHz and 20kHz, are the same as the MM configuration at roughly -65dBrA, or 0.06%.

**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 TA1’s slew-rate performance. Rather, it should be seen as a qualitative representation its relatively extended bandwidth. An ideal square wave 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 TA1’s reproduction of the 10kHz square wave is clean, with some softening of the edges.

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

The final graph above is the damping factor as a function of frequency. Both channels show a trend of higher damping factor at lower frequencies, with the right channel slightly outperforming the left channel. The left channel measured from around 230 down to 130 at 20kHz, while the right measured around 260 down to 150 at 20kHz. For such an affordable receiver, the damping factor figures are quite good.

*Diego Estan*

Electronics Measurement Specialist