Solid State Power Amp Reviews

I tested the Schiit Tyr with my Audio Precision SYS2722 system. I preconditioned the amplifier by following the CEA's recommendation of operating it at one-eighth the specified power into 8 ohms for 30 minutes. At the end of that time, the heatsinks were hot, at 121.3°F (49.6°C), though the top panel was just warm at 103.9°F (39.9°C).

The Schiit's voltage gain is specified as 22×, or 28dB; I measured 27.55dB into 8 ohms for both the balanced and unbalanced inputs. The Tyr preserved absolute polarity (ie, was noninverting) with both input types. Both the balanced and unbalanced input impedances are specified as 47k ohms. I measured a still-high 21.5k ohms for the unbalanced input at 20Hz and 1kHz, dropping to 18.1k ohms at 20kHz. The balanced input impedance was 43.2k ohms at low and middle frequencies and 40.2k ohms at the top of the audioband.

The Schiit's output impedance was a very low 0.09 ohm at 20Hz and 1kHz, increasing slightly to 0.124 ohm at 20kHz. (These figures include the series impedance of 6' of spaced-pair loudspeaker cable.) The modulation of the amplifier's frequency response, due to the Ohm's law interaction between this source impedance and the impedance of our standard simulated loudspeaker, was therefore negligible, at ±0.1dB (fig.1, gray trace). The response into an 8 ohm resistive load (fig.1, blue trace) was down by 1dB just above 100kHz, though the increasing output impedance at very high frequencies means that the ultrasonic rolloff into 4 ohms (magenta) and 2 ohms (red) was greater. The Tyr's reproduction of a 10kHz squarewave into 8 ohms (fig.2) was superb, with no overshoot or ringing.

Measured with the unbalanced input shorted to ground, the amplifier's unweighted, wideband signal/noise ratio was an excellent 88.4dB ref. 1W into 8 ohms. This ratio improved to 96.7dB when the measurement bandwidth was restricted to 22Hz–22kHz and to 101.4dB when A-weighted. This last S/N ratio is very close to the specification of 120dBA when referenced to the maximum power. While spuriae were present in the Schiit's noisefloor at the 60Hz power-supply frequency and its harmonics (fig.3), these were negligible at –100dB and below, ref. 1W into 8 ohms.

The Schiit Tyr is specified as being able to deliver 200W into 8 ohms (23dBW) and 350W into 4 ohms (22.43dBW). With our definition of clipping, which is when the output's percentage of THD+noise reaches 1%, the Tyr exceeded its specified powers, clipping with a 1kHz signal at 252W into 8 ohms (24dBW, fig.4) and at 360W into 4 ohms (22.55dBW, fig.5). The THD+N was very low below actual waveform clipping, though the trace in fig.5 has a peculiar discontinuity above 200W. I repeated this test and found this behavior repeatable. I suspect it is related to the amplifier's protection circuitry, though I didn't notice any flashing of the front-panel lights.

I examined how the percentage of THD+noise changed with frequency at 20V, which is equivalent to 50W into 8 ohms and 100W into 4 ohms. The THD+N was very low in the midrange into 8 ohms (fig.6, blue trace) but rose in the low bass and top octaves, and into 4 ohms (red).

The Schiit's distortion with 1kHz into 8 ohms was predominantly the third harmonic (fig.7), though the second and fourth harmonics were higher with a 50Hz signal into the same load (fig.8), at –80dB (0.01%) and –90dB (0.003%). These harmonics were lower in level at the same voltage into 4 ohms (fig.9) and were joined by the third harmonic at –88dB (0.004%). When the amplifier drove an equal mix of 19 and 20kHz tones at 50W into 8 ohms (fig.10), the second-order difference product at 1kHz lay at a very low –87dB (0.004%), with higher-order intermodulation products still lower in level, at –97dB. At the same voltage into 4 ohms, the 1kHz product dropped to –90dB; though the products at 18kHz and 21kHz were higher in level, this was a still-low –83dB.

The Schiit Tyr offers superb measured performance.—John Atkinson