Measurements of Seta Preamplifier Performance

(Above) Seta™ Rear Connection Panel

We'd like to share the measurements showing the superb performance of the first production run of Seta Moving Coil preamplifier modules, focusing on the frequency bandwidth and signal fidelity. Many more to follow, as we approach shipping the Seta preamplifier.

Of course, the "last word" in the evaluation of audio products should be done by using the world's best measurement equipment: listening! However, we believe that careful measurements are essential, if only to insure that the shipping product actually conforms to the designer's original specification.

Click on the image the in left column to see the full-size image.

1.2 kHz* square wave. Top trace, input (before 1000:1 attenuator); bottom trace, Seta output, 52 dB gain, 600 ohm load.

20 Hz square wave, 600 ohm load.

Magnitude FFT of 1 kHz sine wave showing low distortion (< 0.001% THD at 1 kHz) and noise. Output level 3 volts peak to peak into 600 ohm load; 38 dB gain.

Magnitude FFT of 10 kHz sine wave showing low distortion (< 0.003% THD at 10 kHz) and noise. Output level 2.7 volts peak to peak into 600 ohm load; 38 dB gain.

Magnitude FFT of 1 kHz sine wave showing low distortion (< 0.001% THD at 1 kHz) and noise. Output level 4.6 volts peak to peak into 600 ohm load; 58 dB gain.

Magnitude FFT of 10 kHz sine wave showing low distortion (< 0.003% THD at 10 kHz) and noise. Output level 7.4 volts peak to peak into 600 ohm load; 58 dB gain.

Small signal 300 kHz sine wave test. Input (top) level 300 microvolts (input measured before 1000:1 attenuator).

Seta output (52 dB gain) is the bottom trace. 600 ohm load.

Small signal 2 megahertz sine wave test. Input (top) level 300 microvolts (input measured before 1000:1 attenuator).

Seta output (52 dB gain) is the bottom trace. 600 ohm load. This demonstrates Seta's ability to faithfully reproduce out-of-band signals.

Large signal 300 kHz sine wave test. Input (top) level nominally 5 millivolts.

Seta output (52 dB gain) is the bottom trace. 600 ohm load.

Seta can drive a 600 ohm load even at 300 kHz to over 2 volts peak to peak (over 4 volts peak to peak balanced).

Large signal 2 megahertz sine wave test. Input (top) level nominally 5 millivolts.

Seta output (52 dB gain) is the bottom trace. 600 ohm load.

Seta can drive a 600 ohm load - even at 2 megahertz - to over 2 volts peak to peak (over 4 volts peak to peak balanced).

Large signal 300 kHz sine wave test, balanced output measurement.

Seta output (58 dB gain), 600 ohm load, over 6.4 volts clean peak to peak output at 300 kHz.

Large signal 2 megahertz sine wave test, balanced output measurement.

Seta output (58 dB gain), 600 ohm load, over 6.2 volts clean peak to peak output, even at 2 MHz.

This corresponds to a slew rate of nearly 80 volts per microsecond, much faster than comparable (in terms of noise and gain) phono or microphone preamplifiers.

*While the choice of 1.2 kHz for the square wave test might seem to be unusual, this also is the frequency of the very clean square wave output signal that's conveniently made available by the sampling oscilloscope used for the tests.

Click on the image the in left column to see the full-size image.
	1.2 kHz* square wave. Top trace, input (before 1000:1 attenuator); bottom trace, Seta output, 52 dB gain, 600 ohm load.
	20 Hz square wave, 600 ohm load.
	Magnitude FFT of 1 kHz sine wave showing low distortion (< 0.001% THD at 1 kHz) and noise. Output level 3 volts peak to peak into 600 ohm load; 38 dB gain.
	Magnitude FFT of 10 kHz sine wave showing low distortion (< 0.003% THD at 10 kHz) and noise. Output level 2.7 volts peak to peak into 600 ohm load; 38 dB gain.
	Magnitude FFT of 1 kHz sine wave showing low distortion (< 0.001% THD at 1 kHz) and noise. Output level 4.6 volts peak to peak into 600 ohm load; 58 dB gain.
	Magnitude FFT of 10 kHz sine wave showing low distortion (< 0.003% THD at 10 kHz) and noise. Output level 7.4 volts peak to peak into 600 ohm load; 58 dB gain.
	Small signal 300 kHz sine wave test. Input (top) level 300 microvolts (input measured before 1000:1 attenuator). Seta output (52 dB gain) is the bottom trace. 600 ohm load.
	Small signal 2 megahertz sine wave test. Input (top) level 300 microvolts (input measured before 1000:1 attenuator). Seta output (52 dB gain) is the bottom trace. 600 ohm load. This demonstrates Seta's ability to faithfully reproduce out-of-band signals.
	Large signal 300 kHz sine wave test. Input (top) level nominally 5 millivolts. Seta output (52 dB gain) is the bottom trace. 600 ohm load. Seta can drive a 600 ohm load even at 300 kHz to over 2 volts peak to peak (over 4 volts peak to peak balanced).
	Large signal 2 megahertz sine wave test. Input (top) level nominally 5 millivolts. Seta output (52 dB gain) is the bottom trace. 600 ohm load. Seta can drive a 600 ohm load - even at 2 megahertz - to over 2 volts peak to peak (over 4 volts peak to peak balanced).
	Large signal 300 kHz sine wave test, balanced output measurement. Seta output (58 dB gain), 600 ohm load, over 6.4 volts clean peak to peak output at 300 kHz.
	Large signal 2 megahertz sine wave test, balanced output measurement. Seta output (58 dB gain), 600 ohm load, over 6.2 volts clean peak to peak output, even at 2 MHz. This corresponds to a slew rate of nearly 80 volts per microsecond, much faster than comparable (in terms of noise and gain) phono or microphone preamplifiers.