August 2006
Bryston B100 SST
Integrated Amplifier: Measurements
All amplifier measurements are performed
independently by BHK Labs. Please click to learn
more about how we test amplifiers there. All measurement data, including graphical
information displayed below, are the property of SoundStage! and Schneider
Publishing Inc. Reproduction in any format is not permitted.
 Measurements were made at 120V AC line voltage with both
channels being driven; measurements made on left channel unless otherwise noted.
 This integrated amplifier does not invert polarity.
 AC line current draw:
 at idle: 0.76A
 in standby: 0.00A
 Input sensitivity for 1W output into 8 ohms, volume at
maximum: 24.8mV
 Input impedance @ 1kHz: 47.6k ohms
 Output impedance at 50Hz: 0.026 ohms
 Gain, output voltage divided by input voltage, volume at
maximum: 114.2X, 41.2dB
 Output noise, 8ohm load, 1kohm input termination, Lch/Rch
 Volume control at reference position
 wideband: 0.70mV, 72.1dBW / 0.66mV, 72.6dBW
 A weighted: 0.37mV, 77.7dBW / 0.33mV, 78.7dBW
 Volume control full clockwise
 wideband: 1.86mV, 63.6dBW / 1.84mV, 63.7dBW
 A weighted: 0.67mV, 72.5dBW / 0.65mV, 72.8dBW
 Volume control full counterclockwise
 wideband: 0.63mV, 73.0dBW / 0.59mV, 73.6dBW
 A weighted: 0.36mV, 77.9dBW / 0.32mV, 78.9dBW
Power output with 1kHz test signal
 8ohm load at 1% THD: 140W
 8ohm load at 10% THD: 165W
 4ohm load at 1% THD: 191W
 4ohm load at 10% THD: 213W
General
The Bryston B100 SST is a mediumpower solidstate
integrated amplifier. The overall gain of this unit is on the high side for an integrated
amplifier of the type so popular these days  the kind with a passive selector switch and
volume control preceding a power amplifier. The B100 SST has an active linelevel preamp
stage within, and the overall gain is appropriate for this topology.
Chart 1 shows the frequency response of the amp with
varying loads. The highfrequency response is moderately wide with an approximate 3dB
point of 80kHz. Output impedance, as judged by the closeness of spacing between the curves
of opencircuit, 8ohm and 4ohm loading, is quite low in the audio band. The usual
NHTdummyload curve is not shown as the variations in the response would not appear. The
variation with the NHT dummy load in the audio range is less than +/0.05dB  a
negligible amount. The frequency response was quite independent of volumecontrol setting.
This plot was made with the reference volumecontrol position as set for 0.5V input to
produce 5W output into an 8ohm load.
Chart 2 illustrates how total harmonic distortion plus
noise vs. power varies for 1kHz and SMPTE IM test signals and amplifier output load.
Amount of distortion is satisfactorily low in this design, rising out of the noise at
1020W.
Total harmonic distortion plus noise as a function of
frequency at several different power levels is plotted in Chart 3. Amount of rise in
distortion at high frequencies is admirably low  practically nonexistent.
Damping factor vs. frequency is shown in Chart 4 and is of
a value and nature typical of many solidstate amplifiers, being high up to midhundreds
of Hz and then rolling off with frequency.
A spectrum of the harmonic distortion and noise residue of
a 10W 1kHz test signal is plotted in Chart 5. The magnitudes of the ACline harmonics are
low and simple, and intermodulation components of line harmonics with signal harmonics are
also low. Visible signal harmonics consist of second, third, and fourth harmonics.
Chart 1
 Frequency Response of Output Voltage as a Function of Output Loading 
Red line: open circuit
Magenta line: 8ohm load
Blue line: 4ohm load
Chart 2  Distortion as a Function
of Power Output and Output Loading 
(line up at 50W to determine lines)
Top line: 8ohm SMPTE IM
Second line: 4ohm SMPTE IM
Third line: 8ohm THD+N
Bottom line: 4ohm THD+N
Chart 3  Distortion
as a Function of Power Output and Frequency 
8ohm output loading
Cyan line: 100W
Blue line: 30W
Magenta line: 10W
Red line: 1W
Chart 4  Damping Factor
as a Function of Frequency 
Damping factor = output impedance divided into 8
Chart 5  Distortion and
Noise Spectrum 
1kHz signal at 10W into an 8ohm load
