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SOFSCI SoundSweeper back and front

 Click on the image for a larger description of the connectors and the main functionality.

SOFSCI SoundSweeper Technical description


A free-field measurement microphone aimed for DIY audio enthusiasts for acoustic measurements of loudspeakers and listening rooms, based on an omnidirectional electret microphone capsule (ECM capsule). The microphone body is an 8mm brass tube withSounds of Science - SOFSCI - SoundSweeper logo a gold plated connector for the most reliable connection to a pre-amplifier / soundcard.



Electret condenser microphone (ECM)
Directional Characteristic: Non-directional (omni directional)
Sensitivity: -32dBV ± 3dB @ 1kHz/1Pa (RL=2kohm, V bias=3V)
S/N ratio: 74dB @ 1kHz, A-weighted
Operating voltage: 3V..4V recommended (1.5V min .. 10V max)
Comes bundled with a round plastic mounting fixture with 1/4'' UNC thread (used for most digital camera stands etc). Can be delivered with a 1/2" fixture instead upon request.
Frequency response deviation from flat when not using an individual calibration file +4 / -2dB from 20Hz to 22000Hz
The SOFSCI SoundSweeper comes with an individually measured calibration file
Individual calibration file allows reaching a deviation from flat response of
±2dB 10Hz to 19Hz
±1dB 20Hz to 20kHz
±1.5dB 20kHz to 24kHz

The calibration data is supplied as a text file.
Extracted sample from calibration file around 10kHz is below:
Freq          Mag        Phase
8448.79          0.5          0.0
8633.99          0.6          0.0
8823.24          0.6          0.0
9016.64          0.7          0.0
9214.29          0.8          0.0
9416.26          0.8          0.0
9622.66          0.9          0.0
9833.59          0.9          0.0
10049.14          1.0          0.0
10269.41          1.0          0.0
10494.51          1.0          0.0
10724.55          1.0          0.0
10959.63          1.0          0.0
11199.86          1.0          0.0

Soundcard / Pre-amplifier


16 Bit/48 kHz USB stereo interface
USB bus powered
"Class Compliant” USB audio interface. Works with Windows built-in driver
ASIO driver for Windows XP/Vista/Win7 available from Miditech 
2x TRS inputs
HI-Z Guitar/Bass input
LINE input
MIC input with 3.5V Bias for electret microphones,
Adjustable microphone gain for Left MIC input
Signal activity LED for input (signal activity / overload indication)
Input signal attenuation pots for Left and Right input
2x TRS outputs
Left LINE out is useable as stereo headphone output
Also included: USB-cable, Magix Samplitude SE and IK Multimedia Amplitube 2 Duo

Modifications carried out on this card are as follows:

Output impedance series limiting resistors changed to 470ohm.
L/R input buffer stage before AD conversion changed from 13.5dB gain to 0dB gain
Left channel MIC input gain modified to be variable by adjustment pot on front panel. (Right channel MIC input has a default 20dB fixed gain)
48V microphone phantom power modified to 3.5V suitable for electret condenser microphones
MIC input microphone bias resistors changed to 2.2kohm from original 6.8kohm.
Series capacitors changed in various paths to make the frequency response flatter down to 10Hz for subwoofer measurements etc.