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AmpConnect 621

AmpConnect 621


AmpConnect 621 simplifies your multichannel audio test with 6 inputs, 2 line outputs and one amplifier output, along with microphone power, full TEDS support, impedance measurement and digital I/O in a single USB-connected unit. With sample rates up to 192kHz, it is ideal for the measurement of high resolution audio devices.


  • 6 channels of audio test in a single unit with just one USB connection to the computer
  • Unique high accuracy impedance measurement independent of your input channels
  • Line and Amplifier outputs and Digital I/O
  • Plug-and-play setup with SoundCheck and TEDS support
  • Error-free operation with all control via SoundCheck – no buttons!
  • Clear visual level indicators on front panel
  • Excellent ground loop immunity compared to discrete components
  • Rugged and rack-mountable for demanding production environments

Seamless Integration
AmpConnect 621 integrates seamlessly with SoundCheck® (version 18 and higher). Setup is fully automatic; plug and play functionality auto populates all the input channels in the software with sampling rate, calibration values etc.

TEDS Support
TEDS support enables automatic identification, configuration and calibration of microphones and accelerometers. This saves time during initial setup and any time hardware is changed, as such data does not need to be entered manually.

Error-free Operation
Control is via the software only, either via a test sequence or from a dedicated control panel. This eliminates the possibility of accidental change to the settings as there are no buttons on the front panel, making it an ideal choice for production line applications. Front panel LEDs offer a clear visual indication that microphone, DUT, and power amplifier levels are all operating within maximum dynamic range, and show which amplifier output is selected.

Multiple inputs make this interface ideal for any application where multiple microphones are needed, from the R&D lab to the production line. It is the ideal partner to a 6-microphone array for automotive measurements or sound power measurements. Other applications include, for example, measuring devices with multiple speakers such as smart phones or sound bars.

Two line outputs and one amplifier output enable stereo signal output, and enable the signal to be routed to either powered signal sources (e.g. powered artificial mouths, active loudspeakers, headphones, stereo amplifiers, automotive head units) or unpowered sources such as speakers or artificial mouths that require an amplifier. The makes the interface extremely flexible for use in a wide variety of test configurations.

Impedance Measurement
AmpConnect 621 features Listen’s unique high-accuracy impedance measurement system. This is carried out entirely within the unit, and configured via the software; no external connections are required. It does not require any of the input channels to be used, so all 6 remain free for audio measurements.

Like all Listen test hardware, AmpConnect 621 is designed for production environments. It is 17” wide by 2-Units (3.5”) high x 11.5” deep, and may be rack mounted (optional rack-mounting kit available). A fingerprint-resistant matte finish ensures that it always looks great!

Watch Demo

USB Audio Interface
USB 2.0, Windows and macOS HID compliant
ASIO low-latency audio driver (Windows only)
USB Audio Class 2 (macOS, Windows 10)
Sample Rates: 44.1, 48, 88.2, 96, 176.4 & 192 kHz; 24 bits

Mic/Line Inputs
Connectors: 6 BNC unbalanced inputs
TEDS Support (IEEE 1451.4)
Maximum Input Level: 20 Vp (14 Vrms) at -20 dB gain
Input Impedance: 100 kΩ
Gain Settings: -20, 0, +10, +20, +30 dB
Bias Settings: Off / SCM / IEPE
SCM (Electret) Bias: 10 VDC, 7.5 kΩ
IEPE Bias: 28 VDC @ 4 mA constant current
Frequency Response: 20 Hz – 20 kHz +0.1/-0.4 dB;
10 Hz – 90 kHz +0.1/ -1.1 dB
Equivalent Input Noise: <14 uV (at 20 Hz – 20 kHz BW) THD+N: < -80 dB at -1 dBFS, 44.1 kHz sample rate, 0 dB gain (at 20 Hz – 20 kHz BW) Crosstalk: >100 dB at 10 kHz
Inter-channel Phase*: ±0.5°

Line Outputs
Connectors: 2 BNC unbalanced outputs
Maximum Output Level: 4 Vp (2.82 Vrms)
Frequency Response: 20 Hz – 20 kHz ± 0.1 dB;
10 Hz – 90 kHz +0.1/ -2.0 dB
THD+N: < -97 dB at -1 dBFS, 44.1 kHz sample rate  (at 20 Hz – 20 kHz BW) Crosstalk: >110 dB at 10 kHz, 0 dB gain
Inter-channel Phase*: ± 0.15°

Amplifier Output
Number of Outputs: 2, in parallel, switchable (Off, A, B, A+B)
Connectors: 4 binding posts (A: Red/Black; B: Yellow/Black)
Output Power: 50 W RMS into 4 Ω, 25 W RMS into 8 Ω
Frequency Response: 20 Hz – 20 kHz ± 0.1 dB; 10 Hz – 90 kHz +0.1/ -2.0 dB
THD+N: -82dB (0.008%) typical @ 1W, 44.1kHz sample rate (at 20 Hz – 20 kHz BW); -90 dB (0.003%) typical @ 25 W, 8Ω

Loudspeaker Impedance Measurement
Measurement range 2.5-250 Ω

Without rack mounting flanges: 17”/432mm wide x 3.5”/90mm (2-U) high x 11.5”/292mm deep
Weight: 7.275 lbs (3.3kg) approx.
Power: 100-240 VAC 50/60 Hz, 140 Watts

AmpConnect 621 Datasheet