Low Noise, Low Distortion and Flat Response for Loudspeaker, Headphone and Microphone MeasurementAPx1701 Transducer Test Interface
The APx1701 Transducer Test Interface is an APx accessory device that integrates instrument-grade amplifiers and microphone power supplies for designers and production test engineers seeking clear insight into the behavior of their electroacoustic devices.
Primarily designed for electroacoustic testing, the system drives loudspeakers and headphones with dedicated power amplifiers, enables impedance measurements, and provides power to measurement microphones and microphones under test. Its functions are integrated with the APx500 audio measurement software and a connected APx analyzer. It requires a B Series or legacy APx analyzer and is supported by APx500 audio measurement software version 4.3 or later.
Quiet, Clean and Flat – A New Standard in Amplifier Performance
With an industry-leading signal-to-noise ratio (SNR) of 134 dB, the APx1701 provides 20 dB of fixed-gain amplification from DC to 100 kHz. In the frequency range of 10 Hz to 20 kHz, the APx1701’s residual THD+N is ≤ -100 dB (80 kHz BW), and frequency response is ±0.08 dB (DC-coupled). The system’s power amplifiers are configured as two independent channels, with power ratings up to 100 W for a single channel into 8 Ω. Voltage taps across integrated current-sense resistors in the amplifier outputs enable easy impedance measurements.
For microphones, either as measurement mics or as the device under test (DUT), the APx1701 is equipped with pairs of balanced and unbalanced microphone inputs. The balanced inputs include switchable +48 V phantom power, while the unbalanced inputs support switchable CCP (Constant Current Power) and are TEDS-capable (Transducer Electronic datasheet).
Integrated Analog, Digital and Electro-Acoustic Testing
The increasing complexity of audio devices (wireless Bluetooth speakers or active noise-canceling headphones, for example) is driving ever-more complicated test scenarios, especially if engineers have to repeatedly switch measurement instruments.
As an electroacoustic test accessory, the APx1701 is directly integrated with APx500 audio measurement software and, when paired with any B Series or legacy APx analyzer, provides an integrated platform capable of evaluating the performance of electroacoustic devices as well as their analog and digital components.
Whether in the lab characterizing a design’s performance or conducting QA-testing on the production line to ensure products meet their specifications, confidence in the resulting measurements is key.
Like the APx500 Series audio analyzers it is designed to complement, the APx1701 is a calibrated instrument under ISO / IEC 17025:2005 and all new units ship with an Accredited Calibration. Calibration provides documented and traceable verification that instruments meet or exceed all of their published specifications.
SPECIFICATIONS & REQUIREMENTS
100 W (1 channel into 8 Ω)
60 W (1 channel into 4 Ω)
30 Vrms (2 channels into ≥15 Ω)Frequency Range
DC to 100 kHzFrequency Response
±0.08 dB (10 Hz to 20 kHz, DC-coupled)
±0.30 dB (20 kHz to 50 kHz)
±0.80 dB (50 kHz to 100 kHz)Voltage Gain
20.0 dB [x10]Residual Noise
≤7.5 µVrms (22 kHz BW)
≤13 µVrms (80 kHz BW)Signal-to-Noise Ratio
≈134 dB (ref 30 Vrms output)Output Impedance
≈0.13 Ω (0.1 Ω current sense resistor in series with the – output terminal)Residual THD+N
≤ –100 dB, 10 Hz to 20 kHz (80 kHz BW)
Balanced and Unbalanced (2 each)Balanced Mic Inputs
2 female XLR
Switchable +48 V phantom powerUnbalanced Mic Inputs
Switchable CCP (4 mA, +24 V)
10 Vpk Balanced
5 Vpk UnbalancedResidual Noise
Determined by analyzer; inputs passively switched
≤ –78 dB + 1 µV to 20 kHz