I. Overview
The MegaSig PM 6681 is a high-end audio analyzer specifically designed for acoustic testing . It features 2 channels of analog signal input and 2 channels of analog signal output, supports both differential and pseudo-differential signals, and uses a USB bus as its communication interface. With its abundant channel resources and superior hardware specifications, the PM 6681 is positioned to deliver high-quality acoustic testing performance, perfectly meeting the stringent acoustic testing needs of consumer electronics products during the R&D or mass production stages.
II. Core Functions and Technological Advantages
The PM 6681 boasts an industry-leading acoustic measurement hardware architecture, with key technological advantages as follows:
1. High-quality analog input and expansion capabilities:
This device offers 2 line inputs, allowing for both direct line input and connection to an external IEPE constant current source exciter. When paired with the PM 0084 signal conditioning amplifier, it can condition sensors requiring IEPE power, such as measurement microphones, artificial ears, and accelerometers. Its input voltage range of +/- 125Vp easily handles high dynamic range audio signals.
2. Flexible analog outputs and high-power drive capability:
Two line output channels are provided, allowing engineers to choose between direct line output or output via connection to a power amplifier. This design easily drives high-power loads such as artificial mouths or speakers. The output voltage range is +/- 8Vrms in single-ended mode and up to +/- 16Vrms in differential mode. With external resistors, the maximum output power is 1.56W for a 4-ohm load and 1.125W for an 8-ohm load.
3. Exceptional signal-to-noise ratio and ultra-low noise floor:
The system employs a high-order Δ−Σ type ADC and DAC with 24-bit precision, supporting a wide sampling rate from 1kHz to 192kHz. It delivers exceptional signal purity.
- Extremely low idle noise: At a sampling rate of 48 kS/s, the typical idle noise of the input and output is only 1.4 uVrms .
- Ultra-high signal-to-noise ratio (SNR): The typical SNR values for both analog input (AI) and analog output (AO) are up to 122 dB (measured at fs=48kS/s).
- Low total harmonic distortion plus noise (THD+N): Input THD+N can be as low as -107 dB , and output THD+N can be as low as -106 dB .
- Extremely low crosstalk: Crosstalk between input channels is as low as -138 dB , effectively avoiding signal interference during multi-channel parallel measurements.
4. Extreme Frequency Response Flatness:
For acoustic measurements, a flat frequency response is fundamental to ensuring data accuracy. The PM 6681 exhibits extremely low flatness error at the input (20 Hz – 20 kHz) under 192 kS/s sampling rate and DC coupling, remaining within +/- 0.008 dB ; the output (10 Hz – 10 kHz) error is also less than +/- 0.01 dB .
III. Usage Scenarios
Based on its high-precision transmission and reception capabilities, the PM 6681 is particularly suitable for the following engineering scenarios:
- Mass production testing for consumer electronics products: acoustic testing stations for production lines requiring high production capacity and high stability, such as TWS true wireless earbuds, smart speakers, and microphone arrays.
- Acoustic sensor conditioning and acquisition: precise data analysis is performed in conjunction with measurement microphones, artificial ears (such as testing headphone frequency response) and piezoelectric accelerometers (such as structural vibration measurement).
- Excitation of loudspeakers and electroacoustic components: The output terminal drives an artificial mouth to simulate standard human voice, or combines a power amplifier to drive loudspeaker units for frequency response and distortion measurement.
IV. Specifications
- Channel configuration: 2-channel analog acquisition (AI) / 2-channel analog output (AO)
- Bus and transmission methods: USB bus, DMA data transfer
- Resolution and sampling rate: 24-bit, supporting sampling rates from 1 kHz to 192 kHz.
- Hardware connector type: The signal terminals use industry-standard BNC and CANNON connectors, and the external trigger terminals use an SMB interface.
- Maximum input voltage: +/- 125 Vp
- Input impedance: Single-ended 600 ohms / 100 kohm; Differential 600 ohms / 200 kohm
- Maximum output voltage: +/- 8 Vrms (single-ended) / +/- 16 Vrms (differential)
- Main unit dimensions: 440 × 350 × 88 mm (Length × Width × Height)
- Applicable operating temperature: -20℃ to 50℃
V. Conclusion
The MegaSig PM 6681 is a high-end audio analyzer that perfectly combines the 122 dB high signal-to-noise ratio required by top-tier laboratories with a robust hardware design suitable for production line automation. Whether you are performing precise capture of weak acoustic signals or need to stably drive high-power electroacoustic components, the PM 6681 provides an extremely clean, low-distortion measurement foundation.