HS5661A Precision Sound Level Meter
| Origin | Jiangsu, China |
|---|---|
| Manufacturer Type | Authorized Distributor |
| Origin Category | Domestic (China-made) |
| Model | HS5661A |
| Pricing | Available Upon Request |
| Microphone | 1/2″ (12.7 mm) Prepolarized Condenser |
| Frequency Weighting | A- and C-weighting |
| Time Weighting | Fast (F), Slow (S), Impulse (I) |
| Detector | True RMS with Peak Factor ≥10 |
| Compliance | IEC 61672-1:2013 Class 1 & GB/T 3785.1–2010 Type 1 |
| Range Control | Manual, 3-range switchable |
| Dynamic Range per Range | >60 dB |
| Measurement Ranges | 20–90 dB, 50–110 dB, 70–130 dB (re 20 µPa) |
| Display | Large-backlight LCD with analog bar graph and real-time L<sub>A</sub>, L<sub>C</sub>, L<sub>peak</sub> indication |
| Output Interfaces | AC output (rms), RS-232 serial interface |
| Calibration | Compatible with Class 1 acoustic calibrators (e.g., 1 kHz, 94 dB or 114 dB) and pistonphones |
| Power Supply | 4×AA (LR6) alkaline batteries (24 h typical operation) |
| Dimensions (L×W×H) | 230 × 72 × 30 mm |
| Mass | 300 g (including batteries) |
| Operating Temperature | –10 °C to +50 °C |
| Enclosure Material | ABS engineering plastic |
| Connectivity | RS-232 enables remote control, synchronized multi-unit networked acquisition, and PC-based data logging |
Overview
The HS5661A Precision Sound Level Meter is a compact, Class 1-compliant acoustical measurement instrument engineered for high-fidelity environmental and occupational noise assessment. Based on true RMS digital detection architecture and utilizing a 1/2″ pre-polarized condenser microphone, the HS5661A delivers metrologically traceable sound pressure level (SPL) measurements across three manually selected input ranges. Its design adheres strictly to the performance requirements of IEC 61672-1:2013 (Class 1) and GB/T 3785.1–2010 (Type 1), ensuring compliance with international regulatory frameworks governing environmental noise monitoring, industrial hygiene evaluations, and product noise certification. The instrument employs analog-digital hybrid signal processing: analog amplification and filtering precede high-resolution ADC conversion, followed by real-time digital weighting and time-averaging—minimizing drift and enabling stable readings even under fluctuating thermal or electromagnetic conditions.
Key Features
- Class 1 accuracy per IEC 61672-1:2013 and GB/T 3785.1–2010, validated across full operational temperature range (–10 °C to +50 °C)
- True RMS detector with peak factor ≥10, supporting reliable capture of impulsive and transient noise events (e.g., impact noise, firearm discharges, machinery startup transients)
- Simultaneous A- and C-frequency weighting, enabling comparative analysis of low-frequency energy content and human-perceived loudness
- Three selectable time weightings: Fast (125 ms), Slow (1 s), and Impulse (35 ms rise / 1.5 s decay), aligned with ISO 8596 and ANSI S1.4 standards
- Three manually switched input ranges (20–90 dB, 50–110 dB, 70–130 dB re 20 µPa), each offering >60 dB linear dynamic span and independent overload/underrange indicators
- Backlit LCD with dual-mode display: numeric SPL readout plus analog-style bar graph for intuitive real-time trend interpretation
- RS-232 serial interface supporting ASCII protocol for remote command execution (e.g., range selection, weighting activation, data polling) and synchronized multi-meter deployments
- Robust ABS polymer housing (230 × 72 × 30 mm, 300 g), optimized for field portability and mechanical durability in industrial environments
Sample Compatibility & Compliance
The HS5661A is calibrated and verified for use with standardized Class 1 acoustic calibrators (94 dB and 114 dB at 1 kHz) and pistonphone sources, satisfying daily verification requirements under ISO 9001, ISO/IEC 17025, and OSHA 1910.95. It supports measurement of broadband noise, tonal components, and intermittent signals from diverse sources—including rotating machinery, HVAC systems, transportation infrastructure, construction equipment, and consumer appliances. Its A-weighted range (20–130 dB) covers ambient urban noise (30–50 dB), office environments (50–60 dB), industrial workspaces (80–105 dB), and extreme impulse events (e.g., jet takeoff at 140 dB peak, measured via C-weighting). All calibration records, firmware revision logs, and configuration parameters are accessible via RS-232 for audit trail generation in GLP/GMP-regulated settings.
Software & Data Management
The HS5661A communicates via standard RS-232 (TTL-level, 9600 bps, no parity, 8N1) using a documented ASCII command set. Third-party software (e.g., LabVIEW VI libraries, Python pySerial scripts, or custom Windows/Linux applications) can trigger measurements, retrieve LAeq, LCpeak, and time-history datasets at user-defined intervals (100 ms to 1 s resolution), and log timestamped records with metadata (range, weighting, time constant). Data export supports CSV and plain-text formats compatible with Excel, MATLAB, and noise mapping platforms (e.g., SoundPLAN, CadnaA). Firmware updates and configuration backups are performed via serial interface, preserving calibration constants and user preferences across maintenance cycles. No proprietary drivers or cloud dependencies are required—ensuring long-term interoperability and data sovereignty.
Applications
- Environmental noise mapping around airports, highways, railways, and urban development zones per EU Directive 2002/49/EC and EPA Methods 1, 2, and 3
- Ongoing compliance monitoring for occupational noise exposure under OSHA 29 CFR 1910.95, EU Directive 2003/10/EC, and ISO 9612
- Product noise certification testing for household appliances, power tools, and automotive components per ISO 3744, ISO 3746, and SAE J1211
- Acoustic validation of noise control interventions (barriers, enclosures, damping treatments) via before/after Leq comparisons
- Educational laboratory instruction in acoustics, vibration, and environmental engineering curricula
- Field verification of building envelope sound insulation (ISO 140-4, ISO 140-5) when used with calibrated reference sources
FAQ
Does the HS5661A support integrating sound exposure level (SEL) or equivalent continuous sound level (LAeq) calculations?
Yes — internal firmware computes LAeq,T and SEL over user-defined measurement durations (1 s to 24 h) using true RMS integration and A-weighted input. Results are displayed and retrievable via RS-232.
Is external power required for RS-232 communication?
No — the RS-232 interface operates from internal battery power. An optional external 6 V / 100 mA DC supply may be used for extended stationary deployments.
Can the instrument be recalibrated in-field without returning to a lab?
Field recalibration requires a traceable Class 1 acoustic calibrator and adherence to IEC 61260-1 procedures; however, full metrological recalibration (sensitivity, linearity, frequency response) must be performed by an ISO/IEC 17025-accredited laboratory.
What is the measurement uncertainty budget for the HS5661A at 1 kHz and 94 dB?
At reference conditions (23 °C, 50% RH), expanded uncertainty (k=2) is ±0.3 dB for sensitivity, ±0.2 dB for linearity, and ±0.1 dB for frequency response deviation — consistent with IEC 61672-3 Annex B guidance.
Is the RS-232 protocol compatible with modern USB-to-serial adapters?
Yes — standard FTDI- or CP2102-based USB-to-RS232 adapters (with proper null-modem wiring if needed) are fully supported under Windows, macOS, and Linux.
