Technical Comparison: NTi Audio (XL2 / XL3) and Bedrock (SM50 / SM90 / AM100)
In measurements on Voice Alarm Systems (PAVA / SAA), the NTi XL2 has been widely used for many years—which in practice sometimes creates the impression that the STIPA measurement method itself originated from NTi. In fact, the STI and STIPA methods were developed in the Netherlands at the TNO research institute. From this exact scientific environment emerged the Dutch company Bedrock (Embedded Acoustics BV), which has been manufacturing its own handheld analyzers for speech intelligibility, room acoustics, and building acoustics for several years.
Since we have worked with both the NTi XL2 and Bedrock instruments in our laboratory and rental fleet for years, we regularly receive questions regarding their practical differences. The NTi XL2 is undoubtedly a very solid and reliable measuring instrument. Because its hardware platform has been on the market for over 15 years, its operation is still based on a classic monochrome display with push-button and rotary wheel controls.
With the NTi XL3, NTi Audio now offers a newly developed model featuring a modern touch display and network connectivity. However, it is positioned in a significantly higher price segment and is primarily aimed at classical environmental noise monitoring and building acoustics. For users looking for a compact handheld instrument with touch operation specifically for PAVA acceptance testing (STIPA) and room acoustics, an objective look at the system differences is therefore worthwhile.
Differences in Design, Operation, and Licensing
| Feature | NTi Audio XL2 | Bedrock SM50 / SM90 / AM100 | Practical Relevance |
|---|---|---|---|
| Manufacturer & Focus | NTi Audio AG (Liechtenstein). Focus on pro audio / event technology, electroacoustic testing, and sound level measurement. | Embedded Acoustics BV (Netherlands), founded as a spin-off from the environment of the TNO research institute (developers of the STI standard). | Both systems reliably meet the normative requirements of IEC 60268-16 and IEC 61672-1. |
| Accuracy Class (IEC 61672-1) | Depends on the separately selected measurement microphone: Class 2 (with M4261) or Class 1 (with M2230). | Fixed assignment per model including matching microphone: • SM50: Class 2 (incl. BAM20) • SM90 / AM100: Class 1 (incl. BAMT1) | For most PAVA and room acoustics measurements, Class 2 is sufficient. Where tenders specify Class 1, corresponding systems are available on both sides. |
| Display & Operating Concept | Backlit monochrome display (160 × 160 pixels). Navigation via function keys and side rotary wheel. | Color touch display (3.5" on SM50/SM90; high-resolution capacitive display on AM100) with direct graphical selection. | The monochrome display of the XL2 is easy to read in bright sunlight, though button navigation takes some practice. The color touch display on Bedrock facilitates quick orientation across measurement menus. |
| Battery & Power Supply | Replaceable Li-Ion battery; can also be operated with 4× standard AA batteries or rechargeable AA cells. | Integrated NiMH battery (SM50/SM90), rechargeable via the built-in USB interface (mains adapter or external USB power bank). | Quickly swapping to AA batteries is a practical advantage of the XL2. Conversely, the NiMH battery in the Bedrock SM series is insensitive to extended storage and is not subject to Li-Ion dangerous goods transport regulations. |
| Software Modules & Licensing Model | Modular Option Concept: Functions such as STIPA measurement or the Extended Acoustic Pack (for 1/3-octave RT60 and uncompressed .wav recordings instead of ADPCM) are purchased as separate license options. | Full Feature Set Factory-Included: STIPA (Ed. 4 & Ed. 5), Full STI (65 s), 1/3-octave reverberation time RT60 (T20/T30/EDT), building acoustics, FFT, 1/3-octave RTA, and uncompressed .wav recording are included in the base price. | Whereas on the XL2 only the specifically required packages are unlocked, on the Bedrock SM50 and SM90 all measurement functions are available out of the box without subsequent licensing costs. |
| PTB Pattern Approval & Legal Verification | The former national German PTB pattern approval of the XL2-TA (21.21 / 12.02) was subject to the transitional period under § 62 MessEG until 31.12.2024. Previously initial-verified existing units can still be re-verified; for new units, initial verification on this basis is no longer possible. | Standards-compliant per IEC 61672-1 Class 2 (SM50) and Class 1 (SM90 / AM100) incl. factory calibration, without German PTB pattern approval. | 1. Fundamental Rule: Legal metrology law applies exclusively to pure sound level measurement (dB SPL) in official/legal proceedings—not to STIPA or reverberation time RT60. 2. Current Alternative for Legal Verification: If a newly verifiable instrument is required today for official noise measurements, systems with current type examination certificates such as the NTi XL3 or Svantek SV 971A / SV 977C are used. |
Note on Legal Verification of Sound Level Meters (Initial vs. Subsequent Verification)
In technical consultations, users often consider purchasing an instrument such as the NTi XL2 (or older models like the Svantek SV 979) as a precaution so that it can later be legally verified for official measurements if needed. Two factual points should be noted here:
- Expiration of the Transitional Period for Legacy Approvals on 31.12.2024: According to the official approval list of the Physikalisch-Technische Bundesanstalt (PTB), instruments such as the NTi XL2-TA (approval mark
21.21 / 12.02) or the Svantek SV 979 (21.21 / 13.02) held a national pattern approval under the former German Verification Act. Pursuant to § 62 (1) MessEG, the ten-year transitional period for placing new measuring instruments on the market based on these legacy approvals ended on 31.12.2024. While existing instruments already on the market that were previously initial-verified can continue to be re-verified, initial verification of newly acquired instruments of these types is no longer provided for. - No Legal Verification for STIPA and Room Acoustics: By law, sovereign legal verification always applies solely to the function as a sound level meter per IEC 61672. For speech intelligibility measurements (STIPA per IEC 60268-16) or reverberation time (RT60 per ISO 3382), no pattern approval or legal verification exists. Within quality management systems (ISO 9001 / DIN 14675), proof of measurement accuracy is provided via regular factory calibration or accredited DAkkS / ISO 17025 calibration.
Required Components for a Ready-to-Measure Complete System
Because manufacturer pricing models differ (modular kit system vs. all-inclusive package), it is advisable to compare all five positions for an equivalent configuration when evaluating quotes:
| Position | Modular System (NTi Audio XL2) | Complete System (Bedrock SM50 · Art. 345676) |
|---|---|---|
| 1. Handheld Analyzer (Base Unit) | On request | 2095,80 € Net (2494,00 € incl. 19% VAT) Catalog ↗ |
| 2. Detachable Class 2 Measurement Microphone + XLR Cable | On request (separate item) | Included in delivery (BAM20) |
| 3. STIPA Measurement Function (IEC 60268-16) | On request (separate license option) | Included in delivery (Ed. 4 & Ed. 5 + Full STI) |
| 4. 1/3-Octave Reverberation Time (RT60), FFT & Uncompressed .wav Recording | On request (Option Extended Acoustic Pack) | Included in delivery |
| 5. System Carrying Case | On request (optional accessory) | Included in delivery |
| Total Price (ready-to-measure configuration): | On request Please request current pricing for the NTi XL2 and its associated options directly from NTi Audio. | 2095,80 € Net (2494,00 € incl. 19% VAT) (Alternatively: 1931,93 € Net / 2299,00 € incl. 19% VAT as Demo New unit without case) |
* All prices in EUR Net excl. VAT and Gross incl. VAT plus shipping costs (FCA Dresden). B2B offer for commercial, government & professional users.
Decision Guide: Which System Fits Your Application?
Bedrock SM50 / SM90 / AM100
Ideal for users looking for a compact handheld analyzer with a color touchscreen where the measurement microphone, STIPA (Ed. 4 & 5), 1/3-octave reverberation time (RT60), and WAV recording are already completely included in the base unit.
Svantek (SV 971A / SV 977D) & NTi XL3
Recommended when the measuring instrument is also to be used for official legal sound level measurements alongside room acoustic tasks, where a current PTB pattern approval and initial legal verification are required.
PC Measurement System Akulap
Required when speech intelligibility is to be determined via the room impulse response (indirect method using Chirp per ISO 18233) or in open-plan offices per ISO 3382-3.
Turnkey Bedrock Test Kit
Calculate immediately: Assemble your turnkey Bedrock test kit in our online configurator.
On-Site Practical Trial
Compare both devices yourself on your jobsite: Rent the Bedrock SM50 (199,00 € Net / 236,81 € incl. 19% VAT per week with 100% rental credit) or the NTi XL2 (255,00 € Net / 303,45 € incl. 19% VAT per week as project rental).