Calibration Glossary & FAQ


• Calibration: the comparison of Instrument performance to a standard of known accuracy.
• Uncertainty: no measurements can be perfect – uncertainty is expressed as a range of values in which the true value is estimated to lie, within a given statistical confidence. (NPL)
• Traceability: ability to demonstrate an unbroken chain of comparisons all with stated uncertainties ending with a National Standards Agency – NIST (VIM – International Vocabulary of Basic and General Terms in Metrology)
• Accreditation: demonstrated compliance with a standard – validated by a recognized third party agency. Acts as a basis for Mutual Recognition Agreements (MRA) with accreditation agencies in other countries.


What is the calibration process?
1. Customer submits an Order Request form online or via fax. AP and Customer agree on a date to ship the unit to the factory and pricing is confirmed.
2. When the unit arrives, AP visually inspects the unit and performs an incoming Self-Check. If the unit is non-functional, it will be sent to the service department for evaluation. If the unit is functional, it goes to the calibration lab for its initial calibration with the result of this calibration generating the “as received “ calibration report. The unit then goes to the service department for updates, minor repairs, and adjustment for optimum performance. The unit then returns to the cal lab for a final calibration, from which the results are issued as the “as shipped” calibration report.
3. When the unit has successfully passed the “as shipped” calibration, the unit is returned to the customer with a description of any repairs or updates that were performed, as well as copies of the “as received” and “as shipped” calibration reports.

How much does the calibration cost?
Calibration prices vary depending on the instrument and warranty status. Please contact Audio Precision Service for a quote.

What is an Accredited Calibration?
Accreditation certifies that Audio Precision’s Calibration Lab has been audited by a recognized third party Accrediting agency to verify the lab meets operational and technical requirements. Audio Precision Calibration Services has been accredited under ISO 17025 by the American Association for Laboratory Accreditation (A2LA). A2LA is Full Member of the International Laboratory Accreditation Cooperation – ILAC, which serves as the world’s principal international forum for the development of laboratory accreditation practices and the recognition of competent test facilities worldwide. In the past some calibration customers have assumed that they could only obtain calibration services from providers that were registered under ISO 9001. This perception was based on the false premise that only ISO 9001-registered calibration providers operate under a recognized quality management system. ILAC in conjunction with ISO and IAF have issued a joint communiqué clarifying that calibration providers that are accredited under ISO 17025 do in fact meet the recognized quality management systems requirements under ISO 9001:2008. For further details and information see the ILAC-ISO Partnership.

Which instruments have calibration service available?
All current models of analyzers plus System Two can be calibrated. Support for DCX-127, AUX-0025, AUX-0100, SWR-2755 and other accessories is not currently available. System One is not supported.

How long does the calibration take?
The estimated time for Accredited Calibration of all instruments is two weeks from the date of the arrival of the instrument. Audio Precision does offer a one week Expedited Service for an additional charge.

I just ordered a new instrument. Do I have to pay extra for the calibration?
An Accredited Calibration is included with all new instruments.