For 25 years, NOA has set the benchmark for professional audio migration workflows, trusted by archives, broadcasters, and preservation institutions worldwide. Building on decades of audio engineering expertise and operational experience, AzimuthGuide fundamentally changes how stereo tape head azimuth is analyzed, documented, and adjusted. The process moves from subjective listening-based correction to objective, visual, and repeatable measurement.
From Subjective Listening to Measured Precision
Traditional stereo tape azimuth alignment has relied heavily on operator experience, high-frequency hearing capability, and iterative monitoring techniques such as mono summing or phase inversion. These methods introduce variability and can even degrade signal quality if misapplied.
AzimuthGuide replaces this approach with a measurement-assisted workflow that delivers a quantitative azimuth value expressed in degrees normalized to 10 kHz, accompanied by a real-time validity indicator. Alignment decisions are therefore based on signal analysis rather than auditory interpretation.
Accurate azimuth alignment no longer depends on exceptional hearing or years of experience, but on clear and measurable analysis.
Azimuth alignment should not depend on who is sitting at the machine. With AzimuthGuide, we have turned a subjective listening task into a precise, measurable, and repeatable process. That is a major step forward for standardized audio preservation.
says Peter Kuhnle, NOA CTO
Evidence-Driven Methodology
The AzimuthGuide methodology is grounded in structured evaluation and statistical validation.
In controlled testing involving eight participants, eight randomized azimuth offsets per method, and four adjustment approaches, a total of 256 measurement points were collected. Content included stereo music, mono voice, and classical recordings, each verified by a 10 kHz control tone at the end of the test sequence.
Key findings:
- Among purely manual methods, phase-inverted mono summing performed best statistically
- The stereo monitoring method with goniometer support showed the highest variability
- In 25 percent of cases, the stereo manual method worsened the azimuth setting, with deviations up to 136°
- Measurement-assisted alignment eliminated performance differences between professionals and non-professionals
- Adjustment time was comparable to manual methods, while providing higher precision
Importantly, manual methods showed dependency on hearing threshold and operator age. AzimuthGuide removes this dependency entirely.
Designed for Industrial Digitization
AzimuthGuide integrates seamlessly into the established NOARecord workflow.
- Real-time visual alignment guidance
- Quantified azimuth value in degrees at 10 kHz
- Validity scoring for measurement confidence
- Repeatable and documentable results
- Reduced listening fatigue in high-volume operations
In large-scale digitization environments processing dozens or hundreds of carriers per day, fatigue and subjective variation represent measurable risk factors. AzimuthGuide transforms azimuth adjustment into a controlled, traceable, and standardized procedure.
…and for Verification of Previous Digitization Efforts
AzimuthGuide is not limited to real-time tape transfer within NOARecord. The same analysis methodology will also be made available in WaveScanner, NOA’s server-side audio processing engine.
WaveScanner is part of NOA’s file ingest solution and provides a collection of algorithmic analyses identical to those implemented in NOARecord. With the integration of the AzimuthGuide methodology, WaveScanner will extend beyond its original normalization purpose, enabling institutions to retrospectively analyze previously digitized stereo tape files and objectively verify whether azimuth alignment was correctly set at the time of transfer. For institutions managing large collections, this capability introduces a new layer of quality assurance. Historical transfers can be systematically reviewed, documented, and, where necessary, flagged for re-transfer based on objective signal analysis.
AzimuthGuide therefore supports not only precision during new digitization workflows, but also transparency and verification across past preservation efforts.
Availability
AzimuthGuide is included in the latest NOARecord release and available to existing and new customers.
In addition to its real-time use during tape transfer, AzimuthGuide will be available within WaveScanner as part of a jobDB-based setup for large-scale file analysis, allowing institutions to process existing digital collections to be systematically scanned for azimuth accuracy, with results documented and evaluated against defined tolerance windows, providing a structured verification tool for past digitization projects.
For institutions digitizing or managing stereo tape collections at scale, azimuth alignment is no longer limited to the transfer moment. It becomes a measurable, documentable parameter across both new ingest workflows and existing digital holdings.
