The Difficulty of Identifying NOS Tubes: A Guide for Our Customers

What is an NOS Tube?

By definition, an NOS tube (New Old Stock) is a vacuum tube that has never been used since its production. In the fascinating world of vacuum tubes, the acronym NOS is often synonymous with superior quality and performance. These tubes are highly sought after by audiophiles and vintage electronics enthusiasts. However, determining with certainty whether a tube is truly NOS or has undergone minimal use can be a complex task, even for experts in the field. In this article, we will explore the reasons for this difficulty and how to address it.

The Challenge of Identification

• Storage Conditions: Most NOS tubes have been stored for decades in varying conditions. Even if a tube has never been used, its age and storage environment can affect its exterior appearance. Dust, humidity, and oxidation can alter the look of the tubes, making it difficult to distinguish them from used ones.
• Lack of Documentation: NOS tubes are often sold without their original packaging because they were typically intended for third-party manufacturers like Baldwin Organs, Fender, Marshall, etc. and were stored in honeycomb containers. If they were meant for end customers, the boxes might have deteriorated with age. The lack of original documentation makes it difficult to verify the tube’s history, and in some cases, labels may be faded or missing, further complicating identification.
• External Similarities: Visually, lightly used tubes can look very similar to NOS ones. A tube that has been used for a short time might not show obvious signs of wear, especially if it has been handled carefully. Even lab tests might not reveal significant differences between a NOS tube and one that has been minimally used.
• Tests and Measurements: Electrical measurements can provide clues about a tube’s condition, but they are not always definitive. The technical sheets for NOS tubes show average measured electrical values, so tubes may exhibit variations in measured values compared to reference values, while lightly used tubes can still fall within acceptable average parameters to be considered NOS. Therefore, measurement tests do not always guarantee an accurate identification.

What Does This Mean for Our Customers?

At Vacuum Tubes Treasures, we are committed to providing high-quality tubes and ensuring maximum transparency with our customers. Despite the challenges, we do our best to correctly identify NOS tubes through careful visual inspection, measurement tests, and, when possible, available documentation.

We advise our customers to purchase tubes from reliable sources and to be aware of the inherent difficulties in identifying NOS tubes. Our priority is your satisfaction, and we are always available to answer your questions and provide support.

Kind regards from the Staff of Vacuum Tubes Treasures