Do NOS tubes built to medical or military specifications sound better?
Some of these tubes are visually different than the regular counterparts. They may have red tips to indicate medical grade , while others say JAN on the labels.
Is it Worth paying a premium for this? Or just marketing by the tube sellers?
Thanks
There are two topics:
- tubes manufactured to military specs
- tube screened and selected for specific applications
From what I have seen, the red tip medical and instrument grade are regular production tubes that underwent further screening to find the mostly closely matched, least noisy, least microphonic. In the 12AX7 and 12AU7s I have used in phono stages or CD players, these have always been preferred over the same tube that was not screened.
A 5692 is a 6SN7 that was built for military and industrial applications. Compared with a 6SN7, the 5692 is ruggedized with additional support rods, rated for 10,000 hour life, close triode section balance, shock resistance, harsh temperatures, and stability. For me, these have also performed well.
The ruggedizing means lower noise and microphonics - always a plus for a tube.
As stated above, it depends on the tube. Some military tubes are just production runs with special marking and packaging. Other tubes had specific materials or processes and screening for selection.