VINTAGE 5963 (12AU7) direct drop in variant Introduction
Very nice and quiet 5963 which is a MEDIUM-MU TWIN TRIODE. 9—PIN MINIATURE TYPE
Very little is written about these 5963 tubes.
It's practically today unknown, yet these are excellent fantastic replacements for 12AU7 tubes!
Smooth and sweet,yet bargain priced compared with many European brands!
Very smooth tube from top to bottom with no weakness!
These are a nice industrial/military upgrade variant type which is nearly identical to the standard 12AU7.
The late 1950’s, early 1960's 5963 sounds more dynamic than many of the standard 12AU7
It’s also a very good low-noise tube.
The plate voltage rating is a little lower than for a 12AU7, but for most applications, it will work fine.
It has a rugged cathode and should be quite long lived, similar to the 5814.
That specially-designed cathode is said to withstand long periods of time in cut-off without damaging the tube (cathode poisoning).
This made them a great choice for NORAD computers, which led to a good supply of them on the USA West Coast.
Use them and you will marvel at the quality and value.
They are dead-silent and seem to have an unusually long lifespan.
Very satisfied with the sound they produce.
A truly fine 12AU7 variant
Many tube audiophiles feel these can outperform most other NOS 12AU7 tubes!
In computer (and some other) service, tubes were quite often operated as switches, biased to cutoff (no plate current) for long periods of time and then turned on, while always the heater and cathode were warmed up and ready to go.
In ordinary tubes, this leads to a condition known as "cathode interface resistance" or "sleeping sickness."
The cathode interface is a layer of metal, usually nickel, between the cathode sleeve and the oxide coating that emits electrons. In ordinary tubes, under conditions of long-duration tube cutoff, it generates a growing resistance until at last the cathode "goes to sleep."
Computer tube cathodes were specially treated to survive those long periods of cutoff without developing cathode interface resistance
5963 tubes (12AU7 variants) from $25.00 each
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