The anatomy of numbers
The number in the first position denotes the type of base that
the valve has:
1 = misc. base types
2 = miniature 10-pin base (or loctal)
3 = octal base
4 = rimlock (8-pin)
5 = magnoval
6 = enne-al (9-pin)
7 = wire ended
8 = noval
9 = miniature 7-pin
The number in the second position denotes a randomly assigned
model designator. When all ten numbers in the second position are used a 1 is placed
before the first position. This might cause some confusion, since the number in the first
position denotes the type of base that the valve has.
There is no relationship between e.g. an EF83 and an EF183
although it is a good bet that the 1xx number is a later (but different) model. In
pentodes odd numbers tend to be used for vari-mu/remote cutoff types, even numbers for
sharp cutoff types. e.g. EF183 and EF184. |
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Other things to look for
Sometimes the numbers are inserted after the first letter e.g.
E88CC or E180F. This is usually an indication of that the valve is of a special quality
type - low noise or long life or close tolerances for some parameter.
A trailing S has a similar meaning e.g. ECC803S. The added
zero between the two numbers has no consistent meaning.
Sometimes it indicates a special quality valve as in the
previous example, sometimes it is used to indicate a new model e.g. the ECC804 is not
an ECC84 at all. |