4K7B designation on pot for AH MOD2 master module

[musika]

The schematic I have says dual 4K7B  pot for master volume control.  Was there a different designation for pots in the UK back in the mid 1970's when this console was built?  Should this dual 4K7B be linear or log curve?  There is currently a recently obtained green Omeg pot installed marked 4K7A.

 

[rock soderstrom]

The schematic I have says dual 4K7B  pot for master volume control.  Was there a different designation for pots in the UK back in the mid 1970's when this console was built?  Should this dual 4K7B be linear or log curve?  There is currently a recently obtained green Omeg pot installed marked 4K7A.

It is totally possible that they have used a B (or C) designation in Europe at this time for a log curve pot. I would take a dual 5K log pot for this job. Your existing 4,7K Omeg pot seems to be linear.

https://en.m.wikipedia.org/wiki/Potentiometer

 

[musika]

Your existing 4,7K Omeg pot seems to be linear.

That's what I thought... very informative link - thanks!  How do I make sure with an ohm meter?

 

[analogguru]

Radiohm, Omeg (and in some cases Piher)  used (logically) A for linear, B for logarithmic and C for negativ logarithmic.

The japanese thought that they were more clever and used A ("Audio taper") for logarithmic, B for linear and C for negativ logarithmic.

How do I make sure with an ohm meter?

If there is no (other) resistor connected to the potentiometer than turn it in the middle.  Measure with an ohmmeter between each outer lug and the middle lug.  If the values are nearly the same, then it is a linear potentometer.