when did the codes for potentiometers change?

[Chickenwings]

for example....the wiring diagram for AB763 fender amps from the 60s specifies all the pots as being all "A" taper....but according to this article:
http://sound.westhost.com/pots.htm
it says that the old codes for linear taper pots were "A" and the log (or audio taper) pots were 'C"
So when did codes change from that to the current "A" for audio and "B" for linear?
Are the pots in old (60s) fender amps actually linear or audio?
http://fenderguru.com/wp-content/uploads/2010/05/TwinReverb-AB763-AC568-layout.png

 

[the guy who invented fire]

Re: when did the codes for potentiometers change?

I don't know whey things changed but in the 50's there were dozens of pot tapers now there are only a few.

This is one of the reasons that if you have a vintage amp and a pot goes south you'll likely never get a pot in there that reacts just like the old one did!

 

[Chickenwings]

Re: when did the codes for potentiometers change?

im wondering really if the volume pot in my old twin reverb is linear or audio.

 

[crusty philtrum]

Re: when did the codes for potentiometers change?

The answer is simple .... get one of each. Many times (esp in guitars) an audio taper is the recommended thing to use, and very often the log taper works better. And vice versa. It all just depends how you want to get from zero to maximum really.

I do have some vague memories of generic pots changing their designations in the 1980s somewhere.