Old Japanese Pot Marking A=Log taper?

[pjanda1]

I know that over here, A used to mean Linear taper. But, Rod Elliot wrote that Japanese made stuff used A for Log/Audio taper. I'm rebuilding old amps out of an Akai M8. The tone controls use an Alps pot marked 30K A which they've wired as a variable resistor. See this post for a schematic. The pot is "VR1" down below the circuit. What are the odds that guy is audio taper? If I graph the resistance by hand, is that accurate enough to tell? I'd like to reuse it if I can.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[AuroraB]

I was under the impression that the old US marking was A=log, B=lin and X=special profile....?
At least that's what the guitar folks claim in the schematics....

[Enzo]

That is what I have always thought. A for audio, B for linear.



Turn your control to the mid point. measure resistance to each end from the centered wiper. Are they about the same? Then it is linear. If it is something like 15%-20%-30% of the total to one end, then you have some sort of audio taper.

[pjanda1]

It's about 20% to one end, so they are indeed log taper. I checked the other pot on the chassis, a 500K marked "A" and it is log as well. So perhaps what I read is true! Ya' gotta' love conventions that aren't really conventions. . .

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[HotKava]

Originally Posted by Enzo

That is what I have always thought. A for audio, B for linear.



Turn your control to the mid point. measure resistance to each end from the centered wiper. Are they about the same? Then it is linear. If it is something like 15%-20%-30% of the total to one end, then you have some sort of audio taper.

Ditto