Pot specs

I am trying to figure out the specs of a few pots. One is labeled 15A50K 9637L, the other pot is labeled B20K 9367L. I am assuming the resistance values are 50k and 20k respectively, and both are linear. What are the power specs though?

Thanks!

What type of this device are these potentiometers from?

I’m not sure we will be able to locate the power rating for these unless we can locate what series these are from.

You may have to contact the original manufacturer of the device to see if they can tell you that information.

Hi Travis,
These are from an amplifier for an M&K V-75 Mark II Subwoofer. One pot handles the gain, the other, the frequency cutoff. Unfortunately, the sub is no longer made and the company no longer consists of the original ownership and designers.

Similar products have power ratings ranging from around a quarter-wattt to several watts, depending mostly on the type of conductive element used. Typical audio gain/frequency controls are low-power circuits however, so I’d not expect power rating to be a huge concern in selection of a replacement.

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Gain pots in audio circuits are usually logarithmic taper not linear.

If the pot still works mostly, you can verify linear vs. logarithmic with an ohm meter. A linear pot will read ~1/2 Rt at the mid point. A logarithmic pot will not be anywhere near 1/2 Rt at the mid point (typically 10% or 90%). See the following link for more info on taper: http://www.resistorguide.com/potentiometer-taper/

Most modern audio circuits put only a small amount of power through the control pots. If the pots still mostly work you can get an good idea of the power rating by intentionally burning them up with an adjustable voltage supply. Rotate the wiper to one end and attach the power supply between the wiper and the other end. Increase the voltage while watching the current and when the pot starts to burn out you’ll see the current drop. Then calculate the power that burned it out (W=V^2/R).

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Thanks PaulHutch for the great info! My gain pot is indeed a logarithmic taper pot.