Do some searches on audioasylum.com.
For $50 you are not going to get anything useful, IMHO. Better off just buying from reputable sellers unless you can budget a couple or three hundred for something good. (including calibration of it). Mutual conductance (transconductance) type is the best (only?) choice.
For $50 you are not going to get anything useful, IMHO. Better off just buying from reputable sellers unless you can budget a couple or three hundred for something good. (including calibration of it). Mutual conductance (transconductance) type is the best (only?) choice.