Some quick, immediate lessons from frequency/test records

[13hm13]

Recently, I acquired a few test LPs from local used record shops. One is from Shure (1981), the other from Command (1960).
These are not PROFESSIONAL test records, like CBS, which are filled with test tones, tracking tests, wave specific tones (like square or triangle) , and extended sweeps.
These "pro-sumer" LPs do contain basic tones and stereo balance tests.
Perhaps the most important learned lesson is that the high-freq tones (6khz and 10 khz) REALLY reveal surface noise and pops. No doubt all the high-freq groove angles capture dust and particles that are difficult to remove. The LPs LOOK clean and general record cleaner and carbon fiber brush does not seem to thoroughly remove the embedded contaminants.
The Shure LP has a slight warp, and a steady 1khz tone sways the channel balance on the warp hump.

 

[nopiano]

Perhaps the most important learned lesson is that the high-freq tones (6khz and 10 khz) REALLY reveal surface noise and pops

And when they are decades old, these grooves will be totally clapped out! Even at the time we were warned that using them with a mistracking cartridge could irreparably damage them, so I dread to think what they’re like today. I daresay even thorough cleaning with a wet machine can’t repair past damage.

However, a perfectly aligned cartridge will be much quieter, and lack the buzzing and whistling noises that is the harmonic distortion you are surely hearing.