Hello jsman
If your count of only 30 rpm is accurate, then you're talking about a 10% speed variation. That would be audible.
I too have the KAB, along with several other stobes and other devices to check speed ( Feickert ), and the KAB is just as accurate as any of them.
Do you have another stobe you can use to verify results.
If not, go to vinyl engine and download one of the stobe patterns and check two ways:
1). With your KAB light source
2). With a standard incandescant bulb.
This should at least tell you if the problem is the strobe or your method of counting.
Cheers, Crazy Bill
If your count of only 30 rpm is accurate, then you're talking about a 10% speed variation. That would be audible.
I too have the KAB, along with several other stobes and other devices to check speed ( Feickert ), and the KAB is just as accurate as any of them.
Do you have another stobe you can use to verify results.
If not, go to vinyl engine and download one of the stobe patterns and check two ways:
1). With your KAB light source
2). With a standard incandescant bulb.
This should at least tell you if the problem is the strobe or your method of counting.
Cheers, Crazy Bill