Okay - I purchased a 1968 Bear Cub semi-recurve.
The bow is great - accurate, fast, light, etc.
But it seems (to me) louder than my longbow I just sold. No, the string isn't slapping against the limbs, it's a semi-recurve and the limbs don't touch the string. I can get it down to a manageable "thump" but without string silencers it's like a .22 going off! I took the vrace height from smacking my bow forearm to the maximum recommended, but no change in loudness. The arrows aren't smacking against the bow, because every arrow hits exactly where I point it. So why is this 58" semi-recurve louder than my 69" slightly reflexed longbow?

How does it sound w/ heavier arrows?

A 1968 Cub should be 62" long.

The bow is 60" but not AMO. Using AMO measuring it's 58" and takes a 55" string. It's a 41" draw bow. I'm using the same spine arrows I was for my 45" longbow which I only drew to about 26" so I'm drawing the same weight. I'm using the same cedar arrows from 3 Rivers Archery as I did for my longbow. Accuracy is dead perfect BTW.

I had a customer with a loud bow we could not figure out.  Eventually he found a crack in the riser that was very hard to see.  Strangely this bow was only loud when shooting three under. If he shot split finger the noise went away.  I never figured out why.

What string material ? With B50 you shouldn't have that noise

B50 Flemish Twist. B50 endless loop came with it, and it's even louder.