A quiet compressor?

The old 2 cylinder cast iron compressors ran slow and were quiet. Sounds like your compressor rins fast and screams. RPM and CFM delivered are what you have to look for. Low RPM and high CFM. Not too many are built the old school way nowdays. Big shops pull their air from outside which helps. Boxing in and insulating is not a great idea. Too much heat. Heat causes failures and moisture.