Question about noisy tenants

[Niti Jamdar]

Hi all - I wanted to get your thoughts on a tenant issue that I have encountered.  For about 9 months I rented our 3 bedroom apartment in philadelphia to 3 fresh college graduates (all 3 have a job).  About 4 months back, we got a call from one of their neighbors that these kids are very loud - one of them is in a band, and has jam sessions with drums in the house.  And that they have parties at their house a few times a week.  We had immediately called the tenants and voiced their neighbors concerned, and asked them to keep the volume low, and not practice after 8pm.  They agreed, and they also went and talked to the neighbors and reassured them that they'll keep it down.  

Today, we got another call from a few neighbors who wanted to complain about the noise.  To give some background, our tenants are otherwise good tenants...they pay the rent on time, and keep the house in relatively good condition (other than being messy).     

We're planning to have a more serious chat with them this time, and also involve their parents (their parents are on the lease as co-signers).  Is there anything else we should do?  We don't want to evict them yet.  What should our approach be when we discuss this issue with our tenants?  Any help/advice would be greatly appreciated.

Thanks in advance!