drum machines/AC adapters/ matching power...HELP!

ok i got my hands on 4 old drum machines without A/C adapters. (good price)
most of them seem to want 12 volt adapters. im going through a bag of random extra A/C adapters i have. some of them seem to make the machines work but they are under the voltage requested on teh machine..most of the machines want 12 volt and i have a few 9 volts that will power the machines.

could using these lower voltage adapters damage my machines? or cause any other kind of
problem?

if i cna use htem great..but if im better off going out and buying the adapters then i will do that...

any help is recommended.
thanks.

go to argos, u can get a multi varying voltage adaptor with about 7 different connections on it for about a 5er

what is argos?
is it a website or a store in your area?
im located in america..

ah rite. its a store in uk. try walmart or a local electrical supplier