ARC preamp Voltage convertion from 110v to 220V?

Hi!I have an Audio Research Ls2b Mk2 preamp 110v.I would like to convert it to 220 volts,in order to be used here in Argentina.Does anybody knows where can I buy the transformers of this preamp in order to make it work with 220 volts?I would appreciate if somebody could bring some links of companies which usually sells them.Many thanks in advance for your useful replies!Regards.Rafael