Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: great guitars, lousy strings

ok , so i don't own a martin, but i do own a 74 ovation 6 string that has served me very well . when it came time toreplace the strings , i happened to be drooling over some very expensive martin guitars and thought while i'm herei might as well order some strings. they arrived a few days later and i immediately put them on and wasimmediately disappointed at the sound quality. very tinny . ..... i waited a week or so hoping that thingswould change .. they only got worst...so i went back to amazon and ordered d'addario phosphor bronze .12-.54 whichwere the oem for ovation and they were great. all that rich tone was back... a little more expensive but not much...never thought there could be that much difference in new strings.. valuable lesson