Tweeters for Vienna Acoustics BBG Speakers

One of the Tweeters in my Vienna Acoustics Beethoven Baby Grand Speakers make a slight harsh sound. I have no idea about purchasing a new pair of tweeters. Kindly guide me in this process of purchasing.
Are you sure its the tweeter? Sometimes a bad recording can trick you into thinking you have a blown tweeter. Also, take the cable that runs to the left speaker and connect it to the right one. Then take the right speaker cable and put it on the left speaker. If the other tweeter now sounds blown, the problem is with something else.

As far as getting replacement tweeters, try your local dealer if you have one. If not, call Vienna and see what they say.
You said only one of the tweeters made the sound. Is it constant or did it happen once? Also, since its only one, why buy a pair? Vienna will sell you only one.

But first, diagnose the problem. As Zd suggests, reverse the cables from your amp to see if there is a problem elsewhere. If it truly is one tweeter, your dealer should be able to guide you. If there was no dealer involved with the purchase, email these guys and they will take care of you, assuming your in N. America:

If not, go to Viennas website and look for the distributor taking care of your country.
Thank you very much for your valuable advice. Have changed the cables and the harshness gone now.
Some times it's the cables. Sometimes it's the recording.