Historical classical music recordings
Historical classical music recordings are generally classical music recordings made prior to the stereo era of vinyl disc recording, which began around 1957. As time passes, even later recordings, made in the early stereo era are also being released as "historical" recordings, especially if they were never released or were dropped from the record catalogs due to loss of popularity or "antiquated" sound. Typically such recordings are of artists and performances that were particularly notable at the time they were first released, or were unavailable because they were private recordings made at concerts or radio broadcasts . The latter can be of rather high quality if the recording derives from tapes made and archived by the broadcaster or the organization mounting the performance. Recordings issued by arts organizations. Important sources of historical recordings are the broadcast archives of orchestras and opera companies. For instance, the Met Opera of New York has issued a number of historical broadcast recordings which are only available upon making a donation. In the late 1980s, the Metropolitan Opera Guild issued a large number of two-disc compilations of historical recordings called "Great Operas at the Met". Each album featured recorded performances of  arias from a particular opera, generally beginning in the early 20th century and continuing up into the early stereo era. The Boston Symphony Orchestra issued a 12-CD box entitled "Boston Symphony Orchestra Symphony Hall Centennial Celebration: From the Broadcast Archives 1943-2000" in the 1980s. These recordings are now available for download from the orchestra's web site. Major label reissues. Many of the major record labels have also reissued important historical recordings. For example, Philips Records issued a 200-CD series of recordings entitled "Great Pianists of the 20th Century" in 1999. Record labels specializing in historic recordings . There are a number of record labels that have primarily issued historic classical recordings or have treated them as an important category. Examples include: Recordings made and shared privately by clubs, internet groups, blogs, and other aficionado-run free forums. Recordings made from radio and internet broadcasts, in-house personal microphones and recording devices, and from performer's earpiece monitor transmissions are archived and disseminated in various ways. This kind of documentation of live performance is also known as a Recording Of Indeterminate Origin, or ROIO. Many blogs, clubs, internet groups and other forums exist whose members contribute and receive  ROIOs, many of which have never been available commercially. Most of these forums traffic in non-commercially available broadcast/other classical music recordings for free. Historic recordings that begin as freely traded ROIOs often surface later as commercial products. Grammy Awards. The Grammy Awards have a prize category for Best Historical Album since 1979 which does not distinguish between classical and non-classical albums. Past classical album Grammy winners and nominees have been: