The most uninhibited celebration of Bach's 300th birthday so far available on records is undoubtely that of composer-pianist John Bayless on a couple of records from Pro Arte.

Bayless straddles the line between classical and popular music, and he is also a specialist in improvisation. On "Happy Birthday Bach" (Pro Arte LP or cassette, PAD or PCD 210), he improvises on the familiar "Happy Birthday to You" melody in the style of Bach, throwing in some of Bach's own music as interludes or countermelodies.

Then he presents variations on the tune in the styles of other composers who admired Bach, from Mozart to Gershwin to Stravinsky. Even more ingenious is "Bach Meets the Beatles" (PAD or PCD 211), in which the melodies of Lennon and McCartney receive elaborate Bach-style treatment -- "Hey Jude" becomes a double-dotted French overture, "Let It Be," wreathed in counterpoint, is a chorale prelude and "Penny Lane" a bright, bouncy gigue.

Both records are played with a brilliant technique and a solid sense of form that make it hard to believe they were pure improvisations. And both are a lot of fun for open-minded lovers of Bach.

As American distributor for Teldec records, Pro Arte is also handling a more traditional but no less spectacular birthday tribute. For the combined 300th anniversaries of Bach and Handel, Teldec has reissued some of its notable recordings of these composers in special packages, with two records for the price of one.

All 15 of the packages (labeled "Teldec Special Edition 1985") are interesting in one way or another, particularly at a price of less than $10 for two records. Outstanding on the Handel List are "Alexander's Feast" conducted by Nikolaus Harnoncourt (6.48223) and his recorder sonatas performed by Frans Bru ggen (6.48222). There are also estimable performances of the Organ Concerti, Opp. 4 and 7, with Karl Richter as soloist and conductor (6.48221), but in this music the competition is formidable if price is no object. Among the competing versions, Teldec's own recording with Herbert Tachezi as soloist and Harnoncourt as conductor has more energy and imagination.

Harnoncourt's performance of the "Water Music" (paired with the Op. 3 Concerti Grossi on 6.48224) is not to everyone's taste, but there is a charm of sorts (frankly, I love it) in its self-assured brashness -- particularly the raucous horn-playing. A bit more of that quality would have made his much earlier performance of Bach's Suites for Orchestra (6.48238) and Brandenburg Concertos (6.48237) stand out among their numerous and excellent competitors.

The art of playing Bach on original instruments has advanced considerably since Harnoncourt's groundbreaking performances were taped in the 1960s. A recent and highly satisfying original-instrument recording of the Brandenburgs is available in the superb Reflexe series with Hans-Martin Linde conducting the Linde-Consort. The performances are solid rather than dazzling, but that works well in the Brandenburgs, and the sound on two compact discs (Angel CDC 7 46045 2 and 46046 2) is outstanding.

In Bach's violin concertos (6.48240), the Harnoncourt performance (with his wife, Alice, as soloist) does stand out from the competition. The use of baroque violins makes a considerable difference in this music, and the performances are as technically assured as they are stylish. The Bach violin concertos usually fit neatly on a single LP record, but the Harnoncourts offer a two-record set of six concertos.

One is the familiar concerto in D minor for violin and oboe; the other two (in G minor and D minor) are reconstructed from harpsichord concertos and sound quite right on the violin, particularly in these performances. The G-minor concerto can be heard (in F minor) on the harpsichord, with Gustav Leonhardt as soloist and conductor, on Teldec 6.48293. His two-record set includes seven other concertos for one, two or three harpsichords, all well-performed but not quite as delectable as the Violin Concertos.

Even more than for his pioneering work in the use of original instruments, Harnoncourt has attracted critical acclaim for his recordings of the Bach cantatas using boy trebles and a reduced chorus. A fair sample of this work is included in the Special Edition: the Mass in B minor (6.48233), the St. John Passion (6.48232), and five of the cantatas that he wrote for the swearing-in of new city councils, first in Mu hlhausen and later in Leipzig -- Cantatas 29, 71, 119, 120 and 137 (6.48236). These are fully as devout (and sometimes as intimate in their religious sentiment) as the church cantatas, though -- being ceremonial music -- they also have moments of pomp and circumstance with trumpets and drums.

The performances range from good to superb. In a selection of Easter cantatas (6.48235), Harnoncourt divides conducting duties (as he does in Teldec's complete series of the cantatas) with Leonhardt. Harnoncourt has the three most popular -- Nos. 4, 6 and 31 -- and presents them well. Admirers of countertenor Rene' Jacobs, who has performed with distinction at the University of Maryland Handel Festival, will want to hear his singing in Cantata 134. Harnoncourt uses women as soloists in the Mass, but elsewhere he uses boy sopranos -- a sound that may or may not suit one's tastes but certainly was the sound that Bach expected.

"The Art of Fugue" receives a thoughtful, sometimes adventurous and thoroughly musical performance by organist Herbert Tachezi on Teldec 6.48231. On the whole, this music (which was not written for any particular instrumentation) seems to work better when played by a chamber ensemble, but Tachezi's organ version has all the linear clarity one could ask. My favorite organ performance remains the wildly imaginative one by Glenn Gould, which met such a negative critical response that its part 2 was never recorded.

As a whole, this series has excellent sound, using Teldec's direct-metal mastering technique. The program notes (identical in all volumes) are brief and rather sketchy. If Harnoncourt provoked controversy with his reduction of the choruses in Bach's vocal music, Joshua Rifkin has escalated that controversy with recordings that use only a single voice for each part, solo or choral. His claim that this was the way Bach performed them originally seems to be borne out by the available documents -- though these same documents indicate that this was not always the way Bach wanted to do it.

The performances are not completely authentic, though baroque instruments are used, because the sopranos and alto are women, but the power and clarity of the performance in a new recording of the "Magnificat" (Pro Arte PAD 185) is persuasive and baroque style is strictly observed in such points as the use of vibrato. The record also includes a charming but much less elaborate Magnificat in German by Bach's contemporary, Melchior Hoffmann.

Also conducted by Rifkin in proper baroque style is a collection of oboe concertos reconstructed from Bach's transcriptions into other forms. The concerto in A for oboe d'amore (from the Harpsichord Concerto BWV 1055) has been recorded before, but two other works in D minor and E-flat make their recording debut. Part of these works has also been rescued from harpsichord concertos, but other sections are reconstructed from cantata movements -- a more radical venture but one that sounds completely convincing in these performances. Stephen Hammer performs superbly on oboe and oboe d'amore.

For purely musical impact (as opposed to scholarly accuracy), it is not necessary, of course, to perform Bach's music on original instruments -- at least not when a fine musician is using the modern instrument. On a cassette from a small Canadian company (Skylark 8301, available from Skylark Records, P.O. Box 46624, Station G, Vancouver, B.B. V6R 4G8), pianist Jane Coop makes Bach's keyboard music sing with an eloquence that makes the question of the proper instrument seem irrelevant. The program comprises Partita No. 5 in G and English Suite No. 3 in G minor, and they are played with pristine musicianship, exquisite clarity of line and a lyric phrasing (deeply pensive in the slow movements) that are completely beguiling.

Similar praise can be given to the guitar performances of three works for lute (the Fugue in G minor, BWV 1000, the Suite in G minor, BWV 996 and the Suite in C minor, BWV 997) by Go ran So llscher on DG 410 643-1 -- not to mention all of the Bach performances recorded by Glenn Gould. But those are matter for another column, or perhaps a year of columns.