Tumbao 1
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxxx xxxx xxxx xxx0 (bass pickup)
xxx0 xx0x x00x 0xx0
xxx0 xx0x xxx0 0xx0 tumbao 1 - MIDI example
(there are many variations but this is the most common)

notes: Tumbao 1 has two very rare characteristics. It's the only up-tempo songo we've thus far encountered that's in 3-2 clave, and, although it's not a straight bombo-ponche tumbao, it doesn't hit the downbeat of the 2-side. It marks the clave by hitting the backbeat of the 2-side and the anticipation of the 3-side (underlined notes). It would be more than reasonable at this point for the reader to postulate that the often mentioned tendency of the bass tumbaos we've studied to start on the downbeat has less to do with marking the 2-side and more to do with marking the beginning of the harmonic phrase. After all, it just so happens that every song we've studied so far has been in 2-3!

When we get to the 80s, all will be revealed, but for now, let's turn to some 3-2 timba anthems for a quick sanity check:

NG La Banda: La expresiva (source)
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxxx xxxx xxxx xxx0 (bass pickup)
xxx0 x00x 0x0x 0xx0
xxx0 0x0x 0000 0x00 bass tumbao (many variations follow)
xxxx xx0x 00xx xxxx (bloque)

Paulito FG: ¿Y ahora qué? (source)
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
x0x0 x00x 0x0x xxxx
x0x0 x00x 0xx0 0xxx
x0x0 x00x 0x0x xxxx
x0xx 0xx0 xx0x x0xx bass tumbao

Issac Delgado: Con la punta del pie (source)
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxx0 0x0x 0xxx xxxx
xxx0 0x00 0xx0 0xxx bass tumbao

Pupy y Los Que Son Son: Qué cosas tiene la vida (source)
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
x0x0 x00x 0x0x 0x0x bass tumbao

Charanga Habanera: Para el llanto (source)
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxxx xxxx xxxx xx0x (bass pickup)
xxx0 0x0x 0x0x x000
xxx0 0x00 0x0x 0x0x bass tumbao (one of many variations)

So there's no doubt that the tendency of the the downbeat to mark the 2-side is independent of clave direction (although I could have also quoted a few LVV and Manolín examples which essentially play the clave, thus marking the 3-side with the downbeat). In any case -- for now -- let's just follow along with our timeline and await the denouement.

Tumbao 2
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxxx xxxx xxxx xxx0 (bass pickup)
xxx0 xxx0 xxx0 0000
xxx0 xx0x x00x 0xx0 tumbao 2 - MIDI example

notes: This song demonstrates another great arrangement technique that timba bands like Charanga Habanera would later embrace -- coro sections which answer each other. Coro 1 is que toquen que toquen, yo bailo de todo. It later gets shortened, in the traditional way, to simply yo bailo de todo. Then, at about 3:10, coro 2 enters with baila baila José, which is then answered by the continuation of yo bailo de todo. At this point the bass tumbao also changes. The first phrase has an R&B flavor and the second phrase returns to the feeling of tumbao 1.

Tumbao 3
0xx0 xxx0 xx0x 0xxx 3-2 rumba clave
xxx0 0x0x xxx0 0x0x tumbao 3 - MIDI example

notes: Tumbao 3 stops marking the clave and goes to a bombo-ponche pattern which Humberto varies constantly, and brilliantly. The pattern shown above is just a template. Listen to the MIDI example to hear the variations. When coro 1 returns, so does tumbao 1.