All members of the violin family in the Baroque and Classical periods use gut strings (or covered gut for the lower strings). The neck is shorter than on the modern violin and is square to the instrument (rather than leaning back). Inside, it has a lighter soundpost and bass bar, and on the front the bridge is slightly flatter. Cellos traditionally had no endpin, being supported by the player's legs.
The bow is straighter, and therefore gives a clearer articulation than the modern in-curved bow established by Tourte in the 19th century.
The violin is sometimes held lower on the shoulder, with less grip between the chin and shoulder. The left hand uses vibrato sparingly, generally only as a specific ornament. Bow strokes, articulation and the musical shaping of the shorter motifs so characteristic of Baroque music are important musical elements that make the Baroque sound world so special.
All the instruments of the family are wooden, with fewer keys. The absence of such keys makes chromatic notes more difficult to tune. These notes a special quality - different from the more open notes, where cross-fingering is not used. This is especially noticeable on the flute.
The bore of the double reed oboe and bassoon is wider, giving a timbre that is designed to blend in with the Baroque strings, rather than to contrast with them, as in the modern orchestra. This is why Barqoue composers often double oboes with violins, and bassoons with cellos.
All early brass instruments are natural; that is, they have no valves to artificially alter the pitch of the harmonic series in order to obtain the full range of chromatic notes. Thus horns have a selection of "plug-in" crooks in various keys to enable them to play their more limited range of notes in the required key. Natural trumpets, usually in D, are able to obtain a greater range of notes only in their highest register.