Though perhaps better known as a guitarist, improvising composer Joe Morris has been almost equally present as a contrabassist for the better part of a decade. His rhythmic drive is impeccable and usually spotted within small saxophone-driven groups like those featuring altoist Jim Hobbs or baritone saxophonist Allan Chase. He’s also played the instrument in the fairly open-ended piano trio of Steve Lantner. That being said, and despite the presence of the bass as a frontline instrument in improvised music for over 40 years, Morris has tended to approach it as an ensemble player. You’d notice if the bass was not present, because his time and tonal warmth are so significant, but he tends to subsume his role to the greater sonic landscape. In fact, it wasn’t until I saw him perform opposite bassist Ken Filiano in the Bill Dixon Tapestries orchestra at the late trumpeter-composer’s memorial service that the full range of his playing became clear to me. It’s not that he necessarily stepped out front, but his tone, phrasing, and intricate subtleties as separate from (but related to) his work on the guitar became a salient point.

There probably isn’t any more naked place to give Morris’ bass a dedicated listen than on Sensor, a vinyl-only, unaccompanied recital released on the Lithuanian label No Business. As an instrument able to carry an entire program of music on its own, the bass has come a long way in jazz — the sound on live recordings of clinking glass and cash registers nearly drowning out the epic poems of Jimmy Garrison and Scott La Faro are a thing of the past. The first recorded program of bass soli was privately released in 1968 by itinerant American bassist Barre Phillips as Unaccompanied Barre (and still not on CD). In creative improvisation, artists as diverse as Dave Holland, Peter Kowald, Barry Guy and Yoshizawa Motoharu have recorded major documents. More recently Mike Bisio, Mark Dresser, and Ingebrigt Håker Flaten have followed suit. To make an improvised solo date requires a lot of confidence — one is without a net — as a statement saying that he considers neither instrument primary nor his work on either to be anything less than face-forward. Comparatively, saxophonist/multi-instrumentalist Joe McPhee recorded Tenor (Hat Hut, 1976) eight years after he began playing the instrument, and it’s one of the cornerstones of solo saxophone music.

Sensor consists of seven improvisations recorded in the spring of 2010. Some of the qualities of Morris’ guitar — dusky tone, flecked dexterity, unflagging drive and a curious use of repetition — are apparent on the first piece, played pizzicato. “Sensor I” uses gritty clusters and round, buzzing cells out of which telescope sinewy lines punctuated by the occasional accenting hiccup. Strings and resonance give the instruments some oblique comparison, and Morris inspires a loose and complementary binding through tone and phrasing, miniature glisses and callus scrapes adding filigree to a necessarily stripped-down concept. The second movement features arco bass and follows directly from the first, tense bull-fiddling in deft, throaty harmonics splaying out into pinpricks and circular rhythms. Morris has for some time used a horizontal scraping approach to the guitar as part of his language, goading serrated metal with his pick in a manner that approximates some aspects of West African lute music (“riti”). It’s interesting that many of the subtones he’s able to coax from the guitar can be found in almost equal measure on the bass, and that a horsehair bow is at times analogous to a plastic pick.

The second side’s opener, “Sensor IV,” is reminiscent of Phillips in its bowed twists and turns, nesting into terse harmonic triple-stops and long, curving actions that both gently elide and saw with almost ungainly grotesqueries. That contrast is one thing (of many) that a great bass solo does well, allowing the instrument to sing with classical poise as well as accentuate its bullish low and earthy qualities. The fifth and sixth movements are both pizzicato and fairly short. “Sensor V” seamlessly blends condensed, warm-toned, middle-register movement with spikier phrasing, while “VI” expands into supple intensity. In purposeful ambiguity, one is reminded, perhaps, of the solo piano work of Andrew Hill as well as some of Morris’ own guitar soli. Ultimately, Sensor is an intimate portrait of Joe Morris the musician, allowing one to forget for a moment the specific state of the axe.