On the album, Maupin is joined by bassist Darek Oleszkiewicz, drummer Michael Stephans, and percussionist Munyungo Jackson.

His band is top-flight intuitive, practicing a kind of restraint that never forsakes lyric for mere energy and dynamic.

"[3] John Kelman of All About Jazz commented: "Penumbra may surprise listeners expecting Maupin to carry on the electric vibe of The Jewel in the Lotus and Driving While Black, but in many ways the looser organic nature of this effort makes it his most personal and satisfying record to date.

"[4] Writing for PopMatters, Daniel Spicer remarked: "Finally, it seems, Maupin is summoning up the gravitas we've hoped for all these years — assuming his rightful position as the pre-eminent bass clarinettist in contemporary jazz, stepping out of the shadow cast by his old teacher, Eric Dolphy...

"[7] Writing for Dusted Magazine, Derek Taylor commented: "A relaxed and productive temperament pervades the entire album, making it easy to take [Michael] Stephans' observation in the liners that 'we no longer play the music; the music plays us' as tenable gospel.