Old Blood Noise Endeavors BL-37 Reverb

The Old Blood Noise Endeavors BL-37 is a reverb pedal in the maker's BL line, a series of compact effects built around a shared "variable clock" idea. What sets the BL-37 apart from a standard reverb box is modulation applied at two points in the reverb trail, which the maker says gives "a wandering, lush reverb unlike any of our other reverbs"¹. Where most reverb pedals give you a room, plate or spring, the BL-37 is built to bend the space itself.

The heart of the pedal is its Clock slider, which affects the timing of the entire system. Old Blood Noise describes it as "moving from a quick, tile-bathroom echo out to a dark, lo-fi-stretched reverb, unlike any space in existence"¹. In practice, that means one end of the slider gives you short, snappy reflections, while the other stretches the tail into long, degraded, lo-fi washes. MusicRadar's Jonathan Horsley reported the same framing at launch: set it long and it is "a dark, lo-fi stretched reverb, unlike any space in existence"¹.

The controls: Clock, Feedback, Mix and Volume

The BL-37 keeps its control set deliberately small, four sliders covering everything. Here is what each one does, in the maker's own terms¹:

The pairing that matters most is Clock and Feedback. Clock sets the character of the space, from tight and reflective to stretched and strange, while Feedback pushes the decay longer and brings out more of the modulation. Because Mix goes all the way to 100% wet, the pedal works for ambient playing where you want only reverb, or for a subtle blended tail under your dry signal. Volume then sets the overall output level, as MusicRadar noted at launch².

Delicious Audio's Paolo De Gregorio called the BL-37 "the third pedal in the company's inspiringly quirky BL line," and highlighted the same simplified control set as the key to its appeal³.

Power and switching

The BL-37 runs on a 9V DC center negative power supply through a 2.1mm jack, drawing 110mA, and the supply is not included¹. That current draw is on the higher side for a compact pedal, so it is worth checking that your power brick has a 100mA-plus output to spare rather than assuming a low-current slot will do.

Switching is handled by a soft-touch bypass footswitch, giving true bypass and minimal switch noise¹. With the pedal off, your dry signal passes through untouched.

The BL series and its retirement

The BL-37 belongs to Old Blood Noise's BL line, a series of small-format pedals that share the variable-clock concept. The BL-44 Reverse came first, followed by the BL-82 Chorus, and the BL-37 Reverb arrived as the third pedal in the line³. Gearnews described the BL-37 at launch as "the latest in the series that also includes the BL-44 Variable Clock Reverse and BL-82 Chorus"⁴. The BL-44 Reverse runs on the same 9V DC center negative, 110mA power spec as the BL-37⁵¹.

The series is now finished. The BL-37 itself is listed as Sold Out on the maker's product page¹, as is the BL-44 Reverse¹⁵.

Price and artwork

At launch the BL-37 carried an MSRP of USD 179 / EUR 209, with Gearnews also listing street pricing of $194.00 / £175.00 / 199.00€ at Thomann⁴. The maker's own page lists the pedal at $179.00⁶.

The enclosure art was created by Brandy M Patterson¹, whose work also appears on the BL-82 Chorus⁷. MusicRadar's take on the visuals: "its abstract aesthetic looks very much how this thing will sound"². The BL-37's color option is listed as Retirement Black¹, a fitting name for the final run of a retired series.

Where it sits among OBNE reverbs

Old Blood Noise has a deep reverb catalog, and the BL-37 is the clock-warped corner of it. Players looking for other OBNE reverbs can compare it against the Dark Star V2, the Procession V2, the Dark Light Dual Reverb and the Screen Violence. The BL-37's distinction is that its reverb character is tied to a clock you can slide, rather than to a fixed algorithm or a set of mode switches¹³⁷.

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