RO-SPR

About the RO-SPR

Rooted in the Hammond spring line and the 1963 Fender Vibroverb: the mechanical reverb that gave surf guitar its drip, dub its splash and organs their haunt — starting with Laurens Hammond's 1939 patent.

The RO-SPR is a vintage spring reverb that captures the one thing plates and digital halls can't fake: the bouncy, ringy, low-end-heavy character of a real metal spring tank. Where a plate reverb glues and smooths, a spring reverb has attitude — that instantly recognisable boing when you knock the amp, the mechanical splash, the resonant low mids engineers used to shove under guitars and vocals on purpose. We physically modelled six different tanks — their springs, transducers and resonant behaviour — and deliver them through efficient real-time convolution, so you get four decades of that sound in one plugin instead of one static spring.

From Hammond's patent to surf, dub and stoner rock

Laurens Hammond filed the first spring-reverb patent back in 1939 — a transducer at one end of a coiled spring, a pickup at the other. The idea landed in Hammond organs from around 1960 and standalone units like the Accusonics Type 4 SR, but it was Leo Fender who made it famous by dropping a spring tank into the 1963 Vibroverb. Springs were cheaper and lighter than plates that could weigh 600 pounds, so they spread everywhere. Their low-end-heavy voice was technically a flaw, and engineers loved it — you hear that trick across records from The Doors to Queens of the Stone Age, where the spring's ring became the point rather than a problem.

Six spring tanks, and modern controls to tame them

The RO-SPR ships six faithfully modelled spring types: a late-1970s British stereo unit (A), a 1960s classic dub tube spring (B), a 1970s home hi-fi spring (C), a medium 1980s Japanese echo unit (D), a 1960s Austrian large oil-bath spring (E) and an American guitar-amp large spring (F). Each has its own resonance and drip. Spring Length steps through seven positions that reshape the tank's ring from tight to atmospheric, while Decay stretches the perceived room size from short to long. Because springs are naturally low-mid heavy, we built in a 3-band EQ (Low at 200Hz, Mid at 400Hz, High at 900Hz) and a Bass Cut high-pass (10Hz to 1kHz) so you can keep the character but pull the mud. Pre-Delay places the tail up to 500ms behind the dry, a Dry Mute switch turns the whole thing into a clean send effect, and per-channel Input/Output gain staging lets you balance the natural stereo spread of multiple springs.

Using the RO-SPR on guitars, vocals and synths

On electric guitar, spring type F with a longer Decay is pure amp-in-a-room drip — surf, garage, psych, the lot. On vocals, a shorter spring and a little Bass Cut adds vintage character without drowning the words in low-mid ring. On drums and brass it lends a mechanical, slightly unhinged splash a plate would never give you. Feed it synths and the Mono2Stereo mode is the trick: send a mono source through two non-identical springs and it returns a genuinely wide, slightly detuned stereo image. Chasing smooth, dense, room-like tails instead of mechanical drip? That's what the plate-based RO-140 and the free RO-GOLD are for.

RO-SPR Features

Six spring tanks

A late-1970s British stereo unit, a 1960s dub tube spring, a 1970s home hi-fi spring, an 1980s Japanese medium echo unit, a 1960s Austrian oil-bath spring and an American guitar-amp large spring — six distinct tanks, faithfully modelled, covering four decades of spring character.

Seven-position Spring Length

Step through seven modelled spring lengths that reshape each tank's ring. Combined with the six spring types, the setting takes you from a tight, controlled drip to a long, atmospheric, almost dub-like ring.

Decay control

Independent of length, Decay stretches how long the processed signal rings out, shifting the perceived room size of the selected spring from short and snappy to long and cavernous.

Mono, Stereo and Mono2Stereo modes

Stereo sends the left and right channels to independent springs; Mono2Stereo routes a mono source through two non-identical springs to build a wide, slightly detuned stereo image from a single input — the RO-SPR's secret weapon on synths and mono guitars.

3-band EQ and Bass Cut

Springs are naturally low-mid heavy, so a dedicated Low (200Hz shelf), Mid (400Hz peak) and High (900Hz shelf) EQ plus a Bass Cut high-pass (10Hz to 1kHz) let you keep the mechanical character while pulling the mud — or leave the low end in for that classic, deliberate spring boom.

Pre-Delay, Dry Mute and Dry/Wet

Pre-Delay places the wet tail up to 500ms behind the dry signal, a Dry/Wet control blends the reverb in-plugin, and the Dry Mute switch suppresses the dry path entirely so the RO-SPR drops straight into a send/return bus as a pure effect.

Dual-channel gain staging with link

Separate input and output gain per channel let you balance the natural stereo image of multiple springs, and the Gain Stage Link ties left and right together with a right-click when you want them moving as one.

Physically modelled tanks, convolution-delivered

Each spring tank is physically modelled and rendered through efficient real-time convolution, with the Spring Length and Decay controls reshaping the tail live — so the tanks ring, bounce and splash the way the originals did rather than replaying one fixed sample.

SSE2-optimised code

DSP operations are pipelined on the SSE2 instruction set for high-performance operation despite the RO-SPR's complex real-time convolution.

HighDPI / Retina support

Crisp, high-pixel-density rendering on macOS and Windows for a sharp interface on modern displays.