Universal Audio UAFX Flow Vintage Tremolo

The Universal Audio UAFX Flow Vintage Tremolo is a compact tremolo pedal that uses digital modeling to recreate vintage tube-driven tremolo circuits. Universal Audio launched it in October 2023 as one of three additions to its UAFX compact pedal series, alongside the Brigade chorus and an LA2A limiter pedal¹. It offers three flavors of vintage tube-driven tremolo, and gearnews.com's buying guide describes it as bringing "studio-grade modeling" to the tremolo conversation².

What the Flow does: three modeled tremolo circuits

The Flow's core idea is that it models three tube-based tremolo flavors rather than offering one generic LFO. gearnews.com's buying guide describes them as a harmonic Dharma mode, a smooth '65-style sine, and a hard square-wave chop, each paired with an emulated preamp circuit and a volume boost². The launch coverage from October 2023 describes the same three sounds from the player's side: "Early Fender harmonic tremolo, later '65 style round tremolo and square wave trem-tones are on offer"¹.

Harmonic tremolo is the mode most players will ask about. It refers to the circuit found in early Fender amplifiers, where the tremolo works by shifting the balance between frequency bands rather than simply cutting the volume, giving a pulsing, layered movement that plain amplitude tremolo cannot produce. The Flow puts that circuit alongside the rounder later-'60s style and a hard square-wave chop, so one pedal covers the main vintage tremolo types¹.

On That Pedal Show, Mick and Dan summed the pedal up this way in their March 2024 demo³:

Controls, tap tempo and bypass

The Flow includes tap tempo, and its bypass is selectable between true bypass and buffered bypass. gearnews.com's buying guide notes that "Tap tempo and selectable true or buffered bypass make it easy to integrate into modern boards without sacrificing feel"². For a player, that means the pedal can sit in a larger chain with tempo-synced parts, and the bypass choice lets you decide between a fully untouched signal when it is off and a buffer that suits longer cable runs.

Each of the three modes also pairs with an emulated preamp circuit and a volume boost, which means the pedal can push an amp a little as well as modulate it².

Price and where it sits

gearnews.com listed the Flow at $94.00 USD when it launched in October 2023, alongside a UK price of £86.00 and a European price of 99.00 euros¹. The same $94.00 USD figure appeared in the site's December 2025 buying guide, so the price has held steady across that period². At that figure, That Pedal Show's "exceptional value" comment reflects what reviewers found notable about it: a modeled harmonic tremolo at a compact-pedal price³.

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