Cornerstone Aquarium

The Cornerstone Aquarium is a Uni-Vibe style pedal from Italian builder Cornerstone, the company's first modulation pedal after its lauded Gladio overdrive¹. It is all analog and uses the same rotating bulb technology as the original Shin-ei Uni-Vibe, producing the three-dimensional chorus and vibrato tones players associate with that circuit¹. What sets it apart from a straight vintage reissue is a set of additions aimed at the classic circuit's known problems: volume loss, tonal change and muddiness, plus dual speed controls you can morph between¹².

Guitar.com's reviewer scored it 9 out of 10, calling it "A smart update that's up there with the very best Uni-Vibe types we've ever played"³.

The controls

The Aquarium's control panel covers Speed 1, Speed 2, Volume, Mix, Intensity (Depth), Tone, a two-way Mix mode switch, a three-way Inertia switch, and bypass and speed footswitches³. Here is what each part does:

The Momentary Speed Change function is the performance feature at the center of the design: press and hold the Speed1/Speed2 footswitch and the pedal momentarily swaps to the other speed with a Medium inertia, then returns when you release¹. Guitar.com's reviewer described the inertia control as allowing "various rates of Leslie-style morphing between speeds"³.

One omission worth knowing: the pedal has no expression input for rate control, something Guitar.com's reviewer wished it had³.

Blend and Mix mode

The Mix knob works differently depending on the toggle position¹:

• Blend mode ("B"): the knob sweeps from 100% dry fully down to 100% wet all the way up, crossfading between the two¹³.
• Mix mode ("M"): the dry signal always stays at 100%, and the Mix knob sets the level of the wet vibe sound added on top of it¹³.

Mix mode is the closer cousin to how a Leslie-style effect sits in a mix, since your dry tone never thins out as you add modulation. Blend mode gives you the full-strength vibrato sound of the original circuit when the knob is wide open¹.

Power: 18V and true bypass

The Aquarium runs on 18V DC, center negative, drawing 60mA². Guitar.com notes it is powered by an 18-volt supply only³. Cornerstone says the 18V rail is key to obtaining the classic rich, deep Vibe tones from the analog bulb circuitry, matching the original Uni-Vibe's own 18V operation¹⁴.

Bypass is true bypass, so the pedal is out of the signal path entirely when switched off¹³.

Design and the original Uni-Vibe

The Uni-Vibe was created in the 1960s by engineer Fumio Mieda for the Japanese company Shin-ei, designed to mimic the sound of a Leslie rotary cabinet⁵⁶⁷. Its modulation is generated by photo-resistors: in authentic lightbulb Uni-Vibes, a lamp and light-sensitive components (Vactrols/LDRs containing trace cadmium sulphide) sweep against each other to create the wobble⁸⁹. MusicRadar notes the original Shin-ei units "distinguished themselves by using a lightbulb"¹⁰.

The Aquarium keeps that rotating bulb technology rather than substituting a modern LED-and-LDR scheme¹. The Volume, Tone and Mix controls are there to fix the classic circuit's shortcomings, while keeping what Cornerstone describes as simplicity of operation and tonal flexibility¹.

Guitar.com's reviewer found the result more versatile across a range of musical genres than a standard Uni-Vibe type, "from gentle vibrato wobbles to thick chorusing and rotary sounds," and called the pedal "a vast sonic playground for the creative player," with speed ramping between contrasting settings that sit in any mix from clean to high-gain³. On the design itself:

For more on the effect family the Aquarium belongs to, see chorus pedals.

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