Alesis Quadraverb 2

Overview

The Quadraverb 2 is the significantly upgraded successor to the original Alesis Quadraverb — one of the most popular budget effects processors of the late 80s. Where the original was constrained by 16-bit processing and limited simultaneous effects, the QV2 steps up to 24-bit resolution and a more flexible routing architecture that allows reverb, delay, pitch shifting, chorus, and a 4-band EQ to run simultaneously.

The reverb algorithms are the heart of it: halls, plates, rooms, and ambiences that hold up surprisingly well for a unit of its era and price point. The MIDI implementation is thorough — program changes, parameter control via CC — making it useful in an automated or sequenced studio context.

Two rack units of solid Alesis build quality. By the early 90s, Alesis had figured out how to put serious processing into affordable hardware, and the QV2 is a good example of that.

My unit

I bought it in 2023. I had seen that there were plenty of fans of it, and I wanted to get a taste of it myself and use it in my mixes.

I got it at a bargain price because it was missing its power supply. The peculiarity of the power supply was that it required 9V AC rather than DC. Also, even though it stated that it required 9V, when I found such a power supply (custom), the following happened: When I turned it on, because it was drawing current, the voltage dropped to about 8.2V, and it couldn’t work. The detail was that it required 9V AC when it was connected and powered up (The power supply was “loaded”). That’s why I ordered one from England on eBay from someone who claimed it was specifically for the Alesis QuadraVerb, and when I received it, I found that when the power supply was not connected and powered up, it outputted 10.5V, but when I turned the QuadraVerb on, it dropped to about 9V, which is why it worked correctly.

One problem still remained. When I pressed buttons or turned the Preset Encoder, it behaved as if I had done it multiple times. Instead of, for example, advancing presets one by one, it advanced them randomly by 1, 2, or even 3 steps at a time.

This behavior, occurring in both the encoder and the buttons, led me to investigate the PCB itself—components, central points, and any circuitry that could potentially affect both systems simultaneously.

The fourth time I opened the unit, I replaced a 74HC574 flip-flop latch: U11. Half of U11’s outputs control the scanned button columns, while the other half, together with the entire U10 output, controls the LEDs. The main processor, an 80C31 MCU, directly reads which row is activated from the selected column. I performed extensive testing, and the entire troubleshooting process was highly educational.

Eventually, I revisited an idea that I had initially ruled out: that this might not be a single fault, but rather two separate problems.

And yes—that turned out to be exactly the case. It was simply a double mechanical issue:

The encoder needed cleaning with contact cleaner (super dry cleaner, oil-free) The switches beneath the buttons needed replacement

After addressing both, everything worked properly.

This final repair was completed on April 15, 2026.

Sound & character

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