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Meridian Exciter / Compressor

Based On
Guyatone® PS-021
Effect Type
Compressor / Frequency Enhancer
Build Difficulty
Project Summary
A gem from the 1980s, this effect combines a Dyna-style compressor with an exciter that enables control over the even & odd harmonics.
Meridian Exciter / Compressor printed circuit board

Printed Circuit Board

What's included?
PCB only. Build instructions and parts list can be viewed or downloaded from this page.


In stock

Complete Kit

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Project overview

The Meridian Exciter/Compressor is a clone of the Guyatone PS-021 Guitar Exciter / Compressor and its cousin, the PS-020 Bass Exciter / Compressor, also released under the Nady brand in the USA. Both the guitar and bass versions were originally traced by Aion FX in 2017.

The PS-021 can be looked at as three distinct circuits chained together. First is the classic Dyna Comp, nearly a direct copy but with somewhat reduced sensitivity on the Sustain control, so its use is more as a limiter than a sustainer.

The following stage is an exciter, which is very similar to a circuit from a Japanese electronics book in the 1980s (and not unlike the BBE Sonic Stomp, but with no frequency-specific control).

The last stage is a Big Muff-style tone control that pans between a bass emphasis and treble emphasis. However, unlike the BMP’s classic mid-scoop, there is a very slight mid hump throughout the rotation.

So while it’s composed of familiar circuits, the end result is, as they say, more than the sum of its parts. This is a killer tone enhancer that still enjoys revered status with many, but flies under the radar since it doesn’t have an association with any big-name artists or records.

The PS-020 is the bass version. The circuit is identical to the PS-021 except for five parts that have been changed in the exciter and tone control to make the frequencies more suitable for bass. It also changes the tone control to bring back the mid-scoop frequency curve, more similar to the Big Muff.

The Meridian is a direct clone of the original PS-021 and PS-020 except for two changes. First, it’s been converted to true bypass and the JFET switching has been removed. Second, the obsolete CA3080 chip has been replaced by the current-production LM13700, which performs identically.