A growing collection of information about the legendary Grampian 636: history, schematics, manuals, sound & video clips; plus our Soundgas Type 636 project to recreate this iconic effect.

We’ve begun gathering all the information we have about the legendary (rightly so!) Grampian 636 spring reverb. It’s still being added to – for more Grampian history and our experience with these machines head to Tony’s Grampian 636 blog post.

Scroll down for schematics, sound and video clips.

We are indebted to Frank Mercer, who very kindly sent us much of the original schematics and info you will find on our site – here’s his original letter to us, detailing some of his thoughts and recommended Grampian modifications.

Oh, and this happened once (but it’s a pretty safe bet that it will never happen again!):

And.... the Soundgas Type 636 is here!

A project that has been developing over the last year or so has finally come to fruition and we have opened orders for a limited number of units of our meticulously recreated version of the mighty Grampian.

Find out more & order a Soundgas Type 636


You may not think there’s much of a connection between windmilling sixties guitar legend (and latterly friend of Soundgas) Pete Townshend of The Who, and the original Upsetter – godfather of reggae and the man who is credited with inventing the remix – the one and only Lee “Scratch” Perry, but this humble grey and silver box links the two (in addition to their undoubted shared mastery of the recording studio as instrument). Pete used his for guitar distortion, Lee for the unmistakable spring reverb sound on his productions and dubs. As a result, these unprepossessing little boxes have become extremely sought-after by fans and admirers of both distorted guitars and also of dub, reggae, and the myriad forms of electronic music that have spawned and developed from humble beginnings in Kingston’s Black Ark Studio. Grampian Reverb Units can be found in the studios of many exciting and vibrant artists and producers today; their sound as urgent and vital as when they were first abused by these two sonic pioneers.

We've put a full set of Grampian tech specs and schematics up online, as well as the content of the original instructions. Also included are review articles from the 60s that mention the Grampian - linked below.

Note that all these were given to us to distribute and are free to use, however if you re-post, quote from, or share them then please add a credit and back-link.

– Original Grampian Type 636 User Instructions & Full Technical Specification

– All Grampian Instructions and Schematics


Examples of stems through a Grampian Type 636 (and some other effects) in our studio. It’s a spring reverb, but can also be used a source of incredible germanium distortion.

Soundgas Studio Services · GEAR: Grampian Type 636