Grampian Reverberation Unit Type 636 - Introduction & Background

This is a page we've set up to begin gathering all the information we have about the legendary (and rightly so) Grampian 636 spring reverb. It's still being added to, so currently to read more about the history and our experience with these machines you'll need to head to Tony's Grampian 636 blog post. And if you want some idea of what a Grampian can do then we put some of our instagram demos of one particular machine that came through onto a youtube playlist.

We are indebted to Frank Mercer, who very kindly sent us much of the printed material below - here's his original letter to us, detailing some of his thoughts and recommended modifications, as well as instructions for fitting a mains transformer (this should only be carried out by a qualified technician).

Background:

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.

User Tips & Points To Note:

The original sockets are not built to accept modern quarter inch jacks, they are actually BBC/GPO Type B quarter inch sockets - if you force modern jacks into the sockets you will eventually break the socket connections. Replacing them with modern sockets is the simple solution adopted by most users.

We love punishing our Grampians by overloading the inputs, but beware as sustained high inputs can burn out the all-important pilot lamp bulb. It would be possible to modify the input to the bulb with one resistor in series and one in parallel to lower the input level while keeping the same impedance.

On some units, you can get a wet-only signal from the Remote Output socket, but this would need re-amplifying - it's not line-level out.

The mic input has both balanced and unbalanced input options, and there are two auxiliary channel inputs - the 10mV/50k ohm input is great for guitar and also for maximum distortion levels - the second input is 500mV/1M ohm. Output is rated at 1V 600 ohms. There are controls for on/off via a toggle switch, Reverberate which controls the spring reverb level, and input gain controls for the Mic and Aux Channels linked to the Overload lamp circuit. Some are 240v mains powered, others run on 9v ‘lantern’ type batteries.

Instructions & Schematics/Tech Spec:

We have 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 a backlink.

- Original Grampian 636 Brochure & Technical Specification

- Original Grampian Type 636 User Instructions & Full Technical Specification

- All Grampian Instructions and Schematics

 

 

Articles

- Studio Sound Jan, 1969 - "No whizzy effects are possible, but the quality of the reverberation is excellent."

- Studio Sound June, 1970 - "Many a first class recording and (dare I say?) broadcast has gone out enhanced by the Grampian unit." by Angus McKenzie (founder of London's legendary Olympic Studios)

- Studio Sound Nov,1970 - "It is important to note that a constant current direct to the transmitting transducer is essential to the proper working of the device..."

 

We also picked some info about the rare Grampian 'Ambiophonic' Unit Type 666 pictured above - see the brochure and schematic here.

 

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This page is part of our collection of resources on the legendary Grampian Type 636. We love these units and the beautiful noise they make when functioning well - if you are looking for one, or have one to sell in any condition, please get in touch.