Grampian Reverberation Unit Type 636

This is a page we've set up to gather 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.

Below you will find various pieces of original Grampian documentation, including tech specs, schematics and articles, which you can view and download from the links below. Note that these were given to us to distribute and are free to use, however if you re-post or share them then please add a credit and a back link.


Instructions & Schematics

- Original Grampian 636 Brochure & Technical Specification (coming soon)

- Original Grampian Reverberation Unit Type 636 Instructions

- Original Grampian 636 Wet-only Modification Instructions

- Schematic: Grampian Type 636

- Schematic: Grampian Type 636 Power Unit PU/2

- Schematic: Grampian Type 636 wet-only modification



- 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."

- 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..."


The Grampian Ambiophonic Unit, Type 666

We also picked some info about the Grampian 'Ambiophonic' Unit, Type 666. This is another interesting (and rare) piece of 60s gear: it seems to be a simplified Type 636 designed "to alter apparent room acoustics", possibly mainly for home hifi. We've never had one in our hands and so can't report much more about it, but here is the documentation we have:

- Original Grampian Ambiophonic brochure & technical spec (coming soon)

- Schematic: Grampian Ambiophonic Unit Type 666 - schematic



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