Soundgas Type 636 Family: Germanium Preamps & Spring Reverb

Five machines, one circuit, one obsession

Every product in the Soundgas Type 636 family - the Type 636 Spring Reverb, the Type 636P, the Type 636P2, the Type 636P-500, and also to a certain extent, the Type G - traces back to a single British circuit from the 1960s: the Grampian Type 636 Spring Reverb. We never set out to build a product range. It grew organically from restoring vintage units, gaining a deeper understanding of the circuit and how we could improve performance. We started by deciding to build a Soundgas Type 636 Spring Reverb (and thought we might make ten units). The range developed naturally.

If you've landed here wanting to know what the 636 family actually is, how the models differ, who designed them, and why people from Fontaines D.C. to Radiohead's Ed O'Brien have one on their board, this page is the whole story in one place.

Shop the range: Soundgas 636 Products →

Before we built it: the Grampian Type 636

My love of the Grampian Type 636 began when I first acquired one out of pure curiosity for £52: there was little information to be found about this mysterious, yet appealing, humble grey box. Little did I know how important buying my first Grampian (I still have it) would turn out to be.

As a result, long before Soundgas built any products of our own, we spent many years sourcing, restoring, and obsessing over original Grampian Type 636 units - the spring reverb that gave Pete Townshend his guitar distortion in early days of The Who, and that Lee "Scratch" Perry used to help define the sound of dub from his Black Ark studio, a history I wrote about more fully in Grampian Type 636 — Believe the Hype.

The Grampian 636 was never designed to distort. It was a portable high quality broadcast reverb unit. But push the mic preamp hard enough and all those germanium transistors break up in a way almost nothing else does - warm, dense, and musical rather than harsh. A Grampian got me closer to those mythical Hendrix tones than anything else. That happy accident is the entire reason this family of products exists.

Original units are hard to find, increasingly fragile and in need of refurbishment, and - by modern standards - can be light on low end. We've handled, documented, and restored more of them than almost anyone, and we've made the original manufacturer documentation freely available: the Grampian Type 636 Operating Instructions, the full Grampian 636 Instructions & Schematics, and details of the Grampian Direct Signal Path (Wet-Only) Modification. But do not think that because you can read a schematic you will be able to build one, or even service one well - we’ve seen many otherwise very competent technicians try and come up short.

That hands-on archive, accumulated up over years (often thanks to others’ generosity in sharing) before we built a single unit ourselves, is what the whole 636 range is founded on. 

From restoration to reinvention: building our own

The Soundgas Type 636 was our first in-house design - the point where restoring other people's gear turned into building our own. It was designed by our original Head Technician and father of the Soundgas workshop, ‘Dr’Huw Williams, who re-engineered the original Grampian circuit and turned it into a modern unit that keeps all of the vintage character but fixes the compromises: extended low-end response, improved reliability, lower noise floor and a build that can actually be serviced for decades. You can read the early build updates from that period in Get It While You Can… Soundgas Type 636 Update, (Re)Building the Ark – Grampian Type 636 News, and the Grampian & Soundgas Type 636 Q&A Session we ran with early customers.

From there, the range grew organically, each new model solving a problem the last one couldn't. We told the fuller version of that evolution in the Complete Guide to Design, Build and Availability, but in short:

• Huw Williams designed the original Soundgas Type 636 Spring Reverb which led to the Type 636P. Max Dawson further developed the 636P and the Type 636P2. Max Dawson and Ryan Hingley adapted the circuit into the Type 636P-500 and designed the Type G. 
  

Every unit is hand-built and tested in our Derbyshire workshop, using components selected for consistency and performance - only the best make it into our products.

The Type 636 family, model by model

What's the difference between the Type 636P and the Type G? In Tony's words: "The 636P is a full-featured mic preamp circuit with multiple germanium transistors and an input transformer - complex and extremely picky about components is how we achieve its incredible sound. Expensive and time-consuming to build, and it was never really meant to be a guitar pedal - it just turned out to be exceptional with guitar. The Type G has been designed as a guitar pedal first and foremost, so we've been able to design it from the ground up with this in mind." 

We'd wanted to build a dedicated guitar pedal drawing on the 636 heritage since the very first Type 636 reverbs were built, but held off until we could do it without the tonal compromises a straight guitar-pedal adaptation would have needed.

All five models are built for the same job at heart: adding germanium-powered enhancement, shine, warmth, saturation, and - when you need it - outright drive/fuzz to vocals, guitars, synths, drums, stems and full mixes. For a wider view of how the original 636 Reverb stacks up against other classic units, see Best Vintage Spring Reverbs Compared: Soundgas Springathon.

Who builds the 636 range

This isn't an off-the-shelf circuit with a new badge on it. Every model in the range has a named designer - see the full picture on our Company History & References page:

• Huw Williams designed the original Type 636 - which birthed the Type 636P, distilling the mic preamp side of the circuit into a standalone pedal.
• Max Dawson took the 636P further and developed the Type 636P2, our flagship dual-channel studio preamp - reviewed in depth by Sound On Sound's Sam Inglis.
• Max Dawson and Ryan Hingley brought the circuit into the Type 636P-500, a 500-series module for compact and portable studio racks.
• Most recently, Max and Ryan drew on their experience with the 636P to design the Type G as a guitar preamp pedal first rather than a mic preamp, built from the ground up for the guitarist's signal chain, while still carrying the same germanium DNA.

All units are hand-built, tested, and serviced in our own workshop in Somercotes, Derbyshire - not outsourced, nor assembled from a kit. Read more about how the workshop and team came together on our About Us page and our Soundgas At Abbey Road feature.

In the studio and on stage

The 636 range has picked up attention beyond our own channels:

"This modern take on a vintage germanium preamp offers bucketloads of character." — Sound On Sound, reviewing the Type 636P2

The Type 636P has been featured twice by That Pedal Show, and Guitar World covered Fontaines D.C.'s Carlos O'Connell naming it the secret weapon on his pedalboard. It's also turned up on rigs belonging to Mason Stoops, Ben Frost, and Ed O'Brien of Radiohead. Original Soundgas Type 636 Spring Reverbs can be found in the studios of Richie Hawtin, Chemical Brothers, Kid Harpoon and many others. Tony Miln has also written about spring reverbs and modulation effects more broadly for Premier Guitar, in Lords of the Springs and Modulation Nation: Chorus, Phasing, and Flanging.

Read more: Press & Publications →