Product Description
"A preamp like no other..."
500-series evolution of our improved Grampian 636 preamp circuit. A Type 636 mic preamp with transformer balanced output via the rear connections.
Preorder listing for delivery in 2025
The Soundgas Type 636-500 is the latest incarnation of the Soundgas Type 636, Type 636P2 and Type 636P which both feature our evolution of hairy mic preamp circuit from the original Grampian Type 636.
You can use it exactly like the 636P by using the front panel ins/outs but the 636-500 also features the transformer balanced output circuit from the 636P2 which massively increases versatility and offers a much wider sonic palette.
From subtle sweetening and widening of audio signals passing through with very little gain applied through to maximum filth and gnarl via the original unbalanced input/outputs.
We are hand building a few limited runs to this specification.
How does it sound? At higher gain settings the transformers smooth out some of the wildness of the 636 to deliver a classy - yet still harmonically rich - sound. We have been blown away by how different these sound with the balanced outputs, and by how much we want to use it on everything. And if you want the full original 636 preamp magic, untamed by those beautiful red transformers? Simple - just plug into the 1/4" jack 'break out' socket - this bypasses the transformer circuit and gives you that hairy (out of phase) direct output as found on the 636 and 636P.
What is it? Based on the Grampian Type 636 - famously used and abused by Lee 'Scratch' Perry and Pete Townshend - and many others since. This circuit builds on the spirit of the original vintage units - no tone sapping surface mount components in the audio path or DSP. Designed and built by our team in our new premises in Derbyshire, England.
This is a labour of love and represents the culmination of our collective experience of - and love for - the 636 circuit. It is not the modern way: the expense of working like this means these particular units are not for everyone, but this does mean we are able to control every aspect of the process and build something of which we are all justifiably very proud. The time and outlay just to source and test NOS transistors that perform to our specification is slightly terrifying: the vast majority of Mullard OC45s available do not meet our strict criteria.
What's inside? The design brief was to take one channel from the Type 636P2 preamp and port it over to the 500 series format. While space meant we had to lose the P2's massive red Carnhill iron, the transformers in the 636-500's balanced outputs do not disappoint.
There's a 1/4" jack input, input level control pot (gain), Grampian specification mic transformer, overload lamp and input impedance switch (select between guitar/line use, or adjust to taste) plus switchable 48v phantom power for use with condenser mics.
Staying true to the original Grampian 636 design, the mic preamp 'break out' output is unbalanced on a ¼” jack socket and returns the signal out of phase - plugging into this output will disable the XLR outputs on the rear.
As with our original 636s, we have put tonal considerations ahead of all else. I was originally skeptical that we’d see a real benefit in using germanium transistors in the buffer section as our original prototypes had used silicon and sounded great. However Dr Huw insisted that we build an all germanium version for comparison which blew all the earlier versions out of the water; this became the 636P and 636P2 and which has now evolved into the 636-500.
HISTORY OF THE SOUNDGAS TYPE 636 PROJECT BY TONY:
I’ve been using Grampian 636s for getting on for 30 years having ‘discovered’ one entirely by chance back when they languished unappreciated and unrecognised (it cost me around £70 and needed a fair bit of work - even then it was very noisy and more than a little unreliable). I knew nothing at the time of their history and use by Pete Townshend and Lee Scratch Perry, nor what it was that made these unprepossessing grey boxes so very special. They reacted to liberal overload abuse with such unbridled (and unequalled) ferocity that I was immediately hooked and thus began my infatuation with the Grampian Type 636. I now know, thanks to Huw, that this germanium transistor based circuit is of a slightly odd design (which explains why so few people seem able to figure out how to fix them well).
To say I am proud and humbled by our team’s endeavours over the recent tumultuous years is an understatement. It all began when “Doctor” Huw rebuilt a very tatty Grampian Type 636 for our much-missed friend Philippe Zdar for his Motorbass studio. That unit had been stored on its side for 20-30 years with the battery at the top and was almost completely destroyed by acid leakage - it was not pretty (Zdar later told me it was 'the greatest most expensive piece of shit gear in the studio'!). I said to Huw that as he’d almost built a new one in the process might that in fact be possible? Huw replied, 'I don't see why not.'
We’d never manufactured anything (Huw had custom built guitar pedals and synth modules). The new design had to be as authentic as possible but with lower noise and more low end: Huw triumphed and we cautiously set out to make ten replica Type 636s using refurbished vintage Gibbs tanks.
As soon as Huw had designed the 636, we discussed whether the mic preamp alone could be built in a standalone unit, and one appeared pretty quickly on my bench soon after (built into an old Binson Echorec faceplate we had lying around). Covid-19 played havoc with our plans and with Huw’s health, and what would eventually become the 636P had to wait.
In the meantime the team continued building small batches of Type 636s to satisfy demand. There are now around 80 Soundgas Type 636s in existence and while we’ve no immediate plans to make of this exact design, we do have a new 636 reverb project in mind.
The 636P preamp-only prototypes duly came along. In classic Soundgas style, what was intended as a prototype became the production version - the no-nonsense, minimal, aesthetic seemed fitting for our monstrous sonic wolf in sheep’s clothing. Plaudits started coming - ‘the only drive/fuzz I need’ and ‘this is the sound I’ve been searching for my whole life, thank you’ are two that have stuck in my head. Again, what started as a low key project has ballooned and we continue to handbuild small batches of Type 636Ps in our workshops.
Type 636 series units are built by our team here in Derbyshire, England in the grand tradition of old school British audio manufacturing. Carefully put together by talented people who obsess over - and focus on - sonic detail above all else. My thanks and appreciation go out to our dedicated tech team who have created - or helped in the creation of - these units.
More info on the build of the original Type 636P including photos and demos.
500-series evolution of our improved Grampian 636 preamp circuit. A Type 636 mic preamp with transformer balanced output via the rear connections.
Preorder listing for delivery in 2025
The Soundgas Type 636-500 is the latest incarnation of the Soundgas Type 636, Type 636P2 and Type 636P which both feature our evolution of hairy mic preamp circuit from the original Grampian Type 636.
You can use it exactly like the 636P by using the front panel ins/outs but the 636-500 also features the transformer balanced output circuit from the 636P2 which massively increases versatility and offers a much wider sonic palette.
From subtle sweetening and widening of audio signals passing through with very little gain applied through to maximum filth and gnarl via the original unbalanced input/outputs.
We are hand building a few limited runs to this specification.
How does it sound? At higher gain settings the transformers smooth out some of the wildness of the 636 to deliver a classy - yet still harmonically rich - sound. We have been blown away by how different these sound with the balanced outputs, and by how much we want to use it on everything. And if you want the full original 636 preamp magic, untamed by those beautiful red transformers? Simple - just plug into the 1/4" jack 'break out' socket - this bypasses the transformer circuit and gives you that hairy (out of phase) direct output as found on the 636 and 636P.
What is it? Based on the Grampian Type 636 - famously used and abused by Lee 'Scratch' Perry and Pete Townshend - and many others since. This circuit builds on the spirit of the original vintage units - no tone sapping surface mount components in the audio path or DSP. Designed and built by our team in our new premises in Derbyshire, England.
This is a labour of love and represents the culmination of our collective experience of - and love for - the 636 circuit. It is not the modern way: the expense of working like this means these particular units are not for everyone, but this does mean we are able to control every aspect of the process and build something of which we are all justifiably very proud. The time and outlay just to source and test NOS transistors that perform to our specification is slightly terrifying: the vast majority of Mullard OC45s available do not meet our strict criteria.
What's inside? The design brief was to take one channel from the Type 636P2 preamp and port it over to the 500 series format. While space meant we had to lose the P2's massive red Carnhill iron, the transformers in the 636-500's balanced outputs do not disappoint.
There's a 1/4" jack input, input level control pot (gain), Grampian specification mic transformer, overload lamp and input impedance switch (select between guitar/line use, or adjust to taste) plus switchable 48v phantom power for use with condenser mics.
Staying true to the original Grampian 636 design, the mic preamp 'break out' output is unbalanced on a ¼” jack socket and returns the signal out of phase - plugging into this output will disable the XLR outputs on the rear.
As with our original 636s, we have put tonal considerations ahead of all else. I was originally skeptical that we’d see a real benefit in using germanium transistors in the buffer section as our original prototypes had used silicon and sounded great. However Dr Huw insisted that we build an all germanium version for comparison which blew all the earlier versions out of the water; this became the 636P and 636P2 and which has now evolved into the 636-500.
HISTORY OF THE SOUNDGAS TYPE 636 PROJECT BY TONY:
I’ve been using Grampian 636s for getting on for 30 years having ‘discovered’ one entirely by chance back when they languished unappreciated and unrecognised (it cost me around £70 and needed a fair bit of work - even then it was very noisy and more than a little unreliable). I knew nothing at the time of their history and use by Pete Townshend and Lee Scratch Perry, nor what it was that made these unprepossessing grey boxes so very special. They reacted to liberal overload abuse with such unbridled (and unequalled) ferocity that I was immediately hooked and thus began my infatuation with the Grampian Type 636. I now know, thanks to Huw, that this germanium transistor based circuit is of a slightly odd design (which explains why so few people seem able to figure out how to fix them well).
To say I am proud and humbled by our team’s endeavours over the recent tumultuous years is an understatement. It all began when “Doctor” Huw rebuilt a very tatty Grampian Type 636 for our much-missed friend Philippe Zdar for his Motorbass studio. That unit had been stored on its side for 20-30 years with the battery at the top and was almost completely destroyed by acid leakage - it was not pretty (Zdar later told me it was 'the greatest most expensive piece of shit gear in the studio'!). I said to Huw that as he’d almost built a new one in the process might that in fact be possible? Huw replied, 'I don't see why not.'
We’d never manufactured anything (Huw had custom built guitar pedals and synth modules). The new design had to be as authentic as possible but with lower noise and more low end: Huw triumphed and we cautiously set out to make ten replica Type 636s using refurbished vintage Gibbs tanks.
As soon as Huw had designed the 636, we discussed whether the mic preamp alone could be built in a standalone unit, and one appeared pretty quickly on my bench soon after (built into an old Binson Echorec faceplate we had lying around). Covid-19 played havoc with our plans and with Huw’s health, and what would eventually become the 636P had to wait.
In the meantime the team continued building small batches of Type 636s to satisfy demand. There are now around 80 Soundgas Type 636s in existence and while we’ve no immediate plans to make of this exact design, we do have a new 636 reverb project in mind.
The 636P preamp-only prototypes duly came along. In classic Soundgas style, what was intended as a prototype became the production version - the no-nonsense, minimal, aesthetic seemed fitting for our monstrous sonic wolf in sheep’s clothing. Plaudits started coming - ‘the only drive/fuzz I need’ and ‘this is the sound I’ve been searching for my whole life, thank you’ are two that have stuck in my head. Again, what started as a low key project has ballooned and we continue to handbuild small batches of Type 636Ps in our workshops.
Type 636 series units are built by our team here in Derbyshire, England in the grand tradition of old school British audio manufacturing. Carefully put together by talented people who obsess over - and focus on - sonic detail above all else. My thanks and appreciation go out to our dedicated tech team who have created - or helped in the creation of - these units.
More info on the build of the original Type 636P including photos and demos.