*Soundgas Type 636P 2 - Twin Grampian 636 Preamp

*Update – new transformer balanced output now incorporated into the design/pricing – twin Carnhill transformers give a different flavour (original unbalanced output still available for maximum filth). Brings the 636P2 into contention for more subtle bus or mix sweetening in addition to more full on gnarl. The unit pictured is our latest prototype – we are building a limited run to this specification.

What is it? The 636P2 has evolved from the Soundgas Type 636 and desktop Type 636P which both feature our evolution of same hairy mic preamp circuit as the original Grampian Type 636. However, with the 636P2 you get far more than just two 636Ps in a rack. The addition of Carnhill transformer balanced outputs massively increases versatility and offers a wider sonic palette: we’ve noticed a subtle sweetening and widening of audio signals passing through with very little gain applied.

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 ‘punch out’ socket – this bypasses the transformer circuit and gives you that hairy (out of phase) direct output as found on the 636 and 636P.

Based on the Grampian Type 636 – famously used and abused by Lee ‘Scratch’ Perry and Pete Townshend – and many others since. This circuit is designed and built absolutely in the spirit of the original vintage units – no surface mount components or tone sapping DSP. Everything entirely handbuilt from scratch in our workshops in Crich, England. Even the circuitboards are hand etched. In an era of mass production, these builds are a throwback to a bygone era when small manufacturers made everything themselves.

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 OC45s we have found do not meet our criteria.

Can I hear it? Very soon! We have literally just finished building the production prototypes and testing is underway. There will be demos coming very soon. Currently there are only demos of the original 636P2 build (which was literally two 636Ps in a rack case – no transformer balanced outputs). Take it from us: if you like the 636 circuit, this gives you two channels plus something very special indeed with the transformer output option. Scroll down for many links to the desktop version in action. What you are hearing is the rawness of the mic preamp circuit without the transformer balanced option.

What is this “Prototype”? The photos are our production prototype: two boards from our Type 636P inside a 1U rack case with added Carnhill transformer balanced outputs. The two sides are independent circuits using a common power supply (on a standard IEC socket, internally switchable voltage). Each channel has 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).

Staying true to the original Grampian 636 design, the mic preamp ‘punch out’ output is unbalanced on a ¼” jack socket and is out of phase – plugging into this output will disable the XLR outputs on the rear.

What you receive will may differ from the photos in the following ways:

1. There will be a face plate that matches the 636 family design.
2. The knobs may be different.
3. It will have a serial plate.

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: all our original prototypes had used silicon and sounded great. However Ben and 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 which has now evolved into the 636P2.

More info on the build of the original Type 636P including photos and demos.

To anyone reading this who has seen much cheaper versions for sale claiming they feature the Grampian ‘preamp circuit taken note for note’ we can categorically confirm that, while these units may be interesting in their own right, the circuit is certainly not an accurate recreation of the Type 636, nor do they sound at all close to either an original Grampian, or the Soundgas units. You do get what you pay for. The mic transformer (one element of our design process that took a considerable amount of R&D to perfect) is not the correct value, and the circuit design means the Russian germanium transistors utilised in this design are not actually being driven in any meaningful way. The overdrive/distortion these units produce is not the harmonically rich germanium distortion that is the signature sound of a Grampian Type 636. We have already spent a good deal of time researching whether we could build a modern unit at a much lower price point by redesigning the original circuitry but so far sonically it simply does not stack up.

And if you have seen a certain guitar pedal that claims to recreate the sound of the Grampian Type 636 aux circuit as used by Pete Townshend of The Who, we can confirm that what this digital processor actually does is create a slightly boosted signal with none of the harmonic richness of the mic preamp circuitry (which is what Pete actually used)…