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So, we were really decided to create a pedal version of the 636 preamp but we had a slight problem, we had never tried one. So, in order to recreate it to the finest detail we began our search for an original unit that we could reverse engineer. After many months we managed to get our hands on an original Grampian unit! It was in a great shape and sounded amazing!
As soon as we strummed the first chords with the original 636, we found the combination of Grampian, old Marshall stack and single coils to be pure magic. It enhanced the amp’s natural saturation with a fatter, sweeter tone. This unique coloring comes out of its primitive technology and because of the low input impedance of the 636. This is also quite common on guitar effects of that era, like the Fuzz Face®, Range Master and many other 60’s effect units.
However, we felt the vintage 636 was less impressive when used with other types of amps and pickups, specially humbuckers. Because of that, we challenged ourselves to make this preamp sound beautiful no matter what amp or pickup you use, managing to eventually tweak the circuit to extend its frequency range and include eq controls while retaining its unique tone. The treble response has been refined by adding a Hi-Cut control which allows you to add a sweet sparkle to muddy humbuckers or tame brighter single coils, as well as a Lo-Cut knob to control bass content better, so the player can decide the tightness of the resultant tone.
Another thing we achieved was to refine its background noise. The vintage Grampian has a remarkable hiss, especially when the Aux Channel was used (Townshend’s choice). Chapter two of the Windmiller designing process was to eliminate that hiss whilst maintaining the character and behavior of the original Grampian 636 preamp. After experimenting with a great variety of components and fine-tuning the circuit to make it as quiet as possible, we finally succeeded!
And finally, in order to pay tribute to the last detail, we’ve included the overload indicator lamp found on the Grampian 636, which is sensitive to your playing and responsive to your attack, and you may agree with us, looks really cool!