The "Canadian" Hiwatt (De)Mod

Updated February 2021

During the late 70s, the Canadian Hiwatt importer modifed many of the (then current) two-input amps coming into Canada from the Hiwatt factory for higher gain, something like the Marshall JCM800.

Many people don't care for this mod, or inherited it by accident when buying an amp second-hand. (I think it sounds like a trebly distorted mess). This page shows you how to restore one of these modded amps to "better than stock."

The telltale signs of this particular mod are the coax wire looping back to the NORMAL input jack, sometime with an added 470k resistor (as shown), and the little yellow coil of wire under the turret board:

I highly recommend while removing the mod to also convert it to use a resistive mixer like the early 70s amps used, which is the 2-input (late 70s) amp blocking distortion fix. This approach is shown below.

Restoration

(1) Remove the nut (and lug if present) on the V2 socket mounting screw clostest to the inputs, and replace it with a two-terminal tag strip (or a three-terminal strip if one lug is grounded, as is the case here).

(2) Carefully cut out the blue wire connecting pin 1 to pin 6 of V2, making sure not to disturb the second blue wire on pin 6 that goes under the turret board.

(3) Unsolder the red wire (which is coax under the board) from pin 7 of V2 and connect it to the closest tag board terminal.

(4) Unsolder the loop back coax from the input jack. Remove the added 470k resistor if present.
Solder this coax wire to the other non-grounded terminal on the small strip.

(5) Connect a 470k resistor from each terminal to pin 7 of V2:

That's it! Now the amp is even better then it came from the factory, i.e., more like the classic older early 70s circuit.

Thanks to JR and MC for the use of their amps!