Wouldn't it be great if somebody invented a guitar bridge that would enable your guitar to stay perfectly in tune, even if the strings bind in the nut or stretch slightly during performance? Impossible, you say? Not at all — it just requires some very clever mechanics.

To maintain a constant pitch, a guitar string needs to be under a constant tension. This could be achieved under laboratory conditions, using pulleys and weights, but the Perfect Tune Bridge (which costs $374) uses a system of springs and levers to do the same thing in a more practical way. It is inevitably a bit more bulky (especially in height) than conventional bridges, but — providing palm damping isn't one of your key playing techniques — it is actually very comfortable to play. As you might imagine, any system of levers and springs can only provide constant tension over a limited physical range and you may need different springs fitted to the bridge for string gauges other than the usual 9s and 10s used by most electric players (the manufacturers say the system should be able to handle 11s).

The bridge fits in place of a conventional Tune-o-matic bridge and tailpiece (other bridge types may be in the pipeline), and it locates over one of the two bridge posts, with all the tension taken by the tailpiece studs. The height is adjusted using the bridge-post nut, onto which the bridge is located. If you can't get the action low enough this way, you could replace the bridge-post circular nut with washers to achieve the correct height. The fairly conventional intonation screws protrude from the back of the bridge, and once the intonation is adjusted a single screw at the side of the bridge locks everything in place.

There are further tuning screws on top of the bridge, but setting these up requires understanding of how the bridge works. Essentially, each string saddle is part of a rocking mechanism that applies the constant tension via the spring system. This lever rocks between two end-stops, and providing the setup has it floating somewhere...