Trem(olo) is basically defined as a cyclical variation of volume controlled by a low frequency oscillator, or for us guitar players…something that makes the guitar sound oscillate between quiet and loud either quickly or slowly…..  Made famous in the 50’s and 60’s by bands like the Shadows and Dick Dale for that infamous ‘surf sound’, the Trem stuck around for many other guitar greats like Robin Trower, Hendrix and Page, right up to SRV and beyond.
The Carl Martin Surf Trem has simplified the whole effect  to 2 simple controls (just like the trem circuit on our vintage Fenders and Ampegs), Depth and Speed.  The Depth knob controls how much of the effect you want in your guitar signal, and the Speed knob obviously controls the speed of the oscillation.

Below are some examples of settings you might use, and remember, the Trem is an amplitude (volume) effect, and should therefore be placed before distortion, eq’s and delay/flangers

SLOW AND DRAMATIC
Set the speed knob to match the tempo of the song and keep the depth knob fairly high to create that mysterious and dramatic mood….like the Robin Trower thing or Pink Floyd.


SUBTLE VIBE
Set the speed knob fairly high and the depth knob fairly low to give your guitar sound some unique depth for rhythm and solo work.  This type of setting was used a lot for the ‘surf sound’ to add that air-iness and depth that helped identify this style of music and guitar.


MAXIMUM EFFECT
Setting both controls to the max or close creates a unique sound which can be used cleanly to or to greater effect with a high gain pedal (like the Crush Zone).  Interesting for solo work and adding depth to those gargantuan metal power chords