More and more manufacturers are producing guitars and basses with active circuitry built in; however, a large proportion of these systems do nothing more to the instrument's signal than to add hiss and compensate for the shortcomings involved in using cheap pickups.

At the other end of the scale are some active systems which can really bring an already good sounding instrument to life, further enhancing its sound quality by emphasising the particular character of the instrument, as well as giving it a versatile Eq section. One such system is the Ampro Activator, a unit designed by an already well known guitar maker, Tim De Whalley.

In reading through the information that comes with the Activator in kit form, the list of features found appears to cover most of the failings found on past active circuits; switching between active or passive modes (therefore still allowing the instrument to work when the battery goes dead); high impedance buffering (preventing high frequency loading and therefore loss), power on/off switching by toggle switch as well as disconnection when no lead is plugged into the instrument's jack socket and a battery status indicator.

The actual unit that I was able to have a look at in depth was that designed for the Fender Precision bass or Precision copies. The active circuitry is equally at home on P-Basses with a Jazz bass pickup added, and it was on one such unit that the Activator was fitted.

The first impression on seeing the bass with this customisation was of the small amount of modification needed to be done to the bass itself. From the outside the only signs of customisation were the increased amount of switches on its scratchplate, and a plate covering the battery compartment on the back of the bass. The internal cut-out itself only needs a slight enlargement of the internal cavity.

Knobs and Switches

The Activator circuit requires the bass to have a couple more protrusions from the scratch plate; in addition to the pickup selector switch and individual bass and treble tone controls and volume pot (now a pull-pot acting on both active and passive output levels), there is a single mini toggle switch for switching between active and passive circuitry, and a red LED for battery status indication. On switching on the system, the LED will illuminate briefly if the battery power is okay.

In the passive mode, the bass runs with the usual volume control and selector switch, whilst the tone controls are disconnected. In the active mode, the Activator corrects performance irregularities present in the instrument by high impedance buffering, and a slight gain and treble boost (with the tone controls flat).

The tone controls themselves are tuned to give up to 15dB of boost or cut at 100Hz with the bass pot and 1kHz with the treble pot. These particular frequencies were chosen to give a lot of warmth and fullness from the bass pot, and a heavy edge with the treble pot, that although on its own sounds a little middly, when mixed in context with other instruments is in fact the perfect choice for a solid, cutting sound.

When the circuit is switched in, the active really does bring the instrument to life. Prior to having the Activator circuitry, I was fairly content with the results that I would get from the P-Bass with a little Eq and compression. However, the difference that Tim De Whalley's circuitry makes has to be heard to be believed. Without adding any hiss or hum, the sound of Fender's finest is given an audio facelift. The character of the sound itself is still undoubtedly that of a P-Bass, yet whether it is DIed or put through a bass rig, it sounds punchier, clearer, tighter — in fact the exact sound I had strived to achieve by fussing around with different mikes, parametric Eqs and compressor limiters.

The variation in tone is quite superb as well. The tone controls are non-interactive, and this means that as you increase the bass pot, you will not be affecting the frequencies that are controlled by the treble pot. With 15dB of boost or cut, the range of tone colours available are sufficient for most musicians, ranging from a hard Stanley Clarke-like lead bass sound, to a thick, fat sound that would not shame Moog's Taurus pedals.

Conclusion

As you may have gathered by my enthusiasm I found it rather a good piece of electronics. With very little structural alteration to the bass guitar itself, the Activator, for me at least, will bring out the best in the Precision, as well as giving it quite superior tonal capabilities.

Ampro also have an Activator which is designed to fit a Fender Stratocaster, and if the P-Bass version is anything to go by, then I think I'll be fitting the Activator circuitry to my Strat as well.

AMPRO CD-P ACTIVATOR - RRP £62.30

Available through Touchstone Tonewoods, (Contact Details)

Unfortunately the black, left-handed Precision bass used in this review has since been stolen. It was last seen in the back of a car in the Harrow area. Please contact International Musician on (01) 987-5090 if you have any information re its whereabouts. A reward will be offered to anyone responsible for its return.