Marcel, by "controller" do you mean the pickup system? Older A12's should have the ES-B system, which is an on-board preamp with volume and tone controls and uses an under-saddle transducer (UST). Does your guitar have a barn door side port for the preamp, or three buttons on the upper bout near the neck? I do not own an A12, but have played them nahy times in stores, hence the questions.
It is possible to swap out the pickup system for something else. Some systems will be better, some may be worse in terms of tone. I caution you against sending it to Taylor for any change. They will try hard to upsell you to adding the ES2 system. Many of us do not like how that system performs, and the modifications involved are irreversible. Many have been happy by changing to a JJB or a K&K sound board transducer (SBT) system. That has a sensor glued underneath the top instead of a piezo strip under the saddle. SBT's typically sound more natural but are more prone to pick up body noises such as tapping or rubbing against clothing.
