System for preparing a beverage

Various aspects related to a system for preparing a quantity of beverage suitable for consumption. The system comprises a first exchangeable capsule and a second exchangeable capsule, the second exchangeable capsule being larger than the first exchangeable capsule and an apparatus including a first brew chamber part and a second brew chamber part forming a brew chamber for selectively holding one of the first and second exchangeable capsules, and a fluid dispensing device for supplying an amount of fluid, such as water, under pressure to the first brew chamber part. The cavity of the first brew chamber part provides guidance to an outer part of the second exchangeable capsule, ensuring proper positioning before commencing the process of preparing the beverage. Optionally, the first brew chamber part comprises a centering module for centering the second exchangeable capsule in the cavity.