90% of most enclosures sold online are "pre-fab".
The current situation is one of two with prefabs.
1. They are built on a ship that goes back and forth from the US to China. MDF is supplied here and the work force is supplied by China. The ship has several CNC machines on it, that cut out precut designs. The designs are very generic in nature with unknown specifics. Even when they are specified, they are typically off. This means the net volume, port area, and tuning are not as described. They typically also use cheap adhesive which leads to separation. They typically use moderate enclosure volume, low port area, and high tuning. All of this keeps the enclosure small.
2. They are built in texas but with the exact same guidelines as number 1.(not boat ride obviously)
There are companies out there that suggest an enclosure is built and designed around a particular sub. However, from what I have seen they are not all that different from the other prefabs. Just added a particular sub to the description.
All of these enclosures are on
ebay,
amazon, and normally at your local dealer.
