How to build a high-quality loudspeaker cabinet?

You have bought already the required kit or the necessary components. What to do next and which aspect should be paid attention to?

The cabinet:
It is important that the cabinet is airtight and doesn't vibrate uncontrollably. The most suitable materials are:
- Chipboard (inexpensive, however, treatment of the rough surface is rather complicated and time consuming.
- MDF panels (about 50% more expensive, but with a smooth surface and edges)
Quite suitable are also cabinets made of bricks, concrete or stone - they are, however, difficult to handle.

In order to suppress unwanted vibration internal bracing panels should be fitted to the cabinet (2 to 3 panels for a 80 x 225 x 25 cm cabinet). At least one supporting panel should be fitted in a right angle (preferably in the centre) to the panel running over the full height of the cabinet.

Removable parts should be sealed with car putty, adhesive sealing (e.g. window sealing) or our driver sealing tape (-> damping material). Non-removable wooden parts should be put together using wood-glue or even better structural adhesive.

First you need to prepare all panels and drill the necessary holes. If not indicated otherwise the bass reflex opening should be close to the bass driver. The midrange driver / tweeter should be even closer to the bass driver, otherwise - depending on the listener position - volume differences in the crossover frequency range will develop.

Loudspeaker drivers:
The individual drivers have to be connected to the crossover. It's essential to connect the drivers with the correct polarity. Every driver's plus terminal is marked, usually with a red dot (or e.g. with a white flag like Peerless WA 10). The driver's plus pole may also be determined by connecting the plus pole of a small battery to it. In this case the driver's cone should move outwards.

The crossover's plus pole is tagged as well, either with a "+" or a red marker.

If you design the crossover yourself it's not that important that all speakers are connected with the correct polarity. It is, however, absolutely mandatory that the polarity of each driver of one loudspeaker corresponds with the drivers' polarity of the other loudspeaker.

Important: the correct connection of the tweeter
Please pay attention to connect the tweeter to the correct "tweeter" terminals of the crossover. If the tweeter is connected to the bass driver terminals by mistake then the tweeter's voice coil will be destroyed, should the volume of the amplifier be increased carelessly.

Bass reflex tube:
There is an elegant solution to tune bass reflex speakers: the longer the tube the tighter the bass. The shorter the tube the boomier the bass. If you intent to position the speaker close to a wall, the tube should be longer, since walls enhance bass. On the other hand, the tube should be shorter when the speaker is placed in the centre of a room.