B&W crossover rebuild photos

HandClick on each photo for a larger image.

Before any changes

The thin PCB boards were held to the base of the speaker using push-in plastic plugs which originally provided some damping but were getting a bit old and stiff. The wires were good quality but were getting a bit old too. They were soldered to the crossover apparently without enough length to easily remove the boards so they had to be cut. When I removed the bass drivers I found a lot of the wire bunched up in the foam (probably to avoid rattling) so if you are taking out the crossover on your speakers try taking out a bass driver at the same time! The wires connected to the drivers using clips rather than solder and the midrange and tweeter wires connected to the crossover wires using what appeared to be a low quality connector behind the bass drivers. Considering the high quality of the cabinet and driver construction this seemed a bit out of place.

The prototype

Using a cardboard base and new components I made a prototype and installed it into one speaker. This allowed a comparison of new and old to be made without doing too much damage. The wires were connected very roughly and components were tied down using only cable ties. The cardboard base was just pushed onto the original plastic plugs. The tall oil filled capacitors have to go in line in the centre of the crossover so that they fit into the partitions inside the speaker, so with the limited amount of space and the larger size of the new components there wasn't much choice about the layout.

Almost finished

The crossovers were assembled on 3mm acrylic boards, drilled to allow the cable ties to hold the components. Under each component there is also double sided mounting tape to reduce any movement or vibration. The acrylic board is screwed to the base through some cut up mouse pad to provide damping. Note that the high frequency capacitors have been swapped over from the prototype so that the shorter one is now in the middle. This was to provide extra space under the speaker port for airflow.
The internal speaker wiring has been replaced and the wires are now soldered directly to the drivers.

And complete

After the initial listening tests the two additional resistors have been added. One on the midrange circuit reduces the loudness and some harshness from the kevlar driver and the other is on the low frequency circuit to boost the bass.