JBL's official stance on purchasing transducers through JBL Consumer and HPAV Dealers or Service Centers is as follows as of January 2010:

We only provide parts for our finished units that need repair.

Customers will need to provide model and serial numbers of Harman products they are ordering parts for.

If the parts are not for Harman built products we can no longer complete the orders.

We apologize for any inconvenience this may cause.

Tannoy has a similar edict as found in their FAQ posted on their website.

Q. Can I buy individual parts from Tannoy like Drivers and Crossovers to build my own speakers?

A. Unfortunately not. We at Tannoy realise that some of our customers like building their own speaker cabinets as a hobby, and even though several years ago we were happy to supply individual components, we have recently experienced problems when genuine Tannoy parts have been purchased, custom fitted into homemade cabinets and then sold on improperly as genuine Tannoy products. We can not supply schematic drawings or design information relating to our loudspeakers. If you already own a genuine Tannoy speaker that has been damaged then we will of course endeavour to supply spare parts in order to repair your speakers for as long as the parts are available.

For now JBL Professional will continue to sell certain transducers over the counter.