The late Be Yamamura was a hugely inspirational figure, bringing an uncompromising approach to designing and building hi-end Hi-Fi systems to a wider audience outside his homeland of Japan. This item is from a system he design in the UK.
This is a pair of mid range horn compression drive units. They started out as a Fostex D502 or D506 (the only difference between those that I'm aware of is the diaphragm material). The drive units have had a massive rear chamber made from a billet of stainless steel fitted during the original modifications. These are incredibly heavy, I've weighed them at approximately 23kg each! They have a total length of 260mm and a diameter of 190mm.
These drivers use Alnico magnets and have a 50mm/2" exit and have the HA51 throat adaptor installed to give you the option of a square or round exit. I have measured the impedance and they are both approximately 11 Ohms at 10kHz.
Due to their weight and fragility these are collection only.
