[davidff]

I have used the 55 bulb also.  In most cases that I have used it, it was not as good a performer as the original Mazda bulb.  I believe the reason is the original bulbs have a straight filament that reflects a stronger beam onto the cell.  If I have a replacement cell in my tone arm, the 55 works pretty good because it is more sensitive and does not need as much of a reflection.  On my 42-1008 which has an original cell, the 55 does not sound as good at all.