[Trevor]

"Peter Larsen" wrote in message
k...
A bit of initial data: bass resistance some 2.5 Ohm, mid some 7 Ohm and
piezo some 3.3 Ohm.

It's not a piezo, or there's something wrong with your measurement.


Bulb resistance around 1 Ohm. After opening and
assembling the deviant one its mid and treble went totally silent. Opened
rear panel for bulb access. The main cause of problems was the bulb
fixture.

The bulb has small bullet on end that should match a contact surface that
is
loaded by spring. That surface was not perpendicular to the bulb axis and
consequently the bulb had gone from lacking to no contact.

Finagling with the contact surface and repeatedly rotating the bulb
removed the majority of the difference between the two 4 Ohm boxes.
Sound - nor curves - are not totally identical, but making physically
identical measuring setups so exactly as required by an off-axis tweeter
is non-simple. It probably will require soldering a bypass of the
bulb-protection device to eliminate it as a cause of difference, at least
during measurement and it is a long long way from being roadworthy in my
understanding of that word.


I'd just replace the bulb with a soldered in polyswitch, or at least solder
the bulb instead of a socket.

Trevor.