4A-32B Loudspeaker: the story of a repair

Instaling the main diaphragm (staff metal ring + screws) and gluing the voice coil (epoxy):

It was decided not to set a whizzer (additional cone).
Instead, I soaked the dust cap with acetone diluted epoxy; hope with a strengthened centeral area of main cone it will extend the high-frequency response.

The coil moves without clinging!

The leads.

Originally, the ones were ordinal stranded wires. Such wires are less resistant to metal fatigue failure than so called "tinsel wire" used in modern loudspeakers.

The multiple tinsel wire was extracted from old telephone cord:

At first I tried to remove the insulating skin, but the risk to damage supere thin metal foil strands was very great.

The ends of wires are reinforced by stitches of cotton thread + glue impregnation:

DC resistance is 12 ohm.
The electic responce on mechanical shock (a live equivalent of Delta Function) is presrnted below:

It can be concluded that driver has a resonance frequency around 59 Hz and mechanical Q approx 9.
I'm a little puzzled about large value of Q as folk do report on something around 5.

The final moment - sticking new label:

ILYA, your mechanical method to measure Fs & Q is quite interesting!  I've never seen it done that way but it makes a lot of sense.  What is the Fs of a stock speaker?

42 +-7 Hz.

Folk report 48, 55, 52  and so on, never less than.
My ones are located 250 km from me, will be measured on occasion.

My loudspeaker is still waiting for housing/mounting.

Cheers!