recharging speaker magnets is not as simple as one might think.
there is a huge iron mass to magnetize and in the middle is the Alnico magnet that is surrounded of plenty of iron.
Thats why one need lot of power for to do it properly
I have built my own magnetizer years ago and I use it randomly when JBL speaker come to my possession.
Here are a few pics of the magnetizer Im using, or the parts that composes the machine
Data: 36,000 uF@900Volts (adjustable between 50-900V) = approx 14.6 kJ (kilo Joules)
Tha huge SCR is for 1400V/1600Amps, 20kAmps peak. The magnetizing coil was constructed using rectangular magnet wire of 8x3 millimeter
You could se a 2440 placed in center of coil
The power supply/source is a Lumina Power CCPF that could charge the capacitor bank with 1500 J (Ws)