Probably the worst bit of "soldering" i've ever seen on Citronic Digi 16P
mixer amp, Made in China it says on the rear.
An intermittant fault with one channel speaker, the wires 2.7mm diameter
over the insulation, 1.5mm or so core, the 4 wires go to a rear board for
speakons and 1/4 inch outlets. Each wire is stripped neatly , leaving some
whitish thin coating over the copper core wires that probably holds the
filaments together until solder temperature melts it . Pushed through the
large holes in the solder pads and "soldered" on the blank side of the board
with little blobs of solder relying on melting of the board composite to
hold in place, and unmelted coating plainly visible on the other side. I
assume the holes are plated through or there would be no electrical
connection possible. The assembler must have passed the wires wrong way
through and soldered the wrong side.