My experience at Magnepan is from almost 35 years ago, so it is, or course, going to be largely out of date. I have no idea what has changed in the decades since then.
I primarily worked putting the mylar on the panels. The perforated plates came in to the room next to us, where they gave them a chemical bath to remove any residue on the steel (we were told that if we ever saw people in that room start to fall over, we were
not to go in to try to help them — we needed to exit the building immediately, and call 911.) Then they glued on the magnets, and sent them over to us.
The first part of our job was very labor intensive — because the rubber bar magnets on the panels arrived already magnetized, there was no way to keep them from picking up little chunks of stuff: little magnet bits, slivers of steel, etc. So we went over each panel with tweezers, spotting every single little magnetic sliver or crumb, and removing them. Anything you missed would eventually work its way onto the top of the magnet when you applied a music signal to the panels, because of the vibration and the additional electromagnetic field, and then it would stand straight up and buzz. So we worked very hard to get them perfectly clean.
We'd then mask off the magnet armature, spray adhesive on the edges of the panels, and attach the hardboard strips that would hold the mylar above the magnets. The hardboard strips had adhesive (to hold the mylar), and each pair of panels would be moved to the filming table.
Matching panels were always filmed right next to each other, so that the sound matched as closely as possible. There were rollers on each axis to tension the mylar to a specific newton-meter value, and then we waited a bit for the tension to even out and the mylar to 'relax' slightly before we brought the table up from underneath to adhere the mylar to the hardboard strips. Magnepan records the final tension values and relative humidity for every pair made, so that if a pair comes in for major repairs, they know how to match as closely as possible the original assembly conditions by looking up panels.
We'd trim the panels out of the mylar, add a second set of strips to hold the mylar in place, and then send it on to where the wire grid is attached. I did that too, briefly. They had just changed to a new formulation of miloxane, with a blue tint, which was much less susceptible to the 'sun rot' that plagued Maggies when the rear of the speakers were exposed to sunlight.
QA would occasionally find buzzes in the panels after assembly due to little magnetic bits we missed, and circle the location on the mylar. We'd go straight through the mylar with a sharp pair of tweezers to pull slivers out, and then add a little square of tape to fix the hole.
On breaks I'd visit the repair area, which was on the other side of us, and look at the old systems which came in — Tympani IVs. Older panels that used hexagonal generic perforated steel, instead of the custom-made ones that only had perfs between the magnets. Panels that had been shredded by cats (cats and Maggies are natural enemies!) Panels with sun rot where all the wires had started peeling away.
We had big anechoic chamber up near the front of the building, and an amazing 'closet' filled with old reference amplifiers and some speakers as well (I remember a pair of Infinity RS-IIB speakers, a massive Mark Levinson amp on the floor, and a Phase Linear 700 used as a doorstop!)
The listening room up front was also an amazing place to visit on breaks. Probably the best system I've ever heard in my life was the 'show' pair of Lexan-framed MG IIIa speakers (no fabric, so you could see the panels, and the panels mounted "backwards" so the steel plate was facing the rear, and the mylar was in front) and a pair of Apogee Scintillas being used as subwoofers.
I have owned a pair of SMGa speakers, a pair of super old-skool MG-1s with the sheet metal frame (instead of the modern computer-milled MDF) that my wife found as a basket case in a resale shop and I restored, MG-IIs, and a pair of MG 2.7s which my younger son still owns. I generally ran Carver amps (I used to have a stack of M-500t amps and a 1.5t.)
But I moved from a big house to a relatively modest condo and shed a lot of gear, and run a pretty simple system now with just the Odysseys. Sorry for the small novel.
