The jig

Either use a tension scale (“Force Gauge Spring Dynamometer”) or make your own jig, as Quad did.

Tension scale

For the latter solution, you will need 28 weights of 1.5 lbs for the bass, and 28 weights of 3 lbs for the treble. From a practical point of view, 2 times 28 weights of 1.5 lbs is preferable.

For bass film, use preferably 12 um PVC, alternative being 12 um PE (aka Mylar, Melinex, Hostaphan,…).

For treble film, use 6 um Mylar. Due to higher strength applied, annealing will be suggested for this one.

And for dust covers, use same film as for diaphragms.

Original film stretcher used by Quad (jig)
custom 1.5 lbs weights (680g)
Custom jig used for bass panel. Used film is rather fragile which explains tape bands
New dust cover installed using the jig. Glued with 3M 467MP strips

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