I have noted a couple symptoms on my M3s that may suggest they need re tensioning with a heat gun. I’ve read the excellent posts here about it but wanted to ask a couple questions before I proceed.
First, what I’ve noticed are 1) a persisting ticking or crackling even when there is no signal, and 2) a slapping sound and high volume low bass. Would these both be caused by low tension in the Mylar, or just the slapping?
Second, in one post AcoustatAnswerMan suggested that slapping at high volume might be normal, is that the case? Maybe a certain amount of slap is unavoidable? I don’t want to risk damaging them if this is just normal for these speakers (though that would be a little disappointing).
The stator wires look like they are in very good shape, all straight and none visibly out of place, but I have not yet probed them to see if any are loose. I also don’t see any debris anywhere, these seem to be very clean and the socks are in good shape. I do see some slight puckering of the Mylar in the corners but this seems to be present on every panel even though only a couple of them have the slapping / ticking problems. Is that puckering normal or is that a definitive sign they have lost tension?
Any further guidance appreciated!
First, what I’ve noticed are 1) a persisting ticking or crackling even when there is no signal, and 2) a slapping sound and high volume low bass. Would these both be caused by low tension in the Mylar, or just the slapping?
Second, in one post AcoustatAnswerMan suggested that slapping at high volume might be normal, is that the case? Maybe a certain amount of slap is unavoidable? I don’t want to risk damaging them if this is just normal for these speakers (though that would be a little disappointing).
The stator wires look like they are in very good shape, all straight and none visibly out of place, but I have not yet probed them to see if any are loose. I also don’t see any debris anywhere, these seem to be very clean and the socks are in good shape. I do see some slight puckering of the Mylar in the corners but this seems to be present on every panel even though only a couple of them have the slapping / ticking problems. Is that puckering normal or is that a definitive sign they have lost tension?
Any further guidance appreciated!
The periodic ticking noise is likely caused by some foreign material caught between stator and diaphragm. It doesn't take much, and you may not see it. The offending material causes a (non-destructive) local discharge, and it makes the tick sound. The local charge on the diaphragm builds up again, and you get another tick. Since you need to remove the grille cloth for proper re-tensioning of the mylar, it's a good idea to clean the panels first. This, and the re-tensioning, should be done with the panels completely discharged. Compressed air is the best, applied gently back and forth, on both sides of the panel. Then vacuum both sides. This process may have to be repeated several times but is usually effective in clearing the problem.
The slapping issue may be loose mylar, or it's possible you've reached the dynamic limit of the speaker. Re-tensioning the mylar won't hurt. Be sure to heat the surface gently and evenly, keeping the heat gun always moving and at least 6" away from the louvers. Again, this may have to be repeated several times. The idea is to "sneak-up" on the mylar temperature, heating it only enough for it to re-shrink.
Also check that the felt dampers on the rear of the panels are well-adhered to the louver. If not, peel them off, and apply a spray contact glue on the felt only, wait for the glue to tack-up, and re-apply to the lover.
The slapping issue may be loose mylar, or it's possible you've reached the dynamic limit of the speaker. Re-tensioning the mylar won't hurt. Be sure to heat the surface gently and evenly, keeping the heat gun always moving and at least 6" away from the louvers. Again, this may have to be repeated several times. The idea is to "sneak-up" on the mylar temperature, heating it only enough for it to re-shrink.
Also check that the felt dampers on the rear of the panels are well-adhered to the louver. If not, peel them off, and apply a spray contact glue on the felt only, wait for the glue to tack-up, and re-apply to the lover.