Just about finished reconing a pair of JBL LE8T's. Last thing to do is add the dust caps. Which brings up the following questions:
Should I go ahead and use the aluminum dust caps?
What about paper dust caps? Has anybody tried these on the LE8s? What would be gained/lost?
Phase plugs? Has anybody tried them on the LE8s?
Also, when I removed the old cones, one of the dustcaps had a couple of pieces of foam glued underneath. If I go for the aluminum dustcaps, should I go for some damping with felt or foam pieces?
Your input is much appreciated.
Should I go ahead and use the aluminum dust caps?
What about paper dust caps? Has anybody tried these on the LE8s? What would be gained/lost?
Phase plugs? Has anybody tried them on the LE8s?
Also, when I removed the old cones, one of the dustcaps had a couple of pieces of foam glued underneath. If I go for the aluminum dustcaps, should I go for some damping with felt or foam pieces?
Your input is much appreciated.
Conventional wisdom has aluminum dustcaps somewhat extending the high frequency response compared to paper or no dustcap. Fostex's FF line does just that. Of course, 6" and up drivers with no whizzer - even with an Al dusctap - don't usually produce sufficient HF by themselves. The FF225WK wasn't enough for me, but I've never heard the FF165WK, which might be OK, if somewhat soft-sounding.
I think Al will have a sharper self-resonance than paper or other materials, but possibly higher in frequency due to greater stiffness.
I suppose a small wad of foam behind the dusctap might benefit any material, by absorbing resonance in the closed volume behind it.
I think Al will have a sharper self-resonance than paper or other materials, but possibly higher in frequency due to greater stiffness.
I suppose a small wad of foam behind the dusctap might benefit any material, by absorbing resonance in the closed volume behind it.
There would be a loss of the effective cone area (SD) if the dome is omitted. Given that the LE8 T uses a shallow cone profile , the issue of crosstalk interference at the cone apex should not be a problem that requires a bung ( 'phase plug') to be fitted. If the aluminium dome is fitted it should be treated to reduce ringing. This is best achieved with a light hard coating rather than a soft damping material such as foam plastic. IG81 is correct in advising the fitting of a foam pad on the magnet pole piece will reduce cavity resonance.
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