Polyfill ampeg

[billfitzmaurice]

Well, well......

Interesting.....

I will say that stuffing, done properly, has always resulted in pretty much the theoretical effect for me, however....... if you keep it away from the close-in speaker cone and vent areas it does not seem to affect the Q particularly.....

I have for instance, actually USED the effect to get a slightly smaller box to act larger, and it did , without appearing to flatten out the box resonance......

Presumably the overall effect is sufficiently close to appear to work as described...... Most things acoustic are known to only 10% at best in production....... there is considerable room for variation in that.

I am also not quite with you on the higher impedance when stuffed..... it does not seem to fit on an energy balance basis...... or with the lower Q.

Modeling software that has provision for box lining resistivity and thickness shows what happens when a sealed box is stuffed. In the case of a Beta 10 in a 20L box, for instance, stuffing lowers f3 by about 10 Hz, which gives the subjective impression of a larger box, but as it does so by lowering Q there's a loss of 2dB sensitivity above f3. The 10 Hz lowering of f3 is accompanied by a 15 Hz lowering of the frequency of the impedance peak at Fsc, while said peak value goes up by 2 ohms. If the cab is left unstuffed but volume is increased to 30L the same alterations occur to f3 and impedance, but without the 2dB sensitivity loss above f3.