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Posts by Bill Fitzmaurice

It can be an indication that the limit of the driver excursion has been reached, and that can lead to long term heat build up in the coil and eventual failure. This assumes that the sub is well designed, so that it will not chuff within the maximum excursion range of the driver, and that the amp is high-passed to prevent over-excursion below the sub's pass band. Of course, if it's not well designed that's a different story.
Yes. Some materials are much more difficult, and therefore much more expensive, to work with. For instance, magnesium is a very good material sound wise, but very difficult to make into diaphragms, so you only see it used in expensive drivers.Most of those prejudices are the result of not actually knowing how drivers work.
Don't use spikes on a concrete floor, unless it's carpeted. Replace them with rubber feet of the same height. As to 'feel', that's created by the sound waves that the sub produces, not what it's standing on. OTOH the floor should be carpeted, concrete is not conducive to good sound.
I use measurement software, but for those who don't have that option using individual tones and writing down the results is a good way to spend a week or three.
You're getting different readings because of the tolerance level of the meter. You'll get a much more accurate result on the 200 ohm range. The DCR of an 8 ohm speaker will typically run between 5 and 7 ohms. BTW, you're not trying to determine how many ohms your speaker is, you're trying to determine its impedance, which is expressed in ohms.
If it is a true phase adjustment, using an all pass filter, it shifts all frequencies equally. That means set to 180 degrees it will give the same result as a polarity flip.As for testing the relative polarity of two subs that's a simple matter. Put them together, leave the volume of one off. Play the AVR level test signal for the sub. Bring up the volume on the second sub. The level should go up. If the level goes down as you turn the second sub up louder they are not...
It's considerably more complicated than that. Just looking at the pic you posted I can see that there is no actual crossover in that speaker, just series wired NPE capacitors. That doesn't mean anything to you, but it tells me that the speaker is, to be blunt, a cheap POS that's probably not worth fixing, not even for $20.
I'd have one in the front, one in the back, but the one in the back must be less than 3 feet from the wall.
Go to the Yellow Pages, call the nearest HVAC contractor, ask where he gets the Type 700 that he uses for duct work. That style will have an aluminum foil backing, but that's not an issue if that faces the wall. Or you can strip it off. You can also use fiberglass drop-in ceiling tiles, stripping off the plastic facing, but it's only 1/2"-5/8" thick, so you'd need to stack it.
All subs have exactly the same radiation pattern, 360 degrees. It won't make any difference changing subs.You can fight the physics all you want, but you'll never win. You must place the sub and/or the LP where you get the best results. As for the neighbors, they won't experience the null that you do, because they're not sitting where it occurs. You can be getting no bass where you're sitting while they're getting pounded, especially as your inclination to compensate for...
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