kevox wrote:Alright man....I like those suggestions:) How much air space do you have for your (2) 7" Reference speakers? Ported, correct? What size is the port? I'm guessing, since my little low-excursion Infinity 6.5" utilizes a 2" port that I should go with a good 3" flared port for a pair of Reference 7"s?
I don't know the first thing about crossovers (yet... I'm hoping to fix this problem while at Mobile Dynamics;)) so it would defintiely be nice to spend less on a 2-way that would still "rock my socks off" then a 3-way.
What do you think of 4 7"s per tower though?:D hehe I figure two things...
1. I like going overboard when it's not too costly and 4 7" mids definitely would be.
2. Those mids are only rated for 60w RMS a piece and I have an available 300w RMS @ 4ohms PER SIDE so I'd really like to take hold of that power;) Plus with 4 I can wire them series/parallel to a single 8 ohm load and, with the 8ohm tweet, the whole tower will wire right up at 4ohms whereas with just 2, it'd only go down as far as 6ohms. I realize that's not a vast power difference (about 70w) but it's less power AND less woofage:p
haha seriously....any reason you wouldn't go with 4 7" per side other than cost? Man that sounds TIGHT:D
My towers are around 3 cuft each, IIRC. 3" port that is 5" long (again going off memory, although I do know factually that it's a 3" port)
If you REALLY want to use four 7" drivers per side, your best option is a 2.5 way system rather than a 3-way system. By bandpassing the midrange drivers, you will eliminate their low end response, you'll have to enclose them, and you've essentially come full circle.
A 2.5 way system in this case would run two of the woofers in a conventional 2-way sense, playing from 20-2,000 Hz, or whatever xover point you'd use for the tweeter. The second pair of woofers would be equipped with a simple coil to taper them off around 1000 Hz.
The reason for doing this is baffle step compensation. Conventional speakers brought out from the wall a bit suffer from a loss in the low frequencies due to the changing of the space from one frequency to another. Low frequencies wrap around the enclosure and fill the entire room, thus causing a loss of energy at any one point. Higher frequencies only radiate in front of the speaker, which means there is more energy at any one point (in front of the speakers) at high frequencies. The transition point is directly related to the dimensions of your speaker's baffle, usually the width (as it is the smallest dimension).
There's two ways to fix this problem with a passive crossover. One is using a compensation circuit, which shelves down the high frequencies to match the attenuated output of the low frequencies. An excellent option, but lowers the effeciency of the speaker as a whole. This is what my speakers have, and contributes a great deal to their outstanding bass response in music.
The second way is with a .5 way system (2.5, 3.5, whatever), which uses a second woofer (or in this case, pair of woofers) with an inductor. The inductor allows the second driver(s) to fill in the bottom end, and then taper off as the frequency increases.
Your quad driver tower, built in this way, will have full baffle step compensation (provided you do it right) like my towers, but will be 6db more sensitive. They will have very potent bass and excellent output potential.
If you wish to do more research, Google "baffle step compensation" or "baffle step" and you should get some links and information.