Posted by Scott F. [ 66.82.192.1 ] on February 21, 2004 at 12:20:30:
In Reply to: Re: Who are you calling a Nut :-) posted by akhilesh on February 21, 2004 at 09:12:01:
Hiya,
> Of course, the term "nut" was used in a complimentary way, since in the single driver forum, we are by definition all "nuts" (i.e., enthusiasts).
I know, I was just poking fun :-)
>How big were the boxes for the goodmans? I have a pair of electrovoice EV Force 15s that need about 20 cubic feet BR boxes to go down to about 30 HZ, with 100 DB eff. I can;t make them, since my music room would then be jam packed. I was thinking of trying a music subwoofer.
The Goodmans are in about a 3cf BR box. They used to have two slots about 3"x12" cut top and bottom of the front baffle. I sealed those up and cut 1 1/2" holes in there so I could "tune" the box a little easier. I just played with different length tubes until I got the smoothest response. I haven't gotten around to measuring the TS parameters fo the Goodmans yet. I will one of these days. When I do, I'll model them and build a proper enclosure for them. For the meanwhile, they are in their original cabinets.
What you are seeing with your EV is why I mention looking at some vintage, HiE speakers. They are cheap and they were designed for smaller boxes. Trouble is, there isn't much of a database for the TS params for these old divers. Purely speculation hear but (and I can see the responses already)....if you were to pick up a pair of these and put them in a quickly made, braced, plywood 3+/- cf BR box. You could tune them by ear. You can play with different lenghth ports by using paper towel cardboard tubes. Just cut them to different lenghts, insert them and listen. When it comes to the "wrong" internal volume, you can always add bricks to take up internal volume if the box gets too boomy.
I realize this can be a HUGE pain in the sphincter muscle - but - if you don't have the ability or tools to properly measure the TS params, this is just one way of doing it. It isn't scientific by any stretch but it does get you somewhat close. After you discover the "right" sound for you, then you can build a proper enclosure out of MDF or whatever your fav material is.
>I was thinking of trying a music subwoofer.
My experience very limited experience with commercial subs, all of the manufacturers want to propide the most Xmax they can. Familiar with the statement "Everyone knows the only way to get REAL bass is to move tons of air."? Hate to say this but I (personally) think they are wrong. Not just a little wrong but REALLY wrong. I've tried rolling a 12" Shiva under the Lowthers and it didn't blend at all. I lumbered and covered up loads of bass and midbass details. It stuck out like a sore thumb. When I rolled in the Goodmans (HiE, low Xmax) it was like somebody finally focused the picture. They blended perfectly. These things don't call a bit of attention to themselves at all.
I really think alot of this is due to trying to match a LowE high distortion driver with a HiE low distortion driver. It doesn't work. Match high distortion sub with high distortion monkey coffins and it works just fine. Heck I do that now with my small system and it sounds pretty good.
I have convinced myself (right or wrong) that the Lowther/Goodman matching is pretty simple. These are HiE, low Xmax, low distortion, thin rigid coned drivers. They come closer to matching the Lowthers in construction and design than the loose, flabby, LowE, high distortion subs out there.
Problem with the ProSound drivers is their Q (amongst other issues). Thats not to say they can't sound good but the compromise is the box size. If you ever thought a proper horn was BIG, wait until you build a box 10cf or bigger. I've done it. I built 9.75cf boxes for the Shivas. It takes two people to handle one of these darned things. They weighed well over 200# each. Definately not a project for the faint of heart.
Personally, I think trying one of the cheap, vintage drivers is well worth experimenting with. They are cheap (did I mention that they are cheap), readily availible, and your unfnished, plywood 3cf test box can be made in a matter of a couple of hours. Just a few hours after that, you'll have them tuned and be finalizing designs for the proper enclosure.
Again, this is just one approach to it. Maybe not the best and certainly not the only way to do it but it's worthy of consideration. In my case it just happened to work extremely well. I just wish Lowther, Fostex and others would consider making a LARGE, HiE woofer that had a workable Q. So many of our (collective) problems could solved by that.
> I would also like to say that I have taken Martin's friendly challenge, and am playing with my fullranges ...
Absolutely, go for it. It's well worthy of playing with. When it comes to the filter circuit "choking" the midrange, thats OK. If you are using a fleapowered amp and can live with the efficiency drop, thats absolutely fine. If you use solid state and like the sound thats cool too. Ultimately, all that really matters is that you are getting some decent tunes from the design and that YOU are happy.
Seeya.
Scott