Hi,
First off I have to say that my preferances have always run to forward firing 18s.
For testing it was matched with a JBL EON 510 (remember we are shooting for a truely lightweight portable system). In a 24'x24' double car garage it sounds great. The natural frequency of the sub is around 40 but I ported it at 22hz. It does good from 22-30, but really good above that.
An Ipod playing Lady Marmalade(not my favorite song but good for testing how a speaker handles bass and distortion) with and Eon 510 and this sub fills the room effortlessly.
More info when I can test it in a larger venue.
Steve
First off I have to say that my preferances have always run to forward firing 18s.
For testing it was matched with a JBL EON 510 (remember we are shooting for a truely lightweight portable system). In a 24'x24' double car garage it sounds great. The natural frequency of the sub is around 40 but I ported it at 22hz. It does good from 22-30, but really good above that.
An Ipod playing Lady Marmalade(not my favorite song but good for testing how a speaker handles bass and distortion) with and Eon 510 and this sub fills the room effortlessly.
More info when I can test it in a larger venue.
Steve
Many PAs are more concerned with size in the truck than with weight.
For your weight goal, if you think about it you can do much better.
Think of the specific kind of strength required. The square cabinet wants to blow up like a baloon and then compress like a shrivelling fruit.
One approach is to use a round enclosure that is more ideally structurally suited to withstanding internal pressure changes.
One approach is to tension flat panels with a matrix of tight steel cables inside.
A better (IMHO) approach is the way B&W braces their best cabinets. It looks similar to the boxes that bottles of wine come in. Flat sheets with slots interlock making compartments for each of the individual bottles. I've done this with masonite and it works incredibly well for making a good speaker cabinet with lighter walls. I rout slots into the box interior, then I brush epoxy on it all. But to really be light you would have to use carbon fiber sheets. If you decide to try this, I have some practical advice based on my experience. The identical walls of all the repeated shapes of these sub-divided little cubicles of space can ring symathetically like bells if they are stiff, and if you stuff them they will create little tube-trap acoustical shapes that absorb certain frequencies better than others. So I advise making the spacing of the divider panels irregular, resulting in varous sub-divided shapes (braces closer making smaller sub-spaces toward the middle of the enclosure where more bracing is needed). I also coated the divider panels with rubber automotive undercoating before I stuffed them, but that defeats your weight-reduction goal, and it isn't really necessary once you stuff them with fiberfill. I also cut holes in the interior braces to lighten them and to prevent pressure waves at some insident angels from deforming (bending) or activating the panels...you don't want the brace panels to act like a signal source that the box sides amplify like a guitar sound board. I sometimes added a wood strip or something (plastic) to terminate the ends of the interior panel braces; bracing the braces so they don't ring.
Once you've addressed weight, consider addressing size if you really want it to be portable. It's far easier to carry a heavier but smaller box. Consider telescoping enclosures, or enclosures where the front transport cover latches to the back to make a larger enclosure, or where light folding front doors or hinged side panels make a crude horn/baffle to at least control radiation/dispersion pattern.
Some of the latest extremely flat-shaped woofers (which don't have a deep basket or magnet sticking out the back) designed for tight car interiors are nearly ideal for isobaric mounting. That allows you to make a cabinet that's half the size and weight but sounds the same as its double-sized non-isobaric twin. Doubles the driver weight and power requirements, but cuts the box size and weight in half. Makes in impressive little killer sub.
For your weight goal, if you think about it you can do much better.
Think of the specific kind of strength required. The square cabinet wants to blow up like a baloon and then compress like a shrivelling fruit.
One approach is to use a round enclosure that is more ideally structurally suited to withstanding internal pressure changes.
One approach is to tension flat panels with a matrix of tight steel cables inside.
A better (IMHO) approach is the way B&W braces their best cabinets. It looks similar to the boxes that bottles of wine come in. Flat sheets with slots interlock making compartments for each of the individual bottles. I've done this with masonite and it works incredibly well for making a good speaker cabinet with lighter walls. I rout slots into the box interior, then I brush epoxy on it all. But to really be light you would have to use carbon fiber sheets. If you decide to try this, I have some practical advice based on my experience. The identical walls of all the repeated shapes of these sub-divided little cubicles of space can ring symathetically like bells if they are stiff, and if you stuff them they will create little tube-trap acoustical shapes that absorb certain frequencies better than others. So I advise making the spacing of the divider panels irregular, resulting in varous sub-divided shapes (braces closer making smaller sub-spaces toward the middle of the enclosure where more bracing is needed). I also coated the divider panels with rubber automotive undercoating before I stuffed them, but that defeats your weight-reduction goal, and it isn't really necessary once you stuff them with fiberfill. I also cut holes in the interior braces to lighten them and to prevent pressure waves at some insident angels from deforming (bending) or activating the panels...you don't want the brace panels to act like a signal source that the box sides amplify like a guitar sound board. I sometimes added a wood strip or something (plastic) to terminate the ends of the interior panel braces; bracing the braces so they don't ring.
Once you've addressed weight, consider addressing size if you really want it to be portable. It's far easier to carry a heavier but smaller box. Consider telescoping enclosures, or enclosures where the front transport cover latches to the back to make a larger enclosure, or where light folding front doors or hinged side panels make a crude horn/baffle to at least control radiation/dispersion pattern.
Some of the latest extremely flat-shaped woofers (which don't have a deep basket or magnet sticking out the back) designed for tight car interiors are nearly ideal for isobaric mounting. That allows you to make a cabinet that's half the size and weight but sounds the same as its double-sized non-isobaric twin. Doubles the driver weight and power requirements, but cuts the box size and weight in half. Makes in impressive little killer sub.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.