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Old 11th September 2013, 01:09 PM   #101
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Originally Posted by Trackzilla View Post
Finish...these are for perm install, so they won't need road rash protection...figured paint du jour, inside & out...If someone has a recommendation that comes with reasons that will really affect the performance or lifespan for cabinets that will spend their life installed indoors & being heard but not seen, fire away...
I would avoid MDF just for the lack of resistance to moisure alone.
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Old 11th September 2013, 01:59 PM   #102
sine143 is online now sine143  United States
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Originally Posted by chris661 View Post
Also ensure there's some kind of grill covering the driver cone.

If a can gets sucked in there and starts bouncing off the cone, you'll lose the driver pretty quick.
I work Union club nights, and see this sort of thing quite often. A belt (buckle) tore one of our 18"s apart recently, and the re-cone wasn't cheap.

Chris
truth. ive probably POURED about a 100 cans out of my flhs
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Old 11th September 2013, 06:10 PM   #103
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They will have grills, 3/4" expanded steel with acoustic grill cloth behind, I buy that by full sheets & use that approach for all of my cabs. Beer cans, bottles, glassware, shoes, jewelry, underwear, live chickens, the list of stuff I have extracted from ungrilled horns after shows is amazing. And I am fixing a cab for a DJ this week that some drunken child literally kicked in, won't be possible to repeat that damage when I return it to him grilled my way.

Waterproof is a given, that's why I planned on painting both inside and out. That way I have an internal moisture barrier to keep them from degrading from humidity on the inside as well as liquid on the outside. I have seen cabinets mold from the inside in clubs around here. They will also end up mounted at least 3/4" off of the floor to minimize the layer of wet that would never go away if a panel were resting directly on the floor.

MDF is also a given, at least for one cab as a test unit, I must satisfy my curiosity about the sonic differences (if any) between the 2 materials in this sort of cabinet...but the MDF cab would have to display some unexpected dramatic performance difference before final cabs would run the risk of using it as I have always hated the stuff personally. I already have both MDF and Baltic Birch cut for these first 2 test critters. Regardless, with permanent install (never moved cabinets) I can't see the moisture degradation being too much of an issue assuming I have them properly sealed to begin with. Another club in town here has MDF horns with 2 coats of cheap latex paint that have been living there unchanged for 10 years now
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Old 12th September 2013, 12:03 AM   #104
colofan is offline colofan  United States
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Bartop finish would be a good top coat for this application.
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Old 12th September 2013, 12:07 AM   #105
colofan is offline colofan  United States
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One other item in all the simulations what is the off axis response? I am sure that horizontal and vertical are different. I believe the curves given are on-axis and centerline from the driver. You might want to check to see if there is going to be any "suck out" due to phase issues between the two boxes.
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Old 12th September 2013, 12:56 AM   #106
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Originally Posted by colofan View Post
One other item in all the simulations what is the off axis response? I am sure that horizontal and vertical are different. I believe the curves given are on-axis and centerline from the driver. You might want to check to see if there is going to be any "suck out" due to phase issues between the two boxes.
Hornresp shows power response I believe, not on axis response. I believe I mentioned this a long time ago, having the horn mouths 16 feet apart is going to create directivity issues at the top of the subs' passband. And depending on where the mains are located the situation might be even worse.

Last edited by just a guy; 12th September 2013 at 12:59 AM.
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Old 12th September 2013, 08:39 AM   #107
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It's not 2 boxes 16 feet apart, it's 3 boxes reaching a total of 16 feet between them. However 2 will be corner loaded & one will be in center of the stage. Yes, there will be some imaging issues, but they won't be nearly as bad as 2 cabs 16' apart would be.
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Old 12th September 2013, 04:26 PM   #108
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Imaging and directivity are COMPLETELY different things. And there's no such thing as imaging at subwoofer frequencies anyway.

16 feet between subwoofers is going to cause directivity issues at the top of the subs's passband, no matter if there's 0, 1 or 100 extra subs between the two that are 16 feet apart. This is an issue about physical length vs wavelength.

Anyway, if your room corners are 16 feet apart, that sounds like a seriously TINY room, I thought this was a club. With a room that small I'm not sure directivity would matter too much, but you should probably look it up just to find out what it means if you are working in the industry. (Directivity is aka dispersion, on vs off axis response.)

Last edited by just a guy; 12th September 2013 at 04:32 PM.
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Old 12th September 2013, 06:01 PM   #109
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I'm well aware of the difference between the two terms, I simply used the wrong word when writing a quick post at 4:30AM at the end of a 22 hour day. Please forgive the error. I know you have quite a bit of knowledge & appreciate your help, but sometimes the your posts seem to carry the assumption that I am a rank tyro. After 30 years of pro audio I miss some things sometimes, but this ain't my first rodeo.

This IS a small room, and it IS a nightclub with a very regular performance schedule of national level Rap, EDM, and recently Country artists. The total depth of the room is only around 40' and choices for cabinet placement are extremely limited. That's why I keep acting relatively unconcerned about the directivity when it is brought up, I've run a batch of room sims & this is the best compromise I could find.

IN theory: While 2 subs 16' apart create one diffraction pattern, famous for the central power alley and the dual 45 degree moire pattern of nulls that becomes more dramatic as frequency approaches a critical wavelength, and this could be problematic even in this short of a presentation space, each additional identical sub betwixt those two that is driven with it's own processing line to allow for discrete delay/phase/eq adjustment can essentially allow some steering and breaking up of those sum and null patterns into finer graduations of softer variation in specific directions until you approach the driver density that will behave as a true line in the relevant frequencies...or an end fire if you have enough space to use it that way, where on the one hand it is a continual mass of cancellation and summation variations, and yet on the other hand they are so complex and subtle that they are resolved as no change in the desired coverage area.

In practice: Currently the club rents additional rig a couple of times a week for those larger shows, the rental subs go roughly where two of the new ones will live & complement the existing house subs which are where the 3rd new one will be. With a bit of tweaking we get a very effective result this way, and the performance difference we are adding will be in the 20-50 Hz range where these 3 subs will be within 1/2 wavelength of each other.

Technically the room corners aren't 16' apart. The actual corners are around 35' apart. But at 16' there is a balcony/2nd floor, so at that point the ceiling height for the rest of the area shrinks to 8' 4", and there is a 4' high bar that is very solidly built that the subs will butt against, exiting along the floor. So the airspace becomes something between corner loaded and wall loaded for those two subs, depends on the frequency in question. The upstairs are has the same overall width as the downstairs/stage, but extends slightly deeper. Didn't I mention early on that the acoustic space was somewhat nightmarish?

Last edited by Trackzilla; 12th September 2013 at 06:15 PM.
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Old 12th September 2013, 06:34 PM   #110
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Originally Posted by Trackzilla View Post
I'm well aware of the difference between the two terms, I simply used the wrong word when writing a quick post at 4:30AM at the end of a 22 hour day. Please forgive the error. I know you have quite a bit of knowledge & appreciate your help, but sometimes the your posts seem to carry the assumption that I am a rank tyro. After 30 years of pro audio I miss some things sometimes, but this ain't my first rodeo.
Ok, apologies. I have no idea what you know and when you use the wrong terms (especially when the right terms have been used in the previous post) it makes me think you don't know. I had no way to know that you already know about power alleys and steering.

The best solution is to keep the mouths close together but if that's not possible your experience with steering should get at least most of the bass where you need it to go.
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