DIY System - Starting with Sub - $1500 budget (for sub(s))

[WmAx]

One thing I should explain to the OP, is light fill. With a sub like this you can use no fill, or cover up to 50% of the internal surface with Polyfill.

Forget polyfill. Garbage, to be honest. In this enclosure, if large dimensions are used, say 36" or 40" high as an example, to get a narrow cabinet, then the 1/2 wavelength mode related to this dimension is going to occur centered at about 162 Hz, and as you know, this is just the center; it will start to occur by 145 Hz or so. The 1/4 wavelength cancellation, if the woofer is that distance from a boundary, will be just 84 Hz(!). Polyfill is a non ideal material in this case - and I think the interior acoustical problems are more serious than the port resonance.

So, instead of polyfill, one should use 5-6" of high density rockwool or fiberglass(4-8lb/ft3 density) board located at the farthest boundary, to prevent this cancellation, and 2-4" should be used 2 to 3 other walls to prevent any acoustical issues from occuring in the cabinet. This material has incredibly effective co-efficients at very low frequencies as compared to a material like standard density fiberglass fill or polyfill. The fiberglass/rockwool can be covered with a cloth to prevent the fibers from coming out of the cabinet port. I often use a poly air filter material I get on rolls.

-Chris

 

[GTHill]

Just wanted to let you guys know that I'm not ignoring you. I'm at work and I don't have Internet where I am staying. I'm going to look for some books for speaker building at Borders after work. I'm not optimistic, but we'll see what I can turn up.

Gene

 

[GTHill]

I just did a search for the books that were recommended earlier in the thread and I can't seem to find them. Can anyone help with that? Thanks!

Gene

 

[GTHill]

Sorry, posting for instant notification.

Gene

 

[Guiria]

So what would you power the kappa perfect 12 VQ sub with in a sealed enclosure? Would the PE 500 watt plate amp be sufficient?

Just curious.

 

[WmAx]

So what would you power the kappa perfect 12 VQ sub with in a sealed enclosure? Would the PE 500 watt plate amp be sufficient?

Just curious.

Yes, it would be sufficient. However, for HT use, the ported system is superior by far. In music, it is not likely much content under 35Hz will be present, so it does not matter. But for HT - with 20Hz range LFE being common - the ported system will have far better performance.

-Chris

 

[TLS Guy]

I just did a search for the books that were recommended earlier in the thread and I can't seem to find them. Can anyone help with that? Thanks!

Gene

You can get these books from Parts Express: -

http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=40&ObjectGroup_ID=72

Also from Audio Express: -

http://www.audioxpress.com/bksprods/BKSLOUDES.htm

As far as powering 500 watts will be plenty.

The F3 of a sealed sub is 28 Hz. It rolls off 12 db per octave, a ported sub at 24 db per octave. At full power the driver is at its linear xmax. However I think the power required for subs is greatly in excess of what is required except for Hollywood sound effects. So if you want to build a sealed sub, you can get an amp with an equalizer and boost at 12 db per octave below 30 Hz. This will of course limit the overall spl. A vented sub will have significantly greater acoustic output.

As far as fill. There was a study published in Audio Xpress two or three years ago, or there abouts, it might be longer, that showed Polyfill was excellent damping material for loudspeakers and superior to fiber glass.

I have to say you seem very new to all this, and would advise getting the literature recommended before building.

 

[WmAx]

As far as fill. There was a study published in Audio Xpress two or three years ago, or there abouts, it might be longer, that showed Polyfill was excellent damping material for loudspeakers and superior to fiber glass.

There is a significant difference between what is optimal for bass alignment use(increasing apparent size of enclosure space) and what is optimal for reflection/absorption use. No normal stuffing such as polyfill will match the performance of high density rockwool or fiberglass board. The poly stuffing as commonly used and used in common method of install will not absorb the reflections sufficiently at lower frequencies.

-Chris

 

[jamie2112]

WmAx What brand of fill would you recommend ? I am also thinking of getting a DIY sub kit. What would you go with Chris?

 

[WmAx]

WmAx What brand of fill would you recommend ? I am also thinking of getting a DIY sub kit. What would you go with Chris?

I don't like to recommend kits. You can get better performance by following my or TLS Guy's design recommendations.

For the fill, use 4-6" of high density fiberglass(OC705) on the longest dimension end wall(use 6" if the length is for example, near 36"), and 2-3" on all other surfaces. By high density, I mean 4-8lb/ft^3. Regular fiber glass insulation is usually 1.5lb/ft^3 density. Cover the fiber glass or fiber basalt rock based insulation with cloth to prevent it from migrating out of the port.

-Chris

 

[GTHill]

I will be educating myself as well as possible in the upcoming weeks. I have next week off and was hoping to start work, but I understand that it is premature. Thanks again for all of the help!

Gene

 

[GTHill]

I had an idea that I know has probably been mentioned, but what would it be like to brace an enclosure from the outside? Imagine a thick walled box (or whatever shape is optimum) and then an outside bracing structure. Thoughts?


Oh, what is the optimum shape given no construction limitations?

Thanks!

Gene

 

[WmAx]

I had an idea that I know has probably been mentioned, but what would it be like to brace an enclosure from the outside? Imagine a thick walled box (or whatever shape is optimum) and then an outside bracing structure. Thoughts?

Well, it can be done, but it's a waste of space. It will take more volume to effect the same proportionate wall stiffness/strength unless you use a material like metal to re-enforce it - which would add additional mass.

Oh, what is the optimum shape given no construction limitations?

For a subwoofer; any shape is optimal. The wavelengths of relevance are large in relation to the structure, making it a moot point, except in cases of the lower mid-range where in some cases the crossover breach may extend past the crossover point - which is where the proper absorption material comes into play.



-Chris

 

[GTHill]

Just another update to let everyone know I'm not flaking out on the project.

I have ordered a few Speaker building books and am awaiting delivery.

I have my Paragdigm Servo-15 up for sale in the classifieds to hopefully it will sell. If / when it does, I'll order the drivers, crossovers and amp(s). Thanks for the help so far!

Gene

 

[TLS Guy]

Just another update to let everyone know I'm not flaking out on the project.

I have ordered a few Speaker building books and am awaiting delivery.

I have my Paragdigm Servo-15 up for sale in the classifieds to hopefully it will sell. If / when it does, I'll order the drivers, crossovers and amp(s). Thanks for the help so far!

Gene

Excellent! You are all set to catch the bug of speaker building. If you catch a big dose, you will be glad you did.

 

[GTHill]

I just received my book, Loudspeaker Design Cookbook version 7. Also included was a PartsExpress catalog.

So, can someone suggest the amplifier and crossovers I should use? I don't want to work hard on building a box and be unhappy because I went cheap on the Xover and amps. Thanks!

Gene

 

[WmAx]

I just received my book, Loudspeaker Design Cookbook version 7. Also included was a PartsExpress catalog.

So, can someone suggest the amplifier and crossovers I should use? I don't want to work hard on building a box and be unhappy because I went cheap on the Xover and amps. Thanks!

Gene

The DCX2496 from Behringer is the best solution for a xover; it gives you more control/precision as compared to most, and it will allow ideal integration with the main channels, if you run the main channal pre-amp signals through the DCX.

The Behringer EP2500 is one of the best value amplifiers available; it is of very high build quality and will produce very high levels of power for your application. If you just want to go with a single sub, it will operate bridged, producing a real 2000 watts(measured) into 4 ohm loads. Hard to beat that performance for $350(you can find it for under $300 if you look around and do some price matching). There is also a comparable Tapco model for about the same price and power specifications, if you prefer to go with Tapco. I am not sure if the same super low noise Panaflo fan fits the Tapco.

Some find the fan a little bit too loud in the EP2500. There is a super-low noise Panaflo model that will make it silent from 2 or 3 feet away. It's just like the fan in a computer case - and easy to change out.

-Chris

 

[GTHill]

The DCX2496 from Behringer is the best solution for a xover; it gives you more control/precision as compared to most, and it will allow ideal integration with the main channels, if you run the main channal pre-amp signals through the DCX.

The Behringer EP2500 is one of the best value amplifiers available; it is of very high build quality and will produce very high levels of power for your application. If you just want to go with a single sub, it will operate bridged, producing a real 2000 watts(measured) into 4 ohm loads. Hard to beat that performance for $350(you can find it for under $300 if you look around and do some price matching). There is also a comparable Tapco model for about the same price and power specifications, if you prefer to go with Tapco. I am not sure if the same super low noise Panaflo fan fits the Tapco.

Some find the fan a little bit too loud in the EP2500. There is a super-low noise Panaflo model that will make it silent from 2 or 3 feet away. It's just like the fan in a computer case - and easy to change out.

-Chris

Thanks a lot for the suggestions Chris. Let me make sure I am clear on a few points:

I plan on running dual subs. I will only need one DCX2496 right? From the specs is looked like I could run multiple outputs without a problem.

With those dual subs, I would need an amplifier for each sub right? Well, I know that I don't need an amp for both, but I don't want it to be underpowered.

As far as fan noise, all of my equipment is remote located in a different room so fan noise shouldn't be an issue. I assume that I would just want to run very low gauge wire to the subs with all of that power.

So, let's look at budget:

Infinity Kappa Perfect VQ 12 x 2 = $400
Behringer DCX2496 x 1 = $200
Behringer EP2500 x 2 $600

That puts me at $1200 without the box material, so it looks like I'm on budget.

Before I drop $1200 on equipment, are there any other suggestions?

Gene

 

[Matt34]

Chris, do the EP2500 have 12v triggers? Just asking since he said all his equipment would be in another room.

 

[WmAx]

Chris, do the EP2500 have 12v triggers? Just asking since he said all his equipment would be in another room.

I never noticed a trigger interface. It's a pro audio amp; so it's unlikely it would have such a feature.

-Chris