1st speaker project - was: New Idea For a Small Business, at age 15! (Moved) (1 Viewer)

[bobbyg2]

Woops! Haha, I need to sharpen up on my math. Are those dimentions listed above good for a subwoofer? (20"x20"x11")

 

[Patrick Sun]

You have to work backwards, select a driver that requires a small box (but a lot of power), and then figure out the dimensions that would work for the driver's diameter. You can try shoehorning a driver into a specific box size, but you better get lucky in finding the driver for the box volume (you need to account for the interior dimensions to derive the true volume that the driver will "see" while mounted inside the box).

 

[JohnRice]

That can't be right. A 15" woofer HAS to be better than a 12" one.

 

[bobbyg2]

Classic vs DVC? Hmm... Here's the statistics:

Daytn Classic 15" Specificaitons:
*Power handling: 250 watts RMS/350 watts max *VCdia: 2" *Le: 2.30 mH *Impedance: 4 ohms *Re: 3.1 ohms *Frequency range: 20-500 Hz *Fs: 20 Hz *SPL: 92 dB 2.83V/1m *Vas: 9.70 cu. ft. *Qms: 4.00 *Qes: .50 *Qts: .44 *Xmax: 8.5 mm *Dimensions: A: 15", B: 14", C: 6-3/8".

Dayton DVC series 12" Specifications:
(Note: All specifications are with voice coils connected in parallel.) Power handling: 350 watts RMS/per coil, 600 watts total * Voice coil diameter: 2" * Voice coil inductance: 1.81 mH * Nominal impedance: 8 ohm per coil / 4 ohm total * DC resistance: 2.69 ohms * Frequency range: 20-450 Hz * Magnet weight: 112 oz. * Fs: 21.7 Hz * SPL: 87.4 dB 1W/1m, 90.4 dB @ 2.83V/1m * Vas: 4.25 cu. ft. * Qms: 12.53 * Qes: .38 * Qts: .37 * Xmax: 15.1mm * Net weight: 18 lbs. * Dimensions: Overall Diameter: 12-1/4", Cutout Diameter: 11", Mounting Depth: 6-3/8", Magnet Diameter: 6-1/2".

DVC > Classic: Power rating
DVC < Classic: Frequency range
DVC < Classic: Low frequency

So, ya, the 15" is better if you wanted to go with frequency range/lowness. But, they are pretty close. I'd have to give this one to Rice, he was right. (I thought I'd never say that, where's the flying pigs?[kidding])

So... Rob, is the 12" DVC better than the 15" Classic? I think not.

But, just to show you somethin:

Peerless 12" 830500 Specifications:
* Power handling: 300 watts RMS/425 watts max * Voice coil diameter: 2" * Voice coil inductance: 4.2 mH * Nominal Impedance: 8 ohms * DC resistance: 3.5 ohms * Frequency response: 18.1-500 Hz * Fs: 18.1 Hz * SPL: 90.6 dB 2.83V/1m * Vas: 4.92 cu. ft. * Qms: 3.7 * Qes: .21 * Qts: .20 * Xmax: 12.5mm * Net weight: 14.6 lbs. * Dimensions: Overall Diameter: 12", Cutout Diameter: 11", Mounting Depth: 5-1/4", Magnet Diameter: 5-3/4".

Which kicks the crap outa both of them, so, there ya go, There's a 12" that's better than a 15"

 

[Robert_J]

When comparing, there's about 3db difference between each design. That might not sound like much but that's double the input power. Would the Classic sound bad in any of these designs? No. But you have to look at the other factors like enclosure size. Are you willing to sleep on top of your sub? Not many people are. Plus, I know what a DVC 12 sounds like in a 1.2 CF box since there is one in my theater room RIGHT NOW.

Numbers and modeling software will only get you so far. You have to model a sub and then listen to it after it is built to finally understand what your simulated frequency response sounds like. Here's a few things that I'm playing around with.

Here's my newest sub (TC Sounds 15" TC-3000 top assembly bolted to a TC Sounds 3HP motor) beside a Dayton DVC 12.


Here's my TC-3000 again beside a neo motor. I have 4 neo motors in case my two 15's aren't enough. I'm talking to a build house about getting some parts to make them into 18's.


Finally, here's the 1.2 CF box that normally hold the DVC 12. It has a TC Sounds 12" TC2+ installed right now. Sitting on top of it is a Behringer EP-2500 amp capable of about 1,000w per channel. It will power the TC-3000's. On the top of the stack is the DIII used as a center channel. On the right side of the picture is the TC-3000 installed in my test box. It's 3.5 CF sealed. And yes, that's a rolled up towel that I used to seal the port.

 

[bobbyg2]

Alright, good. Now, I thought about it, and I decided that size isn't an issue any more. I'm gona put it on the left side instead of the right (of the TV). Now, what size box would you recommend? Should I buy some cheap wood as test wood and tamper with the dimensions until I find what sounds best?

I'll go with the DVC 15", as it's better than the 12" DVC and the 15" Classic. I'll figure some dimensions of a 4 cu. ft. box and test 'em all out:

2'wx2'hx1'd
1.777777778'wx1.5'hx1.5'd
1.5'wx1.5'hx1.777777778'd

And then just make up dimensions as I go.

 

[Robert_J]

Box shape does nothing for the sound. A cube will sound the same as a rectangle will sound the same as a cylinder. Pick a size and build the box.

-Robert

 

[Patrick Sun]

Make sure your target internal volume is arrived by taking into account the internal dimensions of the box, else, if you need 4 ft^3 of internal volume, you can't just build a box with external dimensions 2'x2'x1' because the internal volume is smaller due to the thickness of the panels, and the volume taken up by the driver itself.

 

[bobbyg2]

How do I find the volume the driver takes up?

 

[Robert_J]

It is either stated or you find a similar driver and use that. For example, the Adire Tempest takes up 305 cubic inches. The DVC 15" is almost identical to the Tempest so I'd use 305 in my calculations.

-Robert

 

[bobbyg2]

My uncle said that cabinet-grade plywood is better than MDF and is less prone to water damage. Is this true?

 

[ALMOSTHUMAN]

Definitely Do iT! I sarted by Business at 20 and I havent looked back. GOOD LUCK!

RH

 

[bobbyg2]

Thanks very much , glad to hear it. Now back to my question:

 

[JeremyErwin]

a faq on MDF.

 

[bobbyg2]

I've decided to use a high-gloss piano finish on these speakers. It looks good, is cheaper, and easier than veneer.

I'll stick with MDF. Since everyone here has been pointing towards it.

Now, where can I find the stuff to do Piano finish? I'm guessing that THD has it..

 

[Robert_J]

You need to do a little research before making statements like this. A quick search of this section of the forum for the "piano" would have given you a lot of different techniques. For example, this thread goes over the steps required. Pay attention to the prep work (post #8) and the finish work (post #11). By the time you get finished with the Bondo, you could have completely veneered your sub.

This link has steps involved for a gloss black (not as nice as piano black). The last large picture is an example of a gloss laminate. Same steps as veneer, not as much prep and a wide assortment of colors and finishes.

-Robert

 

[bobbyg2]

You know what, I'll stick to wood veneer!

 

[Ballgeier]

I think your ambition is great, but I do not think you have put much "real" thought into this.
I just built my own center channel speaker, and powered sub. They turned out great but that is because I just "mocked" someone else's plans I found on various websites. There really is more to designing speakers than building boxes, cutting holes in them, shoving drivers in it and then plugging it in.
Do you know how to determine the correct crossover point, what drivers "go" with one another, what diameter and length a VENT (not AIR HOLE) needs to be(if, in fact, one is needed at all depending on the drivers) what is the best material for boxes, and how to put them together correctly? I have seen great looking speakers made, but when they were played at higher levels they re-verberated terribly. These are all things I did not understand when I set out to build my own speakers. They are still not crystal clear to me, but I learned alot.
You asked for help "searching" the forum because "I'm not that good at finding information," If you do not know how to search a simple forum for info, how in the world are you going to find the IMPORTANT information you will need to build great speakers? How familiar are you with T/S parameters, do you know what they mean? Do you know what to do with them? These are all things you will need to "FIND" along the way. Yes, I know all about Parts Express having all(or at least most) of the T/S parameters on their site. I bought all of my speakers and acces. there, I only live a 1/2 hour away from the store. Something else they sell, and I think you need to look into, is speaker building books and "real" designing software. WinISD is great for your own personal speakers, but if you are going to try to sell what you make, you NEED better software, and more knowledge.
Good Luck, building speakers for you own personal use is fun and rewarding. I wish I needed more for my house.

 

[MikeNg]

Bobby,

I have a suggestion. Spend some time volunteering at a local electronics repair shop, where guys know all the in's and out's of audio. They can actually DO what you are struggling to formulate into a plan. I'm not saying that you should abandon your garage pursuits - build the dang thing already. You need to spend time with people who can guide you in your pursuit as well. If you have a local shop that also constructs audio equipment (there are a couple I know of in my area) and you tell them what your passion is and you are willing to work for nothing to learn, they just might teach you a thing or two.

Yeah, work for nothing. Which is what you're doing in your garage! Who knows. If you are good at it, it could turn into a paying job and you could leave your bagger position before you build your first speaker.

 

[bobbyg2]

I'll look around for a shop, the only shop I know of near me is a TV repair shop, but I don't know if they'll teach me speakers.

Hmm... I don't know. The only electronics store in my immediate area is that TV repair shop. I'll let you know what I find. I'll just have to stick with my uncle until I find one.