My First Ever DIY Sub

The least challenging approach is sealed. It's also smallest, lightest, etc.. Find what size box will keep the driver within Xmax at rated amp power, and build a box that internal volume. Stuff it with low-density (fluffy) insulation or fiber fill until it sounds good. Put it in the corner with the lowest ceiliing, so you get the most efficient coupleing to the room and maximize room gain.

The most challenging (and highest performance) approach is to design a folded horn, but I suspect fabrication alone would be a sufficient barrier.

That leaves ported, and with enough room for the box, I'd second imagic's LLT. You have box design SW, so look at very large volumes and very low tunings to get an LLT. Plan to put it in the same corner as above, for maximum output.
http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/1820-llt-explained.html

MDF is a good place to start, but plan to double-up on the baffle (side with the driver), especially if you want to recess vs. surface mount the driver. The one advantage to surface mount is that no one sees the hole you cut, so a simple jig-saw is all you need, and the ability to draw a circle (needs a nail, string and pencil) and follow the line. A router and circle jig is commonly used, especially for accurate circles with crisp edges when recessing a driver.

Cutting straight side panels is important. Pay someone to do this if you don't have a good table saw, or you'll need to fill gaps on the outside and add sealant in the interior corners.

PVC makes great ports. Be sure to model with the intended pipe ID. I like to cut a recess on the inner side of the port panel and epoxy the pipe there, where there are no critical dimensions. I then complete the (undersized) through hole and trim with a router roundover bit. I get a smooth transition from MDF to PVC, a nice flare to the port mouth, and no need to worry about how well the PVC finishes as its MDF that I'm painting. Some like to cut a slip-fit through hole, then glue and route the roundover... no functional difference and paint holds well to a routed PVC surface, but you can see the seam.

Assuming ported, you'll want a layer of acoustic absorber on the walls, perhaps 1-2" thick, to damp any harmonics coming off the sub. Anything from air-permenable foams to purpose-designed materials. I use carpet underlayment foam as it's cheap and effective. No one sees what's inside, and in a sub, it's less critical than higher-frequency speakers. Add nothing but braces in the open interior space, especially between driver and port, as you want that volume to resonate, so the port has functional output.

Add cross braces at roughly 8-12" spacings. 1-1.5" hardwood dowels are easy to use and take up minium space for their effectiveness. Cut them a little short and slip some tapered shim stock (like you'd use to align a window or doorway)under when you glue them in. Some do very elaborate braces, but it's inside so audible benefit counts more than visual appeal. The braces don't need to be exactly spaced, and any that touch should be glued or separated to prevent buzzing.

Then be prepared for "room modes;" spatial variation in loudness. Above grade construction with single-layer sheetrock walls and windows/doorways can mitigate a lot of room mode issues compared with a sound-isolated room. If there are obvious issues, you do have options, but hey're more complex than I want to go into here.

Regardless, take the leap and build something. Your first project may not be your best, but it's how you learn...

HAve fun,
Frank
Edited by fbov - 9/25/12 at 9:02am

Horn or ported.

 

As big and tuned as low as you can accomodate.

 

You'll need EQ for High Pass.

 

Corner Load

 

Sell the dayton and get a pro-amp(prefereably one with EQ) you'll not even wake up the TC with a 500W plate amp.

I just built a pair of subs (will post build log later today) but each one uses the epic 12 in 3 cubes tuned to 21 hz. They are each powered by a yung 500w plate amp. I had to go plate to please the wife. Trust me these guys are awake! They could take more power, but I know that the drivers are safe, they move alot though, crazy excursion. It's more bass than I'll ever need honestly.

Dan

Hi mfrey,

 

First off, I'm not bashing your amp.  It is a fine sub plate amp.  As always with any manufacturer take the published specs with a grain of salt.  For example since I couldn't find testing results for your exact amp, take the Dayton Flagship subwoofer amplifier HPSA1000-R. 

 

Specifications:

Measured power output: 512 watts RMS into 8 ohms @ 0.09% THD,
1,024 watts RMS into 4 ohms @ 0.15% THD
Signal to noise ratio: 98 dB (A-weighted)
Parametric EQ: Frequency: 18-80 Hz, Level: -14.5 to +6 dB, Bandwidth: .1-1 Low pass crossover: 30-200 Hz
Phase: 0-180°, continuously adjustable
Dimensions: 17-1/2" W x 4" H (2RU without feet) x 14" D
Power requirements: 110/220 VAC, 60/50 Hz
Dimensions (with feet, without rack ears): 17-1/2" W x 3-7/8" H x 14" D Dimensions (without feet, with rack ears): 19" W x 3-1/2" H x 14" D.

Actual Tested Specs:

 

High impedance specs are easier to hit and the dayton isn't far off @ 8ohms but 4ohms is almost half the published spec, nevermind these were at 40Hz and the numbers would be lower and more unstable at 20Hz since distortion is already at .33% @ 40Hz.

 

 

I would be surprised if the 500W plate amp tested above 300W true RMS output. 

 

Now, having said all that:

 

• I only recommended another amp/pro amp with EQ since you will have to buy one(EQ) anyways and your likely underpowered.
• Is that TC rated 500W/ coil or 500W total?

• 86.6db sensitivity, don't leave spl on the table undershooting power requirements.
• Modeling should help determine your power requirements as excursion will prob dominate your limitations.
• Double the power = +3b

Big room, small sub. What I would do is maybe look for a 15" sub to use in a large ported design and tune it to around 20hz since the Dayton amp has a subsonic filter around 18-19hz in order to maximize your output where it's needed most.

It's too bad that test will always scar Dayton's rep. It must have been a faulty amp. That amp has been measured by other members on other forums and it was shown to put out rated power. I have one of there 1000 watt plate amps and you can just tell that it's much more powerful than my 500 watt yung amp or oaudio 500 watt amp.

Dan

Nonsense!!! Everyone knows that if a single sample of a amp can't deliver the rated power in continuous sine waves then it's junk!

+1

I doubt it. Even if the speaker was capable of handling twice the power it would only be at best a 3dB difference, probably less, due to thermal and mechanical power compression. What you're hearing is likely attributable to different gain structures.

For one straight hour right? LOL!
I toast my home brewed Oktoberfest to ya man, that was good comedy.

Can anyone comment on how the Yung plate amps compare to other plate amps and pro-amps? Debating on going with a Behringer iNuke 1000 (non Dsp) versus a Yung 500 watt plate amp.

 

Hi Dan,

 

Can you link me to those tests?  I like the amp just don't believe the specs.

 

 

Well it doesn't help.

 

 

The dayton amp is a fine plate amp.  It appears very well built.  You should have no problem besting those commercial subs you mentioned with your current hardware.  A properly designed ported sub should perform well with your current setup.  As prev mentioned one twelve is gonna drown in your room, it just has too many cubic feet to compress.

 

One band of EQ will help, you might be able to squash one constructive mode, but thats about it.

 

I do believe you'll be underpowering the driver:

 

The amp ships with a 5A fuse.  Assuming a max current draw of 5A.  120V*5A=600W.  Efficiency is rated at 75%.  .75*600=450WRMS This is a generous assumption assuming the amp would pull current at the max rating of the fuse.  Acutally its prob pulling close to 3-4 Amps since fuses are over sized(typically by 33%) for acutal current draw dropping your max calculated power to 360WRMS.

 

Back of the amp claims 500W draw.  500*.75= 375WRMS  The amp can't make more power than it draws, its not a generator.

 

The devil is in the details.  They rate their amps 1/3 peak power, not RMS.  Measuring "Peak Power" is highly dependent on the methodology used to test.  Numbers are only comparable to others tested exactly the same. 

If you decide to return the Dayton, I recommend the Behringer NU3000dsp.  620W RMS per channel into 4ohms.  Then you can build another sub later and power off the other channel.  Trust me you will want another.  Sub building is like a sickness, you will want more.

Ain't that the truth!

That is the very reason I went with the iNuke3000DSP.

Sealed boxes have a natural drop in output at low frequencies. They do protect the driver, but it's a tradeoff between box size and power handling - you can still bottom a driver in an overly large sealed box unless the driver's designed for that application. Due to the roll-off, sealed works best with some active boost at the low end, and they are best used in a room that's small enough for room gain to augment the boost at very low frequencies. Your room is so large (35' with large openings to other rooms) that room gain isn't much help, and boost just hurts your headroom.

That's where the LLT comes in. Being low tuned, port output is infrasonic; you're hearing only driver output in the range where "tighter and more accurate" actually matter. In one case, F3 is 20Hz with an F10 in the low teens for LLT, compared with F10 of 20Hz for sealed. The same driver gives ~7dB greater output at 20Hz for the same applied power... and you need it with that size room. Hoffman's Iron Law cannot be broken - size, loudness, extension: pick 2.

It's all about matching the device to the application...

Have fun,
Frank

The devil is in the details and unfortunately, you've gotten them all wrong.

1) Do you know what the 5A rating on a fuse means? Wait, I can answer that. You post shows you don't... A 5A rating means the fuse can sustain either 130% (North American) or 150% (IEC) of it's current rating for 1 hour (continuous) before it blows. For short peaks and transients you can pull 200% of the rating and it still won't blow.

2) The manufacturer puts a typical power draw on the device. They are not obligated to put the absolute worst case peak power draw number. That UL rating doesn't mean the amp can't put out 500W.

 

1)  I think YOU may be confusing a fuse with a breaker which meets your stated criteria in some cases.  Fuses are rated fast blow, slow blow, etc and dont meet any "continuous" requirement.  Fast blow "common fuse" blow if they pass more than rated current which in this case is 5A.  Slow blow fuses are much more tolerant too transient spikes etc.

 

2)  I never said the 500w was a max rating, but you are correct in that its an average of the power draw.  thats a good observation, however depending on the amp architecture some amps draw the same power reguardless of how hard their driven.  IDK about the architecture of this one, it states special circiutry but its prob just a tweaked A/B.

 

Nitpicking someone else's post is easy, why don't you come up with something positive and constructive to add for the OP.

I'm not confused. The information I provided is 100% accurate. Why don't you educate yourself instead of trying to claim the person debunking your smear attack is wrong.
First, correcting blatant misstatements is not "nitpicking". Second, I'm doing something constructive for the OP. I'm demonstrating your attack on the Dayton amp to be baseless and without merit.

I helped a buddy integrate a berry dsp on two f20s they are the easiest pro amp/eq ive ever used.

Did you already buy the driver? If so, a single sealed 12 in that size room will have underwhelming performance and you'd be better off building a larger ported box tuned to around 20hz. It would at least give you more performance within an octave of your tuning frequency. 100db@20hz might sound like a lot of bass, but it's not. At your listening position, you might be at 90db...

If you wanted to go sealed in that size room, a good starting point would be twin 15's and >600w total power. But you'd likely want to double that within the year if you're like most folks around here.

here is the dilemma. 2.1 sealed in yellow. 5 cubic feet net ported to 20hz (that is about what the svs pb13u cab is).

350 watts into each cab. in a large room, you won't get a ton of gain, so if you want strong 20hz... :-)