Building powered subwoofer for Christmas, recommendations?

[MrPirate2882]

My father has given me the task of designing a powered subwoofer for his home theater system on the cheap. I pick out the electronics and figure out the enclosure, then he builds it. This will be my first time with an enclosed sub, my car runs in infinite baffle.

The max budget is $200 (preferably $150 + cost of enclosure building). Not much, I know, but we surely can design something better than the pioneers and sonys for $150 at bb and cc right? I'd also be willing to buy the amp used (possibly ebay) in order to get a better quality amp within the budget. I don't know about getting the woofer used as you never really know how much abuse its taken.

It will be mainly used for movies, so volume is not as important as accurate, deep bass.

Enclosure size isn't that important, as long as its not much bigger than a maybe 3 cubic ft. Smaller would be better but it doesn't really matter.

Everyone has their own opinions, so I would love to hear your's.

 

[Matt34]

This amp:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804

Sub:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-464

Here is a sub that will keep you within your budget.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-555



It goes a bit over your $200 budget but I think it would be worth the cost over the lower priced sub offerings. PE has free shipping right now also.

 

[TLS Guy]

Alignment for the cheaper QT 305-4 12 inch

Here is the alignment data for the cheaper QT 305-4 12 inch

Name: Dayton QT305-4 12" Quatro Subw
Type: Standard one-way driver
Company: Dayton
No. of Drivers = 1
Fs = 27 Hz
Qms = 10.5
Vas = 120 liters
Cms = 0.0913 mm/N
Mms = 380.7 g
Rms = 6.15 kg/s
Xmax = 10 mm
Xmech = 15 mm
P-Dia = 350 mm
Sd = 962.1 sq.cm
P-Vd = 0.962 liters
Qes = 0.37
Re = 3.5 ohms
Le = 2.5 mH
Z = 4 ohms
BL = 24.72 Tm
Pe = 250 watts
Qts = 0.36
no = 0.615 %
1-W SPL = 90.04 dB
2.83-V SPL = 93.6 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square
Vb = 4.317 cu.ft
Fb = 24.31 Hz
QL = 6.281
F3 = 31.1 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 10.81 in


F3 is 31.1 which is pretty good for a sub that price. Vent air speed is 29m/sec which is acceptable.

This is the port you need.

http://www.madisound.com/catalog/product_info.php?cPath=404_85_388&products_id=713

Cut it to 10.81 inches. Glue the flares on with Oatey plumbing cement, that the plumbers use on plastic pipe.

Make the enclosure out of 3/4 MDF board. Put two boards together, 1 1/2 inches for he driver mounting board. Brace it well with vertical and horizontal
3/4 inch MDF boards, with large holes cut out. Glue them into 1/8 inch grooves made with he router.

For fill go to Walmart and get Premium polyester fiber fill that is used for stuffing pillows. Minimal fill means you place a layer on one of each pair of opposing walls.

The volume of your box is 3.17 cu ft. Add back the volume of the braces, the speaker and amplifier.

I can't stress enough how important the bracing is. If you don't get that right it will ring like a barrel.

 

[abefroeman]

Check this out.

http://forums.soundandvisionmag.com/audiovideo/board/message?board.id=57&message.id=4342

 

[TLS Guy]

Vent air velocity off the clock

The vent air velocity is off the clock. It is at least 20% of the speed of sound around 65 m/sec.

If you use a 2ft port 4 inches in diameter flared at both ends, you can get the vent velocity just slightly over the acceptable at 37 m/sec. Here is the alignment with this vent.

Name: Dayton TIT320C-12
Type: Standard one-way driver
Company: Dayton
No. of Drivers = 1
Fs = 22.2 Hz
Qms = 6.12
Vas = 73.91 liters
Cms = 0.0977 mm/N
Mms = 525.8 g
Rms = 11.98 kg/s
Xmax = 18.7 mm
Xmech = 28.05 mm
P-Dia = 304.8 mm
Sd = 729.7 sq.cm
P-Vd = 1.364 liters
Qes = 0.47
Re = 3.07 ohms
Le = 3.17 mH
Z = 4 ohms
BL = 21.89 Tm
Pe = 500 watts
Qts = 0.44
no = 0.166 %
1-W SPL = 84.35 dB
2.83-V SPL = 88.6 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 4.303 cu.ft
Fb = 17.28 Hz
QL = 6.283
F3 = 18.18 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 24.41 in


The box volume is very close, so you could use the same cutting plan.

 

[MrPirate2882]

Thanks for your opinions guys. I was originally looking at that amp, so that's good to see it recommended. Would you recommend the new Dayton 240w over the older 250w (used) (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794)?

Let's say I could get a Dayton TIT280C-4 10" Titanic Mk III Subwoofer (http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=295-414) used for under $100, would you recommend the new 12" Quatro or the used 10" Titanic?

 

[TLS Guy]

Need to run simulation

The posted sub used the 12 inch Titanic. I would have to run a simulation to see what the 10 inch Titanic looks like. Do you have a line on a 10 inch Titanic? If you do I will run a simulation. Every driver needs a different box and design.

The simulation I ran for you this morning, shows is a pretty good sub. I would go ahead and build it with the new driver specified and stay in budget. It looked surprisingly good, especially for the money. Don't be obsessed with getting an F3 below 30 Hz, unless you are a pipe organ enthusiast and want to hear the 32 ft pedal stops. With reflex loading those low F3 points cause a lot of problems, not the least of which is high vent velocities.

The bracing plan on that Titanic sub was good. You can follow that as a guide to build the specified sub enclosure. Modify the dimensions to get the correct enclosure volume. That project will be an excellent first project. I assume you are young in years. If you catch the bug, you will have plenty of time to learn the craft and build more speakers.

 

[MrPirate2882]

Here is the sheet for that 10", I don't know if it has everything you need or not:
http://www.partsexpress.com/pdf/295-414dumax.pdf

If I go with everything through PE to get the free shipping, would this port work the same? : http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=268-352

I'm a little young, 21, I've still get a lot to learn.

 

[Guiria]

My bro and I just built a 10" sub w/ 10" passive radiator tuned to 25 Hz in a 3.2 cubic foot box for under $200.00

We used the following.
Sub = $34
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-485

Amp = $100
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804

Passive Radiator = $21
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-494

8' x 4' x 3/4" MDF = $27

Glue + primer + paint and you are right at $200.00

If you can spare more money then do it and buy the best amp/sub combo you can afford. You really get what you pay for in the DIY realm.

I have yet to hear the sub we put together but my bro-in-law says it sounds pretty dang good. He has a living room that opens up to the kitchen so it's quite the space to fill.

I'll be over there hopefully over the next couple of days and will get a chance to audition the sub.

I could send you box dimensions, PR tuning weight, etc if you are interested.

 

[TLS Guy]

Here is the sheet for that 10", I don't know if it has everything you need or not:
http://www.partsexpress.com/pdf/295-414dumax.pdf

If I go with everything through PE to get the free shipping, would this port work the same? : http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=268-352

I'm a little young, 21, I've still get a lot to learn.

Yes, that port will be fine. Have a good Christmas, and don't be afraid to ask more questions.

These pictures of my last project may give you an idea how to go about construction. You need lots of cabinet clamps. Don't stint the carpenters glue where the boards butt against each other. Everything must be strong rigid and airtight. The only air entry point must be the port.

http://mdcarter.smugmug.com/gallery/2424278#127083295

 

[MrPirate2882]

Are there any benefits to designs that use passive radiators?

On that one enclosure recommendation, is there a difference between the performance of the pillar and the cube design?

 

[Guiria]

for all intense purposes tuning a box using a port or a passive radiator is the same. A correctly designed sub using a PR will not be different than a correctly designed sub using a port.

We chose a PR design because we like to watch speakers move and two moving in sync with each other is pretty cool

 

[TLS Guy]

Yes

Are there any benefits to designs that use passive radiators?

On that one enclosure recommendation, is there a difference between the performance of the pillar and the cube design?

Yes there are. The tuning is the same principle. The advantage is, it gets round the problem of vent turbulence and noise. The problem is that the passive radiator has to match the design exactly. A manufacturer can build a passive radiator to his exact specifications. There are not a large range of passive radiators to choose from.

The driver they used is only 80 watts with an xmax of only 6mm. I think that driver will reach its mechanical limits when the when the LFE output cuts in with the canons.

I have run the passive radiator alignment for the driver that the kind member selected for you and I ran the ported simulation on this morning. You will see that this driver is unsuitable for passive radiator alignment.

Name: Dayton QT305-4 12" Quatro Subw
Type: Standard one-way driver
Company: Dayton
No. of Drivers = 1
Fs = 27 Hz
Qms = 10.5
Vas = 120 liters
Cms = 0.0913 mm/N
Mms = 380.7 g
Rms = 6.15 kg/s
Xmax = 10 mm
Xmech = 15 mm
P-Dia = 350 mm
Sd = 962.1 sq.cm
P-Vd = 0.962 liters
Qes = 0.37
Re = 3.5 ohms
Le = 2.5 mH
Z = 4 ohms
BL = 24.72 Tm
Pe = 250 watts
Qts = 0.36
no = 0.615 %
1-W SPL = 90.04 dB
2.83-V SPL = 93.6 dB
-----------------------------------------
Box Properties
Name:
Type: Passive Radiator Box
Shape: Prism, square
Vb = 2.273 cu.ft
QL = 6.707
F3 = 33.64 Hz
Fill = normal
No. of Passive Radiators = 1
Fs = 8.515 Hz
Qms = 23.49
Vas = 734.5 liters
Cms = 0.398 mm/N
Mms = 878.1 g
Rms = 2 kg/s
Sd = 1140 sq.cm

The cone area is huge at 1140 sq.cm, and the VAS is out of site. The FS of 8.5 Hz, would mean the cone would have to be too heavy.

I would not start out with a passive radiator sub. They are tricky and for the home constructor next to impossible, because looking for the right ABR is like looking for the needle in the proverbial haystack.

As far as the enclosure shape is concerned, it is a little better if it is not an exact cube. If it is then all the refections from the walls are identical and reinforce. So it is better to make HWD different dimensions. I was just pointing out, that it gave you a good idea how to do the bracing.

 

[MrPirate2882]

Thanks for all the info. Is a bottom firing enclosure suitable for hardwood floors?

We have cats, and a grill for a woofer on the side would be an extra expense. A bottom firing woofer would be protected from destructive kitty feet, without the need for a grill.

 

[TLS Guy]

Thanks for all the info. Is a bottom firing enclosure suitable for hardwood floors?

We have cats, and a grill for a woofer on the side would be an extra expense. A bottom firing woofer would be protected from destructive kitty feet.

I would put some carpet under the sub.

 

[MrPirate2882]

I would put some carpet under the sub.

Sounds good.

I'm still wondering about the amp. The older model had fully adjustable phase control, and the new one just has the 0 or 180 settings. Other than that, I don't know how else its different.

Old (can get it used):
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-794

New (new with warranty intact):
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804

Any thoughts?

Edit:

I think I found my answer: The new one has a 24db lowpass crossover but the older one only has a 12db one.

Plus, its new.

 

[MrPirate2882]

Alright, someone assure me that the 12" quatro and 240w dayton will kick the pants off of this pre-made sub and I will buy them:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-635


Also I noticed that there are two similar amps for the same price, one has bass boost:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-805

What is it, and do I want it?

Now I'm starting to think that maybe we could do a bigger enclosure, and I'm looking at the 15" quatro being only $10 more. Would it be worth it?

 

[TLS Guy]

Alright, someone assure me that the 12" quatro and 240w dayton will kick the pants off of this pre-made sub and I will buy them:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-635


Also I noticed that there are two similar amps for the same price, one has bass boost:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-804
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-805

What is it, and do I want it?

Now I'm starting to think that maybe we could do a bigger enclosure, and I'm looking at the 15" quatro being only $10 more. Would it be worth it?

I think it is the same sub we specked for you. You can use two flared 3 inch vents 13 inches long, instead of the single 4 inch one originally specified. It lowers the vent air velocity marginally, but will add to the cost. For that money I doubt the build quality will be as good as a well done DIY rig. I suspect a home built well braced enclosure would win the day. It would likely be cleaner with less panel resonance artifact. You can use real wood finishes rather than the artificial plastic veneers. I think a more powerful amp was specked for you, buy the kind original correspondent. Also if you buy it complete you will learn little. I would guess the experience and education are worth more than the sub.

 

[MrPirate2882]

I agree, I was just starting to wuss out on the construction.

So get the amp without the bass boost (I honestly can't find any info on what it does anyways)? And go for the 12" quatro (the one originally recommened) over the 15" quatro for $10 more?


Also, since shipping will be free, am I forgetting anything that I won't be able to pick up locally? Sub, amp, and port is all I can think of.

 

[TLS Guy]

I agree, I was just starting to wuss out on the construction.

So get the amp without the bass boost (I honestly can't find any info on what it does anyways)? And go for the 12" quatro (the one originally recommened) over the 15" quatro for $10 more?


Also, since shipping will be free, am I forgetting anything that I won't be able to pick up locally? Sub, amp, and port is all I can think of.

The 15 inch is not suitable for a reflex (ported) alignment. Here is the closed box data.

Name: Dayton QT385-4 15" Quatro Subw
Type: Standard one-way driver
Company: Dayton
No. of Drivers = 1
Fs = 21 Hz
Qms = 14
Vas = 186.9 liters
Cms = 0.134 mm/N
Mms = 427.6 g
Rms = 4.03 kg/s
Xmax = 10 mm
Xmech = 15 mm
P-Dia = 355 mm
Sd = 989.8 sq.cm
P-Vd = 0.99 liters
Qes = 0.42
Re = 3.45 ohms
Le = 3.5 mH
Z = 4 ohms
BL = 21.53 Tm
Pe = 300 watts
Qts = 0.41
no = 0.397 %
1-W SPL = 88.14 dB
2.83-V SPL = 91.8 dB
-----------------------------------------
Box Properties
Name:
Type: Closed Box
Shape: Prism, square
Vb = 2.006 cu.ft
Qtc = 0.659
QL = 17.88
F3 = 43.24 Hz
Fill = heavy

Note that although F3 is 43.24, the roll off is second order (12db/octave), so it will only be 12db down at 21.5 Hz.

The box is smaller and there is no port which will save you money. The Qtc is 0.659, and will be on the tight side, but in the range of 0.5 to 1.0. ).5 getting too tight, 1 or over boomey.

Note that the fill is heavy. So the whole enclosure needs filling firmly, but without compaction. Pressures are very high in this type of sub, so bracing is VERY important.

This actually will be a very good sub, bit it will have a different type of bass to the ported enclosures. This bass will be tighter, and more understated, but very good. There is no significant ripple.

I think if you ponder this anymore you will get all the more confused. I think you have enough information to get started and stay within budget.