Feedback on simple, cost effective DIY sub?

[duck911]

Hi all!

I have recently been upgrading some 15 year old, crappy HT equipment. After a very brief and unacceptable experience with a boxed Klipsch HD-500 satellite system (which thankfully I was able to return), I went back to the drawing board.

Anyhow, I have a pair of Infinity P362's and a center PC351 heading my way.

The HT is in a room that is 25x12x8.

The old sub was/is a real P.O.S. KLH powered sub from Sams Club So, it should not be difficult to improve on that.

I am looking for a reasonably simple DIY job that meets the following requirements:

1) Plate Amp. I know, I know. But to ease the wife into my new hobby I need to keep the first build simple and compact, and, for my first build it just seems like the right first step.
2) Space is a little bit of a consideration. I'd like to keep the box at or under 1.5ft^3.
3) I'd like to be under $400 for the plate amp and SW. (materials not included)

I realize I have half the forum cringing now with my requirements but that's where I am at. As I learn more and have more funds to play with, this sub will be retired to the basement and I can upgrade. Baby steps!!

So with my cost and size considerations, I think this is where I am at:

500w O-Audio plate amp
Sealed enclosure somewhere around 1.0ft^3 to 1.5ft^3
10" or 12" SW (I wanted to go JL Audio or Infinity but wonder if the Dayton RSS315HF would be a good bet, too. Any thoughts on the SW?)

Is this even remotely doable? With my requirements and high-level parts list, can I build something better than a $400 store bought powered sub?

Any concerns with a sealed enclosure?

thanks all!

--Duck911

 

[annunaki]

If you could add an external EQ the Dayton Titanic MkIII 12" will work near that volume with the plate amplifier.

The Dayton Titanic Mk III works best with 1.75 ft^3 sealed (with an f3 at 28hz) though you can probably go down to 1.5ft^3 but it will require more EQ.

I will not go into this further unless you are interested as you would need to add an EQ.

 

[duck911]

Thanks for the reply!

I wasn't able to find anything on the recommended closures for the Dayton drivers but dinking around on some calculators I kept coming up with 2.75ft^3 to 3.0ft^3 as the recommended size, so 1.75ft^3 sounds better

thanks!

 

[GranteedEV]

Here's a turnkey kit I recommend:

http://www.creativesound.ca/details.php?model=QUARTET12(TRIO12)B

 

[annunaki]

Thanks for the reply!

I wasn't able to find anything on the recommended closures for the Dayton drivers but dinking around on some calculators I kept coming up with 2.75ft^3 to 3.0ft^3 as the recommended size, so 1.75ft^3 sounds better

thanks!

Remember that this would require an Eq to help shape response. Without Eq, it may get a touch boomy in room near 55hz-60hz depending upon room placement and room modes/nodes.

 

[duck911]

Thanks for the additional links and feedback!

After some thought, searching through these forums most of the day yesterday, measuring, and checking with the wife, I actually think I can go quite a bit bigger than just 1.5ft^3.

That changes things quite a bit and obviously opens up the possibility of a ported build, sized correctly.

So, I have downloaded WinISD and am modeling some different subs.

Mind you, I have about no clue what I am doing, but I am fact-checking my numbers with known builds on these boards and it seems like I am close, so that is reassuring.

Once I start to narrow down a build I am sure I will be posting again!

thanks for the help,

--Duck911

 

[wormraper]

or you could just put your foot down and TELL your wife what size sub you'll be putting in

I did that with my THT I'm building

 

[annunaki]

Thanks for the additional links and feedback!

After some thought, searching through these forums most of the day yesterday, measuring, and checking with the wife, I actually think I can go quite a bit bigger than just 1.5ft^3.

That changes things quite a bit and obviously opens up the possibility of a ported build, sized correctly.

So, I have downloaded WinISD and am modeling some different subs.

Mind you, I have about no clue what I am doing, but I am fact-checking my numbers with known builds on these boards and it seems like I am close, so that is reassuring.

Once I start to narrow down a build I am sure I will be posting again!

thanks for the help,

--Duck911

There are many items that you must take into account when modeling a vented enclosure in WinIsd. It is significantly more difficult than a sealed enclosure.

Set your input power first and foremost, then add your lowpass filter. (for both any enclosure type)

Next ALWAYS use the SPL screen, NOT the transfer function screen when looking at modeled response. Many people make this mistake as well. (for any enclosure type)

Thirdly, be sure that you monitor the cone excursion and the vent velocity with vented enclosures. So many people forget about this and it can change all of their plans once they realize how poorly the design/plan will perform with the "stock recommendations" WinIsd offers.

Aim to keep your vent velocity below 17m/s This will prevent any sort of vent compression or noise throughout the system's intended bandwidth. Keep excursion at or below xmax with the power level you intend to run on the system. You will also want to understand how adding different filters into the signal chain will affect response, etc.

You may also want to check out my recommendation of the Image Dynamics IDQ12v3 for a small box sealed woofer. Though this may push your budget up some. The thread was here: Small Sealed Driver Recommendation

 

[duck911]

or you could just put your foot down and TELL your wife what size sub you'll be putting in

I did that with my THT I'm building

I save THAT trump card for my other, more expensive hobbies

 

[wormraper]

I save THAT trump card for my other, more expensive hobbies

lol, touche

 

[just-some-guy]

i messed with WinISD. i realized it was much more complicated than the time i was willing to invest in it. so i just searched the threads for someone elses build that i thought suited my needs. and went with that. i am quit happy with what i have.

 

[lennon_68]

There are many items that you must take into account when modeling a vented enclosure in WinIsd. It is significantly more difficult than a sealed enclosure.

Set your input power first and foremost, then add your lowpass filter. (for both any enclosure type)

Next ALWAYS use the SPL screen, NOT the transfer function screen when looking at modeled response. Many people make this mistake as well. (for any enclosure type)

Thirdly, be sure that you monitor the cone excursion and the vent velocity with vented enclosures. So many people forget about this and it can change all of their plans once they realize how poorly the design/plan will perform with the "stock recommendations" WinIsd offers.

Aim to keep your vent velocity below 17m/s This will prevent any sort of vent compression or noise throughout the system's intended bandwidth. Keep excursion at or below xmax with the power level you intend to run on the system. You will also want to understand how adding different filters into the signal chain will affect response, etc.

You may also want to check out my recommendation of the Image Dynamics IDQ12v3 for a small box sealed woofer. Though this may push your budget up some. The thread was here: Small Sealed Driver Recommendation

Great advice! I just wanted to add one last thing to watch for is the 1st port resonance. This is shown on the main window for the subwoofer on the "Vents" tab where you can change the number, dimensions, and length of ports. You want the first port resonance to be well outside the range the subwoofer will be used.

Also note that the enclosure volume you enter does not include the volume taken up by the port. This can be a real pain if your subwoofer volume cannot be changed as it requires recalculating the "enclosure volume" any time the tuning frequency or number/size of ports is changed.

 

[annunaki]

Great advice! I just wanted to add one last thing to watch for is the 1st port resonance. This is shown on the main window for the subwoofer on the "Vents" tab where you can change the number, dimensions, and length of ports. You want the first port resonance to be well outside the range the subwoofer will be used.

Also note that the enclosure volume you enter does not include the volume taken up by the port. This can be a real pain if your subwoofer volume cannot be changed as it requires recalculating the "enclosure volume" any time the tuning frequency or number/size of ports is changed.

Very good points here!

When it comes to vent resonance, remember that most systems are using an 80hz crossover point 2nd order. Most sub designs have a 1st vent resonance well out side where it may represent an issue.

This why I use my enclosure volume calculator in conjunction with WinIsd

I can calculate the correct volume tweaking numbers back and forth until things are all aligned. I can model a sub with enclosure dimensions, etc. in just a couple of minutes.

 

[GranteedEV]

Very good points here!

When it comes to vent resonance, remember that most systems are using an 80hz crossover point 2nd order. Most sub designs have a 1st vent resonance well out side where it may represent an issue.

Actually, I'd say most receivers cross over 4th order on the low pass.

So if you can push your port resonance up to around 160hz or higher you're home free.

 

[duck911]

Actually, I'd say most receivers cross over 4th order on the low pass.

So if you can push your port resonance up to around 160hz or higher you're home free.

I am clearly in the company of experts who quickly forgot that I can barely spell "subwoofer!"

I liquored up the little woman last night and she may or may not remember, but gave the the go-ahead to buy some gear. Before she sobered up, I went ahead and ordered the Dayton Audio RSS315HF-4 and O-Audio 500W BASH amp. If nothing else, they should provide me with a decent starter sub at a good price.

So now the question is, ported or sealed? Or to Just-Some-Guy's point, anyone care to help a newbie with some specs?

thanks guys,

--Duck911

 

[wormraper]

something tickled my brain... I know you're space concerned... does she mind height???? or does it HALF to be short as well as width and depth constrained. if not and she doesn't mind height building a sonosub is easy and you'll get some great extension with some decent height

 

[annunaki]

Actually, I'd say most receivers cross over 4th order on the low pass.

So if you can push your port resonance up to around 160hz or higher you're home free.

With better receivers you are probably right. I was thinking highpass when I typed that.

 

[annunaki]

I am clearly in the company of experts who quickly forgot that I can barely spell "subwoofer!"

I liquored up the little woman last night and she may or may not remember, but gave the the go-ahead to buy some gear. Before she sobered up, I went ahead and ordered the Dayton Audio RSS315HF-4 and O-Audio 500W BASH amp. If nothing else, they should provide me with a decent starter sub at a good price.

So now the question is, ported or sealed? Or to Just-Some-Guy's point, anyone care to help a newbie with some specs?

thanks guys,

--Duck911

Well if size was/is an issue and you were at all planning to go vented, you picked the wrong woofer. It will need near 5.5ft^3 gross volume or more to be properly vented.

Don't get me wrong though, it is a great sub.

As for sealed I can get you some actual dimensions if you give me the size limitations you are dealing with.