Subwoofer design ideas

[Wilk]

I am looking at building a new Subwoofer for my HT setup. The room is very large (about 20' by 30') so I will need something fairly powerful. I am also married so the giant waterheater looking designs are a no go. Everything else is a possiblity. I do have some DIY experience, just not subs. My friend just built a kit from parts express, and I was very unimpressed so I figured I would come here for help.

So here are my question?

1. Sould I go for 1 12' Sub, or 2 10's spaced in the room.

2. In that large of a room is ported, or sealed going to outpreform the other?

3. Any suggestions on companies for the plate amps, and Sub's.

4. What kinda power are we looking at. The rest of my system is powered by a Denon 4806. Usually never gets run much over 1/2 volume. Runung as full 7.1 system. The rest of the speakers are vifa 7" drivers and aluminum tweeters is a MTM, config on the front, and center, and a bipole type setup on the rears, and sides. All based off of a design at zaphaudios site.


Any, and all help is appreciated.

[ThomasW]

A single 12" or pair of 10"s is a drop in the bucket for a room that big.

Also the cost difference between a 15" and a 12" is such that the 15" is the best buy,

What's the largest box size you can live with? And what's the budget we're working with here?

[dynamowhum]

I smell IB, Thomas can tell you all about that as well.

[ThomasW]

I smell IB, Thomas can tell you all about that as well.

Well that's certainly a possibility if he has an appropriate location.... :T

[Wilk]

Budget wise I would like to top out at about $700-$900 for a DIY setup. Less if at all possible. I would like to buy some other toys for the new room also.

I would like to keep the box size to a minimum, Thats why I was looking at 12's, or possibly running dual Subwoofers to get the SPL needed in that room. I can handle 2 midsized boxes much easyier than 1 big ass one. Please Keep in mind that I am not trying to break any SPL records here. I am much more interested in quality versus volume. I am open to looking at a 15 depending on box size/shape though.

What were you thinking? I have seen both of the sites on you sig block. Most of your builds are bigger than I would ever really go, but very impressive. You got something I could scale back a bit?

Oh ya, what is
"I smell IB, Thomas can tell you all about that as well."
refering to?

[ThomasW]

I would like to keep the box size to a minimum.

And that box size would be????

Oh ya, what is
"I smell IB, Thomas can tell you all about that as well."
refering to?

IB- infinite baffle. This is where a box is put in an attic, basement, garage, or whatever and it fires into the listening room via an opening between the 2 spaces. It's the ultimate 'stealth' sub. Here are some examples

http://home.comcast.net/~infinitelybaffled/page2IB-Gallery.html

[Wilk]

Sorry that I am still very short with box size. I still have yet to really furnish this room. It was built just for my HT, and I wanna get the speaker placement right first, and then the furniture. The audio setup comes first unless it is so ugly that the wife veto's it. I have a 30" cube of space on either side of the front stage, and the rest of the room is empty. I would prefer to use those 2 spaces that I metioned, as putting subs elsewhere is going to raise the wifes eyebrows, unless I can make the things look really classy.

The IB idea is not going to work though because This room is in by basement. 2 of the walls are cement (framed, well insulated, and drywalled), and the drop ceiling hanges only inches below the floor joist. Not really any room left fo the designs I saw. I may refer back to that when I get around to doing my sound system on the upper level. I have plenty of room in the attic above that room to play with that idea in the future.

[dynamowhum]

And the hook is set. Hahahahahahahaha. Real him in.

[ThomasW]

30" cubes are fine. Put one 15" or 18" in each.

[Wilk]

Any suggestions on subs, or plate amplifier's MFR's to take a look at?

Still wondering if a ported or seal design would work better in this much room?

I was kinda hoping to find something a little more interesting to take on than a sealed cube.

[---k---]

Have you looked at the DIY Subwoofer Showcase Thread located in Mission Acomplised? Start there.

Sealed or Ported can be a holy war, with few really knowing why they beleive what they beleive.

If you are looking for the smallest size, then go with sealed. If you are looking for the best bang for the buck, go with ported.

With your budget and goals (and extrapolating a bit), I think one standard SS RL-P15 sub in a 260L tube, tuned to ~15hz, and powered by a Behringer EP2500 would be a good fit. There are a couple of examples of this exact design floating around, and easy to copy.

[ThomasW]

With a 30" cube you can go sealed or ported. Ported you'll need to put an elbow in the port if you want a low tuning

[Inu_Yasha]

One design I liked is this round table-sub:

https://www.htguide.com/forum/showthread.php?t=20936

I couldn't possibly see the wife vetoing it, plus if you want something that looks nice and is functional, this would be the way to go.

As far as an amp, I would say go with the Behringer EP2500. That's the best bang for the buck and it allows for future expansion.

[Wilk]

The amp, and subs look very good. I am still pooring thought the finished projects page looking for ideas. It just seems that everything I like is a little to big. Also will have to figure out is my existing software can work with ports that have elbows in them. I have only worked on sealed speakers in the past becasue I never had a reason to go very low in the spectrum. 40 or 50 Hz was always seemed good enough for my musical taste. Unfortantly some of my DVD's want to go way below that.

[RandyMidd]

To help you make your decision maybe checkout the DIY Subwoofer site and Thomas' Intro to Subwoofers.

If your shooting for as small as possible you have no other practical option but sealed...and that's not a bad option....you'll lose some efficiency (SPL) to a ported design...you'll have the ability with an EQ / LT to force them deep into the bowels of hell...

If size is no object I think most people around here will agree with ported as a natural choice.

I like my hidden sonotubes because they're going to sneak up on the unsuspecting and whack them just below the knee caps...then when they're bent over, clock them on the back of the neck...I daydream.

[RandyMidd]

My thoughts on selecting sealed units over ported went something like this...

A big ported sonosub would do the job...but how would I blend it into the room? I couldn't convince myself that it wouldn't be obtrusive...and maybe I would think it to be cool after I put in my sweat equity but how would I feel about it 5 years from now?

I figured two small end tables would blend much better in the room and I...err ahhh... I mean my wife, could live with that.

So that means I would just spend more $$ to have something that met the criteria I weighted as most important... this is the beauty of DIY...but you have to decide what compromises you can live with for the advantages you'll get.

You and I are in touch with our metro sides...it's OK...we're all friends here. :dancenana:

Since you're building a new HT and indicated you wanted a build challenge...BTW my sealed sonotubes as simple as they are have required more of my time than what I thought they would...maybe consider a couple Greek columns that double as subwoofers on either side of your stage.

[Wilk]

I am thinking something loosely based on this sub. It has a good look, and should fit nicely in the spots that I have avaliable.

http://www.axiomaudio.com/ep500_main.html

Still need to see if my software can handle bent port tubes, and or multiple port tubes. I think one of these will be a requirement do to my size contraints. If my software can't handle it does anyone know of a good software package that can handle that?

I am hoping to be able to use a 15, but I will have to run some numbers once I get home. If not I'll go with a 12" in each corner of the room, and tune em as low as I can get.

As far as amps go the Beringer you all seem so fond of looks like a great amp, but I am looking more for a plate amp setup that I can install onto the sub box itself? Anyone got any suggestions on that type of amp, or do I just buy whatevers on sale at PE, or Madisound?

Don't most sub boxes shake to much to be used as psudo furniture pieces? My friends PE 12" kit sub shakes all over the place. We had put a 50lb on the top of it just to keep it from rattling. I can acutally hear it rattle from accros the room. I was going to build one of those up untill I heard his.

[---k---]

My sealed RL-p15 subs are like 20"x24"x20". The are constructed from two layers of 3/4" MDF. I feel a just a bit of vibration on the top when turned WAY up. If you use the typical overkill construction recommended here, your box will be nice and heavy, and I wouldn't hesitate to use it as furniture.

Not sure how light tubes fair, but I've never heard complaints.

[ThomasW]

If you downfire the driver onto a bottom plate it's physically impossible for the box to 'walk'. Look at the box SVS subs to see an example of this.

Front firing subs can walk, using a heavy box and spikes goes a long way toward eliminating that issue.

One doesn't need special software to model a port with an angle. All good software will model multiple ports.

I guess I need to sit down and write a whitepaper about sealed vs ported since there's so much misinformation posted on the web..... :roll:

[---k---]

I guess I need to sit down and write a whitepaper about sealed vs ported since there's so much misinformation posted on the web..... :roll:

That would be great, and I would love reading it. But, do you really want the headache that would bring you? :huh:

[JonW]

I guess I need to sit down and write a whitepaper about sealed vs ported since there's so much misinformation posted on the web..... :roll:

Oh, there's no need for that, Thomas. Because I just **KNOW** that sealed is better. No... wait... I meant ported. Or was that sealed...?
:P

I'd be interested to see a paper as well. Heck, I'm almost tempted to build 2 small subs, one sealed and one ported, just to experiment.

[soho54]

Heck, I'm almost tempted to build 2 small subs, one sealed and one ported, just to experiment.

Bingo, we have a winner. :B

[Inu_Yasha]

I guess I need to sit down and write a whitepaper about sealed vs ported since there's so much misinformation posted on the web..... :roll:

Jon just released one of his articles about building speakers, why not make it a competition and show him some of your writing skills and knowlege. I mean of course I'm not selfishly looking forward to this... no... quite mistaken...

Back on the topic though, Wilk, you're going to need long ports in a small box in order to reach a certain tuning point without chuffing. I actually built my sub using bent ports (2 to be honest) and it is not, imho, the best thing to do. Driver clearence comes into play and port clearance also becomes a problem. If you want some pics, I'll send you some, just pm me. I can say though, go ported, you'll have a way smaller box and you'll save some headache!

[Wilk]

I like the look of the SVS square subs, and the Axiuom Audio one that i liked to eairlier. Gonna try to draw up plans for both tonight, and see what will fit the best from there.

I think the sound splitter sub that somewone pointed out eairlier is a great way to go. So I will build the box models around its parameters. I am still looking for a decent plate amp, If I do not find somethign soon I think i'll just get the Dayton 500W model from PE.

With the down firing woofer box design is there any thing i need to be aware of in regards to the distance between the Sub, and the bottom plate? Is there like a defaullt formula for this? Also is this a bad desgn for me considering that there will basically be walls 6" off of 3 of the 4 sides of this box?

Oh, and Inu_Yasha I wouldl love to see pics of your sub if they are available.

[ThomasW]

That would be great, and I would love reading it. But, do you really want the headache that would bring you? :huh:

No headache for me.

Facts are facts, and the physics involved doesn't change regardless of how much anyone posts to the contrary.

Jon just released one of his articles about building speakers, why not make it a competition and show him some of your writing skills and knowledge.

There is no competition between Jon and me. His engineering skills and word-smith ability easily eclipse mine..

Why? Well his IQ is 167, mine isn't.....

BTW that 'just released' article was published 3yrs ago. I was the proof reader for the article while it was being created.

[Wilk]

Well I started runinng running numbers on the soundsplinter subs, and I was getting ports lengths of over 5 ft. Tried using a more common peerless sub to see what I was doing wrong, and I got simular answers.

I have got to figure that my soundeasy software just can't handle sub design to well. I have always just used it for simple sealed speaker designs. Shit most of the time I do not use it at all.

Anyways, what software do you guys use for box modeling and such?

[ThomasW]

Unibox

[jdybnis]

I second that recommendation. I use Soundeasy for most things but I switch to Unibox for box design.

[Inu_Yasha]

Unibox and winisd is what I used. How small of a box volume were you using? If you're using a small box then 5 ft would be around a reasonable answer if you're going for a low tuning. The box that I made is 5.5 cubic feet and it required a 54" pipe length to reach 16hz tuning (I have the SS RL-p15 D2).

[---k---]

make sure you're using 6" port for one driver.

[Wilk]

Inu_Yasha I would really like to see plans for your setup. I think I am headed in that dierction, but shrunkin down for a 12" sub. I just do not have room for a 5.5 cubic box. I am looking more at a 3.0 cubic foot box tuned around 25 Hz. I just am having alot of problem getting the box design to work around those numbers. Probably not up to your guys standards, but if 1 doesn't give me the kick I need I will build myself a clone for the other side of the room.

[Wilk]

Is a 4" port ok if I am goign with a 12" versus a 15

[ThomasW]

In this day and age why would you tune a HT sub to 25Hz?

The first action/adventure movie you play with any significant subsonic content will destroy the driver.

You might want to explore some of the dozens of sub threads in this forum where we design subs for use in HT's. All are either sealed or tuned low (~15Hz) if ported. This protects the driver from unloading at most subsonic frequencies.

[Wilk]

Well the main reason being that I am finding it next to impossibe to place a 5 ft long port into a box without running into all kinds of clearance issues, and thats if I get lucky enough for it to fit at all.

At this point I am actually quite confused as to what to even take a look at doing. I would love to look at a whole design or two, but after 3 days of reading through this forum I can not find a full design thread on any subs except the tube type.

And actually you have hit on the part that is confusing me the most. In a sealed box you will never ever get any where near 15 Hz. Yet you are telling me that it is almost a requirement in a ported box. The sound splinter website says in the specifications page on their 12 to tune between 20-28 Hz. Once I figure out that little tidbit I think I'll be alright.

I understand, and have noticed that you guys tend to build top of the line, specification pushing designs. That is why I started asking questions here, I like that type of work. I just can't seem to get on the same page as the rest of you for some reason.

You got to remember I have never built anything that went below 40Hz. Everything I have done is music only, and there is little use below that range in music. Shit, I have never used a driver bigger than a 7".

[WillyD]

Wilk - I understand your hesitation, but if there is anyone you should put your trust in concerning subwoofers, it is Thomas. He knows his stuff. Its too bad you can't go with a "waterheater" design.

With a sealed box, one doesn't have to worry about the driver unloading. That is why Thomas says you should tune low for a ported HT Sub (Definitely <20hz, IMO) so the driver is better protected.

So 3 ft^3 is the enclosure limit for your sub?
Shoot, I'd go with this:

http://www.rythmikaudio.com/servo_product.htm

The 15" kit's optimum enclosure size is 3ft^3 anyway.

[Wilk]

It's not that I don't trust him at all. I think I have just been scatching my head on this to long tonight, and am getting grumpy.

I took a look at that kit, It looks pretty good. Right Size, and price

[ThomasW]

Well the main reason being that I am finding it next to impossibe to place a 5 ft long port into a box without running into all kinds of clearance issues, and thats if I get lucky enough for it to fit at all.

You need to double check your box model because it's in error. No one needs a 5' port to get a tuning in the 15Hz-18Hz range.

In a sealed box you will never ever get any where near 15 Hz. Yet you are telling me that it is almost a requirement in a ported box.

It's a requirement for a ported box because the drivers 'unload' (flap wildly back and forth) when playing frequencies below the port tuning.

And it apprears you don't understand that box models show anechoic sims, not how the driver will perform in a room. With a sealed box room gain boosts the bottom end.

This graphic is from my small IB sub. The blue line is the nearfield plot. The magenta line is the output 13' into the room. See how much the output has increased? That's not EQ that the effect of room gain

The sound splinter website says in the specifications page on their 12 to tune between 20-28 Hz. Once I figure out that little tidbit I think I'll be alright.

Mike is a nice guy but his experience is with car audio. With car audio it's pointless to try and reproduce very low bass, since it can't be heard above the road noise. My area of expertise is home audio so I deal with reproducing as much as possible of what's on the recording.

I would love to look at a whole design or two, but after 3 days of reading through this forum I can not find a full design thread on any subs except the tube type.

There's no difference between the performance of a tube sub and a box sub. But here are some links to box subs.....

https://www.htguide.com/forum/showthread.php?t=17206

https://www.htguide.com/forum/showthread.php?t=19686

https://www.htguide.com/forum/showthread.php?t=20164

https://www.htguide.com/forum/showthread.php?t=19805

https://www.htguide.com/forum/showthread.php?t=17740

https://www.htguide.com/forum/showthread.php?t=16774

https://www.htguide.com/forum/showthread.php?p=225359#post225359

https://www.htguide.com/forum/showthread.php?t=14644

[Dennis H]

I have a 30" cube of space on either side of the front stage

I am looking more at a 3.0 cubic foot box

I think you've made a math error there. A 30" cube will give you a 27" internal cube if you build it with double 3/4" layers. That's 11.4 cubic feet. Subtract a cubic foot for bracing, ports and driver volume and you still have over 10 cubic feet or 280+ liters net internal volume. That's right in the ballpark for one of Steve Callas's LLT alignments. Tune it to 15 Hz or a bit below with a 6" diameter port 30" long and you're stylin'. A single elbow in the port will get you the length.

[RandyMidd]

and actually you have hit on the part that is confusing me the most. In a sealed box you will never ever get any where near 15 Hz

Sealed subs go lower.

This isn't just for the elite it's for mere mortals who are in touch with their metro sides like you and I.

The sealed subs are forced to play that low by a seperate electronic device called an "LT". Here's an explanation of an LT.

I've purchased on Thomas' recommendation and have yet to use my Behringer DEQ 2496. I'll EQ the subs and be able to force them to play lower than they otherwise would.

[Dennis H]

So, would that be a "metro transform"?

[Martyn]

And that box size would be????

IB- infinite baffle. This is where a box is put in an attic, basement, garage, or whatever and it fires into the listening room via an opening between the 2 spaces. It's the ultimate 'stealth' sub. Here are some examples
http://home.comcast.net/~infinitelyb...B-Gallery.html

Thomas, some of those under-floor examples use very small openings - like a 4" x 10" forced-air vent with one or even two 15" drivers firing into it. What are the constraints here? Is there a simple rule-of-thumb for determining the minimum area of the opening?

[ThomasW]

Martyn,

If you look at the main FAQ page pretty much everything is spelled out.

There's a reason gallery page #5 is titled "Infamous Designs" and carries the following disclaimer.

Occasionally, situations arise where people have created IB installations that technically model as less than optimal. Although I can't recommend these types of installs; the owners have assured me that they are pleased with the results of their creations. So with the obvious caveat, here are those IBs.

[Inu_Yasha]

You need to double check your box model because it's in error. No one needs a 5' port to get a tuning in the 15Hz-18Hz range.

I was looking at the graph that winisd generated when using a RL-p15 with a 5.5 cu ft box with a 6 in pipe and 15hz tuning and it was returning 59in as the tube length. I made sure all the t-s parameters were put in there correctly. Any thoughts? Or is it because the box size is really small for that size of a sub?

[ThomasW]

Or is it because the box size is really small for that size of a sub?

Correct with low Fb ported boxes, it's 'go big or go home', unless one want's to pay for PR's

https://www.htguide.com/forum/showpost.php?p=295040&postcount=38

[Wilk]

Well after pretty much pulliin my hair out of not being able to fit appropriate sized boxes in the 2 spaces nessecary I showed my wife the SVS tube subs. She was less than immpressed, but I talked here into 2 of the smaller ones possibly. I even got real sizes this time. I am lookin at 18" dia by 38" Hieght. Using a 12" in each one of these, and build 2 do you guys think this might work?

Next question is where do I go for a good set of build plas for these tubes?