Is it possible to build a sub that has two active 15" drivers and one 15" passive radiator? Would the amp you use have to match the wattage level of the active 15" drivers combined, or seperate?

Whoa, I think I might build something like this....

Dual 18" subs.

So what happened to "I want to move into my own place" ?
Are you recanting and immersing yourself in stereo gear?

SJ

If your going to build something that big, you might as well build a slot loaded woofer and call it a day.
It doesnt have to be big to do good bass.

Bigger isn't always better when it comes to subs. To me, what's most important are the T/S parameters of the driver(s) and xmax.

Speaker building is a black art. For every variable or design consideration there are many possibilities. And publicly the debate
will go on forever for each. Even on something as simple as wire.

Ya just gonna give me a hard time don't cha? Yah I've decided to stay at home and go to college to get my degree in architectural design, so as to design home theaters for rich people. I'll do a private contracting kinda thing.

To the point of the sub, I'm not up on the different "types" of subs. Can you explain a little on how a slot loaded sub works? The reason I am looking at bigger subs is because they generally go much lower in frequencies. I'm aiming to get very very low frequencies for movies and games with high output.

Funny you should mention that, I actually watched two builders from an IASCA meet debate the virtues of copper purity in heavy gauge cables.

There are some nice freeware programs out there to help you build the ideal enclosure for your subs. I forget the one we used, but if you followed the design faithfully, it always came out with a good solid box that was tuned well for the woofer. If you are really looking for subsonics then you should probably look into a transducer and mount it on your couch. boom boom boom.....

Blake you obviously want something that reproduces sub audio frequencies but as SJ said “It doesnt have to be big to do good bass” the key words in there are good bass.
You might want to have a look at these subs designed by Siegfried Linkwitz. I haven’t built the sub but I have built a clone of his Orion and going by there performance I see no reason that this sub should preform equally well. One of its features is its small size which is achieved by deliberately designing the box to have a high turning frequency and then electronically modifying the signal to get a very flat extended response. There are also DIY surround speakers on the same site if you’re interested.
Here’s another slightly less elegant approach to a modified signal sub.

DJ

Good for you!
Education is really a great thing and I think it helps a person become more well rounded.

The sub question is kind of "loaded". Depending on how you build it, subs can produce very tight bass or very boomy base. The preference will be to the users ear. Bass can also be a tricky thing because it behaves differently than mids and highs due to the larger "waves" needed to make bass. Corner loading is a trick some folks use to get more bass out of subs. In essence, if you put a sub in the corner of the room, it will effectivly increase the bass because of the doubling up effect of the larger waves.

Ported sub woofers are the type that have the extra hole in them. They are designed to produce bass with woofers that cost less wattage to run. Slot loaded is also this way in that it has a port, but the bass in the lower frequencies can be tuned due to the size of the slot. Bigger port equals bigger wave, supposedly. Sealed units dont have a hole ( also referred to as Acoustic Suspension...) and rely only on the woofer for bass. As a GENERAL rule ported units are bommier and sealed are tighter. Sealed units usually take more energy to run due to the resistance of the air. BUT...

These are all generalizations. Because with each model there are exceptions to the rule. Paladin is correct when he says that it is black magic. I have seen professional woodworkers who couldnt build a speaker to save their lives and I have heard absolutely gorgeous sound come from hideous boxes that werent even square.

The thing I would keep in mind is that you have a lot of hard surface in the basement and you may want to use a smaller sub with a more even range. Hard, high pressure bass is a great way to irritate the folks and get a sound violation ticket.
Trust me on this one...

SJ

Thanks for the suggestions. I just emailed the guy from that first link.

Oh believe me, I've taken that into consideration. That's why when I build the new walls, floors, and seeling this summer for the new room I'm moving into (garage), I will be using sound proofing material and acoustic padding.

Acoustic foams and other similar sound treatments do work but only for higher frequencies where the energy of the wave can be easily absorbed, bass energy is another story. The only sure way to reduce it is to build a totally isolated listening room that means building a room within a room where the only connection is via rubber supports under the floor. Any direct connection between the inner and outer walls will allow the low frequency wave a path to travel.
Just thought you should know this in case you were thinking of just applying some acoustic foam and it alone will stop the bass.

DJ

I was just going to post the same thing!!!

Heating and cooling vents are another means of sound getting where it shouldn't.

Yah I'm aware of that. I just figured using sound proofing material in between my walls would certainly help make loud movies more tolerable.

If you’re building it in a basement that has five walls that are buried then you would only need to build the ceiling and connect it at each wall.

DJ

So you're saying I wouldn't need sound proofing in the floors?

I forgot to mention the other way to stop bass is mass . So if the walls are brick or concrete and have soil behind then it would be very difficult for the sound to travel through such a rigid and dense mass. Give a basement wall a good hit with your hand and you can tell how the sound doesn’t travel mechanically to other parts of the building. So yes just a good acoustically separated ceiling is all that would be needed.There are other little subtleties that would be required such as electrical connections and ventilation that paladin mentioned but there are ways around them.

DJ

Yep, the walls and floors are mostly concrete down there, so it souldn't be a big problem. Any other tips are more then welcome on how to stop the sound from traveling to other parts of the house.

Do a search for "sonotube subwoofers".
I get the feeling you would really like them....BOOOMMM!


SJ

Holy brown-note Batman!
3 15's?!?

Oh nice! I've seen something similar to those... I believe SVS makes subs that are sonotube right? I may just have to use this design... (I really do love extremely low frequencies in movies and games )



Actually, I think I'm gonna go with four 15 inchers. Two 15" subs with dual 15" drivers in each one, and a 1000 watt amp in each one as well.

You should check out The Legend of EL PIPE-O (at the bottom of the page) if you want some subwoofer ideas. Ten feet of sonotube and two 21" drivers per woofer.

Actually, this design from Parts Express looks really cool to me. It uses four 6.5" Tang Band speakers and is very compact.

Yah I've seen that first link, INSANE! But that's just a little "too" big. And true subwoofers actually start at 8", 6.5" would be way too small for me. I'd rather not go below 15", might even go up to 18".

Hey SJ, what determines how low a sub driver can go? Does the frequency of the driver make a big difference? For example; would a driver that goes down to 15hz be superior to a driver that goes down to 20hz?

if you're looking for high output low bass, don't get into dipole subs or ported subs, .... just build one horn loaded sub and load it with an 8" or 10", drive it with a 100-200 watt amplifier and eq it flat (or as desired), . no need to go to 15s etc for a home environment. You could look at http://billfitzmaurice.com/TableTuba.html . I built one of his smaller subs a few years ago, and it was a good thing

as it happens, .. i actually built a 17 ft (i think) version of the el-pipo a few years ago driven by a single adire shiva 12", .. not bad, but the room had a suckout mode which led to plenty low bass and not enough mid bass. nice , but not workable in my situation. i eventually built a (relatively more compact) 135 litre EBS aligned sonotube sub for that driver tuned to 17 Hz

at some point, i'l build another horn loaded sub

"Superior" is a very subjective word in the speaker world. One person's ideal is anothers nightmare. The ears you have are ideally capable of hearing from 20-20,000 Hz. In reality you have already lost a lot of low end and high end due to street noise, TV, loud music etc...So your practical range is really more in the 28-18,000Hz range. As your ears get older, hair cell damage in the inner ear becomes more prevalent and those edges start to get eaten away. One of the things that you want to stay away from is "high pressure" noise. Its the leading cause of hair cell damage. No matter what anyone tells you, hair cell damage cannot be repaired.

Woofers can be interesting things. The response of the woofer can be ideal and yet it can still sound bad due to rapid drops in response etc. Put a good woofer in a bad enclosure and you are gauranteed garbage sound. But a well built enclosure can bring out the best a woofer can offer. In theory there is no reason to shoot for 15 Hz because you really cant hear it. It also uses a good bit on energy to produce. Once you go down into that area, you probably want to start looking at transducers to anchor everything. The ideal way for you to get the bass you want is to actually decide on what type you like. In the car stereo area we referred to them as "Boomers" ( frequntly pronounced " BOO-Mah"), 'Purists, and "Tweakers".

Boomers are folks who like a lot of bass even to the point where it overwhelms the other portions of the music. These are the kids who pull up next to you and all you can hear is the Dub. Thanks for sharin guys!
Rap, hip hop and anything with a solid beat is the mainstay of this crowd.

Next off are the Purists. These are the folks who desire as accurate a bass response as possible in relation to the music and seek to make it as even as possible. Classical music figures highly in this audience as does jazz and opera.

The Tweakers are the ones who always trying to get their sound"just right". These folks are usually fond of the Loudness button and the "California Curve" settings. Although they lean more toward the Purist side, they like to tweak things a little to get a bit more beefieness to their music. The musical tastes of this crowd usually vary quite widely.

Titles will vary by shop and culture... And there are always exceptions to the rule. One system I designed was for a Boomer who was into operas. Needless to say the system was very dynamic. He had it inside a diesel Mercedes....?
One of the worst things is to get one design when you reall want another. Boomer systems will grow tired for tweakers and purist sytems will never be "quite good enough". A boomer who succumbs to the pressure of a purist system will always feel that something is lacking. Etc etc etc...

You have to be honest with yourself if you are going to get "GREAT!" sound.

So basically what you want to do first is decide how you like your bass and then start to build your subs from there. I will confess quite readily that I am a Tweaker. I change my settings about once a month. I like to enhance the bass and the highs just a wee bit and I very much like analog sound due to the warm "color" of the analog. My favorite bass notes are down in the 32 range and I love a good 100 resonant.

So its brutal honesty time with yourself. There is absolutely no camp that is better than the others. Its all personal choice, since music is a very personal thing.

SJ

Awesome, great response and well thought out, much appreciated. Although I must say I personally very much see a use for bass that goes below 20hz. I don't want to just "hear" my bass, I want to "feel" it too. For instance; in the scene where they are dropping the depth charges in the movie U-571 the frequency levels easily drop below 20hz to the point where you really FEEL the bass, that's what I'm after.

I am certainly not a "boomer", yuck. (sorry I just hate overwhelming bass that drowns out the other speakers )

I am definitely a "tweaker", no dought about it.

Most of the bass that people "feel" is between 30-26 hz. At least that type is responsible for a lot of the sensations associated with truly deep bass. I still think you should look into a couple of transducers. If they are tuned right, they can produce the same effect, without running the risk of your heart messing up.
Yes it can happen.
Another thing you want to be aware of is that around 10mhz is where the sentinel cells for your balance operate. Too much exposure to these sounds can leave you feeling like you are spinning. Dont forget that while these sounds will effect you, they will also effect everything else around you. Walls, ceilings, cats, dogs, parents neighbors etc...

Dont get me wrong, I love the good thrash of an explosion too, but I go about it a different way. Instead of pumping hundreds of watts into a massive woofer, I used a transducer system built into the couch. When its tuned right, its down right scary. Remember that scene in Jurassic Park where the puddle does the ripple thing?
Pure heaven...
You CAN feel it.

... or better yet... nothing like getting that feeling like your gonna' puke in the middle of a movie! ... this is certainly something to consider when designing you bass... IMHO... [burp..] ... not like that's ever happened to me...

gs

What type of transducers do you use?

Great breakdown of users. Wouldn’t two 15" and dual sub amps cover most people? My brother in-law is doing that system wi8th two of these.

http://yellow.mynethost.com/~bv126368/shop...973aacc0f47b537

And two of these amps. The ADA600 Made in the USA

http://www.adireaudio.com/Home/ADASubAmps.htm

SQ should be good and high SPL for the hard of hearing.

Bass shakers mounted to the couch. Wired in series to produce 8ohms. I use four of them. I used to use a clarke unit, but it was too rough on the floor, and then we got tenants....87% of the mortgage is a great incentive to tune your bass better. Im going to buy some more soon, since mine were involved in a rather complicated trade. New ones soon.

Like I said before, bass is all about personal taste. Plus not everybody will give up 6 cubic feet of space in their trunk for a rig like that. Nice woofies though...

Ever seen the AL woven carbon fiber ones?

I haven't been in the audio grove for a while. I still can't believe what all the car guys are doing. There is so many great 12" woofers right now that can take massive power and work in small boxes I wouldn't know where to start.

I haven't seen the "AL" before.

OT
I turned on the local FM rock station the other day just to see what was hot. I know now why Barry Manilow was the number one albumen in the country last month. He is proof that if a 60 year old pop singer can out sell all the other rockers there is a reason. The new stuff is cr@p. When we were young 60% to 70% of the kids liked the "big hit of the day" some of them are still being played now. Today a big hit might reach 20% of the kids and it's a big deal. But they can't help themselves and keep pushing the cr@p on the kids. Most just tune it out or off there is vary little love in or for music today.
At this point I'm not even sure if I want music played in the house. I guess it's OK as long as my guys are the Pimps but I think the(your) girls might not want to be the Wh****.

I don't think he is ready to learn how to be a Pimp

Click to view attachment

I did just buy a new used Luxman hybird amp sounds nice so I might sell the halfler/carver setup.

"I don't think he is ready to learn how to be a Pimp"
AV.


OT again, but funny...

Popular music is really bad these days... worst part is the worst of it is targeted at the really young demographic. Sucks, but if ya bring them up good, they will see through the BS quickly. They have a smart dad. They will likley end up in SJ's Tweeker catagory with the rest of us.

Oh but when your little guy IS ready for pimphood, you can go here:
I heard about this on NPR...
http://www.pimpfants.com/Results.asp?category=4

Acording to these marketing geniuses he's long overdue!

Wow.

I usually hang out on the alternative stations. They seem to produce a lot more "memorable" music. But the POP stuff they shovel at the kids these days is total trash. Seriously some of the POP acts make Duran Duran look like classical music.

The Al's were Altec Lansing speakers. They came out with a beautiful design for a 12 inch three way that used a woven carbon fiber woofer. It produced "unusually good" sound. They based off their VOTT speaker line. They also made these for cars in a 6x9 flavor. With a nice amp behind them, it was hard to believe you DIDNT have a subwoofer in your car.

I just ordered some bass shakers and I think I will try to do a little photo shoot of the install, at the suggestion of AV.

SJ

You don't need 4 - 15's and 1000 watts to shake your walls in a basement. No sir.

If you have a bit of money, like $550 to $600. Get one of these (JUST ONE!)

JBL JRX118S ($400)
and a bridgeable amp that does like 600 watts @8ohms bridged (you can pick one up for like $150-$200 or less on the auction site) and you are set.... That's your $550 to $600 total.

I Guarantee this sub (yes, just one) will pound your chest in - in a small area like you've described your basement.

4 - 15's is so overkill for that small of an area it isn't even funny. Well, unless you get extremely "cheap" 15's.

One heavy duty 18 will supply ALL your bass needs.

The specs on that speaker says it only goes down to 55hz???

I'd like to build a driver that can at least get to 25.

I'm guessing you already know about it, but the DIY Forum over at AVS is a good place to browse, particularly the DIY Gallery. I built the one in the first post for a modest $275 and with the help of a Behringer Feedback Destroyer have EQ'd it fairly flat (+/- 3db) from 20 to 80 Hz (the range you basically want your sub to cover)



That 240 PE Plate amp is on sale at the moment as well...

I am definitely going to have to look into getting some of those.

A good rule of thumb for audio is to have just as much power to your highs as you do your subs. Gonna take ALOT of highs to equal 4 -15's. If you insist on producing that kind of bass, you would be better off using multiple smaller drivers, say 6- 10's. You would use less airspace and have the same output. Also remember that a ported system is always 3db louder than sealed, thats twice as loud. Don't let anyone tell you that a ported system can not be tuned low either. One example is a vehicle owned by JL Audio. ITs a Mini Cooper that has 3 10's in it. It is set up as both a ported and sealed system (not a bandpass). I'm sure you can find it on the net.

When you do, you will regret it when you see your next light bill.

Oh, you think JL audio is somethin.......look up Dr. Crankenstein
my system(stated in my sig) is no where near his.

A transducer? is that like the vibration motors in a game controller? Iv heard of them before, i think.
Oh, and about your heart messing up, iv had mine skip a beat or two.

I guess you could say im a Boomer and a Purist, I dont like bass where there is none, but when there is bass.....its defening

one thing to think about too is that most recievers and soundsources souch as CD\DVD players or various digital equipemt are optimized to work between 20-20 000 hz, hitting anything below 20 hz will have that amp of yours running on full steam and then some to even produce a decent rapid move.. have you ever listened to one of those typical bas-test CD's where a busty babe says "50 hertz" and then "RRRUUUMMMBBBLLLEEE" an she goes on like that down to 20 hz? it should give you the idea of what 20< hz is all about. a tactile transducer is a better way to go if you want to feel the base.

one other thing to consider is distorsion.. when the subwoofer is trying to play 35hz rappidly (wich is a daunting task for any sub) a rumbeling pushing 15hz note would throw that rappidness all the way to china before it finds its way back to where it was before..

i buildt my box based on 2x 15" acting as one single driver (one of the drivers has it's phase flipped 180degrees and cones facing eachother airtight, basicly makes the whole thing work like only 1 15" driver with twice the stability of the suspension and magnetic power from 2 drivers) in other words, an isobaric-box.

I can take some pictures and draw up some sketches for ya if ya like, it's tuned to have an F-3dB point at 27 hz and im loading it with 120W at 8 ohms and when i hit that sucker with a 25hz note from a sinus-producing pc program souch as a music-tracker or similar it makes a simple thing like watching the backyard through my livingroom windows a daunting task since im having a hard time to focus my eyes through my vibrating windows, it's incredible, and you say you want 3 15" ? i have "one" and i could easily use it as a PA subwoofer on a smaller stage outdoors and it would perform very well, it outruns the rest of my 5.1 system with miles, i can reach inside one of the ports on my box and when i play the oh so lovely scene from jurassic parc it moves maybe 8-10 mm in total, meaning 5 mm out and 5mm in.. wich is nothing considering the woofers active stroke-length is 48mm before the coil starts to get a lil too far out from the magnet to be controled... so it still has alot to give.

A well constructed cabinnet makes 90% of the whole experience.

I remember back in the days when i build horn loaded woofers from old car-speakers and god knows what crap u could use (stuff dad had layin around since we where walking on all 4..) and it would produce some impressive results, just from a well designed box.

Ditch the idea of "more is better" cuz in general it isn't..

If you're willing to go 4-5cuft, you can easily achieve a F3 of 20hz using a good 12" subwoofer with no EQ at all.
Keeping your box this size, the more active drivers you add, or the bigger drivers you have, the less linear your response will become, and thus your 20hz response will start being noticeably fainter than your 30hz response.