Should I, can I build a sub? (1 Viewer)

[steve nn]

I keep thinking about building my own sub so maybe I ought to give it a try. I run a vel ct 150 now and do like it but I would like more. Is there a sub I can build that would be as good as a vtf-3 or one of the better SVS's ? Well If I were to do this I would rather that it would be even better. I would want this to be a MAJOR SUB within reason. I like the idea of achieving this myself with my own hands. If this can be done with a DIY project what should I be looking at and roughly how much of a cost ? This sub would basically be for 100% HT. I bet you guys that have built your own sure feel good about it. I talk so much sub now when I have friends over that I can't imagine what a pain I would be if I was to build one myself.

 

[Dustin B]

My brother gripes about me in that reguard
We need to know more specifically what you'd like to spend, and if you have any enclosure size restrictions.
If you'd like to wait a little while Adire's new 15" driver (~$300) will be out. That driver in a 4-5ft^3 enclosure with a pair of 18" passive radiators (a little over $200) and an over kilowatt pro amp (depending on what you get and new or used, $300-$1000) might even be able to best dual SVS Ultras

 

[Craig Woodhall]

Steve,
that wouldn't be a problem at all.. Figure a couple hundred on the woofer (after shipping,etc a Tempest is only $150), a couple hundred on materials and a couple hundred on an amp and you will be WAY beyond the velo and your friends will think you're a TOTAL pain in the ass..

 

[steve nn]

Hay that sounds good. I really don't have any size restrictions. My wife is a tad wore down from all my shenanigans. The corner I place my sub is a non used corner. I guess I would like to keep this project to a $1000 or under. $500-$750 would be ideal. But like I say, "I want this to be a MAJOR sub". I will need to have the option of cutting it way back when I need or want to. I guess what I mean to say is I want my bass to be pleasant and if I want to unleash hell, I will have that option. Thanks guys for your help.

 

[Craig Woodhall]

In that case, I would go with what Dustin said.. If you can wait a couple months this is what I would do:
$300 - New 15" sbuwoofer from AdireAudio
$300 - QSC RMX850 amp (830w @ 4ohms)
$250 - 2 stryke 18" pasive radiators
$150 - building materials
You would be hard pressed to better that with $1000, it would also be better than multi-thousand dollar commercial subs available... If you wanted to save a little money and step down a level in performance, you could change the new adire driver for a tempest (-$150) and swap out the pro amp for a plate amp (-$150) and it would bring you down to around $700.. If it were me and you've already wrote off the g-note, I would do it right the first time and don't look back.. I think the first combo would as you say unleash hell and maybe a little drywall.
For me, I like having more and using it if I want to as opposed to maxing out all the time and wishing I had more.
Craig

 

[Rich Kraus]

4 tempests, ($600)
QSC amp ($300)

hole in wall/celing for IB mainfold- priceless.

 

[Craig Woodhall]

hehe

 

[Bryan Michael]

would the new sub 1 of them be beter than 2 tempests?

 

[steve nn]

I here you Craig. I could not stand the thought of running my sub at Max. Head-room is a good thing. When I feel the need for a bass fix I like to plop in the intro to ARMAGEDDON and turn the gain on the velo up to 6 on a scale to 10. Then I crank up the sw on the receiver to +6 on a scale of -10 to +10 and watch it at reference. Maybe not the same kind of rush I used to get back in the 70s but pretty darn close. I did plan on a new set of speakers the 1st of the year but after springing this on my wife she said those will have to wait until the next year. I will let it be so on account of she is right. This will be my 4th sub this year. I should have done it right at first. I would think there has to be stage where a guy can say " yip this will do it"! I think a sub on the scale you speak of will definitely do it. Could you tell me what the passives do? They are passive so where does there power come from?

 

[Dustin B]

Bryan,
With enough power and the right enclosure Dan says yes. The XBL^2 allows the motor to stay more linear as it approaches it's extremes. So besides a slight Vd advantage over a pair of Tempests it should have better sound quality when pushed to those extremes. You may want to give the Brahma owners manual a read as well.

And Steve (heh, oops), passive radiators do the same thing as a port. They allow you to provide sufficent porting to a smaller enclosure. There is no way you could fit a port big enought to handle the air this new driver can move in a 4-5ft^3 enclosure. A pair of 18" passive radiators is like having a pair of 18" ports. They are weighted so that they would have the same mass as the air that would be contianed in the length a pair of 18" port would have to be to tune the enclosure to what you want. The problem is the Styrke 18" PRs have a Vd slightly over 6L, so you are looking at a Vd to Vp ratio of 5.something to 12.something litres. That's cutting it close, I know Jack would like the ratio higher, but it should work.

I also think I remember reading that PRs have a little steeper roll off under Vb than a ported enclosure does.

Hmm, thinking about it a bit, I wonder if you would be better off with 3 Adire PR15s in a 5.5 to 6 ft^3 box than a pair of Stryke 18" PRs.

 

[steve nn]

Dustin it was me steve that was wondering about passives. So do the passives produce bass then. Sorry you are way beyond my limited understanding.

 

[Craig Woodhall]

Steve,

the passives, like Dustin said, are like ports. if you wanted to build a smaller sized box, the port would be too long to fit in the box.. these newer high excursion drivers move lots of air so they need big ports, too big for a box, unless you make it like 10ft3 and that is a big box. You sound like a bass freak, so I would save your pennies, put your name on the pre-order for the driver, and buy the amp you want. Also, as the driver gets closer to being on the market, you will see a bunch of threads talking about different boxes for the driver.. If you don't feel comfortable using box design software, just copy one of the designs that come up on the forum.. You then have 2 months or so to aquire your amp, build your box and wait for the driver.. I think this will be the last sub you need to build..

would the new sub 1 of them be beter than 2 tempests?

yes and in a smaller box! The Tempests need a big box to work best.

Craig

 

[steve nn]

Thanks Craig. I understand ports in a small way, it is using passives for ports that I don't get. No sound comes from these "speaker" passives that serve as ports correct?

 

[Dustin B]

Steve, maybe this will help

This is a cone excursion graph. X-axis is frequency in hz, Y-axis is excursion in mm. The solid line is a Tempest's excursion. The dotted line is the excursion of a pair of PR15 passive radiators. They are tuned to 18hz.
A port or a passive radiator acts as a Hermanholtz (sorry engineers, I'm sure I spelt that wrong) resonator. When you get close to the PRs tuning frequency, they start to take over the output. You can see this happening in the graph. The drivers excursion starts to go down, but the PR's excursion goes up. Until you get down to the tuning point at 18hz. Then the driver excursion starts to rise again (you'll notice much quicker now), while the PR excursion continues to rise (again quicker). This is why ported or PR enclosures output drops so quickly below their tuning point.
Same thing happens in a port, but instead of PR excursion, you have port airspeed.

 

[steve nn]

Thanks Dustin I will ask again. Does any sound come out of these passive speakers that are used for ports?

 

[Dustin B]

Oops, thought I was being clear. The higher the excursion the more sound coming from the driver or PR. So from 40hz and up, the PR produces almost nothing. From 40-26 hz the PR starts to produce some sound. From 26hz down to 18hz the PR starts to take over the output (don't ask me why this happens, nothing is powering them but the motion of the active driver). If you watched the sub with an 18hz tone, the driver would hardly be moving and the PRs would be flapping away. Then when you go below 18hz both the driver and PRs will be flapping away, but output will fall fast.

Now these numbers I'm using are in reference to the above graph. These will change with different drivers, PRs, box size, tuning points etc.

 

[steve nn]

OK- now I understand. I have been reading about passives but could not grasp how this happens. My next question was going to be are they wired? You addressed this for me to in your last reply. When the pressure hits a certain point the passives start to kick in? Hu! I would need two amps to run two 12"s right.

 

[Adam O]

Sorry if someone already mentioned this but, do take into consideration the tube and mdf for price. That might run over a 100, maybe more.

Same with all the little things, paint, glue etc it all adds up if u spent 1000 on the woofers and amps im sure u would end up spending closer to 1200 when its all said and done.


Adam

 

[Craig Woodhall]

do take into consideration the tube and mdf for price. That might run over a 100, maybe more.

I counted that as $150 for material, included in the $1000

Craig

 

[Dustin B]

What are the two 12"s you are talking about Steve?

Also remember it will be impossible to use this new driver in a sonotube design with passive radiators. The PRs need to be mounted vertically (and I strongly recommend antipodally so they will cancel each others mechanical forces; over 1.5kg flapping back and forth 20 times a second can create some big movement forces on the box). And besides that, there isn't enough room on the end caps to mount a 15" driver and two 18" PRs.