New project - design stage - AVS Forum
DIY Speakers and Subs > New project - design stage
jayHRC51's Avatar jayHRC51 12:02 PM 06-28-2012
Hey guys,

I'm looking to start two new projects. 1) sealed dual sub towers next to front L&R channels 2) large ported sub for behind couch. I'm looking for some suggestions for subs and may need help figuring out the best enclosure volume to go with. I'll give more detail on this below. I plan to build a sub enclosure to mimic either the JL Gotham sub or the bass section of a B&W 801, or maybe a hybrid of some kind between the two. They are both reasonably similar in style...I've been looking at so many different subs that I think I'm loosing my mind.

1) budget of ~$1000 for everything
  • Need 4 subs for somewhat small sealed enclosures (assumed max ~$600 spend)
  • Need pro style amp or a plate amp for each enclosure that can operate at the correct load that the speakers will present to the amp. (assumed max ~$400 spend)
  • Usage for mostly music
I'm thinking that I would prefer 12" subs for this build due to size/aesthetics of the tower enclosures I want. Two 10" in each cabinet would also be fine. I'm thinking pro style amp (Crown or similar) because the enclosures will have curved backs. I have seen pretty ridiculous pricing for some Clarion car subs. Could something like that be an option? Plate amp could work if mounted on top of the enclosure but not sure I'm cool with mounting them there. I think a pro style amp would just be easier. It's my goal to have these integrated mostly for music duty. Maybe 40-150Hz???

2) budget ~$500 for everything
  • Looking to use 1 15" sub in a long but narrow enclosure for really low frequency "movie duty"
  • I'm open to any ideas as long as they fit within a 12D x 22H x 72L space
  • Playback of only really low freq stuff during movies
My plan is to place this sub behind my couch. The above dimensions should give me 11cu/ft to play with; not accounting for driver displacement, bracing or port. I think I would like this to be tuned pretty low as it will be used for reinforcement bass during movie playback. Maybe 15-50Hz???

There will also be a part 3 of this project, build new front stage, but that may not happen until later this year. I plan to build something like the Statements lineup which will replace my current SR71's.

Thanks in advance for your thoughts and let the planning begin!

LTD02's Avatar LTD02 04:09 PM 06-28-2012
the epic 12 by tc sounds is a nice looking and good performing 12" driver that should work for your gotham style subs. available from parts express. they work fine in 1.0-2.0 cubic feet sealed, though the larger enclosure will have a little more sensitivity on the low end. if you don't care how the drivers look, then there are many options...as you know.

the behringer amps are probably the best bang for the buck even though they look like something by fisher price. be careful to match the amp to how you intend to wire the subs. some of the amps are 2 ohm stable per channel, while others are 4 ohm. some are bridgeable, others are not. there are some options with dsp (digital signal processing--essentially anything that you want to manipulate: eq, crossover, delay, limiter, etc). sealed tend to need a little eq to "lift" the low end, so keep that in mind. the mini dsp is an affordable eq if you don't get one built in to the amp.

you might want to build the dual 12" subs first and see if it is enough. 4 epic 12" drivers should put you at full reference level in a medium sized room (>115db at 20hz). and most folks don't even listen at full reference.

gotham clones are going to take some work, but they do look nice.

good luck with your projects.

the infinity 1260/1262 may be the best bang for the buck but it runs out of gas about 4db earlier than the epic because of less excursion.
jayHRC51's Avatar jayHRC51 07:19 PM 06-28-2012
Quote:
Originally Posted by LTD02 View Post

be careful to match the amp to how you intend to wire the subs.

sealed tend to need a little eq to "lift" the low end, so keep that in mind. the mini dsp is an affordable eq if you don't get one built in to the amp.

you might want to build the dual 12" subs first and see if it is enough.

4 epic 12" drivers should put you at full reference level in a medium sized room (>115db at 20hz). and most folks don't even listen at full reference.

gotham clones are going to take some work, but they do look nice.

good luck with your projects.

the infinity 1260/1262 may be the best bang for the buck but it runs out of gas about 4db earlier than the epic because of less excursion.

Thanks for the input! I was looking for subs and an Amp that would allow either 2ohm stereo or 4ohm bridged. I figured that as long as the subs could be wired as such that I would have plenty of options for both. How difficult are amps that include DSP to operate? Are there any that I should steer clear of? I have a pretty large room that is open to other areas. That said, I'm not looking to pressurize the room. I just want to have some decent impact while listening to music. I do not listen at ref levels. I was hoping to use the second sub build to help fill in the low end if the four 12's didn't cut it. Would the additional ported 15 show me any appreciable gains in db or not really? In other words, if I went with something a little cheaper on the 12's (like the infinities) and added the ported 15, would that make up for any db losses realized by using lesser quality 12's? Also, would I kill those infinities by using an amp like the Crown XLS 1500?

Thank you for the good luck. If I can get some decisions made pretty quickly on drivers and amp, I would like to order everything this weekend and start building as soon as the drivers get here and I lock in dimensions of the enclosures. I'm hopeful that might be in the next week or two.
jayHRC51's Avatar jayHRC51 05:06 PM 07-01-2012
Okay, so I ordered some subs today. I went with the infinity 1260W's. I couldn't pass up the price and even thought the cone isn't that attractive it'll be covered by a grill anyway. Manufacturer recommends 1.25 cu/ft per sub for sealed applications. Is there any benefit of going with an enclosure of a different size?

I have no idea how to figure out the best enclosure size for these things based on power input. Or if it would even make a difference. Could someone help point me to a good free enclosure design software? I am interested to see what kind of response I'll get running these with about 700 watts per pair. I'm planning to use a Crown XLS 1500 running in 2ohms stereo. Is that too much power for these subs? I haven't ordered an amp yet. How much of a benefit would I see by going with an iNuke or a plate amp in a separate enclosure? I've downloaded WinISD and I've come to the conclusion that that program is the least user friendly program I've probably ever tried to use. I just don't feel like I'm doing it right.
Jay1's Avatar Jay1 05:49 PM 07-01-2012
What configuration are you trying to run? Did you order 4 1260's for a pair in each cabinet? If that's the case, 700 watts is a pretty good match, you wont hit xmax until 23hz sealed in 2.5ft3 for each pair of drivers. You will definitely want another sub to fill in below, as these start rolling of -3db 44hz. The problem is those 1260's are going to be extremely capable above 40hz, and you wont likely find a single sub that can keep up. You might have an easier time just porting the 1260's, and adding a MiniDSP to the equation.
jayHRC51's Avatar jayHRC51 03:07 PM 07-02-2012
Yeah, I'm going to run a pair of 1260's in each enclosure. Since I'm saving some budget by using cheaper drivers, that frees up some cash to use towards the build for the lower end frequencies. I think I'm going to get this first build put together and see how things sound and then determine how much help they need.

If porting the 1260's, how large of an enclosure and port would I need? I have no idea how to determine the best tuning frequency and enclosure size.

Also, I may be able to squeeze 2-15's behind my couch. I could maybe fit two 10 cu/ft enclosures back there. Would two ported 15's help to solidify that 15-50hz range? I know there have been a million ported Dayton RSS sub builds, but are there any that really stand out as better then others? If so, why?
Jay1's Avatar Jay1 06:48 PM 07-02-2012
You could do 9ft3, with three 4" x 25" ports for a 20hz tune. If you use a 20hz HPF it will handle 700 watts, and get you over 115db from 26hz up (-3db point 23hz).


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LTD02's Avatar LTD02 07:50 PM 07-02-2012
"some decent impact while listening to music. I do not listen at ref levels."

the four 12's with 2 cubic feet each will give you ~116db at 30hz and there is almost no music with content below that. one exception is if you are really into pipe organ music and want to shake your house down by recreating the sound of those 64 foot pipes at full blast. most of the low bass in music, even what sounds really deep, tends to be in the 30-45hz range. 116db is really loud and since you don't even listen at reference levels, they should be fine.

the inuke 3000 dsp would be a good choice for you. the dsp is graphic in nature, so it is pretty easy to see the effect of each change. you will likely only need just a hair of eq to help flatten the response.

i don't think that you need a 9 cubic footer ported to be happy. definitely start with the gotham clones and go from there.
Jay1's Avatar Jay1 08:05 PM 07-02-2012
"i don't think that you need a 9 cubic footer ported to be happy"

"budget ~$500 for everything

Looking to use 1 15" sub in a long but narrow enclosure for really low frequency "movie duty""

The added cost and complexity of this need would be eliminated. Of course it depends on if a pair of large subs up front is even an option.
jayHRC51's Avatar jayHRC51 09:03 PM 07-02-2012
I think porting the front subs would cause them to be a little too big for my liking. I think I can get away with a little over 6ft3, but I don't really want to get any larger than that. They start to get dimensionally too large above 6ft3.

Would I see any improvement by going a little larger than 2ft3 per sub in a sealed application? Do you hit a point of diminishing returns after a certain enclosure volume? 4ft3 would make for a perfect sized enclosure as far as aesthetics go for me.

Sounds like these things will have some pretty impressive output for a really cheap build price. I'm really looking forward to getting started on this build. Drivers will be here tomorrow and I'm buying wood Thursday. Should have the enclosures started this weekend.
LTD02's Avatar LTD02 09:41 PM 07-02-2012
"Do you hit a point of diminishing returns after a certain enclosure volume?"

kind of, but there are additional considerations that complicate things.

smaller enclosures are less sensitive, so require more power to hit the same spl on the bottom end. as the driver moves in-stroke, it compresses the air. that compression pushes back against the driver. the smaller the enclosure, the faster the pressure builds against the driver, so the less the driver moves. the less the driver moves, the less sound you get. however, once your driver runs out of excursion, you are pretty much done.

a total of 1400 watts will push 4 of your drivers to xmax in 6 cubic feet total, whereas it will only take 1200 watts to do the same with 8 cubic feet total. so, anything in the 1.5-2.0 cubic foot per driver range will work just fine for that driver and a 1000-2000w amp. i don't know how much that driver has past xmax, so if you go with the more powerful amp, go with the smaller enclosure. just to be double clear, if you go with an amp with 2000 real watts such as the behringer nu3000dsp, go with 1.5 cubic feet or even a little less cabinet per driver, for a total of 6 cubic for four drivers. if you put two drivers in each of two cabs, that would be 3 cubic feet per cab. sorry for being redundant.

how do you plan to build the curved backed cabs?
jayHRC51's Avatar jayHRC51 01:33 PM 07-03-2012
Quote:
Originally Posted by LTD02 View Post

how do you plan to build the curved backed cabs?

I'm going to kerf the plywood to allow for the bend. Then I'll use a jig to hold the panels to the correct curve so that I can fill the voids with fiberglass resin. Once that cures I'll remove from the jig and clean up any mess left from the resin. Glue in my bracing pieces, the tops and bottoms and then glue the baffles in place. Not sure if I want to paint the cabinets and use some veneer for accent pieces on top and the base or if I want to veneer the cabinets and paint the base and accent pieces. Still kind of up in the air on finish...I do have a few ideas in mind though. I'm envisioning a cross between these two cabinet styles. Obviously no upper section like the 802d's

700
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jayHRC51's Avatar jayHRC51 06:47 PM 07-03-2012
Somebody got some subs today!

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jayHRC51's Avatar jayHRC51 03:59 PM 07-06-2012
I'm trying to figure out driver displacement and I've read that an average 12" driver is about 2.51 liters (zero help to me) or 0.08 cubic foot per driver. Is that correct? This sounds very low to me. Is there a special name for driver displacement in the T/S parameters?

How in the hell do I figure out how much space the bracing will take up? Is there a good average to use? I plan to brace the crap out of these cabinets. Should I just build to about 2.25 cu/ft per sub and assume that bracing and driver displacement will bring me back down to about 2cu/ft?

Should I include any stuffing in these sealed cabinets? How do I determine how much to use and how much of an effect does it really have?

Thank you
A9X-308's Avatar A9X-308 04:47 PM 07-06-2012
1 f³ is ~28 litres.

Driver displacement is not all that critical and not something you need to go to two decimal places on. For a pro style 15" 6 litres is close, 8 for an 18, 4 for a 12 and proportionately for other drivers. If thy are unusual, say have a ridiculously large magnet, take the previous numbers as a base and add the estimated structure volume of the motor to that.

Bracing volume? Pencil, paper and calculator.

Stuffing? I would, but it's not necessary and even after reading the thread I'm sot sure of you decided to go sealed or ported. If the latter, keep the path between the driver and the port clear.
jayHRC51's Avatar jayHRC51 05:18 PM 07-06-2012
I've decided to go sealed; about 2ft3 per driver and two drivers per cabinet. I'm planning to run a pro amp in 2ohm stereo with a goal of about 700 watts per channel.

Is there a rule of thumb for stuffing amount?
A9X-308's Avatar A9X-308 05:38 PM 07-06-2012
Quote:
Originally Posted by jayHRC51 View Post

I
Is there a rule of thumb for stuffing amount?
Not really, just don't jam it in solid. Lightly filling with offcuts of fluffy pink batts is what I use, but won't really make much difference in a sub. Make sure it can't move over time and settle against the cone or impede it's movement.
jayHRC51's Avatar jayHRC51 05:40 PM 07-06-2012
Quote:
Originally Posted by A9X-308 View Post

Not really, just don't jam it in solid. Lightly filling with offcuts of fluffy pink batts is what I use, but won't really make much difference in a sub. Make sure it can't move over time and settle against the cone or impede it's movement.

Cool, thank you.
jayHRC51's Avatar jayHRC51 10:27 AM 07-09-2012
Well, started cutting wood over the weekend. I'll post some build pictures shortly. I will also say that a full radius back cabinet is more difficult than it's worth doing in a home shop. Kerfing plywood is a complete pain in the balls. Even for a relatively easy 11" radius it involves faaaaaaaaar to many cuts. The only way a full radius back would make any sense is if I had a press and a mold for the shape that I wanted. Then I could glue up multiple layers for whatever thickness I wanted. Unfortunately I don't have access to that type of equipment in my garage... So, it's angled cabinets and round-overs for this build. I can always build a new cabinet at a later time.

So, on to my next question. Given the choice, what amp would you choose out of the three listed below? Why?

  • Marathon MA-2050 listed at 800x2 into 2ohm (class AB) - $350
  • QSC GX5 listed at 500x2 into 8ohm (class H doesn't run 2ohm stereo) - $399
  • Behringer NU1000DSP iNUKE w/DSP listed at 500x2 into 2ohm (class D and cheapest option) - $299

jayHRC51's Avatar jayHRC51 01:19 PM 07-09-2012
Start with a few sheets of this -

450

make a bunch of this -

450

Make a template that doesn't work... -

450

Make more of this... -

450

change design to something like this -

450

and start to assemble something like this - The bracing is not nearly done in this pic, but it's mid assembly

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