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Diy subwoofer selection and enclosure design


michael hurd

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I have been doing lots of reading, and have looked at a few subwoofers that have been built by diy's. There sure are quite a few on this board even. I would like to use Adire Audio's tempest in a large vented tube, because it requires moderate power, will generate high spl's, and is very reasonably priced. The fact that I can obtain this driver in canada, without monetary exchange, and $ 1 shipping makes it even more appealing than others.

I know that a lot of people have used sonotube, or builder's tube as it's also known with great success. I looked at some in home depot and decided that while it can be made to look great with fabric coverings, that's just not my cup of tea. Has anyone here made an enclosure out of Pvc sewer pipe before? I'm thinking that a completely smooth cylinder, with a great paint job ( automotive paints ) would be a little more pleasing to me. The nature of the smooth plastic, would require very little prep work to paint.

I have also located a behringer feedback destroyer pro eq for $ 130 cdn, just minutes from my apartment in thunder bay. I have a yorkville ap 500 power amp that's not being used right now. The only thing is to find a length of sewer pipe 16" or bigger inside for the enclosure without breaking the bank. Any suggestions? Maybe local contractors? Would it be better to buy a circle jig and use a router for the mdf endcaps? Or would using a jigsaw to rough them out and turn them on a lathe until they are a tight fit, be a better plan. I'm sure dustin, formica and fire pinch will chime in here. Single large port or two smaller ports?

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I know I'm kind of rambling on here, but I'd like input, before I save up money to do this. Another thing i'd like help on is enclosure tuning, and sizing. While I have built sealed subwoofer boxes for vehicles, I have never attempted a vented box design before. Before I left Thunder Bay for trade school, I downloaded Adire Audio's demo lsp cad. However, I really didn't use it that much, and I'm hoping someone else has more experience with it. Enclosure size is not really that big of an issue with me. Tuning? I was thinking of tuning it pretty low, like 18 - 20 hz to help limit the driver excursion at the lowest frequencies. Ports? Simple straight tube? Or flared ports to reduce noise?

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I would like to use Adire Audio's tempest in a large vented tube, because it requires moderate power, will generate high spl's, and is very reasonably priced.

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Yes... I agree... great "bang for the buck" driver esp once you factor in the amplifier power required.

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Has anyone here made an enclosure out of Pvc sewer pipe before? I'm thinking that a completely smooth cylinder, with a great paint job ( automotive paints ) would be a little more pleasing to me.

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Have read about people wanting to do it... but haven't seen any completed projects. A 16" tube will be too small to fit a 15" driver... so you may have to look at 18" drain pipe. Either 16" or 18" are very expensive, so unless you can find yourself a long piece of scrap... it might not be worth it. A cardboard tube would require much more work to paint in a glossy finish.

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Would it be better to buy a circle jig and use a router for the mdf endcaps? Or would using a jigsaw to rough them out and turn them on a lathe until they are a tight fit, be a better plan.

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Definitely use a router... if the circle jig is too expensive (they are) you can make yourself a simple one out of a couple of scraps of wood... works like a charm. IMG_1231-web.jpg

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Single large port or two smaller ports? Simple straight tube? Or flared ports to reduce noise?

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No difference between one large or two smaller ports if their cross sectional area add up to the same. As for the flares, it depends on the size of port you choose, either flared or straight can work. In other words a flared port can be smaller and shorter than a straight one for a given amount of port noise.

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Enclosure size is not really that big of an issue with me. Tuning? I was thinking of tuning it pretty low, like 18 - 20 hz to help limit the driver excursion at the lowest frequencies. Ports?

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You can use one of the Adire recommended alignements... and in your case either an EBS or Adire Alignement would seem to match the 18-20Hz tune range.

Later...

Rob

post-11489-1381924990025_thumb.jpg

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Rob: I think that 16" diameter inside pipe would be fine, as it would still give me around an inch of mdf all the way around. The cutout is a little bigger than 14", if I remember correctly. Any suggestions for the legs? I don't own a router, but could definately get my hands on one. I guess you'd have to trial fit the plugs and make a circle jig with a few holes in it to try, as i'm assuming that the first measurement won't be that accurate. I'll have to check for scraps, for the pipe, as it is quite expensive, when I priced it out a year ago.

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Michael, do a search on (tempest sonotube project)I built one and there is some good information on that thread. Dustin B, helped me a lot figuring out the lenth of the port. You will need a router, you can make your own circle jig. Read that thread it should help you out.

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PVC has been discussed on the HomeTheaterForum and I believe the consensus was that it will/could vibrate. I covered my sonosub in naughehyde and it looks good. If you want a truly smooth finish you could try drywall compound to fill in the grooves and sand it smooth before painting.

Mine is a dual Tempest/dual port tuned to 17Hz. 480liters which is a 28" round tube by I think 54 1/2" long. Don't remember exactly. For a single Temmpest you could make a 240liter with a single 6" x 20" port, should give the same 17Hz tune. I'm using the Hypex HS500 amp which provide 250watts to each sub. This thing is unbelievable, rattles the drywall and makes your pants legs move. You will NOT be disappointed. I say build a dual Tempest just for the headroom, and/or no builder's remorse later on.

If I can answer any more questions feel free to e-mail directly as I don't get on here all that often....Mike

Mlstrass@Hewitt.com

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Hmm.. never thought about wrapping the sub with something smooth and hard, and then painting that. Good idea! I have seen the pics of your dual tempest before, the one with little mirrors on it right? I can't really see the pvc vibrating, as it is slightly flexible, but not as flexible as sonotube. Also, there are varying wall thicknesses, depending on the pressure rating on the pipe. I think even the thinnest 16" that is made by Ipex is stil near 3/8" thick, going up to over 5/8" for the higher rated pipe. I kind of like the wrap idea, it would work, but would be a real pain to glue and clamp, that's for sure.

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I've removed the mirrors as I didn't care for them.

I think that PVC would resonate is the issue that was discussed before. I thought someone on the other site made a small sub with a 10" driver to test it and had problems with is resonation. Not sure. Give it a shot with the PVC and let us know how it works.

So did I sway you towards a dual Tempest sub? 2.gif

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A dual tempest sub would be great! Maybe I don't need that much output, but sure would be nice to have. I'll have to search your pics, mlstrass. How exactly did you accomplish that? Did you have a driver and a port at either end? Really, it's not that much more work to even make two enclosures, as the setup is more time consuming. If you make multiple cuts, and the like it would take only a little more time. The mdf is not expensive, just the addition of another tempest, and a little more tube. I hear what you mean about builder's remorse - you learn a little more each time, and where you kind of made a mistake, or did things a little differently. That is why I would like input from lots of people. Everyone has good suggestions, and tips. Thanks for the input so far guys!

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To me it's better to over-build than to later discover you don't have enough bass. One tempest & port in each end. MDF for the endcaps is 3 layers of 3/4". Like you said very little extra work as you're just duplicating the cuts for each end. In such a large enclosure the Tempests don't require very much power either.

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The Tempest is a really simple forumla. One Tempest, one ~250W at 4ohms amp, one 6" schedule 40 PVC pipe of ~24" (actual length will depend on tune choosen and size of enclosure), enclosure of 240-320L and tune to 16-20hz. Really you can pick any size and tune in that range and you will be very happy with the end result.

The sub Mike is describing was a design from Mr. Wiggins himself. 480L enclosure (roughly a 72" tall 24" diameter enclosure) tuned to 18hz with a 6" port in each endcap and a Tempest in each endcap. Stuff with 8lbs of polyfil and goose each driver with ~250W and you'll have a sub that would shame just about every commercial sub out there. Especially after you compare the price tags.

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Sounds like a great performer this dual Tempest 24" ported sonotube design.WIth 500W of solid amp backup it should equal(or beat) a Tumult in an optimal volume with dual 18" PR's powered by a similar amp.

Tempest go for under $300 for both and the Tumult eats a $500 chunk plus PR's(150-200).

The tempest may not the the most gorgeous woofer out there but its still a champ at what it does,providing the most bass for the dollar.

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Yes its a great time for those who build their own subs,at $200 Canadian the Tempest is a sure hit,get two.Buy an inexpensive sonotube,make solid endcaps.Just have to find the right ports and a two channel 250W or more amp and voila.

You have monster performance at a beer budget

I think renovation stores like Home Depot should carry 6" PVC tubing you can cut and make the port you need.Or get a few smaller flared ports sold on a few DIY stores.

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As Dustin stated, the non-flared 6" ports are fine. NO port noise whatsover. During The Haunting in DTS this thing is pushing a ton of air, and still no noise, just the subs moving crazily and everything not nailed down rattling and vibrating. Just adds to the effects!

Time to start making MDF dust 3.gif

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