Here Is The definitive Way To Build A SUB!
drew spelts
Posts: 310
Hello Polk Brethren,
Today i am going to share with everyone how I created a truely outstanding subwoofer with way more punch and low end than I could ever need. About a month or two ago, I started doing reasearch into purchasing a subwoofer and looking at all the options (mostly in ebay) and came across a brand called NHT which stands for Now Hear This. Well they make a great looking sub that comes in two models 2 ten inchers and 2 twelve inchers both models have the speakers stacked on top of each other to simulate a tower speaker and suprisingly enough both are astronomically out of my price range. The shipping on those guys would have killed any middle class guy and now I know why, but more on that later. I read a ton of reviews on the NHT dual setup and was very impressed. So now I knew that I wanted a sub with stacked 12inchers. However there were almost no other brands out there with this design. So the ony logical thing to do was to make my own. Then this crazy Idea occured to me, "Drew, If you are making your very own sub, why not make it look exactly like the new RTi line of speakers." So at this point I knew exactly what I wanted the unit to look like. Now I just need to find out what speakers would do it justice. I was looking at the silver colored coned momo polk subs for car audio, you know the ones with the yellow MOMO on them, but then I read some reviews and that quickly turned me away. So I went back to the drawing board and studdied my pair of RTi6's. I noticed that they had a rubber surround and I had remembered being in a car adio shop one day and having them test out some subs for me just to hear them. This was way back before the move The Fast And The Furious came out. I say this because there is a seen in the first quarter of the movie when Vin Diesel pulls up with his red ricer and it has Alpine type R's loaded to the gills. So back to the car audio shop, I had them test ACDC Thunderstruck on those babys and have never and I mean never been so impressed buy a pair of subs in my life, only 4 Eclipses could touch those two bad boys, it was just eye opening. Now I needed an amp and talked to lots of people on here about it and they told me so much good information but basically that I did not need huge amounts of power and I did not believe them at first untill I talked to one guy on the phone named Dennis and he told me that he had to keep his turned down really low or else it would drive him out of the room with all the base. He also recomended me to Parts Express and we conversed for almost two hours about the plate amps and so on. I decided on a Bash 300W plate amp for several very simple reasons, no heat fins to get bunged up, looks killer, class G circuitry, and the most important one of all---LFE input. So I ordered the plate amp for $150 within a couple of days and found a slightly used pair of alpines Type R's for $200 shipped on the bay which now I find out I paid about $50 too much for but hey, live and learn. Then a trip to the hardware store (actually like 5 trips, you know how that goes) right at about a $100 for all the materials including a gallon sized pail of bondo (very important). Now I decided for a truely superior sub I needed to start with a truely superior box. It was decided by my dad and I that two sheets of half inch MDF board laminated together tightly with wood glue would create a super rigid chassi along with substantial cross bracing (BTW this is a completely sealed sub, sorry for not mentioning that earlier) So I designed everything with several hand sketched drawings and used a scaling ruler to see if I could get all the pieces out of a single sheet of MDF. Sure enough with almost less than 3 square feet of waste I could get double thickness out of one sheet. So we carfully cut all the pieces and made it so that all the side walls would have a simulated mitered edge to them. This was done by cutting one piece say 18 inches wide and then the piece to laminate to it that would be on the inside only 17 inches wide and an inch shorter. Then laminate the two together over night and whala its as sweet as it gets for strenght and sureness of fit. But before I could just slap it together I needed to cut out the speaker holes in the front even befor I laminated it together. So with a circular guide that attached to my dads really cool jig saw I was able to cut some perfect cookies out of the two face plates. The outermost plate had a diameter of and inch and a half greater than the inside plate tha way the speakers could be recssed in to the sub and look a little nicer. Now with all pieces cut and laminated together it was time to put them together with 2X2's in ALL and I mean ALL corners and edges. The center of the front and the back even got 2X2's and from the left to the right side was braced with a 2x4 precision placed. Every joint, including all bracing got thuroughly swabbed with wood glue.
Today i am going to share with everyone how I created a truely outstanding subwoofer with way more punch and low end than I could ever need. About a month or two ago, I started doing reasearch into purchasing a subwoofer and looking at all the options (mostly in ebay) and came across a brand called NHT which stands for Now Hear This. Well they make a great looking sub that comes in two models 2 ten inchers and 2 twelve inchers both models have the speakers stacked on top of each other to simulate a tower speaker and suprisingly enough both are astronomically out of my price range. The shipping on those guys would have killed any middle class guy and now I know why, but more on that later. I read a ton of reviews on the NHT dual setup and was very impressed. So now I knew that I wanted a sub with stacked 12inchers. However there were almost no other brands out there with this design. So the ony logical thing to do was to make my own. Then this crazy Idea occured to me, "Drew, If you are making your very own sub, why not make it look exactly like the new RTi line of speakers." So at this point I knew exactly what I wanted the unit to look like. Now I just need to find out what speakers would do it justice. I was looking at the silver colored coned momo polk subs for car audio, you know the ones with the yellow MOMO on them, but then I read some reviews and that quickly turned me away. So I went back to the drawing board and studdied my pair of RTi6's. I noticed that they had a rubber surround and I had remembered being in a car adio shop one day and having them test out some subs for me just to hear them. This was way back before the move The Fast And The Furious came out. I say this because there is a seen in the first quarter of the movie when Vin Diesel pulls up with his red ricer and it has Alpine type R's loaded to the gills. So back to the car audio shop, I had them test ACDC Thunderstruck on those babys and have never and I mean never been so impressed buy a pair of subs in my life, only 4 Eclipses could touch those two bad boys, it was just eye opening. Now I needed an amp and talked to lots of people on here about it and they told me so much good information but basically that I did not need huge amounts of power and I did not believe them at first untill I talked to one guy on the phone named Dennis and he told me that he had to keep his turned down really low or else it would drive him out of the room with all the base. He also recomended me to Parts Express and we conversed for almost two hours about the plate amps and so on. I decided on a Bash 300W plate amp for several very simple reasons, no heat fins to get bunged up, looks killer, class G circuitry, and the most important one of all---LFE input. So I ordered the plate amp for $150 within a couple of days and found a slightly used pair of alpines Type R's for $200 shipped on the bay which now I find out I paid about $50 too much for but hey, live and learn. Then a trip to the hardware store (actually like 5 trips, you know how that goes) right at about a $100 for all the materials including a gallon sized pail of bondo (very important). Now I decided for a truely superior sub I needed to start with a truely superior box. It was decided by my dad and I that two sheets of half inch MDF board laminated together tightly with wood glue would create a super rigid chassi along with substantial cross bracing (BTW this is a completely sealed sub, sorry for not mentioning that earlier) So I designed everything with several hand sketched drawings and used a scaling ruler to see if I could get all the pieces out of a single sheet of MDF. Sure enough with almost less than 3 square feet of waste I could get double thickness out of one sheet. So we carfully cut all the pieces and made it so that all the side walls would have a simulated mitered edge to them. This was done by cutting one piece say 18 inches wide and then the piece to laminate to it that would be on the inside only 17 inches wide and an inch shorter. Then laminate the two together over night and whala its as sweet as it gets for strenght and sureness of fit. But before I could just slap it together I needed to cut out the speaker holes in the front even befor I laminated it together. So with a circular guide that attached to my dads really cool jig saw I was able to cut some perfect cookies out of the two face plates. The outermost plate had a diameter of and inch and a half greater than the inside plate tha way the speakers could be recssed in to the sub and look a little nicer. Now with all pieces cut and laminated together it was time to put them together with 2X2's in ALL and I mean ALL corners and edges. The center of the front and the back even got 2X2's and from the left to the right side was braced with a 2x4 precision placed. Every joint, including all bracing got thuroughly swabbed with wood glue.
Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes:
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes:
Post edited by drew spelts on
Comments
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I then proceded to cut the back out of this beast to fit the plate amp and decided it best to locate it near the top rather than the bottom just so i could make adjustment slightly easier. I put it all together and tested it out to see if it sounded fairly decent. So of course the first thing I did was play the part in Finding Nemo when the girl was tapping on the glass of the fish tank....... WOW literally just made my jaw drop to see those large speakers move that far in and out. I only had the volume on half and it was better than I ever thought it would or could be. My dad came in from the garage and said that everything was rattling prety good out there. So with a little more testing on some CD's I was completely satisfied that this sub was tigh and just needed to be finished.
Now to the excruciatingly long drawn out job of Bondo (My buddy). See, the new Rti line have this neat curve right at the edges and a very broad raised surface making the the whole silver face. I think it looks cool as hell so I wanted to replicate it onto my sub. So I started just adding medium sized amounts of bondo until I quickly realized it was going to take a whole lot more than I had originally thought and was wondering if I even had enough. So I mixed larger batches and just lathered it onto the face and filled the screw holes with any spare stuff off of my mixing plates. BTW, The waxy paper plates work awsome for bondo jobs. It took 2 days of spare time to get ebough on there to make it look like something. Now it was time to inlist the help from my artist girlfriend because she is the hands on type and I knew that this was three times more work than I had bargained for. So I let her form the inner wells where the speakers mounted inside and I would make sure the face was perfectly flat and smooth along with doing the outside edges.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
Fancy... look foward to see some more pics
edit: nvm I saw the pics in your test thread. Looks cool. -
I found that the best way to form the outside cuves was to cut a strip out of a seasoning continer and line it with a piece of sand paper. so about 3 days of more bondoing and sanding and it was looking prety damn perfect. I took a good helping of some watersoluable woodfiller and watered it down till I could paint it on to the bondo so that it would fill any pinholes that you get from air bubbles. I then sanded this down with 800 grit. Then wiped it clean and blew it out with a leaf blower outside. Then Came the 5 coats of white primer which I sanded down with Two packs of 1000 grit sand paper untill it looked like glass. I then took the Rustoleum Silver spray paint and began painting. This turned out like absolute garbage. The color was way too shiney and showed absolutely the smallest imperfections a mile a way and pissed me off the whole night. So back to the hardware store, luckily they cary like 1000 different kinds of spray paint. I found a different can made for sheet metal like out on a farm. Its the same brand but the "professional" grade (I have never in my life met a professional spray painter but maby someone else has). The number off the can incase anyone wants to know is "Stainless Steel 7519" and this stuff is so dang close that you absolutely can not tell unless the sub is touching another speaker from the RTi lineup. I was so delighted to find as perect of a match as I could ever hope for. Silver is a heck of a lot harder to match than black, who woulda thunk it. And the other huge bonus was that this stuff is dull enough with the larger and darker metal flakes in it that it shows no blemishes shwwwoooooo (wipes forehead). So I coated it like 3 times with the new grayer silver and was completely satisfied. Then something happened. Something had landed on my speaker..... A hair and had become one with the paint. So I carfully removed it with my fingernail but crushed some of the fine folicles that develop on the surface with this paint. So I thought about it and it occured to me that when a freshly vacumed room has the carpet all pulled one way it looks great just so long as its all pulled the same way. I carfully and lightly crushed all the paint follicles on the entire surface in the same direction with my pinki finger. I have to say the thing looked damn good at this point and I did not want anything marring up the surface so I decided to seal the face with an entire can of clear coat. This did not change the look at all, just kept the follicles crushed in place and left an invisble coat of protection on the speaker face.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
So now it was time to put it all together again and let it sit till I could decide what I would cover the rest of the sides with. I was looking into the vinyl from Parts Express but that costs money and looked prety hard to get perfect seems with. Then my dad told me that we had a quart of black semi gloss exterior latex in the garage. So we took it back out to the garage and I just kinda taper the stuff off that I was worried about and started putting the paint on. Well my dad forgot to mention to me that I should probably put killz on it first to prime it. So I put the first four coats on and you could still see some areas that I had tested my spray paint on the sides first. So incase anyone is wondering It takes right at 10 coats of black latex to cover things up if you dont use killz. I pulled the tape off and did a little touch up work with a super fine paint brush and called it done till summer when I am thinking of adding spikes to it. I just have to take time to say thanks to a few outstnding people that helped a ton. Thanks to my dad for all the time commitment and borrowing of tools and use of his heated garage. Thanks to my mom for not bitching when I took up her parking space in the heated garage for a solid week. Thanks to the girlfriend for being so understanding in my passion for perfection and the hours of hand sanding. Thanks To Earl B., Dennis, and Bizill for advice on this outstanding website with such a great group of guys full of information and help.
This thing not only looks great and sounds great but matches all the new Polk RTi linup!Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
sorry last attachment was just toooooooo BIG This one should be alot smallerHarman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
Wow I was sure that this thing would get some comments with over 60 views but I guess no one has anything to say.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
I think its pretty cool. I also think it was nice that, in one way or another, your entire family got involved with the project - your gf too. Maybe you should post this in the DIY section
Anway, good job 
Audio: Polk S15 * Polk S35 * Polk S10 * SVS SB-1000 Pro
HT: Samsung QN90B * Marantz NR1510 * Panasonic DMP-BDT220 * Roku Ultra LT * APC H10 -
Great job. It's interesting that you used car audio woofers. Got a couple of questions --
The most important question, of course, is how does it sound (especially with music)?
How low does it go?
How many c.f. is the box? Did you use the same dimensions as the NHT?
What is the room size that houses your HT system?
I have a 500 watt amp powering a 10" sealed sub, so I'm wondering if your amp has enough power for two 12 inchers in a sealed cabinet? Did you consider building a passive sub with dual binding posts powered by a 2-channel pro amp?HT/2-channel Rig: Sony 50 LCD TV; Toshiba HD-A2 DVD player; Emotiva LMC-1 pre/pro; Rogue Audio M-120 monoblocks (modded); Placette RVC; Emotiva LPA-1 amp; Bada HD-22 tube CDP (modded); VMPS Tower II SE (fronts); DIY Clearwave Dynamic 4CC (center); Wharfedale Opus Tri-Surrounds (rear); and VMPS 215 sub
"God grooves with tubes." -
Looks good...
I hope you factored in all that bracing.. 2x4 are fairly large...- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
I have always thought about using some good car subs for a project, but figured the subs I have in my car (Orion H2's) were better left in the car.
But with your little write up, maybe I'll bring it in the house and run my sub amp to them and see how they do...just one more thing on my long list to do..
Scott -
Car subs are called car subs for a reason... - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
-
The most important question, of course, is how does it sound (especially with music)? Well I think it sounds so good that I dont believe I will ever buy another sub again. See I went to a speaker place that does only pro installs and they have the best subs on the market in there theater rooms. The Sub that this guy sounds really close to but not quite equal is A brand name I am having trouble remembering. magelan, or galileo or something like that it uses 2 passive radiators along with a twelve incher and only costs about 2grand. So I think I did prety good and I believe that the sum of the parts are far greater than seperate. I would not part with this thing for anything under $700 just because it is that impressive.
How low does it go? I created a test disk with HZ starting at 100 and going down to 15. Well I am not sure what to look for in how low it goes because it will go all the way down but at about 20-25HZ is a decrease in volume this could be due to the fact that it is sub sonic at this point and can not be heard. There was no flapping or weird efects noticed.
How many c.f. is the box? Did you use the same dimensions as the NHT? The outside dimensions are 16X30X14 The internal volume will then be 14X29X12=4872 Devide that by 1728 gets you 2.8194 cubic foot. now I have at least a half cubic foot of bracing and each speaker should take up about a 1/3 cubic foot. this brings the internal volume down to around 1.6534 The manufacturing specs stat that each speaker should have between .75 and 1.00 cubic foot in a sealed inclosure so this box is about perfect. 1.6534/2=.8267 And boy does it sound nice.....
What is the room size that houses your HT system? 15 X 15 X 9 at the most
I have a 500 watt amp powering a 10" sealed sub, so I'm wondering if your amp has enough power for two 12 inchers in a sealed cabinet? Did you consider building a passive sub with dual binding posts powered by a 2-channel pro amp? Seriously I never And I mean NEVER turn up the power to half. It is just toooo much low end and drives you out of the room. Another great thing is that even when I was first testing it out at close to the 3/4 volume the plate amp barely got warm and that was for 10 minutes of hard grind bass tests. This thing is literally built like a tank. It weighs 95lbs.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
Drew
The most important thing is that you are happy with it. Hell if it sounds good to you, then it is a keeper. A subs job is to reproduce LF's and if your sub does it well, then you did a good job with the build simple as that. And you saved yourself a bundle.
I can't see any reason why a car sub wouldn't work, and you proved in your case that it worked well. Congrats..
Scott -
Ok I just tested out ZZ Top Greatest Hits--La Grange Holy hell that was soooo impresive. Then I tested out Kid Rock, The History of Rock--3 Sheets to The Wind (aka Whats My Name). And this one literally almost made me tear up kinda a weird feeling. Then it gets even better.... I pull out an oldie from my childhood.....The Bevis and Butthead Experience--#15 Sir Mix-a-Lot called Monsta Mack This one for sure I knew the neighbors were feeling because everything and I mean everything in the room mooves. I move the couch moves the 200Lb Tv looks like its mooving But the thing sounds so good..... I mean no distortion and I still have not turned the plate amp up to half So I dont know about your 500W Amp Earl B but those numbers just can not be right. I think that if i would have let the Monsta Mack song play for an hour in a loup at those levels that the wall would start to show splits in the corner. This thing is nearly unparalleled in my small theater room. BTW I am still trying to post the room up on the website. So.... Thats how it sounds with music.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
Great! It's good to hear that you're loving your DIY sub. Welcome to the club. Glad we talked you into it.HT/2-channel Rig: Sony 50 LCD TV; Toshiba HD-A2 DVD player; Emotiva LMC-1 pre/pro; Rogue Audio M-120 monoblocks (modded); Placette RVC; Emotiva LPA-1 amp; Bada HD-22 tube CDP (modded); VMPS Tower II SE (fronts); DIY Clearwave Dynamic 4CC (center); Wharfedale Opus Tri-Surrounds (rear); and VMPS 215 sub
"God grooves with tubes." -
WOW I just wanted to say thanks too all for the 205 views, thats twice as many as I expected. Thanks again everyone.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
You could name it Soliloquy Duo.
Or some song by the DiVinyls. . . .
Or Captain Flagellean-Ignorance is strength - -
Hey Drew,
I can't believe I missed this post after talikng to you on the phone about the project for what over and hour?!!! It looks good and I'm sure that it sounds great.
BTW, Sid that woofer models out almost exactly like Adire's Shiva does. I worked that through with Drew before he built it. Not all car drivers are made for car installs only, tell that to those that use Tumults for HT!!
If I recall those Alpines have around 15mm Xmas one-way.HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable
2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable -
Well thats good...
And Id love to have a Tumult...whos buying?? - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Ba dum boomp. . . . .
Would that be Xmax or Christmas.
not to be confused with Mms or moving mass which could occur on Xmas, but not if it moves without too much warning.-Ignorance is strength - -
SKsolutions wrote:Ba dum boomp. . . . .
Would that be Xmax or Christmas.
not to be confused with Mms or moving mass which could occur on Xmas, but not if it moves without too much warning.
I talked to him over his Xmas break, so I guess it was a little brain **** huh...nice catch! HT Optoma HD25 LV on 80" DIY Screen, Anthem MRX 300 Receiver, Pioneer Elite BDP 51FD Polk CS350LS, Polk SDA1C, Polk FX300, Polk RT55, Dual EBS Adire Shiva 320watt tuned to 17hz, ICs-DIY Twisted Prs, Speaker-Raymond Cable
2 Channel Thorens TD 318 Grado ZF1, SACD/CD Marantz 8260, Soundstream/Krell DAC1, Audio Mirror PP1, Odyssey Stratos, ADS L-1290, ICs-DIY Twisted , Speaker-Raymond Cable -
Yeah, Thanks for the time and knowledge Dennis it was more than appriciated and used only for the forces of good. Although I bet the neighbors think it is pure evil. You were right about not needing too strong of an amp. I think the 300W is perfect because I could really crank it if i wanted but its way more powerfull than I bargained for already. I love when Dora taps on the glass in Finding Nemo and whenever I have a friend over thats one of the first scenes I show it off with. Oh and BTW I finally got a pair of RTi10's for only $525 shipped in mint condition. And a CSi5 for $225 shipped in mint condition. This Polk Community sure is great.Harman Kardon AVR635
RTi10's Up Front
CSi5 Center
RTi6's Rear Surround
Furman RA-1210:rolleyes: -
looks better than mine. that is what i have to say.
http://www.polkaudio.com/forums/showthread.php?t=37229ELECTRONICS
arcam cd93
linn wakonda
MC2 MC450
Teac ud h01 DAC
SPEAKERS
Tannoy DC6 t se . -
wrong thread- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
