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Old 25th January 2006, 07:50 PM   #1
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Default need help new to building

After browsing the web for days on end reading everything i could find i have become completely lost on what i want or should do.
Basicly I want to build a sub with really good low response 20hz or so for reasonable money. I was looking at either a the 12" assassin or the Dayton 12 DCV. In either a closed or passive radiator design or how big either box should be?????

I have a Kenwood HT subwoofer with a 160w plate amp that I was going to rip out and use for the project or possibly going with a Cerwin Vega 200w amp i have seen on Ebay (65 bucks lol).
Part of the reason I am aproaching this is because i tested a Velodyne CHT 12 and found it boomy and not as tight as id like specialy after listening to U-571 the depth charge scenes. In turn i wasnt even thinking about buying a CHT 12 i was going to buy a Velodyne VRP 1200.

My 'media room' (lol) is 15x23 with 7' ceiling (drop ceiling in the basement) i have carpet flooring (no pad) and sheet rock walls.

I also have in my room a set of Kef Coda 90's a teatro center jbl north bridge sides with 8" and jbl book shelf in the back 6". along with two 8" powerd subs a onkyo (first suround sound set up) and a kenwood 8" the one i might cabbage.

I want a all around sub that will be capable of music and watching movies full tilt if this is possible with a budget of 200 to 300 bucks not including wood and such just electronics . (hey id like 2 matched also guess i should start with 1 tho)
i just need some good direction on whats the best way to go and not waste my money. After reading the last 5 pages of posts i have the upmost faith in the peeps in the forum to steer me in the rite direction.
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Old 26th January 2006, 12:16 AM   #2
Volenti is offline Volenti  Australia
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Something to keep in mind is that room acoustics play a very large role in how a sub sounds in a given room (and in different locations in that given room)

It's possible that the Velodyne CHT 12 may have been located in a spot that excited a room mode and caused the boomy response you heard.

This is something that will affect a diy design just as much as a commercial sub.
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Old 26th January 2006, 01:07 AM   #3
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i have read some about placement of the subs i just dont have the ability to move my subs very far from left or right of the front of my room. I wish i could afford to treat my room for accoustics but thats another nightmare of spending money and not knowing what may be in my best intrest or not. I do have a basic bass trap made outa stacked insulation rolls coverd in burlap. Just a cheap way of tyring to keep it in line a bit. I have everything set width wise so im on the cross way not the long way.
And i should give the CHT props it does sound good for alot of applications i just feel that the low lows didnt satisfy. Guess I really wana DYI a sub and have acess to all the wood working tools i could ever use for this project i just dont know what is best for my situation. Or what the pros, like your selves, would do.
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Old 26th January 2006, 02:49 AM   #4
MarkR is offline MarkR  United States
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bostonswoop,
My first DIY endeavor was a 85L ported sub using the Dayton DVC 12. It sounded good but not as good as I expected from what I had read. The Shiva was all the rage at the time but when I was ready to order no shivas, so I went with the dayton which was supposed to be a good alternative. Well I used the 85L vented shiva cabinet plans as I wasn't confident enough to design my own. Well when I was finished it sounded good but not as good as I had hoped for. My build wasn't fueled by need, just wanted to build one after all I had read about. It didn't stand up well to my Mirage BPS-400 dual 12" 400Wrms sub. The dayton driver seemed to bottom out fairly easy. So when the Atlas's went on sale I scooped up a 12 and 2 15" I put the 12 in the box the DVC was in and I finally go the results I expected. Since they clained it was a"bottomless" design I threw everything I could think of at it U-571 in DTS at reference level the Haunting in DTS etc. the usual torture tracks and it never burped farted flopped or anything. Sounded great,even my gf said she couldn't believe that the driver would make that big a difference.
I used a rythmikaudio 250W plate amp. no boost and the rumble filter is set at 12hz unless you ask for them to change it for you ($5) charge. This may have been the problem I had with the DVC. With the Ascendant driver it wasn't a problem at all.

I haven't heard the new Assassin 12 but Chad @ ascendant says it is a good drop in for the Atlas 12 which I have heard. I would definately recommend the AA sub over the Dayton DVC which I also have. It now sits in the Atlas 12's shipping box.

This is a quote from another forum(carstereo.org) made by Chad @ AA "A couple of quick things to mention: The Assassin is essentially bottomless. The voice coil would have to swing well past the gap to hit the back plate. I have yet to get one of them to bottom out while testing it. The suspension won't let it get that far anyway."

Right now there is only a $5.00 differance in price between the DVC and the Assassin(before shipping). In my opinion it would be $5.00 well spent.
I calibrate my system with a RS SPL meter and re-did so whenever I switched subs.

Yikes,sorry for the long post.

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Old 26th January 2006, 03:31 PM   #5
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thats great info i really appreciate you giving me so much. I also didnt realize those Rythmik 250 Amps were so cheap. (is it worth getting the 5 dollar mod im not even sure what that does)

So in general an Assassin 12" with the Rythmik 250 Amp would be a good start combo and is the best enclosure the 85L?

Or is there a good solid design for a passive radiator that would work good for this? Are passive radiator sub boxs even worth the extra money? Or (lol or or or) would i be better suited with a ported design. I wasnt sure if a radiator would give me the tighter response i was looking for or not??

really appreciate the help and i kinda hope this first experiance will lead to more builds of more speakers. would like a pair of Dipoles for the rear speakers in my suround sound hmmmm.....
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Old 26th January 2006, 05:43 PM   #6
MarkR is offline MarkR  United States
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Well the rumble filter is there to help keep your sub from bottoming out. If you know how to solder you can always add it later there is directions on rythmik audios website on how to do it. I run mine without it and haven't had any problems. I would give Chad @ AA a call and ask if he recommends using one with the Assassin12.
As far as the "best" enclosure size that is some what up to you. I believe Chad recommends a 3.5 cu.ft. tuned to 20Hz. You could go bigger or smaller thats up to you and how much output you want. I have the driver Assassin 12 loaded into unibox at home I'll play around with it tonight and see what it looks like.
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Old 26th January 2006, 06:27 PM   #7
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So sounds like a good plan for the box how long and what diameter does the port tube have to be for somthing like this in a 3.5 cube box? 20hz is where id like to be for sure im just a little intimdated by the exact tunning that i dont completely understand. Oh and do you have to stuff the box at all with poly fill in a design like this?
Cant waite to start this project just want to have my ducks in a row so to speak.
Thanks for helpin a noob
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Old 26th January 2006, 11:13 PM   #8
MarkR is offline MarkR  United States
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bostonswoop,
You should give Chad a call and see if he has box plans. He provided me nice plans for the Atlas drivers.
He would be able to tell you port diameter and length also. I would assume he would say 1, 4" precision port. Unibox is showing a port length of 20.5" which is longer than the standard precision port(18"). The 3.5cu.ft. (99L) does look real good in unibox. Overexcusion isn't a issue until around 16Hz. It just goes over 16mm at that point. This may not even be a issue. I am sure Chad has tested the Assassin in this alignment. I can send you a email of how the box models if you would like. You can get a "idea" of the output, the software doesn't factor in room gain and other room specific issues.
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File Type: gif vb response assassin 12 99l.gif (19.9 KB, 197 views)
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Old 26th January 2006, 11:31 PM   #9
MarkR is offline MarkR  United States
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Here is the 3.0 cu.ft./85L with one 4" PP 18" long 23Hz. Still pretty nice and a little smaller. I have cabinet plans in a pdf if you want them. One that is 3.0cu.ft. and one that is 4.5cu.ft.According to the plans this would be a 20Hz tuning for the Atlas 12. You can see the smaller box has slightly less output below 20Hz. Which if Chad recommends a 20Hz rumble filter that wont matter much.
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File Type: gif vb response assassin 12.gif (20.0 KB, 191 views)
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Old 27th January 2006, 12:37 AM   #10
MarkR is offline MarkR  United States
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bostonswoop,
The descrepencies I have found shouldn't be anything to worry about. I started reading up on things on other forums. I found a post from a guy who I know has built way more subwoofers than I probably ever will. He said the tuning of the enclosure is more enclosure based than driver based. In other words if you have a 20Hz tuned canbinet it will remain a 20Hz tuned cabinet even if you switch out the driver.

Have you decided on a budget?

I think the Assassin 12,port,MDF and Amp will run you around $300.00
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