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I Need A Summer Project


derrickdj1

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I have wanted to build a sub for some time and thought about building a IB sub or a single or dual box sub with the FTW 21 in; driver from the company that makes the ULX 18 driver. The HT is in the basement an I have a storage room, furnace room and a couple of closets for the IB. Parts Express has some IB drivers .http://www.parts-express.com/dayton-audio-ib385-8-15-infinite-baffle-subwoofer--295-455 Here is a link to the 21 in. driver to do a single or dual box sub. It can also be use for IB. http://www.istonline.ca/mach5_ftw_21.html

To even consider the IB, I need some ideals on design, tools neede, and to be certain that I understand the concept of sealing off the two sides of the sub. Or is regular sub build a better I deal since this is my first time. I don't want to start a project that will take me forever. I have never built anything more complex than a simple deck bench. I may have to find some good help.

Edited by derrickdj1
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Thanks. Take a look at those drivers from Parts Express. I don't know if they are worth considering. I will be keep my other subs so the new sub will not be doing all the work.http://www.parts-express.com/dayton-audio-ib385-8-15-infinite-baffle-subwoofer--295-455

I like the 21 in driver except it is out of stock.

Edited by derrickdj1
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Dang Derrick, you made me bust out my calculator.

Bass in an IB is all about moving air. You want the most economical way to do that. The driver you linked has a surface area of 819cc and an xmax of 14.3 mm. that give you 1.1 L of displacement. At a purchace price of $99.00 it costs you roughly $83.00 per liter of displacement. my favorite driver is the Ficaraudio IB315 18" driver. It has a surface area of 1210cc's and an x-max of 30mm for a displacement of 3.63 L per driver. At $274.00 per driver it costs you $75.48 per liter.

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I FUBAR'd but just slightly. To figure displacement, you'd need to double the above numbers. X-max is one way. It doesn't change the results though. Cost per liter would be halved. That's what I get for being in a hurry.

Edited by CECAA850
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not gonna lie, that 99" 15 inch driver is probably a freakin joke compared to the 620$ 21" driver. derrick ill tell you right now, if you are gonna spend your time to do something either make it worth your while or dont spend near as much money. maybe a small sub to go with your 2 channel setup? or if your gonna do an ib, make it worth your while cause it aint gonna be easy.

what's your budget? maybe you can spring for 2 of the 24" si drivers? lol you would be on a whole new level then.

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The guy from Canada called from the company that makee the ULX 18 driver. I will get the FTW 21 in. drivers. They will be custom built with a vas of 0.4 and weigh 65 lbs.

Features
Parameters
76mm IST PS Series low distortion voice coil

Fs (Hz)

21.3

Cast aluminum basket

Re (Ohms)

3.2

Low distortion motor with demodulating rings

Qes

0.40

Internal stray flux shielding

Qms

8.76

Heavy Craft pressed pulp cone

Qts

0.38

Extra wide heavy foam surround for high excursion

Cms (mm/N)

0.136

Conex spiders with double woven tinsel leads

Rms (kg/s)

6.24

Large spring loaded connectors

Mms (grams)

409

1200 watts RMS power handling

BL

20.92

Excellent for home theater

VAS (L)

521

34mm Xmax excursion for maximum output

Sd (cm^2)

1640.3

Lp (2.83v/1m)

96.9

Dimensions

Suggested Box Sizes

Outside Diameter - 54.3cm

Sealed - 170L (6cu. ft.)

Mounting Diameter - 50.9cm

Bass Reflex - 283L (10cu. ft.) 24Hz

Mounting Depth - 26.4cm

EBS - 700L (25cu. ft.) 17Hz tune

Infinite Baffle - *

These drivers have an Xmas of 33 and should be equal to 2 1/2 ULX 18 driver. Tomorrow I will talk to a guy that can do the carpenter work. I told the wife that this will cause more things in the house to vibrate and she said OK. Later in the afternoon she got me to buy her some new patio/deck furniture. I think I got jacked, lol.

Edited by derrickdj1
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I Need A Summer Project

I got some post holes to be dug.

This would be a time for Carl to explain how to properly dig post holes.

threadjack/ How many? Seriously, I built a fence last year and this was the worst part. Even with a good auger it sucked - of course a lot of the was plot of land our house sits on. /threadjack

Back to subs.

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This is still my project. I will start with two of the FTW 21 drivers and wall mount in line array and not use a maniflold I think at this point. Location of the subs will be, 1.) in a storage room or 2.) the furnance/water heater room.. Each of these areas is at least 10X 10X9 ft. This should be 10X the vas of 521. or very close to it.

Questions:

1. Can I run my current subs and IB with a little work ( I know there will be phase issues, I don't think Identical sub would be any easier since all

the subs are in asymmetical locations in the room and I am ok in dealing with this aspect)

2. The basement has a drop ceiling, will that be a problem

3. Room #1-Furnance room,sub in rear of HT so one Chase sub near mains to blend with the mains

4. Room #2-Storage space is 25 ft in front of the mains (current sub are widely spaced out)

Edited by derrickdj1
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A drop ceiling is definitely a problem with an IB. The tiles will end up flopping around.

I wouldn't run an IB with conventional subs. Phase issues can be overcome but you'll never match the output of the 2 different subs over their entire frequency range.

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