dcmo Posted April 14, 2008 Share Posted April 14, 2008 RSW15 but for some time I have wanted a sub which could dig down deep (my basement is 25 X 20). I thirsted after the JL F13 but at 3000 was out of my reach. Then I saw the Epic Conquest, but 1600 (plus shipping) is still too much for me. I've never built a sub or any other speakers before ( I have always been good at building things though), but have reached the conclusion this is the route I have to go to get what I want. I've got maybe 800 to spend total on everything, and am not sure what kind of driver or amp I need to get to reach the lower ends I desire. I would like it to be very musical, but outstanding with the movie side of things also (power on the bottom end). Am I looking at 18" drivers or 21"s? What kind of power does the amp need to have? If 18's which drivers would fall into the overall range of building the sub at the specified cost? Which amps fall into this range? Just what goes inside the cabinets? I've looked at some designs on the web, with much more research to do. Could you give me a rough breakdown (or more extensive if you like) of what goes into making a sub, from beginning to end. What are some good websites which goes into these things? I have been to diysubwoofers.org, will be going back again. I could go a little higher on cost, I want a high quality sub (doesn't have to be the best) and am not willing to build something subpar. I want to thank you all ahead of time for your help, couldn't do this without people like you. Quote Link to comment Share on other sites More sharing options...
TheEAR Posted April 14, 2008 Share Posted April 14, 2008 Quick one since I am at work and busy.... For around $800 you need to spend the money the wise way. Here the Berhinger EP2500 power amp will be a solid start ~$350 online. You should reserve $100-150 for cabinet materials,conectors and speakers wire(10GA). You should be left with a solid $300-350 In this price range the upcoming Exodus Maelstrom-X 18" will outdisplace anything on the market under $500! And it goes for $299 plus shipping!!! With a bridged EP2500 into an 4Ohm load driving a Maelstrom-X in a vented cabinet tuned to ~15Hz you have a MONSTER for ~$800 or less!!! Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 14, 2008 Share Posted April 14, 2008 To expand on TheEar's post, the Behringer EP 2500 is a cheap and powerful amp, tested independantly to produce ( with stable line voltage however ) 633 wpc into 4 ohm in a stereo configuration. It will do 1336 watts into a single 8 ohm load. ( in bridged mono configuration ) If you have sagging AC service ( which you will ) figure 1-1.1 kw in 8 ohm bridged configuration. It uses a class H ( multiple power rail ) supply with a conventional torroidial transformer. You might want to consider first off that you must open up the amp and swap the fan for a quieter one, as the stock one has been compared to an airplane taking off.... LOL.. easy to do modification. Google it, and you will find many options. You will also need adapters from RCA to 1/4" mono phone plugs. Obviously if you want a lot of output, a large driver ( or multiples thereof ) is needed. I have not modeled the Malestrom-X yet so I can't speculate on it's performance. You may also want to consider a pair of the CSS SDX -15 drivers ( low distortion linear XBL^2 motor ) with low power compression, 30 mm linear stroke one way on the motor with 40 mm xmech. A large diameter spider and 3" VC round out this top quality unit. Other features are NBR rubber surround ( instead of foam ) and a very nice strong cone. Low inductance make it easy to blend even with bookshelves, as it goes quite high in frequency. These were tested in Finland by a fellow by the name of illka on the Home Theater Shack. He also tested a bunch of popular commercial offerings as well. This would put you over the $ 800 mark in amp and drivers alone, without materials. Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 15, 2008 Author Share Posted April 15, 2008 Basic question. What does this sign mean ^ Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 15, 2008 Share Posted April 15, 2008 It is a symbol to represent the squared function.... it was / is a trademark of Adire Audio ( defunct now ) but they still designed all the parts for the SDX 15 woofer. The voice coil and motor has a linear stroke of 30 mm before the motor strength falls off. Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 16, 2008 Author Share Posted April 16, 2008 First I would like to thank you and ear for your responses. Hopefully you don't get too tired of answering questions, some of which will be totally basic for you. Is there a website I could go to that would break down terms into layman answers. Anyway I have a few more questions for now. 1) VB. The formula I found for the Maelstrom was VB = 20 * QTS ^ 3.3 * VAS. Would this be correct QTS = .36 VAS = 324L VB = 20 * (.36 * .36 * .36 * .108) * 324 VB = 20 * .00503855 * 324 VB = 32.65 2) How do you convert foot size to litres. 3) What is a resonance frequency? What does it mean when it says in free air it peaks at this freq. 4) What is "Q"? 5) What is BL? Thanks again. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted April 16, 2008 Share Posted April 16, 2008 http://en.wikipedia.org/wiki/Thiele/Small Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 16, 2008 Author Share Posted April 16, 2008 On the Berhinger EP2500 ; I though this would be mounted insided of the cabinet but I'm not sure how that will happen. I purchased this today (ships on the 25th) and then looked at the photo in more detail tonight. What I noticed was the volume controls and the power on switch are on one side, with the rest on the back side. Am I wrong in thinking that this is mounted in the sub cabinet, or is this going to be external to the cabinet with the driver connections coming thru the back of the cabinet. Thanks again. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 17, 2008 Share Posted April 17, 2008 With the Behringer EP 2500, it is a stand alone amplifier IE: not designed to be mounted inside a subwoofer. It is a 19" rack mount product like all pro audio devices. You would usually ( in a home ) put it upon a shelf or in a closet of sorts. The driver connections would be through the cabinet, correct. Most all AVR's ( audio / video receiver ) will output enough voltage to drive the inputs of the pro-amp without the need to resort to an impedance matching device such as the ART cleanbox. ( which also features an undesireable high pass filter, but can be modified ) If you own a Pioneer AVR, they are known to have low outputs in the pre-amp sections. Can you give us a bit more detail about your system? If you have an un-used closet or space that you could turn into an infinite baffle set-up this might be your best option. Otherwise, stick to a conventional design subwoofer. Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 17, 2008 Author Share Posted April 17, 2008 I do have a Pioneer; a VSX53TX (elite) which I'm using as a pre-amp. For amplification I am using a Gemstone Blue Diamond. Speakers include RF-7's, RC-7, RS-7's, D9's, and a RSW15. The sub will be placed by a rear wall behind seating positions. With the wires feeding thru the back of the sub cabinet I presume I will have to seal the two holes where they come thru, if so what would be the best thing to do this. Thanks for all your help Michael. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 18, 2008 Share Posted April 18, 2008 Most people use some sort of connector plate or raw binding posts through the box. You might find that having a sub behind the listening position to be noticeable, as there is not a brick wall type of filter ( IE some higher frequencies that you can determine the origin of ) but they will be down in level compared to the low bass. If you face the driver against a wall this will also act as a bit of a low pass filter to reduce the possibility of localization. You may need a device in-line to boost up the voltage or you will not get all the power out of the amp that you are paying for. The Pioneer's have known low output. The ART cleanbox is a popular device, but as stock it has a filter in it that will be detrimental to the performance of your sub. Good thing is that switching out a few capacitors can change this, and they are inexpensive. You do need a good soldering iron and some practice soldering. ( an old circuit board is the best for this ) Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 18, 2008 Share Posted April 18, 2008 As a side note do you have a y-connector to hook up both of the inputs on the sub? If not you are not getting enough voltage into the RSW-15. You might want to run to a store and grab an RCA y-connector ( few bucks ) and give it a whirl. It would need to have 2 male and one female RCA plugs on it. Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 18, 2008 Author Share Posted April 18, 2008 It's pretty late here, but since you are on here can you look at this for me and tell me where I'm going wrong. It's got to be wrong and is bugging the heck out of me. I've looked around but haven't been able to find someone that actually broke down the forumla. QTS = .36 VAS = 324L VB = 20 * QTS ^ 3.3 * VAS. VB = 20 * (.36 * .36 * .36 * .108) * 324 VB = 20 * .00503855 * 324 VB = 32.65 I just don't see how this could be right. With a little over 28L equaling 1 cubic foot it doesn't leave enough room for the driver. Where am I messing this up? I do have a y-cable but haven't had it hooked up to the sub for a while. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 18, 2008 Share Posted April 18, 2008 I would use a freeware box modeling tool such as Unibox for MS excel or WinISD ( linearteam ) for Windows. Google them and give them a shot. I am pretty sure that Kevin Haskins ( Exodus Audio ) has the pre-production parameters up for the Maelstrom X on the AVS forum. With WinISD, you must follow the instructions in the Help tab to enter in your own drivers. ( the maelstrom x will not be in the database ) It does not accept data that is slightly off at all. It is pretty straight forward to learn when you read up on the help section, plus there is other information of interest as well. The Maelstrom x will not require huge boxes to work well, as it has a strong motor. Pre-production parameters...: Pre-Production Parameters Fs: 17.7 Hz Le: 0.87mH Re: 3.1 Ohms (Voice Coils wired in parallel) Qms: 7.8 Qes: .38 Qts: 0.36 Mms: 494g Cms: 0.17 mm/N Vas: 324L Sd: 1182 cm^2 Vd: 7.8L BL: 21.17 X-max: 33mm X-mech: 42mm Pmax: 1500W dual voice coils... wired in parallel. Quote Link to comment Share on other sites More sharing options...
TheEAR Posted April 18, 2008 Share Posted April 18, 2008 I have a pair of the Maelstrom-X on pre order. [] Plus FaceAudio amps... Ready to roll....ROLL. Now I cannot be stopped...sub woofer wise I have the power. When my subs are completed and electrician adds the four circuits to those I have now in each room...INCREDIBLE. 30AMP times three and an extra 20AMP...all for sub amps and future JL f212. [] Bring on the most impressive bass , this audio hobby is a dangerous drug...dangerously great. The Maelstrom-X will be a bruiser of a sub driver. Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 19, 2008 Author Share Posted April 19, 2008 I've been running over the vb numbers and the one I came up with in WINISD was 222.5. Are these numbers set in stone? I ask because the program let me adjust the box size and I came up with output I liked even better with a vb of 327.9. At 33hz they are pretty equal but the vb of 222.5 is down 3-4 db for most of the rest (compared to 327) of the way until they meet again at 10hz. The 222.5 graph line is more consistently curved (from 30hz on down) with the 327.9 having less curve at 15hz but becoming more pronounced after that. Can I make this sub with a vb of 327, is it recommended. Thanks. Quote Link to comment Share on other sites More sharing options...
homemadeheresy Posted April 19, 2008 Share Posted April 19, 2008 I'm not a subwoofer fan, but have run across this set-up that sounds like it would be a good one. Let me know what ya think http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-764 Seems like it would move quite a bit of air !!!!!! Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 19, 2008 Share Posted April 19, 2008 Nothing is set in stone, as long as the driver does not exceed Xmax in your alignment with the amount of power you are throwing at it, it should be just fine. Are you modelling a sealed box or a vented box? Quote Link to comment Share on other sites More sharing options...
dcmo Posted April 20, 2008 Author Share Posted April 20, 2008 It is going to be vented. The winisd program wouldn't allow that to happen, would it? The driver is the Maelstrom (which will ship on the 9th) (Xmax is 33) and I went ahead and got the Berhinger EP2500. Quote Link to comment Share on other sites More sharing options...
TheEAR Posted April 20, 2008 Share Posted April 20, 2008 Maelstrom-X and EP2500...great combo! Win Win situation here,the Maelstrom-X works great in sealed and ported. Quote Link to comment Share on other sites More sharing options...
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