Homemade Speaker System: Need Help
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New member Username: GunmetalPost Number: 1 Registered: Mar-04 | I was needing some help finding the Cubic inches or feet needed to create a ceiling mounted speaker box that will hold: 4 tweeters, 4 mid range, 4 12" subs, and 2 12" passive radiator subs. the conceptual design is to use the speakers in a 360 degree patern, that will reverberate the sound off the walls evenly when centered in the middle of the ceiling... giving the surround sound effect. a few rough sketches, follow the link: http://www.angelfire.com/bug/gunmetal2/speakerdesign.JPG |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 13 Registered: Dec-03 | Box volume (Vb) is determined by the specifications of the lowest frequency driver in the grouping, in your case the woofers. The minimum specs you need are Qts, Fs, Vas and Re. A more accurate prediction can be made if you have Qes, Qms and Xmax, and the more measurements the better. |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 16 Registered: Dec-03 | Probably not the answer you were expecting. Was it? |
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New member Username: GunmetalPost Number: 2 Registered: Mar-04 | Nope actually, that is a highly complicated thing, im trying to beat it around the bush.. just some quick dimensioning would be great. your statement about the lowest frequency takes the measurement will probably help me though |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 20 Registered: Dec-03 | What drivers are you using? Have you thought about the crossover? |
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New member Username: GunmetalPost Number: 3 Registered: Mar-04 | it's 4 crossover's actually ;), which was going to bring me to another point... is it taboo or some sort if you put more than one crossover in one cabinet? another question: will two 12" woofers work well on one 12" passive radiator? if not, i'll just port it like none other |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 22 Registered: Dec-03 | You can have a crossover for each driver if you want. It depends on your goals. As a general rule of thumb, the passive radiator(s) must be able to displace roughly double the amount of air as your active driver. For example, this means that for a single 12" woofer, a single 15" radiator or two 12" passive radiators are recommended. You'll also want to isolate your midrange drivers. The back pressure from the woofers will cause problems for them. The tweeters are ok as almost all of them are built with their own back chamber. |
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New member Username: GunmetalPost Number: 4 Registered: Mar-04 | ok, thanks.. i had an alternative idea, this is for my room, ima stick it either on my ceiling, or put it under my bed with the woofers aiming at the floor, the passive subwoofer might have been not such a good thing, because i didnt have enough of them to do any good, so i will just stick with 4 12" subs and cap off into 2 different sections so they dont have interference when determining l/r sound and just port both in the back or front, with the mid and tweeters in the front, i'll see if i can draw up another picture if you are thoroughly confused |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 26 Registered: Dec-03 | This has been somewhat entertaining but I'd hate for anybody to get the wrong idea. You're going to spend a lot of time and money on this and get mediocre results. This isn't a car where you just put drivers in the door, a sub in a box, pick up pre-made crossovers, and away you go. Designing good home audio speakers requires gathering knowledge about Thiel/Small parameters, learning how to use modeling tools, measuring tools, and finally testing and making changes. A two-way crossover is a challenge. A three-way crossover is a mind-bender. If you're not willing to go through this lengthy process be prepared to be disappointed with the results. Either that or build from a kit. My first question, which was the most important one, remains unanswered. What drivers are you using? Second to that is what are the T/S parameters of the drivers? Without this information you're driving blindfolded. |
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New member Username: GunmetalPost Number: 5 Registered: Mar-04 | i have no problem with money, the speakers were given to me, hence the fact i didnt answer your question, because i have no clue what they are... dont be disappointed, im kinda at a loss to really understand the concept, and i thank you for your cooperation  they are three-way crossovers, 4 of them for that fact, i could take a long time in planing and adjusting settings to get perfect sound etc out of it, but i dont have much time on my hands, which is where your "alot of time" comes into play, so i will just make the best of what i have, and do the best that i can. the measurements for the maximum/ and or minimum size prefered for the box, and the port holes would be nice |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 27 Registered: Dec-03 | Is there a brand name and model number on the back of the woofers? |
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New member Username: GunmetalPost Number: 6 Registered: Mar-04 | that would be a negative, these are anonymous speakers in my posession, all i know is... i had them hooked up before and they sounded great, i just need to combine them into a single cabinet and hang it up on my wall to conserve space |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 28 Registered: Dec-03 | Sorry Josh. Without some basic measurements it's all trial and error. There are huge performance differences in drivers and I can't even venture a guess. Good luck. |
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Unregistered guest | Josh.....I think you'd do well to read the "loudspeaker cookbook" before starting this project. Fist off, all those drivers? Dude, your gonna create an amplifier NIGHTMARE! You'll have to wire them in series or series/parallel combo. Either way sucks. Any speaker wired in series is not seeing an ideal output impedence, but rather is being driven off the speakers output preceding it, which is constantly fluctuating in frequency and impedence. Also, your gonna have more phase shift in that crossover than your ears could tolerate. Not a good idea, in my humble opinion. Old chinese proverb: Keep it simple. |
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Chica Unregistered guest | I need to make a home made speaker for science class can any one help me on that how to get started becuase it needs to be almost like a regular speaker |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 63 Registered: Dec-03 | What are the project requirments? Is it single driver or mulitple driver? Is it supposed to have a crossover? I would think there are some guidelines to follow. |
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New member Username: MongoTucson, AZ USA Post Number: 8 Registered: Apr-04 | Designing loudspeaker enclosures for optimum performance is not simple. To really do it right, I recommend a graduate-level course in Electroacoustics taught by Dr. W. Marshall Leach at Georgia Tech: http://users.ece.gatech.edu/~mleach/ The textbook he wrote, Introduction to Electroacoustics and Audio Amplifier Design has a thorough treatment of the design methodology, but it is aimed at people who have a degree in Electrical Engineering. The essence of the enclosure design method is available in several files on Dr. Leach's web page, plus some "cookbook" plans. Also, there are a number of books on the subject in print (search Amazon.com). One of them might be more of a "cookbook" which you might find useful. |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 66 Registered: Dec-03 | Some of the best loudspeaker makers got their start through DIY projects. It's obviously a good thing to take courses and such and many have but it's not a requirement if you have the desire and a penchant toward math and science. The basic principles have been laid down for many years. I know several people that have designed very nice speakers, including myself, and not one of us has a graduate degree in Electroacoustics. I know one person that actually taught a class of fourth graders how to build an MTM loudspeaker from scratch based on the purchase of some very low priced drivers. There is so much information available on the subject it's staggering via the Internet, books, magazines and other publications. I'm not saying you can just slap a box together, throw some drivers and electronics in it and have a successful design but if you do your research and try your hand at a few designs in time it is possible to come up with something pretty good. |
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Unregistered guest | Let me tell the people in the white vans you better watch out because if i see one of yous i'm gonna beat the hell out of you. i am pissed.Please help me someone buy theses KV2500 ti speakers from me or i'll go crazy email me at Juicebox04@aol.com |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 68 Registered: Dec-03 | Are the white van people making DIY speakers now? |
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Silver Member Username: KeggerMICHIGAN Post Number: 221 Registered: Dec-03 | timn8ter i agree with you completely with enough research and desire you can build some dam nice speakers. it takes a little understanding of electronics/ good hand skills and soldering. if you can do that pretty well and gather enough information you can do a very good job. josh. i'm sorry without sitting down and playing with your project and not knowing anything about your drivers even someone who knew what they were doing it would take weaks to figure out a design. i hate to even put this out there but if you had to fly by the seat of your pants and guess, some kinda average specs for a single 12" driver even might be. sealed box size 1 to 2 cubic feet and a ported size of 1.5 to 2.5 cubic feet per driver. so using the average of those 1.5 sealed and 2 vented. multiplied by the number of 12" drvr's would try to give you a starting point. as many have said you are more than likely not going to be happy with the outcome but it seems you are hell bent on doing this. so there you have it. something to try. |
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Bronze Member Username: MongoTucson, AZ USA Post Number: 12 Registered: Apr-04 | Timn8tr, I agree with you about DIY speakers to some extent. Using the "cookbook" guides that are out there (even Dr. Leach has them on his web page), a reasonably handy person can build a speaker that will sound about as good as the drivers he puts in it. My point is that using store-bought drivers, once you have determined whether closed or vented box is best for the driver and what the optimum box volume is, the rest is a carpentry project, not an electroacoustic design project. After taking Dr. Leach's course in electroacoustics, I realized that the real design challenge is in the drivers themselves. Since my personal talents and desires led me away from electroacoustics, and not being very interested in carpentry, I chose to buy speakers already made. But I do agree that a DIY speaker can sound as good as a name-brand speaker at a much lower cost for the builder. Just beware of "Beranek's Law" (see the link on Dr. Leach's web page). |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 70 Registered: Dec-03 | That's why we like to have get togethers such as our NWWA DIY Audio Meet 2004. Our last outing had about 60 people in attendance. We have a chance to play our systems right next to other people's designs and get unbiased opinions from others. It's also important to remember that different people have different tastes. Were that not so there would be a standard "good" loudspeaker. If you don't like building things that's understandable. This is definitely a hobby for people that want to build things and also tear into things to see how they work. I realize this is not a DIY forum but if somebody asks I enjoy telling them about this wonderful hobby. |
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Bronze Member Username: Timn8terSeattle, WA USA Post Number: 71 Registered: Dec-03 | If anyone is interested here's the link to some pictures from our meet. http://www.alegriaaudio.com/pictures_from_nwwa_diy_audio_mee.htm |
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