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Loudspeakers speaker building

Discussion in 'Sound, Music, and Intercom' started by bestboy, Jan 3, 2009.

  1. bestboy

    bestboy Member

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    Hey im looking into building my own speakers. When my dad was my age he started to build some for his guitar (dimensions 4 foot tall 2 foot wide 1 foot deep) and im thinking I could just use those. I want to use them for my DJ business and keep them versatile by being able to use them as the lows and or mids.

    First off, are the dimensions good enough to get the best quality sound out of them or should I build new cabinets that resemble more of a dual 15 speaker? I was thinking of putting 2 12" lows and a 12" mid speaker in each.

    Also is there any easy way to wire the 3 speakers up so it equals 4 ohms? Or should I go for smaller speakers and fit 4 of them in the cabinet and wire them together by parallel and series?

    Im open to anything...
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    It really comes down to the exact speaker you want to put in the cabs. Speakers cabinets have just as much of an affect on the final sound coming out of the unit as the speaker itself does. Different speakers require different styles of cabinets. The size of the baffle board, how much breathing space the speaker has, and how you pack the cabinet all affect the sound. You need to pick the speakers first, then you can worry about putting in a crossover and what dimensions the cab should be.
     
  3. avkid

    avkid Not a New User Fight Leukemia

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    What kind of a shop do you have access to?

    You should definitely consider getting professionally made plans, such as those B&C suggests or Bill Fitmaurice's designs.
     
  4. museav

    museav CBMod CB Mods Departed Member

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    Just a couple of thoughts...

    Cabinets built for guitar usually make poor PA cabinets and vice versa. Each has very different goals.

    Building your own speakers can be great learning experience, fun and personally rewarding. However, it is usually not a way to reduce cost. It is difficult to get the same quality components and construction as any major manufacturer without spending at least as much as you would for one of their equivalent boxes.

    I believe you need to first decide what you want from the speakers. That can be output, response, coverage, size, weight and many other factors. That will then drive the size, type and general design. Let the requirements drive the design rather than the design drive the results.

    Since you mentioned DJ use, are you going to use these alone or in conjunction with subwoofers? That can also affect what you may want and I would say that unless they have to run without subs that most people are moving towards more compact mains and separate subs, that keeps the weight and size of the individual boxes more reasonable and gives more options for placing and mounting the mains.

    I'm not quite clear on the comments regarding using them as lows and/or mids. What do you mean by that? What would you use them with in order to get full range? What do you have as far as speaker processing?

    I am a little concern that your questions regarding using two 12" drivers for lows and one 12" for mids with series/parallel wiring of all three shows some lack of understanding of speaker design, for example the apparent lack of any crossover or filtering. If that is a valid assumption then Phil is absolutely right that you might be better to use a proven design and components rather than just winging it.
     
  5. bestboy

    bestboy Member

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    What I want most out of these speakers is output, I want to be able to fill a gym filled with around 700 kids in it as well as a whole football sized area to do any outdoor large venues. My business has also done sound for a few bands. My school last year hired us to do sound for our end of the year carnival where our guitar club plays outdoors. the main system was my 2 peaveys as well as another 15" off-brand speaker. it sounded horrible and it looked weird.

    Well what I have right now is a mixture of two systems. I have 2 mackie 350 powered speakers and a 15" mackie powered sub. I use that system for basically most of my gigs. Then I also have a pair of 15" peavey cabinets that we use in our church to power those I have a 1400 watt mackie amp.

    I just purchased a peavey 3 way stereo/ 4-5 way mono crossover. Now with this I am planning on using the mackie 350s for my high end. The peavey cabinets for my mids and then run the sub with the speakers im building. But when I am unable to get the peavey cabinets due to church events and or other gigs when my buddy takes them out I want to run the 350s as high, speakers to be as mids and then run the sub for the lows.

    And yes I am quite new to this all. Im only a junior in high school. I figure before I buy/do anything I do a bit of research to better understand everything.

    Sorry if I left any information that needs to be mentioned. However I think I covered the basics.

    thanks
     
  6. waynehoskins

    waynehoskins Active Member

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    These days mids and highs are usually in the same box (called tops or mid-highs), often a two- or sometimes three-way box with a high-frequency horn, a front-loaded woofer for its bottom range (low mids, sometimes up to mids), and in a three-way box a horn-loaded midrange driver. These generally are used to reproduce 100 Hz and up, give or take.

    They'll be augmented with subs to cover the bottom octave, sometimes (almost) two.

    Separate midrange and high-frequency cabinets are less common than they used to be.

    Constructing a loudspeaker is probably a good exercise in construction and design, but it's probably not a good solution for something that you want to use to make money. Certainly not Revision A.

    One of my favorite racks-and-stacks rigs is EV T252s over MTL-1Xs. The MTL-1s are discontinued a year and a half or more now, and probably the T series as well; the QRx series is its most direct replacement. LA325s over LA400s is nice too, as are KF650s over LA400s or SB650s (pretty sure that's valid; SB850 is).

    For large outdoor gigs, you're way way out of your league. To do an outdoor gig well, you need line arrays, typically 9 boxes a side, over as many super super subs a side as you can. Vertec, M3D, Vdosc are popular. And even with 8 subs a side, the bottom end drops off tremendously a couple hundred feet out. I did a small outdoor gig the other month where we used two double-18s a side with plenty power, and only one top .. and it worked surprisingly well, but the bottom end was gone between 50 and 100 feet out.

    Indoors is much easier: put together a rig of two or three tops a side and two or three subs a side, and you'll be good to go. Most of the time you'll be pushing the subs, if not the whole rig, pretty hard.
     
  7. avkid

    avkid Not a New User Fight Leukemia

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    You've entered into dangerous territory.
    Mix and match is acceptable and the candy store, but not with loudspeakers.

    Here's my idea.
    Sell the 350's and buy some used 450's along with an additional Mackie sub of the same model that you currently have.

    If you have some $$ to spend the Mackie powered enclosures get better as you go up in price.
     
  8. museav

    museav CBMod CB Mods Departed Member

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    Which of these requirements go together? A system that can handle a rock band in a gym may work as a basic PA system for a football field sized area but not for a rock band for the larger area. Nor is a system that will support music over the larger area necessarily a cost effective or practical solution for smaller venues. I don't know what the options are in your area, but if it is practical you might want to start looking closely at what others in the area provide for the various situations and what you seem to feel works or doesn't work, that might provide you some better idea of what you want to do.

    You might also want to participate here, PSW Sound Reinforcement Forums: LAB Lounge, this is a forum specifically for the situations and applications that you note. Just hearing what others do and what others think is appropriate for situations like those noted may be very helpful.


    I have to admit that this sort of left my head spinning, especially since you initially mentioned "I was thinking of putting 2 12" lows and a 12" mid speaker in each" and now you say those would apparently be used as subwoofers. Two-way (high/low) or three-way (high/mid/low) systems are usually related to specific drivers or dedicated cabinets designed just for that purpose covering each band, for example a speaker may have a 15" LF driver, 8" MF driver and a compression driver on a horn for HF with either an internal passive crossover or an external crossover dividing the signal to the appropriate drivers. As Wayne and Phil noted, going multi-way with essentially random full range boxes with internal crossovers and a subwoofer of unknown performance can easily lead to the result being much less than the sum of the parts.

    I remember being very disappointed with the first speaker I built. Although I did some research in advance, I had no real understanding of matching drivers or matching the crossover to the drivers or of good cabinet construction or of many other factors. I spent a lot of money on components and pieces only to have an overall result that was very disappointing. I learned from that, it made me go and figure out where I went wrong, but I was not really counting on that speaker to be anything other than a learning experience. If you are counting on the speaker to be usable for rental situations then you cannot really afford a similar experience.
     
  9. mixmaster

    mixmaster Active Member

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    I think this sounds like a great project. It seems like you need to do some research first though, because you're not just talking about speaker building (as in woodworking) but system design at both the system and component level.
    Here's a couple thoughts:
    A 4/12 cabinet makes a good guitar rig. As a portable SR rig, it'll suck. using 12s as subs only works well with some of the more advanced designs, think folded horns. That's computer program design stuff. with four of them in a box you'd be looking at a baby version of the old EV MT4 rig or something. If you're going to go that route, 4 single 12 scoops may be a more flexible approach. With 4 12s as mids you're going to need a lot subs to keep up with them, or you will be turning them way back so they don't overpower your existing sub, which becomes a waste of the drivers and a lot of extra weight to carry around. I worked for a guy who had 12s as low mid drivers in a homebrew system and it sounded good but each 12 was in a box with 2 horns and an 8, I'm not sure 4 12s in a single box would play well together. Off the top of my head, it seems like there could be some potential for some interference between the drivers.
    A four ohm load on a single cabinet is too low of a goal IMO. If you are thinking outdoor gigs, you'll be hooking a lot of cabinets up. If you design 4 Ohm cabs, and you put two on an amp channel, you're already at a 2 Ohm load. That's as low as any amp I've worked with will go. For that matter, most entry level amps will only go to 4 Ohms. If yours amps only go to 4 Ohms, and you build multiple 4 ohm speakers, how are you going to power them? I'd look at an 8 ohm speaker at least.
    How are your woodworking skills? Do you have access to your schools shop and shop teacher? This would have been a great Woods 1 project when I was in high school. To do it right, I would suggest you would need access to a table saw for cutting side panels, chop saw for cutting interior support members, hand drill, router, and an assortment of finishing tools. Good fasteners and wood glue is a must. Soldering gun, shrink tube for the electronics. Sturdy handle and casters hardware. Speaker cabs are subject to a lot of abuse and vibration, you'll want to overbuild everything.
    As for matching speakers to enclosures, this is the most important part of the design after you figure out what you want the speakers to do. Google Thiele-Small Parameters. The T/S parameters are the measurements that get used to match boxes with drivers and include things like box volume, excursion distance and a host of other things. If you don't put the right speaker in the right enclosure, at best things will sound like crap, at worst you can ruin speakers. I did that once. I put a pair of 12s in a home built box with no regard to box volume. Things sounded good for about 6 months. Then the speakers slowly got quieter and quieter until they stopped a together. Turns out the weren't designed to be used in a sealed box of less than 1 cubic foot. I wish I knew then what I know now.
    I did learn a lot from that experience, and a few others since. Mostly I appreciate what speaker designers and manufactures go through.
    Go for it, have fun
    Matt
     

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