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A/V surround-speaker questions

Discussion in 'Hardware' started by Zogthetroll, 31 Oct 2004.

  1. Zogthetroll

    Zogthetroll New Member

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    alright, *dusts off keyboard* been a while since i've posted here last. my next project that i'm planning is to build a set of surround speakers. in planning the design i keep trying to finalize it, but seem to be generating more questions than answers. so i figured i'd ask around here since i knew bit-tech had an AV section. first off, i'm planning on 5.1 eventually. i'll do the sub later since that's a decent chunk of change and i want to do the surrounds at one time (same make of speakers and all that) btw, read zap's sound sticky already, good writing. so for starters, the four surrounds and and center channel. been looking through the part's express site for a while now, and i think i want to go with the morel mdt20 tweeters and peerless 5" woofers. most people seem to agree that 6.5" woofers are good for bookshelf systems, but i figure for surrounds i don't need that much. (wrt peerless, i've heard good and bad things from people, some say they're crap, other swear by them. is this like a Intel vs. AMD thing that i don't want to even start with, or should I know something about peerless before i go any further?)
    ok, speaker configuration, i've seen a number of high-end systems with D'Amato (sp?) type front left and right speakers (vertical MTM, dual woofer boxes) which supposedly form a better listening area (how does that work? I like the idea) also, wiring for those since i'm going to have to do it for the center channel anyway, i thought the impedance for the speakers was supposed to match (wiring in series or parallel would give 16 or 4 Ohm for two 8Ohm speakers, right?) so how do those fit in to the overall system (also, what does that to do power handling)?
    more about wiring, wrt power I understand RMS and peak, (most recievers in a price range i could look at without laughing uncontrollably tend to hit 100, or if they're higher-end, 110 watts RMS per channel) so do i guage the power handling of my speakers off the weakest link, for example, the woofer can take 150 and the tweeter, 120 so the speakers are good for 120 watts or does the crossover wiring do strange things to that? basically, i want speakers that can handle 110 watts per channel rms.
    more on wiring, can anyone recommend some good books on speaker and crossover design? i've read some by Vance Dickason (don't feel like reading any more of his overillustrated guides on how to use his expensive design software to come up with perfect speakers), and the library isn't very usefull since they have a very slim collection of books on building simple bookshelf speakers. I just finished "Great Sound Stereo Loudspeaker Guide" by Weems which I thought was pretty good and was considering buying it for the software but the book got ripped apart on the amazon reviews, so yet again, i'm confused. any good freeware design software out their for crossovers? the other book i was considering was "Bullock on Boxes". please help, i really want to learn, and i hope these aren't seen as stupid questions or anything, i'm just having a hard time finding answers. thanks.
     
  2. igotid24

    igotid24 New Member

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    well, I personally can't answer many of those questions myself....but you may want to do some searching over in the DIY section of the Head-fi.com forums, the site mostly has to do with headphones and such, but still a decent amount of discussion over speakers. from the quick search I did I found a couple of decent looking links that could help you out, but theres just a ton of info over there...

    http://home.earthlink.net/~etunstal/diy.htm
    http://www.speakerbuilder.net/web_files/default.htm

    oh wow, this one might keep you busy for a while...
    http://www.diyaudio.com/forums/forumdisplay.php?forumid=6
     
  3. Zogthetroll

    Zogthetroll New Member

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    thanks for the reply, speaker-building forums are good also. :) another question that i forgot about earlier. L-pads, I get the basics of what they're for, evening out the sound between the woofer and the tweeter (basically to make up for the difference in SPL's, right?) but can i realistically expect to design the system without them? obviously a correctly sized resistor could be used since they're basically oversized pots, but can they be theoretically designed close enough so that any diferences can be made up for with the graphic equalizer? or is it more complex than that? thanks again for the help.
     
  4. Cougar4

    Cougar4 New Member

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    I think it is great you are trying to learn about speaker building. It's fun to do.

    As far as your question about power handling you need to understand that most of the music power is in the lower frequencies. The crossover's job is to match the impedences of the speakers to a common input, filter the frequencies to the proper drivers and balance the levels. A low frequency driver may be able to handle 100 watts for example. The midrange/tweeter for the speaker will only have to handle around 20 to 25 watts of the total power as a guess. Some power will be lost in the crossover circuit so you might have a speaker that would be safely rated for around 110 watts. You should be able to find a off the shelf crossovers from Parts Express or build your own from their parts.

    The efficiency of a speaker can make a big difference in loudness. Using horns in the design will mean you will need less power to drive the speaker. Some box designs require a lot of power but tend to be more accurate in sound.

    There are a lot ways to go about building a nice set of speakers. I would say that anything you try will sound decent. I wouldn't worry about what other people say about David Weems book or Peerless drivers. I wouldn't hesitate to try out a design from his book if you want to try it. I don't think there is a more contested area for different opinions than in audio. There are a lot of "experts" out there who believe they have the best and if you have something different they may look at you strangely. I think the speakers you build will sound great if you just take reasonable care in building them. Just doing a project like this will be rewarding from the things you learn.

    If I were to get back into this I think I would go with a dual subwoofer-satellite design since I like the sound so well. Big sound, little boxes, well the satellites anyways. Have fun with the project.

    Edit:
    As for external equalizers, they are normally used to make up for frequency problems in the room environment, not for deficiencies in the speakers. The tone controls in the amp should take care of any small speaker problems. Hopefully the speakers are designed so that their output is pretty flat across the audio spectrum range. Just my opinion anyways.
     
    Last edited: 1 Nov 2004

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