My DIY System - Best Bang for the Buck!!!!!

Discussion in 'Archived Threads 2001-2004' started by Chris Carswell, Oct 12, 2002.

  1. Chris Carswell

    Chris Carswell Supporting Actor

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    Hello all. I just finished a temporary web page with some of my latest creations. Bear with me. It is under heavy construction but it will cleaned up and updated later with more tips and all build pics. You can see them here:
    http://plaza.ufl.edu/cdoggy81/DIYstryke.html
    http://plaza.ufl.edu/cdoggy81/hometheater.html
    I will say for the $money$ I don't think you will find a better speaker. So far I am very impressed with the sound.
    Cost for 1 MTM center $50
    Cost for 2 MTM towers $100
    Cost for 2 TM surrounds $50
    For a little over $250 you can have a complete 5 speaker system [​IMG]
     
  2. Shawn Solar

    Shawn Solar Supporting Actor

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    hmm... I like it! [​IMG]
     
  3. Chris Carswell

    Chris Carswell Supporting Actor

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    Thanks Shawn [​IMG]
    Tim, YGM back - other plans included.
    Sorry to all who have dial up. It is a little slow with the pics the way they are. When I finish cleaning it all up I will have thumbnails and links to larger pics.
     
  4. John E Janowitz

    John E Janowitz Second Unit

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    Hi Chris,
    Glad to hear these worked out well for you. FYI, I'm working on new designs now. I'm doing a full 7 channel speaker system with them. They will use a TMM tower design for the 2 fronts, and standard 2 ways for the surrounds. The center channel design will be like this:
    [​IMG]
    The woofers will be closer together though with the tweeter a little higher. This gives a much better dispersion pattern than a horizontal MTM for a center channel.
    In addition, I may also be doing an upgraded system that uses the same design as the center channel for all 7 speakers.
    The subwoofer for this system will be a Thunder12.3 cabinet using the AV12 woofer. I'll be starting a thread to talk about this soon.
    As far as your designs go, couple things to look at. First, placement of tweeters. To minimize the diffraction issues, you'll want to use a 1.41 ratio for the offset. Distance from tweeter center to one side of the cabinet will be 1.41 x the distance to the other side. Distance from the short side will be 1.41 x the distance from the tweeter center to the top. The distance from the top of course doesn't apply with an MTM design.
    Next, also regarding diffraction effects is the edge radius on the front baffles. With the offsets shown, use a 3/4" radius on the edge closest to the tweeter. The other side, use a 1/2" radius. On the top, you don't need any radius, but can use 1/4" if you like.
    Using this offset ratio, along with the different radiuses as shown will keep variations due to diffraction down to about +/-.25dB. This is a very acceptable level. If you wanted, you could increase the edge radius and this would pull down the variations to even lower levels. IMO, this is a very acceptable level though and nothing more needs to be done.
    John
     
  5. Neil Joseph

    Neil Joseph Lead Actor

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    Real Name:
    Neil Joseph
    That's one bitchin' centre channel.

    I like the rack on your site byt he way Chris.
     
  6. Chris Carswell

    Chris Carswell Supporting Actor

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    Thanks John for the info. Cool center as well. I liked the one you showed me a long time ago with the 12" PR (IIRC)!!! That was neat. Way to get that F3 down hahahah.
    2 questions for you:
    1st - Why do you prefer the TMM over the MTM or what do "you" feel are the benefits to this type design.
    2nd - Round over vs Chamfer the edges. Looks like your center used a 5/8" 45° or 1" 30° (can't tell) as apposed to the standard 3/4 round over. Enlighten me [​IMG]
    P.S. Why didn't you tell me you & Mark were in cahoots with a new design :wink: . I take it Marks new MTM/Your new TMM xover should be a little sharper since it will be tested out more & tweaked with your Clio??? Are you using the same basic xover for your TMM as the MTM +/- a bit for size, baffle, etc.??? How does the current one I'm using (check my site) look compared to what you & Mark are coming up with so far?
    P.S.S. Are you designing the surrounds? Have you talked with Steve for an updated TM 2-way? He CC'ed you a copy of our emails & should be getting back to me with something soon as well. From our conversations he has been spending a lot of time on these & the results are well worth it. The xover will be a bit more complicated / costly but that's the nature of "this" game. [​IMG]
    This all should be fun as it already is [​IMG] [​IMG] [​IMG]
    -Chris
    Oh ya, almost forgot :b . Thanks for the rack plug Neil. I appreciate it. BTY, which one did you like? The Kappa/home base one or ????
     
  7. John E Janowitz

    John E Janowitz Second Unit

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    Chris,

    Mark isn't working on anything now. If you notice, that thread was from June 23rd 2001, and someone just did a new post to it. The plans he worked on then are the ones that I sent to you. or at least i think i sent it to you.....

    I prefer the TMM over MTM just because it has beter vertical dispersion. I like to be able to stand up and have the sound not change that much.

    Round over is much better than chamfer. The center is done that way for appearance only. If I would have thought about it more, I proably would have rounded it. I like the chamfer look more though.

    I will be doing a whole new design for the TMM's, center channel, and the 2 way surrounds since they will use slightly different baffles sizes than the previous stuff. Also the baffle will take care of the diffraction issues so I'll have better data to work with. I'll take a look at Steve's Xover too. He said he'll be sending it sometime. Hopefully I can put one together soon also.

    In the meantime, i just finished an Xover for a line using 6 of the SA071's and 4 RTW2's. This is sort of a half line that doesn't go floor to ceiling. It still sounds pretty good though. I will have response graphs, and Xover to post for this shortly.

    John
     
  8. Chris Carswell

    Chris Carswell Supporting Actor

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    John:
    :b Wow, didn't even notice the date :b
    At least I got the chamfer part right.
    What size baffles will you be using, < 9" or > 9" ?
    Cool line array!!! Did you see the guy who did one with 12 SA071's? IIRC it was painted silver. I can't find the link now but will look for it.
    I can see you have been very active these past few days, specially on the boards. I certainly hope with all the recent activity along with these new speaker designs & exposure, there will be a large upward shift in your revenue curve. You & your well designed products deserve it [​IMG]
     
  9. John E Janowitz

    John E Janowitz Second Unit

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    Hi Chris,
    I will be using the 9" wide baffles, but apparent baffle width seems a little less when you round the edges. I just want to redo everything to make sure I get it all done properly.
    I did see the line with the 12 woofers. It looked very nice. I'm also working on my own here. It's a dipole baffle.
    [​IMG]
    It shouldn't be too much different now than working on the line with 6 drivers and 4 tweeters. I actually used the same baffle for that and just unhooked the top and bottom woofers and ribbons.
    The response is a little bumpy, but this was not time gated properly to eliminate reflections. This also means that this is about the response you will get in room. The response is also only smoothed slightly, 1/12 octave. Other than the bump at 200Hz, response is about +/-4.5dB. For an in room response curve, this is very good. Phase is also coherent at the Xover frequency. Inverting tweeter phase gives a 30dB dip.
    [​IMG]
    I think some of this will get a little smoother when a full line of 7" drivers and ribbons are used to eliminate some other reflection issues.
    The crossover is a 4th order at 3Khz. I used inexpensive components. It should be about $30 for a pair of Xovers. There are not many comb filtering effects at all. The only thing i noticed is that between the ribbons, response is pretty good out to 20Khz. At the center of the ribbons, there is a very narrow dip of about 10dB at 11khz. This is not easily audible because it is so narrow. All I can guess so far is that it is due to the ribbon spacing, and length of the ribbons. I plan to look into that more yet.
    All in all, these sound VERY good. The repsonse curve doesn't show it properly, but this array has good output down to 30Hz in the dipole baffle. In a sealed or vented box, you could easily achieve flat in room response to under 30hz.
    John
     
  10. Chris Carswell

    Chris Carswell Supporting Actor

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    [​IMG] Very Cool [​IMG] I'm sure it does sound very good. How did you do the big curve for the right side?
    Do you remember what tweeters that guy used or have his web site?
    Any updates on a TMM or MTM using the same speakers, SA071 & RTW2 ? If not, looks like this is going to be it:
    woofer ckt:
    ---- 0.9mH ---- + ---- +
    |
    10uf
    |
    0.1mH
    |
    --------------- - ---- -
    tweeter:
    ---- 7uF ---- 2ohm ---- +
    |
    20uF
    |
    0.5mH
    |
    ------------------------ -
    [​IMG]
    I found the pics of that center with the 12" PR. Well I guess it isn't really a center after all. Just a nice size stand mount MTM with dual 12'PR's & an F3 of 35Hz!!! Not bad at all. [​IMG] I guess if one wanted to have a center ch that played low they could build this since you couldn't fit a long enough port inside a small center ch box. Move the tweeter up & the woofers in a bit. Just an idea [​IMG] [​IMG]
     
  11. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Nice Chris, looks like you spent some time on those diagrams.
    I've been looking to design a 2 way for my car and those drivers might fit the bill. The problem is I don't know how many HT drivers can endure through temperature and vibration abuse.
    DIY audio is so intriguing, I can't wait till I have the time to begin researching line arrays and horn designs. I can hardly imagine what kind of speakers I'll have ten years from now when I'm 30. [​IMG]
    Where are you getting all those pictures of speakers from BTW?
     
  12. Chris Carswell

    Chris Carswell Supporting Actor

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    Hi Chris,
    Thanks for the complement. I spent more time playing with Unibox/WinISD, changing pics, & re-adjusting diagrams than I did actually building these bad boys.
    I too would worry about HT drivers in a Car. I still worry about my SVS, but I think it will be fine (I hope).
    DIY audio is great! I love it but it is like a disease. I can't get rid of it. I wake up in the night thinking about a new design or I'll hear constant sounds of the table saw ripping MDF [​IMG] .
    As for the pics it's all stuff that's been built. I know people......they only work at night.....muuuhahahaha [​IMG]
     
  13. Jeremy Hopkins

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    Chris, nice system!
    I agree, DIY is a disease. Its very addictive..... too addictive sometimes.....damn I wish I had time to finish my speakers....and space to put them in.....that box full of speaker parts on my floor is so lonely *sniff [​IMG]
    [​IMG]
    Cheers,
    Jeremy
     
  14. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Wow nice speakers around here.

    Im still researching for start building my own, but today Im a bit sad. I got (from a friend to test) a nice set of bookshelfs, they are DIY, the cabinet is extremely stiff and seems acoustically dead, they sport a Vifa woofer (5 1/2) an Vifa 1 inch dome tweeter. I don't know the exact models because I don't want to open the box (I tried, but apparently they are glued or something), after all, I will have them only for a week or so.

    Anyway. Im extremely disappointed. They sound good, comparable to some Polk's and B&W I have listened to. But or I am to accustomed to the sound of Horns (my main speakers are Klipsch Heresy's) or the sound of dome tweeters and cone mids doesn't make me smile.

    Talking about soundstage and imaging they blow away my ol' Heresy's, but talking about dynamic range, percussivity, accuracy for brass instruments or piano, and clarity in general the "magic" is simply not there.

    Can this be a flaw of the design? Im a newbie about speaker design (in case you didn't noted) :b
     
  15. John E Janowitz

    John E Janowitz Second Unit

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    Manuel,

    Vifa makes several 1" tweeters. The D27TG05 is the cheapest and is non-chambered, and has no bulge on the faceplate. It is a decent tweeter, but nothing spectacular. The 1" SATW1 that Chris used in the designs above is nearly identical. The other Vifa D27TG35 is a much better tweeter. The chamber on back gives it a lower Fs, and it overall sounds much smoother.

    With proper design, even the less expensive tweeters can sound very good. What you are hearing is probably one of two things, flaw in the design, or just your preference to horns.

    John
     
  16. Chris Carswell

    Chris Carswell Supporting Actor

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    Jeremy,
    What speakers are you working on?

    Manuel,
    Sorry to hear your friends DIY speakers aren't that great. Like what John said, the key lies in with proper design. You can have the most expensive drivers but with a bad xover & cabinet it won't sound as good as a cheaper drivers in a proper design. What kits/drivers are you looking to build?
     
  17. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    John,

    The tweeter appear to be D25AG-35-06, but Im not sure, the picture i found is not high resolution. You mention a "proper design" what is that, exactly?. To my ears the tweeter is louder than the mid woofer. But I measured the FR using an RTA software and the SPL Meter and it seems pretty flat. Still the sound is harsh and tinny, so to speak. Could this be related to poor crossover design?

    Chris,

    I was looking for some bookshelf's, but Im rather disappointed by my friend's speakers. They do have advantages over my Heresy's, like an impressive soundstage and better imaging. But the tonal caracteristics are lacking IMO. This can be because I have been accustomed to Horns, or perhaps a flaw in the design, but I don't know where is the flaw. The cabinet is really stiff and I doubt it adds any color, besides part of the soundstage capabilities are because of its stiffness. Does the crossover can produce tonal differences? or make a driver to sound louder (relatively speaking) than the other? What about "group delay"? "phase"? and other oscure (to me!) variables?
     
  18. Jeremy Hopkins

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    I'm working on a 3-way system using all Seas drivers. They are the 25TAC/D, P17REX, and P21REX. This is my first project, and its a big one for a fist try. Luckily I got the crossovers designed by someone else: http://home.hetnet.nl/~geenius/index.html
    Thanks Tony!!!!
    That made things a little easier. I'm just insanely busy right now so I don't have time to finish them. Plus I don't have much room cause of my currently small room. That will change over christmas when I move into the basement. I'm going to try and get the top halves done in the next three weeks. They are pretty much a cheap Watt/Puppy look-a-like. The top enclosures were hell to build, my dad almost slapped me when I showed him the design. But we pulled through. Now all thats left is to cut the driver holes and bulild the crossovers.
    I will post a website about them when I get something done.
    Cheers,
    Jeremy
     
  19. John E Janowitz

    John E Janowitz Second Unit

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    Manuel,

    Many of those tweeters sound much better if you use a zobel in the crossover. In woofers this is used to eq the impedance rise with frequency. In tweeters it's typically used to combat harshness.

    In any case, it could easily be an issue with the crossover. Just about any drivers can be made to sound good with a proper crossover. A poor crossover can make even the best drivers sound horrible.

    John
     
  20. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    John

    Understood. Are there any directions, parameters or rules to make a good crossover? Some hints or Internet sites with info will be appreciated.
     

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