Help me choose designs for my HT build

Discussion in 'DIY Speakers and Subwoofers' started by memmo, Nov 14, 2012.

  1. Hello folks,

    I stumbled upon the SEOS thread over on AVSforum the other day and have been reading about the projects since then. I've decided I'd like to try DIY speakers for a dedicated home theatre I'm about to start construction on partly because of budgetary concerns, but more because It would be a fun project for the winter.

    I'm overwhelmed at the sheer number of options and configurations available and would love to hear some opinions on options that may work for my project.

    A little background:

    Theatre dimensions: 14' x 22' x 7.5'
    Will have a 2 foot deep false wall for an AT screen - so LCR need to be placed behind that.
    Surrounds need to be conceal in columns that I'll build in the room -- I'm thinking they will be about 9-10 inches deep.

    Budget -- As this is an experiment, if I could keep speakers at or under $300 each I'd be delighted. I have access to a local cabinet maker who can cut MDF for cabinets inexpensively (assuming I provide them with CNC/CAD files).

    If I've left anything out, let me know... like I said, I'm excited at the possibilities, just overwhelmed at the options.


  2. I would recommend only putting the center being the screen, and instead placing the L and R in the corners toed in. By toing them in about 45 degrees (or in front of you so that you are about 22 degrees off-axis) you will get a much better sweet spot. Narrow directivity speakers like this inherently do not want to be shooting straight out the way more typical speakers do.

    For surrounds, I personally wouldn`t be looking at a SEOS build. I want very tight driver spacing as chances are the listeners are not sitting on the vertical axis of the design. The CBT line arrays are most optimal but most expensive. Large format coaxials are a great option but few designs exist. So I say, just go with the smallest you can go with - an omni of sorts. Make sure the crossover was optimized for near wall or in-wall placement though as lower midrange frequencies are augmented here.

    I imagine that can be done. As far as wood, I would stress having narrow spacing of braces more than anything else. Even 1/2" MDF can work if you've got a brace every 4 to 6 inches. I would use more MDF however for the baffle (the part of the speaker where the drivers are mounted) - usually around three layers of 1/2" or two layers of 1" MDF for example.

    Now as far as drivers go, I think the DNA-350 with the SEOS-12 are a very safe bet with your budget. Both will give world class high frequency reproduction above 1khz. As far as beyond that, I would stick to designs that are already established and voiced if I were you. Most good pro-sound 12" woofers will really realistically sound well and fine with a correct crossover. The most offensive issues in drivers tend to be the surround resonance (seen in the measurements often as a dip in response and a spike in impedance) and early cone breakup. Next up is a good motor design. Personally I look for ceramic magnets with flux shorting / demodulation rings, as that seems to be the least expensive way to get low distortion.

    As far as T/S Parameters, if i'm using a subwoofer, i don't really see the point in making things convoluted with a vent. So I do want something that, sealed, can have an F3 in the 70hz to 100hz as this is similar to THX spec.

    To my undestanding, One of the drivers that most intruiged me, the Eminence Definimax 4012HO, was used in a new SEOS design by Jeff Bagby. That could certainly be an option, although the design isn`t public yet.
  3. All great advice from GranteedEV
    the only thing I would add is if your new to this hobby and wanting to learn no matter what you decide to build, pick a proven design that others have built and posted that will help you along the way. There are many proven designs here to choose from that will work within your budget.I recently built a pair of seos12/DNA360/deltalite2512 right around $300 per speaker and I am very happy with them.
    Have fun,and good luck.
  4. Any suggestions on designs for LCR and for Surrounds?
  5. I think he's looking for outright suggestions and less interested in the technical details.

    Here's a shot at it. 3 of these for LCR

    As much as I agree with EV (I've preached this issue myself) I'd still go SEOS for surrounds for matching. Find a 10" kit that fits the rest of your budget.

    Also talk to Java. He's going through this exact process right now.

    If you're patient, more kits will come along soon.
  6. With the construction of my theater and other stuff going on, I don't have the time (nor interest) in going the trial and error route. I guess I'm not the traditional DIYer. I'm more interested in finding an established design for my LCRs and surrounds that I can purchase flat-packs and perhaps even finished cross overs for. In other words, I'd like to be an "assembly man".

    It appears the surrounds are the more tricky part as I'd like the finished cabinet size to be about 7.5-8 inches deep so I can conceal them in my columns.

    I do have friends who could help me with the building the cross overs and I do have access to a local CNC shop that has experience building speaker cabinets so if CNC/CAD plans were available, that is also an alternative.
  7. I think everyone's on the same page. We want you to do an established design, and you want to do an established design.

    All it really comes down to then, are the following:

    - A SEOS-12 / DNA-350 is a good starting point.
    - How do the woofers sound? I can only tell how they will measure. I would suggest a 12" woofer to narrow things down.
    - How do everyone's crossover voicings sound? I'm sure they all sound great and it would come down to personal preference.

    The reason I didn't post any specific design earlier was because the ones i've seen so far all look fantastic. You'll see plenty of SEOS-12 designs right here:

    I can't decide for you because your own personal criteria might lead you in different directions. I think Bill's Eminence 2512 design is a really safe bet. Personally, as I stated earlier, if I were in your position, I'd be waiting for Erich to get out Jeff's 4012HO design. In my own position.. i'm just screwed with this endless wait on AE drivers.
  8. Yah, I've been hearing about this new design. I suppose it is a matter of weeks from release?

    Could I use an SEOS 8 for the surrounds to save on depth?
  9. I would suggest doing some more research.

    My humble HT setup serves double duty for music. So what I would do is decide will I play music or concerts through this system? They have some really awesome blurays coming out like Satchurated. It is a 3D bluray of a concert in 7.1 sound! If you are going to listen to music what do you listen too? Do you like to bang your head to Metallica or groove out to Dr. Dre? If classical is your thing reply back and let us know. You can get a lot of great recommendations if we know what your tastes are.

    Also here is a list of projects. As you can see when you click on the link that the list goes on and on. Let us know what your tastes are and we can help you narrow it down. ;D
  10. I would say the room will be 80% movies. I do have a subscription to the Berlin Philharmonic's Digital Concert Hall and also would enjoy watching some concerts on Bluray in surround.

    I have a separate room for my 2 channel setup (Harbeth SHL5), and would love it if the theater would perform well when playing back concert material.
  11. Well here are some links to some cool projects:

    This has flat packs available from DIYsoundgroup:

    This one has a kit available from Meniscus Audio:

    This is a HT that just might serve your needs:
    The swopes are also avalable in a three way tower at: for 200.00 a piece for parts. I hear the swopes are pretty killer.

    These would be the bomb if money was no object:

    All the speakers above would come into your budget accept for the statements. Hopefully this helps.

  12. Great smaller options (except for the statements)!

    But if the room will be mainly movies, memmo has to tell us if movies will be viewed at or near reference level, and what amplification will be used to drive these speakers.

    If you are going to watch at or near reference, you will need high sensitivity speakers with ~100W or statements driven with over 400W each. Overcoming an 87dB sensitivity will take a lot of power, and result in thermal compression arriving sooner than expected, SPL-wise.

    If watching movies at 13dB below reference or below with AVR power, the lower sensitivity options are great and have better WAF.

  13. I'm aiming for as close to reference levels as possible. I'm hoping to power everything with a few Bryston 4B ST amps I have sitting around.
  14. Then you need not bother with any design below 92-93dB sensitivity, with 95+ being the target. Reference level with low distortion and compression is not easy to achieve. Asking an 87dB speaker to do it is just the wrong way to approach the problem, IMO, unless you will be sitting only a meter away, then 100W will get you there with 2dB of headroom. Otherwise, for every doubling of distance above 1 meter, you are looking at a 4x power need for each speaker. That adds up quickly. 400W for 2 meters, 1600W for 4 meters.

    Before the naysayers shoot the argument into pieces, yes, I do realize speakers indoors get boundary and pressure vessel gain, but with the dips that accompany small room response, and the attempts of auto EQ to correct them, these power figures are, on average, accurate, if your speaker can handle them.

    People who say they play their systems with 85-87dB speakers and AVR power at reference simply do not understand what undistorted sound is all about, as their AVR clips away.....


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