Ht Sub

Discussion in 'Home Theater Projects' started by BenLev, Feb 27, 2006.

  1. BenLev

    BenLev Agent

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    Someone reccommended that I ask about the HT sub I choose to use. First off this is what I have/am getting.

    What I have so far for my sub.
    HT SUB

    My other stuff I Bought Already.
    Amp for sub
    TV

    Stuff I will buy
    Speakers (2 of them)

    I do have an older kenwood surround sound system that I might hook up for now. Not sure of the specs. I just know it has 5 100 watt speakers. So for now I will use those speakers. They may even be better than the ones I am going to build. I am mostly doing it for the learning experiance.

    Let me know what you think of everything and feel free to comment. I am really starting to get into this HT stuff.
     
  2. Brent_S

    Brent_S Second Unit

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    Ok, I'll bite.

    First off, I'd be a little suspicious of that driver. WinISD says a lot of its T/S parameters don't add up. By stripping them down to just the basics, I was finally able to get WinISD to at least accept it.

    The SI, if the basic T/S parameters are accurate, models some fairly impressive output from 25hz up in a 2.5 ft^3 @ 25hz box. However, the PE DVC12 ($110), RS12-HiFI ($130), Titanic 12 Mk3 ($160) have output within 3-4db of the SI ($499) from 25-50 hz and 1-2db more output at 20hz. The lowly DVC12 actually equals the SI in output from 50-100hz, if you want a sub to go that high. All three PE drivers need less power to produce their max SPL as well. You could use two of any of the PE drivers to get more output capability than the single SI and still save anywhere from $100-$280 on drivers alone.

    Step up to something like the $130 DVC15 and you exceed the output of the SI across the spectrum and still need less power.

    I haven't bothered to model OAudio, Soundsplinter, AE, or Ascend's drivers, but I'm sure they'd show similar performance/price advantages.

    If it's not too late, I'd get a refund and go with a proven home oriented driver. Use the savings to improve other parts of your home theater.


    wbs
     
  3. BenLev

    BenLev Agent

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    Well I am pobably going to end up putting the mag in my car. 2 of the 12's actually. It is just in my HT for now. What do you think of the Adire HT drivers. I was thinking of getting a 15" tumult in the near future. In case you don't know you can find all the specs you need on it here.

    Tumult

    It is mainly a HT sub so I am thinking it will be better than the mag 12 which is made for car audio.

    Let me know what you think.
     
  4. BenLev

    BenLev Agent

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    Also, you said the output at 20 Hz wasn't that great with the setup I gave you on the mag. I think part of that is due to the fact that I want to be able to play music too on my HT, so I didn't want to tune the box that low. Let me know if that is why it isn't getting a huge amount of output at 20hz.

    Thanks.
     
  5. Brent_S

    Brent_S Second Unit

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    Can you explain this theory that more output at 20hz is somehow bad for music reproduction?

    I think you need to start at the beginning and define your performance goals and overall budget. Right now, you're asking about some of the most expensive subwoofer drivers available to the DIY market and matching them with what sounds like a HTiB. For the price of your sub amp and potential drivers, you could have an SVS Plus series sub, no cabinet building required. Yes, you have the potential for a little more output with a high dollar DIY, but unless you have a cavernous room or a "deaf wish", you'll never hear the difference.


    wbs
     
  6. BenLev

    BenLev Agent

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    I was just told tuning a box to 20hz wouldn't sound that great when music was played on that sub. That is what the person making my box told me. By all means let me know if that is untrue.

    Money isn't much of a problem. I mean I don't want to be spending thousands, but any sub in between the $300-700 price range is fine. Also, I would like to only buy subs from either Adire, or SI. SI I will most likely only use for car audio. I just decided to try out their sub in a home application for now. I will most likely switch to the tumult soon and put the Mag in my car. Also, I prefer going the DYI route since it will probably give me more output and is just a lot more fun to put together than buying everything made already. Where is the fun is just paying money?

    Also, I have another questions. You had the specs on the mag and you told me about what it could do. How accurate is that? I always heard that you can look at specs but they only tell you so much, and that you have to actually hear the sub to know how good it really is. I was just a little confused about that. Or were you just using that program to give me a rough estimate of what you think the mag would be able to do.

    Thanks for all the help so far. I wish this forum was a little more active though.
     
  7. Brent_S

    Brent_S Second Unit

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    There's nothing magical about the tuning frequency and the quality of music reproduction. You choose the tuning frequency to get the desired frequency response and power handling from a given driver. Most ported designs' output drops off rapidly below the tuning frequency. So, in the case of the SI, if you tune to 25hz, you get more output at 25hz, but give up output below that. And quite a bit happens in modern soundtracks below 20hz. Ideally, you want to get into the teens, if you can.

    You seem to be putting an inordinate amount of money into the sub at the expense of the rest of your HT. An analogy would be putting a Civic's tires on a Corvette, or dropping the Corvette's motor into the Civic. Each car is a sum of decisions made when choosing its individual components to reach a design goal. Swapping engines or tires between designs would drastically compromise performance relative to the overall goal for each vehicle.

    You're not seeing much activity on your questions, because frankly, your approach probably doesn't make sense to a lot of people. Why buy a $600 driver to use with a HTiB type system? Your goal seems to be the biggest, baddest subwoofer you can buy, without regards to an overall system design.

    The simulation s/w is usually as good as the data given to it. Which is why I made the point about the SI's T/S parameters not adding up. For the record, WinISD wasn't real happy with the new Tumult either. The free programs like WinISD don't take into account distortion and harmonics, which could make one driver sound different than another at the same frequency and SPL.

    Just for fun, I loaded up the numbers for the Tumult 15d2 (the only model actually shipping, it appears). For simulation purposes, I picked about the biggest box that *most* people would be willing to live with in a typical decor...6.5 ft^3 tuned to 20hz. You can go bigger and get more output in the 20-30hz range and/or tune lower to get more output below 20hz.

    Tumult 15d2, series vc 6.5 @ 20:
    maxSPL: 15hz/105db, 20hz/115.5db , 30hz/117.8db
    power needed for maxSPL = 1000 watts

    DVC15 parallel coils 6.5 @ 20hz:
    maxSPL: 15hz/99.4, 20hz/111.8db, 30hz/114.3db
    power needed for maxSPL = 600 watts

    The Tumult maintains about a 4db advantage if you continue to increase both box sizes. Probably, the Tumult will have a distortion advantage when both drivers are approaching max output. Is the difference worth $470+?

    All of those numbers are without any room gain. Figure 5-10db more below 30hz for a typical room. The DVC15 as modelled, will probably be a better compliment to room gain by being -5.7db @ 20hz. The Tumult at -1.5db @ 20hz and actually +.7db/30hz is likely to sound bloated and bass heavy with room gain. Solved by building a bigger box and/or tuning lower...which have tradeoffs of their own.

    For a point of reference, my "show off" volume registers about 105db peaks at the seats with the THX intro on SW3. Typical listening level probably puts peaks down in the mid to upper 90s. I haven't had anyone yet say it wasn't loud enough.

    wbs
     
  8. BenLev

    BenLev Agent

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    That was an impressive response. The problem is I get these subs vertually free and I don't have a place to get speakers from. That is why it seems as if I am just going bass crazy. Thanks for all your help with the sub reviews. I have a lot to learn before I will be able to get a great sounding system.
     

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