Will someone please explane this.

Discussion in 'Archived Threads 2001-2004' started by Joe Tilley, Oct 29, 2002.

  1. Joe Tilley

    Joe Tilley Supporting Actor

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    Ok I feel like a broken record asking this but I never really get any anwsers when I ask. I am at a loss with some of the different things here when it comes to tuning enclosures, TS parameters of a speaker & how they effect how it will perform, how room modes effect how everything sounds & what to do to fix them, ext ext.
    I just keep finding myself getting more confused with everything as I get more involved in this hobbie. I'm picking up on some things but yet some of you guys are way over my head with some of it & I know its probably real simple but I just dont understand it all. All I can ever find is pieces of the answer with a hole in the middle & I cant figure it out. I've always been the type that can build anything & just by dumb luck been able to make it sound good, but as I get more involved into this stuff I'm getting much more picky & wont to learn more than what I do know in hopes of making what may have sounded just good from dumb luck, to it just don't get any better from an educated decision.
    Anyway I would be grateful for any help that anyone can offer with any of these things. And if this is the appropriate place for this please feel free to move it where it belongs. Thanks Joe
     
  2. Joe, try this: List (ie. 1) 2) 3)) specific questions. List them all, or a few at a time. I personally find it easier to answer questions when they are listed..perhaps others are this way too.
    Here is something I started a while ago and never finished... but it may have some answers.
    http://www.hometheaterforum.com/htfo...threadid=93856
     
  3. ThomasW

    ThomasW Cinematographer

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    Unfortunately an internet forum is a poor substitute for an education. Online Q & A sessions often tend to create as much confusion as they eliminate.

    There is a science to speaker design. Learn the science (physics, mechanical and electrical engineering), then you'll understand the designs.

    If you really want to learn the who, what, when, where, why and how of loudspeaker design, start by picking up a copy of Vance Dickason's 'Loudspeaker Design Cookbook'.

    Follow that with 'The Master Handbook of Acoustics' by F. Alton Everest and you'll be good to go.
     
  4. Brandon_M_S

    Brandon_M_S Agent

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    wish i could help ya, but i don't know much about T/S specs either, i just go by trusted people's recomendations and what i've heard. and i aite gonna try to pawn you off on some book, kinda lame to do. [​IMG] i know how you feel, i'd like to know, but it seems the people who do know don't wanna take the time to explain it, and the only things you can learn from are from two people who know the stuff to each other about it, try to learn from that is nearly hopeless [​IMG]
    [​IMG]
    brandon
     
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  6. Travis G

    Travis G Stunt Coordinator

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    Joe,
    I know exactly how you feel. What helps me is every time I have a question, I go to half a dozen forums and ask the same question on all of them. The links sections of audio web pages are great places to find these forums. Chances are at that at least one person's reply will be phrased in a way that I'll have an epiphany.
    Here is a list of easy to understand books
    1. Advanced Speaker Systems by Ray Alden
    2. Designing Building and Testing Your Own Stereo Speakers by David B. Weems.
    3. Loudspeaker Design Cookbook by Vance Dickason
    4. High Performance Car Stereos by Joe Pettitt
    5. The Sound Reinforcement Handbook by Gary Davis, Ralph Jones
    6. The Master Handbook of Acoustics by F. Alton Everest
    There are other great books but in my experience some of the beginner books have some good information mixed in with some misinformation. I wouldn't take anything written by Consumer Reports to the bank. I would stear clear of AudioVideo101.Com and HowStuffWorks.Com as well. These sites are dumbed down and only somewhat accurate.
    I am currenty building a resource of info on the web at WWW.Angelfire.com/film/travis_gibby/primer.html
    Feedback is appreciated (It helps me make the page better.)
    Travis
     
  7. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I think it you should buy some audiophile books to really understand things. I might be able to give some brief definitions:

    Tuning: A ported enclosure boosts sound due to resonating air like when you blow into a coke bottle. Ports usually add additional SPL but it varies depending on the tuning. To find the right tuning you can first decide what kind of frequency response you want your speaker to produce.

    Room modes: These are room specific frequencies in the bass range that cause spikes and nulls throughout the room. It is the primary enemy to bass because it causes subwoofers to produce uneven response throughout the room. To fix the uneven response the invention of equalizers and acoustic treatments were invented.

    TS parameters: These are detailed specs for speaker drivers handy when designing enclosures for them. Most people type these numbers in programs such as winISD or LSPcad to predict how a speaker will sound.
     
  8. Brandon_M_S

    Brandon_M_S Agent

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  9. Travis G

    Travis G Stunt Coordinator

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    Brandon,

    I know books can be expensive and loudspeaker design is not a quick and easy hobby. But you know what they say... Nothing worthwile comes easy. The challenge half the fun.

    Maybe you should have your local library order some of the books I mentioned above. Not only will you get the information without the extra expense, but you will also be helping others in your local community learn about loudspeaker design.

    Travis
     
  10. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Joe, forums are really good for getting answers to specific questions, but learning how to design speakers, is, unfortunately full of the difficult, math-oriented electrical and acoustic engineering disciplines. As Tony and ThomasW are aluding to, there is a lot to it, especially crossover design. You really do have to do a lot of serious studying and experimenting to learn the subject.

    I don't think the experts here are avoiding answering questions, they just realize that a question like What are TS parameters? for example, would involve an overly long answer to give you the detail required to design speakers. If you asked a question like: "What is the general definition of the term T-S parameters?", then a short answer like Chris' above would be the obvious answer and suffice.

    I'm a newbie to speaker design and will buy the books ThomasW recommends when I can devote the time. For now, I follow the experts' advice and build known good design kits. Now if you have any cabinet building/veneering/finishing questions, I've done a little of that.

    p.s. That #1 book on Travis' list is the one sold by Radio Shack, I believe. I'll make you a deal. Buy it and read it. There is a LOT of info packed in that book. For now, you can skim over the heavy math formulas. The non-math part is very clear, well-written English that doesn't try to talk down to the reader. If you don't think that little paperback is worth the money, pass it on to someone else and I'll send you a money order for the price. Whaddya say?
     
  11. Kyle Richardson

    Kyle Richardson Screenwriter

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    I agree with the others in that books are the best way to get complete answers if you are serious about learning the hobby. If you just want some quick answers then try diysubwoofers.org
     
  12. Rory Buszka

    Rory Buszka Supporting Actor

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    One can even be guided through the entire process of designing a subwoofer by DIYSubwoofers.org's in-depth articles on sealed, ported, passive radiator, and other enclosure designs. My personal favorite is the Passive Radiator, though they're a bit more expensive than just a port.
     
  13. Joe Tilley

    Joe Tilley Supporting Actor

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    Thanks for all your responses guys. I have thought about getting a couple of the books mentioned here but I keep putting it aside not really wonting to spend the money. But I'm getting to the point where I would like to get into building crossovers & such so I think that will be my only option.
    The biggest things I'm trying to find out right now is how TS parameters come into play with how a speaker will perform. I see alot of people here saying that this speaker has a better Qts or Qms than that speaker so it would perform better but, what I don't know is what numbers are good & what is not so good. I realize that looking into it farther with a few good books is my best option but right now I just don't wont to spend the extra money quite yet so I'm looking to pick up on what I can for now. I know that sounds pretty cheap but I'm not quite ready to dive into everything I just would like to understand some of the more common aspects of it all.
    Thanks again for your help & any other advice anyone can offer.
     
  14. MichaelAngelo

    MichaelAngelo Stunt Coordinator

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    Joe,
    I think the reason that some of your questions are being answered by telling you to read certain books, is, because these individuals may have answered these questions before, and with each question asked, more questions arise. You ask about TS parameters. One of the "elders" may answer that for you, only to have a question, of the USE of the paras, or how they relate to say loudness or sound quality or freq response or enclosure choice or any of a thousand other things, in this time you Could have read the book, and then other questions, which haven't even occurred to you yet, will be answered. I plan to order those books,by Dickason and Everest.

    Good luck, and I hope this helps.
     
  15. ThomasW

    ThomasW Cinematographer

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  16. Todd Shore

    Todd Shore Stunt Coordinator

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    I think that newbies also get the impression that building a set of speakers is easy and will save them money. That may be true if all you are willing to do is assemble a kit or build a well documented design. Of course, you will still need to buy that soldering iron or some other tool you don't have.
    If you are wanting to design something of your own, though, you should be prepared to devote time and money to your new hobby because that is what it will be.
    You will need to purchase several books, read many forums and white papers, buy some tools, buy some drivers, buy some crossover components, buy some more crossover components because the ones you ordered last time weren't quite what you needed, and on and on and on.
    I started over a year ago on a quest to build a center channel speaker. I figured that since the center carried so much information in HT audio that would be where I would start. I purchased drivers, amps, active crossovers for educating my ears, books, etc. and built boxes and more boxes, experimented with passive crossovers... and I'm still in the prototype stage.
    I've built one kit and will soon build a pair of speakers for my brother using a design by someone highly regarded in DIY circles, and you know what?
    I'm still a newbie.
    I read this forum, Madisound, PE, and others daily. I follow links. I punch numbers into software, I download spreadsheets. If you check my post count you will notice it is very low. Why? Because I'm a newbie and it isn't the job of the people here to spoon feed me.
    Sorry if this sounds like a rant. It was intended more to let you know what you are in for if you continue down this sick, sick path.
    [​IMG]
     
  17. Travis G

    Travis G Stunt Coordinator

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    Joe,

    TS parameters are not a usefull way to know the quality of a speaker IMO. They can be an indicator, but nothing more. Mainly TS parameters can help you decide if a speaker is suitable for a particular situation, and to help you predict the way a speaker will perform in a given box. The best way to know if a speaker is a good one or not is to either talk to people who have used the same driver, or use it yourself and find out how it sounds. I know this isn't the answer that you wanted but unfortunatley there is a lot more factors involved in loudspeaker performance than just the TS parameters, such as the materials the cone, surround, former, dust cap and even the way the driver is built.

    Nevertheless you can still learn usefull information about a driver from it's TS parameters. So here is a quick run down of a few of them.

    Fs is the resonant frequency of a driver. In other words, the frequency that the driver likes to move at naturally. For subwoofers it should be below 35 Hz. For tweeters and midrange drivers, it should be at least an octave below the desired crossover frequency.

    Q can be though of a device's tendency to resonate. The device may be a loudspeaker or an electrical circuit.

    Qts is a drivers total tendency to resonate. A higher Qts means that the drivers motion will be less controlled in a given enclosure. This is heard as a loss in "tightness" of sounds like kick drums. However if Qts is too low, the driver will have little low frequency extension.

    Qes is the electrical Q of a driver. You can use this parameter to help determine what type of box is more suitable for a driver with the following formula.

    EBP (Efficency Bandwidth Product) = fs / Qes

    If EBP is less than 40 you should probably use the driver in a sealed box. If it's > 80 a vented box is probably better. If it's somewhere in the middle either type of enclosure may be used.

    Vas is a measurement of how compliant the drivers suspension is. In other words, how much give the driver has. Smaller numbers mean that the driver is a stiffer one. Vas is an indicator of the realative size of the enclosure needed for a given target response. Higher Vas means a larger enclosure. Vas is measured as a volume because air too has a certian amount of compliance to it. A larger body of air has more compliance and a smaller body of air is stiffer so it has less.

    Xmax is the distance the speaker's cone can move before the number of coil windings that are in the gap start to go down. When a speaker moves beyond Xmax, distortion increases and its motor force decreases. Speakers with a higher Xmax are best used in subwoofers. Closed enclosures generally require drivers with a higher Xmax.

    Sd is simply the cones surface area.

    Vd is the amound of air that a driver can displace before it moves beyond Xmax. (Sd * Xmax). Subwoofers need a higher Vd than other types of drivers. This is because every time you decrease the frequency one octave the amount of air that needs to be displaced increases by a factor of four.

    SPL 1W/1M is the sound level that can be produced with one watt of power, one meter from the drivers surface in without any help from room gain. Drivers with a higher sensitivity will need less power to reach a given sound level. However the trade off is either in larger enclosure or a reduction in low frequency extension (or both).

    There are other TS parameters but these are a few of the most important ones. The most usefull use of TS parameters is to plug them into box design formulas, but hopefully I have at least cleared up a few things for you.

    Travis
     
  18. Joe Tilley

    Joe Tilley Supporting Actor

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    Thanks again everyone.

    Todd, you said ( sorry if this sounds like a rant ) don't worry I know how it feels. I feel like I'm one of my annoying buddies that are always asking me about body work trying to get me to do it for them, so I think I know where your coming from.

    Travis, that was what I've been looking for on TS parameters all I kept finding was brief descriptions of things. What you posted explains it better than what I've found.

    I also went to DIYsubwoffers.org & had a look around there was a good amount of information there that helped to clear a few things up for me.

    And finally sorry if someone listed this & I didn't see it but' dose anyone know the cheapest place to get some of the books listed here. I've seen a few books in Parts Express from 17 to 30 dollars but I know there has to be better sources out there.
     

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