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  1. #1
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    DIY speaker build. Kexodusc?

    I know Kexodusc isn't the only DIYer here so i'm dedicating a thread to this project. I own a pair of close to full range 4" drivers (not much going on beyond 10KHz) and am thinking (well have pretty much decided) to build an enclosure for them. They are Tang-Band W4-616S
    I'm thinking ported, around 10L (0.3 cubic feet), tuned around 60Hz or so. I bought some damping stuff to fill the inside as i'm guessing it will help with standing waves etc...

    Now, I wanted to know a couple things:
    1. What's the golden ratio for speaker cabinets? I hear this minimises standing waves.
    2. What sort of dimensions should I be looking at for the front baffle and where should I place the driver on the baffle for optimal results?
    3. Is there such a thing as a cabinet that is too rigide?
    4. I'm thinking of using thick (3/4" MDF) to avoid the need to use bracing for this fairly compact bookshelf. Considering the small cone, I'm guessing there shouldn't be too much cabinet flex. Am I correct in this assumption?
    5. I'm thinking rear firing slot port (very easy). Is this ok? Or should I mount it on the front baffle close to the driver?
    6. Is there anything i'm missing?

    The loudspeaker cookbook is on my Christmas wish list but i want to do these before then. This is why I need your advise

    Let me know what you think ASAP. Thanks!
    ps. I'm not fussed if they don't turn out 100 percent perfect, it shouldn't be an expensive project.

  2. #2
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    Quote Originally Posted by audio amateur
    I know Kexodusc isn't the only DIYer here so i'm dedicating a thread to this project. I own a pair of close to full range 4" drivers (not much going on beyond 10KHz) and am thinking (well have pretty much decided) to build an enclosure for them. They are Tang-Band W4-616S
    I'm thinking ported, around 10L (0.3 cubic feet), tuned around 60Hz or so. I bought some damping stuff to fill the inside as i'm guessing it will help with standing waves etc...

    Now, I wanted to know a couple things:
    1. What's the golden ratio for speaker cabinets? I hear this minimises standing waves.
    2. What sort of dimensions should I be looking at for the front baffle and where should I place the driver on the baffle for optimal results?
    3. Is there such a thing as a cabinet that is too rigide?
    4. I'm thinking of using thick (3/4" MDF) to avoid the need to use bracing for this fairly compact bookshelf. Considering the small cone, I'm guessing there shouldn't be too much cabinet flex. Am I correct in this assumption?
    5. I'm thinking rear firing slot port (very easy). Is this ok? Or should I mount it on the front baffle close to the driver?
    6. Is there anything i'm missing?

    The loudspeaker cookbook is on my Christmas wish list but i want to do these before then. This is why I need your advise

    Let me know what you think ASAP. Thanks!
    ps. I'm not fussed if they don't turn out 100 percent perfect, it shouldn't be an expensive project.
    AA, I don't have Thiel Small parameters for that driver, so I can't guess size. 10L sounds we bit big to me just guessing blind, but it's quite possible that driver could easily handle that size.
    As for golden ratios, there's a lot of them, and a lot of people have come to accept that your in room acoustic issues are going to dominate internal cabinet resonances, so you can be a bit flexible here. You can also use damping material to cover for some of those problems, so it's not 100% necessary to follow any "golden ratios"...but if you can, why not? You don't want a perfect cube. And you don't want any 2 dimensions the same, or multiples of each other...once you figure out the size, you can google some ratios and pick some dimensions from there.

    3/4" MDF is fine. Remember to calculate internal volume. For a 4" driver, you can probably easily get away with 5/8" MDF too if the cabinet is built well. I've never heard a cabinet too rigid, I'm sure some people will subjectively hear speakers and attribute cabinet density, or material to sound. I don't dispute those claims, but I'd rather an overly rigid cabinet than one that is resonating and coloring the sound. At that size of cabinet, with that material, you don't have to worry. A 4" driver isn't going to give 3/4" MDF any problem. There's a lot of $1000-$1500 speakers with multiple woofers that don't have cabinets made out of material as strong as 3/4" MDF. They seem to do fine.

    I prefer rear ports unless the speaker is close to the wall or a cabinet by necessity. Not that front ports introduce any sound issues per se, I just fine building and fitting everything inside to be a lot easier with the ports in the back. Just me.

  3. #3
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    Thanks a lot Kex, quick and helpful as always.
    The numbers I gave don't mean much, i may change them. Regarding this actually, i used WinISD alpha to model the speaker, but this only shows the sub 500Hz response. Is this program ok to work with for this application? Is there anything I should be aware of when determining cabinet size/tuning etc? Also, does the EBP say anything about full range drivers or does it only work for subwoofer drivers? (EBP if you don't know determines if the driver works better with a sealed or ported cabinet).
    Lastly, can you say anything about placement of the driver on the baffle (middle top bottom side etc..)?

  4. #4
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    Quote Originally Posted by audio amateur
    Thanks a lot Kex, quick and helpful as always.
    The numbers I gave don't mean much, i may change them. Regarding this actually, i used WinISD alpha to model the speaker, but this only shows the sub 500Hz response. Is this program ok to work with for this application? Is there anything I should be aware of when determining cabinet size/tuning etc? Also, does the EBP say anything about full range drivers or does it only work for subwoofer drivers? (EBP if you don't know determines if the driver works better with a sealed or ported cabinet).
    Lastly, can you say anything about placement of the driver on the baffle (middle top bottom side etc..)?
    I've only ever made 2 speakers with full range drivers, and both times I used a filter to tame the response a bit. I don't know how this one will do. WinISD isn't a program I've used. It sounds like it'll model the bass response and a bit more.

    If you had the T/S parameters we could determine ported vs sealed. Does Tang Band have them on their site? Do they recommend a specific enclosure?

    I would avoid putting the driver in a place on the front of the baffle that has the 4 edges the closest in distance from the driver center...but if you don't build the front baffle perfectly square (speakers are usually rectangular) you'll be ok.

  5. #5
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    Cool, thanks. I didn't want to bother you with T/S specs but if you want to/have time to have a look here they are:
    http://www.parts-express.com/pdf/264-818.pdf

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    As far as filters go, I really want to keep this simple so for the moment no filters. I hear fullrange drivers tend to have exagerated HF response with no filtering?
    Last edited by audio amateur; 12-21-2009 at 03:01 AM.

  7. #7
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    Ok, I crunched a few numbers really quick. You definitley want a ported design. A 10L cabinet is going to be too big.

    Better off to go with something in 3-5 L size. I like 3.5L my self but that's me. 5/8" or 1/2 MDF is fine, could use 3/4" MDF for the front baffle though. You can experiment with tuning, but these are going to sound better with a sub, no question, to fill out the bottom 2 octaves.

    I don't know about exaggerated HF response in full-range drivers. Most I've seen roll off firecely the final octave (which is not a big deal at all) but have ragged response in the 2-5K range which can be annoying. Some roll off too much. I don't think there's a hard rule of thumb really.

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    Any particular reason you'd go with 3-5L? Why is 10L too big?

    I'm aware they will need a sub. They'll be part of the HT

  9. #9
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    Quote Originally Posted by audio amateur
    Any particular reason you'd go with 3-5L? Why is 10L too big?

    I'm aware they will need a sub. They'll be part of the HT
    Your low frequency extension would be better in a 10L box, but only in that you'd hit a lower note around 60-70 Hz (because there'll be a peak near the resonace frequency of the system). Problems is, for a significant range of bass/midbass above that low end response, you risk a thinner sound - a slight dip from 100Hz and 200 Hz or so. That will sound like mid bass is missing compared to the midrange and bass. And the power handling would not be as good.

    10L is typically the size of box where you'd but a 6-7" woofer in with much lower bass response and better power handling than a 4" full range driver.

  10. #10
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    Ok, I noticed the same thing. I guess you're right I should go smaller. I'll try and post some pics when i get started

  11. #11
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    I've been busy but tried to take some time to work on the speakers, and they are assembled. I've briefly heard them in very bad conditions but i'll give some impressions and post some pictures soon.

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    A little update

    I was supposed to do this about a month ago but anyways better late than never. Here are a few pictures of the semi-finished product
    DIY speaker build. Kexodusc?-tmpphp8ixbhm.jpg

    DIY speaker build. Kexodusc?-tmpphptmc12r.jpg

    DIY speaker build. Kexodusc?-tmpphpkqdjgg.jpg

    As you can see I haven't done any sanding/painting.

    edit: I was going to add some pictures of the driver but my hard drive is letting me down the pictures are corrupt so no more for the moment.
    Last edited by audio amateur; 01-30-2010 at 01:21 PM.

  13. #13
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    Now for sound. To start off, I wasn't really sure what to expect but i'm pretty dissapointed. I must point out that at no time were they properly setup, first of all because the HT is in the corner of the room so I have to do with that, and second of all because I didn't have time to assemble the stands I had planned to make for them.

    They definitely need a tweeter. There's no sparkled and the sound is muffled, similar to when you're just running the woofer and have the tweeters unplugged. Even though they masure 'flat' to 10KHz + there is clearly some treble missing. Another important issue is the fact that I notice the sound is really coming out of the speaker, I guess this is what you call soundstage. Well, there is none to speak of. It sounds boxy too.
    Its forte is the bass, it extends a lot lower than my sealed Velodyne satellites but everywhere else the Velodyne trumps these.

    The tests I have done so far were in less than ideal conditon so this is about all I can say. At the moment, they are only good for surround duty. I'm thinking I should implement a crossover for them and add a tweeter. I really think they need it.

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    Ported?

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    Quote Originally Posted by Poultrygeist
    Ported?
    Yes, it's hard to make out but you can see the slot on the back of the speaker under the binding posts.

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