New 2-channel DIY speaker project

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  • michael_w
    michael_w Posts: 2,813
    edited August 2005
    The ones paul h made are absolutly stunning. I'd love to make a pair like that but need to read up on building crossovers first :p
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    michael_w wrote:
    The ones paul h made are absolutly stunning. I'd love to make a pair like that but need to read up on building crossovers first :p

    Yeah I love the curved sidewalls and the dark stain with the huge gold woofers.

    The crossover isn't too hard to build. Soldering takes a little practise but other than that you just copyh the layout.
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    I just measured the speakers in Speaker Workshop. Everything checks out. I'll post the frequency response as soon as I can. I am so relieved, if anything went wrong, I would have had to cut the boxes open to get at the crossover boards.
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    Here is a quick frequecy response plot. This is quite flat but it is not the whole story. A on-axis FR plot is like the peak horsepower number. It's interesting, but over rated and only tells a small part of the story. You still dont know + or - 15, 30, 45 degrees horizontal and vertical. It doesn't give any indication of group delay, distortion, decay, etc etc. The speakers should be flat from about 50 Hz to 30 kHz.

    Anyway, this was done far field ungated MLS at a distance of about 50 cm. I used a RS meter and Speaker Workshop. The RS meter is limited in accuracy and is only good up to several thousand Hz. I use this mainly to make sure the crossover is working properly and everything is wired correctly.
    The results are 1/3 octave smoothed.

    I'm very happy with this. Now it's on to finishing the cabinets.
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    Here are some pics of the weigh in. It measured exactly 50.0 lbs! :confused: No wonder cement isn't very popular for speaker enclosures.
    Graham
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  • tecmo04
    tecmo04 Posts: 421
    edited August 2005
    looks like a hernia and a half. but heres the real question, how do they sound??
    My Stuff
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  • michael_w
    michael_w Posts: 2,813
    edited August 2005
    With cement won't sound waves bounce inside and cause lots of resonance problems or is it just so damn dense that it absorbs everything. I'm just thinking about when you're in a concrete building and what happens when you yell.
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    tecmo04 wrote:
    looks like a hernia and a half. but heres the real question, how do they sound??

    Good. :D But dont take my word for it. See below
    Jakub wrote:
    I was at the Toronto DIY meet where these were auditioned extensively. The room there was quite large, and these speakers did very, very well. IMO they were the best speakers at the event, though in a smaller room the Dennis Murphy Seas excel + Ribbon tweet design would have given them a run. That right there should tell you something about the pedigree of the speaker. Kudos to Jon and Graham on these , I predict they will keep you happy for a long time.
    and

    http://www.polkaudio.com/forums/showpost.php?p=277714&postcount=38

    This version will sound almost identical to the old version, other than this is sealed. The old cabinets were very substantial aswell. Butcher block and heavy bracing. They were just too big.
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    michael_w wrote:
    With cement won't sound waves bounce inside and cause lots of resonance problems or is it just so damn dense that it absorbs everything. I'm just thinking about when you're in a concrete building and what happens when you yell.

    You dont end up with any resonances, nothing is resonating. But you're right, concrete or cement is poor at absorbing acoustic energy. You do, or can have reflections and standing waves (no standing waves in these boxes though). For that I am lining the box with polyfil, and lots of it. You dont want reflections hitting the back of the cone, it is inevitable, but you try to minimize it.

    After doing more research on this, there are others who have lined their enclosures with cement. Works very well, except for the weight issue. Having two materials bonded together like this works even better for controlling resonances.
    Graham
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  • michael_w
    michael_w Posts: 2,813
    edited August 2005
    Sounds like a good idea. Who cares how much they weigh once they're in place :p Polyfil should do well in taming the air bouncing around inside a bit. You could probably help kill any standing waves by rounding the inside corners with cement too.
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    michael_w wrote:
    You could probably help kill any standing waves by rounding the inside corners with cement too.

    The inside corners are rounded, but non-parallel walls or ratios of 1.62:1 help as well.

    I dont have to worry since the entire enclosure is full, really full of huge 14 gauge inductors and caps bigger than D cell batteries.
    Graham
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  • michael_w
    michael_w Posts: 2,813
    edited August 2005
    gatemplin wrote:
    The inside corners are rounded, but non-parallel walls or ratios of 1.62:1 help as well.

    Good to know for future projects thanks.

    BTW where do you live? I'm asuming somewhere in canada because of the trailor park boys thing. I'm in steveston (BC). Just curious cause if you're close I'd be cool to check these beasts out and give them a listen.
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    michael_w wrote:
    Good to know for future projects thanks.

    BTW where do you live? I'm asuming somewhere in canada because of the trailor park boys thing. I'm in steveston (BC). Just curious cause if you're close I'd be cool to check these beasts out and give them a listen.

    Yeah I'm a trailer park addict. I live in Toronto now, but I'm moving to Waterloo in a couple weeks.
    Graham
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  • michael_w
    michael_w Posts: 2,813
    edited August 2005
    Mmmm that's too bad. Good luck with the move.

    I love the show too but I always seem to be busy and don't have time to watch it when it is on.
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    michael_w wrote:
    Mmmm that's too bad. Good luck with the move.

    Well I'm just going off to school. Not a big move, just gotta pack some clothes and speakers! ;)
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited August 2005
    I'm finally done with the wood putty and 220 grit sanding now. Ready for the final base coat of satin black acrylic. Then I'll spray on some polyurethane clear coat.
    Graham
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  • gatemplin
    gatemplin Posts: 1,595
    edited September 2005
    I didn't get them done in time unfortunately. But at least they work, which is the most important thing. Afterall, I'm in engineering, not arts. :p

    I might get the painting done on one of my trips back home.
    Graham
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  • Willow
    Willow Posts: 11,039
    edited September 2005
    Hey Graham, those are looking very nice. I will have to wait till we meet either in TO or here in Ottawa to listen to those. Looking forward to it.
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  • michael_w
    michael_w Posts: 2,813
    edited September 2005
    So now that they are all purty and functional what do you think them?
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  • gatemplin
    gatemplin Posts: 1,595
    edited September 2005
    Willow wrote:
    Hey Graham, those are looking very nice. I will have to wait till we meet either in TO or here in Ottawa to listen to those. Looking forward to it.

    Hey JF,

    I plan to bring them up to Ottawa some time. I'll PM you when I know. Hope everything is still going well for you two.
    So now that they are all purty and functional what do you think them?

    Well they sound great, at least everyone says they do. I tweaked the crossover to get it just the way I like it. I am very happy with them, it was a very fun project.
    Graham
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