Active DIY HT MTM Speakers
Comments
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You may not have to recess those tweeters after all. It appears with steep slopes and MTM style speakers it's not very important.
http://www.musicanddesign.com/Dipole-offset.html
http://techtalk.parts-express.com/showthread.php?t=208939
http://www.htguide.com/forum/showthread.php4?t=33343
I'm planning on the electronic delay for the tweeters. I have to recess the tweeters the thickness of the woofer flange so I can reduce get the woofers closer together, but not enough to line up the voice coils.
I now have the mdf, and if anybody in DFW needs to know where to get a really good deal on that, they should contact Jeff at Casino Supply Company. -
I now have the mdf, and if anybody in DFW needs to know where to get a really good deal on that, they should contact Jeff at Casino Supply Company.
Thanks for the tip!I know just enough to be dangerous, but don't tell my wife, she thinks I'm a genius.
Pioneer VSX-816
Monitor 40's - fronts, bi-amped
Monitor 30's - surrounds
CS1 - center
PSW10 - I'll let you guess
Blue Jeans Cable - speaker cable
Daewoo 27 incher - one step up from a console
Sony Progressive scan DVD
XBOX
SOPA since 2008
Here's my stuff. -
Thanks for the tip!
$1.50 for a 1' x 6' x 3/4 sheet is a great deal. I got 20 of them. He's got maybe 150-200 left. -
Great deal.I pay nearly $10 for 2'x4'x3/4" MDF at my local HD.$1.50 for a 1' x 6' x 3/4 sheet is a great deal. I got 20 of them. He's got maybe 150-200 left.Testing
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With exchange rates, that's pretty much what I pay here, $35ish for a 4'x8'x3/4" board. To special order a 1" or 1.25"x4'x8' it's $100 though! :eek:Great deal.I pay nearly $10 for 2'x4'x3/4" MDF at my local HD."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche -
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Too funny...I ordered six of them.:eek:Testing
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HAHHAHAHHAHA!!! Wow, I hope he isn't serious...SDA 1C, SDA 2A, SDA SRS 2, CMT-340SE, Swan M200MKII, Swan D1080MKII, Behringer MS40
Outlaw Audio M2200 x2, GFA 555 II, BGW 750C
GDA 700, Outlaw Audio Model 990, Sansa Fuze, X-Fi Platinum Fatality -
HAHHAHAHHAHA!!! Wow, I hope he isn't serious...
If you're interested, he's 100% serious.
Seriously! -
And back to speaker building...
I have a problem with the side surround design (using direct radiators in back). If I use a layout similar to the LSi f/x, with two woofers and two tweeters, my impedance changes because of the second tweeter. I could solve this by using a tweeter similar to the others, but in a 4 ohm nominal impedance, eg, use this:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-834
for the two tweeters in the side surrounds, instead of this:
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=264-822
which I'm planning to use for the MTM designs. The sound would have to be a little different, being a different tweeter, but it is side surround, and the high freqs are really rolled off anyway. Thoughts?
Also, I got the woofers in. They are very pretty, that's for sure. -
If you plan to also actively xover the side surrounds then impedance should not be an issue.2x the 264-822's in parallel will be 4 ohms which IIRC correctly your amps will be OK with.
Are they to be a dipoles or bipoles?Testing
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If you plan to also actively xover the side surrounds then impedance should not be an issue.2x the 264-822's in parallel will be 4 ohms which IIRC correctly your amps will be OK with.
Are they to be a dipoles or bipoles?
I haven't decided bipole or dipole, yet. I'm leaning toward bipole, but will read more before I decide. My concern with the impedance is that I'll get a very different response curve at 4 ohms than I would at 8, which is what the woofers would be at, like the rest of the system. Can that be compensated with gain? -
There may be some frequency response alterations due to comb filtering(interference)between the 2 tweeters because of the dipolar or bipolar radiation but otherwise the response will not change because of the lowered impedance.The output should be a few db higher , but thats as you mentioned easily fixed with a gain adjustment if need be.My concern with the impedance is that I'll get a very different response curve at 4 ohms than I would at 8, which is what the woofers would be at, like the rest of the system. Can that be compensated with gain?Testing
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Attached are wireframe and hidden views of the cabs. I'm using .75" mdf all around, with an additional 15/64" plywood layer behind the baffle for added stiffness and screw-holding capacity. I haven't shown the cutout for the binding posts, but it will probably go in the middle of the back panel.
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I like the clean look of that box and the rounded corners on the front; very professional.
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Thanks. I don't know how hard it will be to get a 1" radius quarter-round bit, but that's what ebay is for! When I get my shop set up, I'll post some pics.
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Any opinions on the Axiom QS8 configuration for surround?
http://www.axiomaudio.com/qs8.html?1071#
I figure it's either that or the LSi f/x arrangement. -
Interesting design.If you are looking for more of a diffuse vs directional response then that driver arrangement should do it.Testing
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I've slightly altered my design, reducing the height by .5", to make MUCH more efficient use of the the big stack of mdf that I have. Still maintaining the golden ratio in internal dimensions. Will post plans soon.
Now, anyone got suggestions for some really pretty screws to mount the drivers? I figure I might skip grilles, and if I do, the screws should be very pretty. Nothing too shiny, as that would be distracting in an HT environment. But something damned cool. -
"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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I agree, and that's what I was thinking of. I wish they'd put the head diameter on those - my woofers have countersunk screw holes. -
You might be able to give them a call and ask. What's the worst they could say, "We don't know?"
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That's what they'd probably say, actually. But I'll try.
Any opinions on grille-less speakers? -
As long as you don't have children that would destroy your dustcaps or domes, why not?"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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Ah, the blessings of a DINK household...
And dogs really aren't irresistibly compelled to "press the buttons." Oddly, though, my wife admits to finding it very hard to resist. -
ALMOST ready to begin construction, and I have some questions. After I get my Sonic barrier internal damping sheets for the insides and F13 felt for the baffle outside, I'm going to build a trial box. I'm going to start with the 2" Precision Ports with no tube between the flares, for an effective 4" port.
When I get a box built, I'm going to test near-field outside using my Rane RE-27. Here's where I could use some help:
I'm building these to be used with subs crossed at 80 Hz. I plan to use the 7.1 analog outputs of a blu-ray player with bass management, just using my Sunfire pre/pro as a preamp only. To mimic this configuration (I don't yet own a player) I need to know what kind of crossover slope the players typically use.
Any ideas? -
I was wondering what happened to you:D
I believe most pre/pro's will use the THX standard of an LR4 lowpass and 12 db hi pass both at 80hz.As for Blu Ray players I can't say specifically but if they are built to the THX standard then it should be the same.I'm building these to be used with subs crossed at 80 Hz. I plan to use the 7.1 analog outputs of a blu-ray player with bass management, just using my Sunfire pre/pro as a preamp only. To mimic this configuration (I don't yet own a player) I need to know what kind of crossover slope the players typically use.
Any ideas?Testing
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I was wondering what happened to you:D
I believe most pre/pro's will use the THX standard of an LR4 lowpass and 12 db hi pass both at 80hz.As for Blu Ray players I can't say specifically but if they are built to the THX standard then it should be the same.
Here I am!
I read some stuff like that, saying that the 12 db hi pass slope complemented THX cert speakers with a 12 dB cutoff slope for a summed 24 dB slope. I want the port tuning to be well below the crossover point, around 50 Hz, to achieve a flat response when crossed, and to avoid port-related nastiness. My Rane xovers are 4th order, so they won't properly mimic THX standards. But my RE-27 eq/analyzer could be set to mimic that slope somewhat, I guess. -
Oh, and I went with the Dayton 1-1/8" Neo silk domes for the tweets. They were reviewed more favorably than the TB tweets, and I got a heck of a deal on them.
