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My MT122 idea
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sKs01 View Drop Down
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Joined: 11 April 2008
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Points: 1744 		Post Options Post Options   Thanks (0) Thanks(0)   Quote sKs01 Quote  Post ReplyReply Direct Link To This Post Posted: 10 July 2008 at 5:46pm
bullets, wouldn't have thought they'd get low enough? might well be worth it if they do, i like them not too keen on slots though don't ask me why maybe its purely aesthetic but a lump of titanium is more appealing than a plastic slot to me, cant remember where but some hifi horn fella made some phase bungs out of a succession of different shaped light bulbs think in the end a candle bulb got used. though not terribly practical for pa use it must be said, lathe oh no no, ill get my penknife out LOL sounds like a good idea to me, just need to work out a sensible 6.5" driver to use and some way of designing a horn....
You're a big man, but you're in bad shape. With me it's a full time job. Now behave yourself.
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Deadbeat View Drop Down
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Points: 3167 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2008 at 9:18am
If you're really scared, I'm sure some people have CNC lathes. Otherwise, I think Grame's electric drill lathe was a winner, just need some 1" square tube and welding skills. When you're dealing with tiny drivers, accuracy is key.

There are lots of midrange drivers that will work, if you're on a budget, the Eminence Alpha 6 seems like a winner, and the LA6 closed back might work.
http://speakerplans.com/index.php?id=faq10

From the diyaudio guide:

How high can you model before the results become inaccurate?

Hornresp models the power response of the horn. This is different than the on-axis response which you might measure with a microphone. The power response is what you would measure at a point if sound radiated evenly in all directions away from the horn, within the solid angle specified in the ANG input. So the modeled results should be fairly accurate up to the frequency where the horn starts to have directivity - where the polar pattern starts to narrow. This is typically at the frequency where the wavelength falls below the diameter of the horn mouth. Above this frequency, Hornresp will predict lower SPL levels than what you would measure on-axis. Hornresp now includes tools to investigate this effect. Once you calculate the model, go to the SPL Response chart. Under Tools, select Directivity. If you enter a blank input, you will see the power response. If you enter 0, you will see a prediction of the on-axis response. You can also enter other angles. Also under tools, you can look at the Pattern tool. This will predict the polar pattern at the frequency you input and show you the DI, directivity index at that frequency. Directivity index is a number in dB giving the gain over what the level of the power response is.

If you're still fussy, learn Akabak.

Slots vs Bullets...
Cross at 4-6khz depending on model, if you design the phase pug right, the horn will be able to reach that high, but it needs to be good. Otherwise, a 1" comp would love the high xover point. Slots and bullets operate similarly, the difference is the exit style, one gives more dispersion, one is more directive.
The difference is really obvious with these:
http://www.loudspeakersplus.com/html/fane_hftweeters.html
Who says slots are always plasticky?
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norty303 View Drop Down
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Points: 8800 		Post Options Post Options   Thanks (0) Thanks(0)   Quote norty303 Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2008 at 1:08pm
As a slight aside, given that a lot of people are building MT121 or separate mid and top sections, how would it work if you were to use a co-axial 12"/2" in the MT121?  The box would be slightly deeper but small frontal area.  What I'm not sure about is the effect on the 2" dispersion from the horn that is optimised for the 12"
 
Is this why most co-axial implementations are not horn loaded?
 
 
edit: those Fane slots in the link are not as 'slotty' as I'd have expected.  I've got 4 Fane slot tweeters (really nice big heavy buggers! Wink) which don't have a dome centrepiece, but a toblerone section mounted vertically so one of the peaks just pokes out between the 2 side edges which sit very close to it.  Like this...
 
 
 
Actually thats quite a good article about line arrays there....  Wink


Edited by norty303 - 11 July 2008 at 1:17pm
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Deadbeat View Drop Down
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Points: 3167 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 11 July 2008 at 1:59pm
I'm not sure, Norty, some people do mount 12s and 2s on the same axes (dynacord...), but i've never seen a hornloaded coaxial midtop...

The Fanes are really nice, I chose those particular ones as examples due to the obviousness of construction, the Beyma CP21 and the JBL it replaces are like that as well.

Steve's website is loaded with great info, i must say. Came across it when running a search on diy line arrays as well.
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AndyWave View Drop Down
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Points: 381 		Post Options Post Options   Thanks (0) Thanks(0)   Quote AndyWave Quote  Post ReplyReply Direct Link To This Post Posted: 04 August 2008 at 11:06pm
How about this http://www.tannoy-speakers.com/s.php?product=87

Andy
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Points: 352 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MikeHunt79 Quote  Post ReplyReply Direct Link To This Post Posted: 25 February 2009 at 6:30pm
Excellent info in this thread, I think building the mids and tops into separate boxes is a nice idea as you can easily turn a mt121 into a mt122 by adding a mid.
Originally posted by norty303 norty303 wrote:

 
 
Actually thats quite a good article about line arrays there....  Wink

Nice site, I think piezo's get a bad rep myself. Wink

If they are crossed over above 3k and arrayed them vertically then they sound nice IMO.

If the 6.5" driver can get up to 3k without any drama then I think it would be worth giving piezo's a go. Smile


Edited by MikeHunt79 - 25 February 2009 at 6:30pm
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