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Mid Waveguide... |
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gwarntek 
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Joined: 17 November 2008 Location: South East UK Status: Offline Points: 766 |
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 Topic: Mid Waveguide...Posted: 13 March 2009 at 7:37pm |
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EDIT: Right, Iv now changed the title, and il make this the place for all my questions/discussion, as its probly easier than starting thread after thread hahaha
 Yet more speaker related pondering has gone on today, at one point about possible MT121s. The only problem being the flare sections, and how theyre a proper mission to construct.
I came up with a sort of plan using a jig. It may have been thought of and done before, but you never know...
So.
You make a 3D jig, of the internal dimensions of the flare. You then cut and glue mitres as appropriate, but not worrying about the [height] dimensions of the bits of ply, only the angle involved in the mitre.
 You can then whilst on the jig use a flush trimmer router bit to cut along the red lines. This gives you the correct mitre, whilst ensuring that you get perfect alignment with the top and bottom flare sections.
 What do you think? Theres gota be a flaw somewhere, or been done loads of time before... haha i never think of something semi-ingenious
 Peace Edited by gwarntek - 13 May 2009 at 7:07pm |
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Silas ))))))
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Joined: 10 January 2008 Location: SUFFOLK Status: Offline Points: 1003 |
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Posted: 13 March 2009 at 8:03pm |
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like it
 wanted to build some mt's but gotta work out if i can get them from the basement (the workshop) to the door (very tight space)
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power in the blood
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Deej
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Posted: 13 March 2009 at 8:53pm |
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Surely the jig would be at least as difficult to make as the flare sections themselves? If you could construct the jig you would already have the dimensions of both flare sections, which was the problem in itself I found. Unless I'm missing something as well? I'm in the middle of making a pair of MT122's myself, so I know how you feel. Once I get the flare section modelled properly out of MDF, I will post the dimensions up as noone else appears to have them.
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Sequence Empire:::..
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Joined: 13 January 2009 Location: New Zealand Status: Offline Points: 84 |
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Posted: 13 March 2009 at 9:50pm |
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Are there any merits in converting the two angle flare into a laminated curve section like the mt102's???
Keep the rectangular window through to the driver's cone, leave the rear chamber unmodified, keep the horizontal flat plane flares the same but modify the sides so they are a curved section similar to the mt102's. What would this do to; a)dispersion b)freq response of the mid woofer c)SPL??? As I understand it, the 2-section flare is an approximation of a curve or am I completely off the idea? Jim |
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MikeHunt79
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Joined: 12 February 2009 Location: Bristol, UK Status: Offline Points: 352 |
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Posted: 13 March 2009 at 9:58pm |
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The jig looks like a good idea.
I'm almost done building the mid-section of an mt121, and with a mixture of measurement, trigonometry and lots of planeing and sanding I got it all to fit together. I still need to build 3 more tho so I imagine a jig is the way forward... Edited by MikeHunt79 - 13 March 2009 at 9:59pm |
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I'm English, and as such I crave disappointment. I actively seek it out.
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gwarntek
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Posted: 13 March 2009 at 11:10pm |
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Yeah thats what i was thinking, also in answer to Sequence empire's question. If the jig can help measure cut and trim down one half of a mid horn, it would save a fair bit of time and effort every time you have to do it.
And if youre making 4 MTs, having to do that 8 times would take aaaagges plus it probably isnt the most fun thing in the world. And MT122s would mean 16 times!!
Im not doing that many, but still may be a long project...
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ceharden
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Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
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Posted: 14 March 2009 at 12:56am |
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If you make the bits you'd have to trim off the right size to fit inside the cab, then they'd just form part of the support for the horn. Don't know if that would be easier or harder.
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gwarntek
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Posted: 30 March 2009 at 11:57pm |
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Il have to start creating this jig and giving it a try. More refinement may be needed....
But yeah onto drivers...
Been looking at comp drivers. The Beyma 750/755 range would be IDEAL! and supposedly sound really nice. But theyre well exspensive. And BMD750 is cheap, but im guessing that again you get what you pay for.
Any suggestions on other models people have tried or would work ok?
Peace
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roborg
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Posted: 31 March 2009 at 3:33am |
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i would go for a much cheaper driver, i presume u mean the p-audio driver? http://p-audio.co.uk/products/db_product_2_6_bm-d750.htm
I've done a 1 to 1 of this with a beyma cp750ti & at sensible volumes there was little in it. Its 1/2 the price too.
As the driver is only keeping up with one 12" theres no need for the beyma, unless you really must have one. IMHO the mt121 is such a compromise cab i would put a 1" driver in it & use the sn12-b to 1.5-2khz.
The mt122 really shines because it has two 12s coupling to let it go low enough to meet most bass horns nicely. In pairs side by side the mt122 is almost the ultimate kick-horn mid-top. The only redeeming part of am mt121 is it's smaller size.
cheers,
Rob.
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What I cannot create, I do not understand
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roborg
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Posted: 31 March 2009 at 4:58pm |
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the trimming bit will only work if the top & bottom sections of the horn are not splayed. In this design they are. Its tricky getting this exactly correct. The best way is to calculate the top & bottom panel dimensions+mitres & cut them really accurately
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What I cannot create, I do not understand
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gwarntek
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Posted: 31 March 2009 at 11:24pm |
I don't really understand what you mean... The top and bottom flare sections are straight bits of wood, so surely cutting a single straight edge will work ok? I was considering building another two mid horns to maybe go on top of a pair of MT121s to make them 122s when needed/possible. Does anyone happen to have beyma or p-audio comp drivers in the south east or london area that would be available to test in this setup? Would like to hear them to compare
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trebor
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Posted: 01 April 2009 at 6:48pm |
Are you meaning one 12" driver section from the MT122 design? If so, I was planning on doing exactly the same! If you build them before I do, I'd be very interested to hear em. An MT121 is an MT122 with one of the drivers omitted, so I reckon that makes what we're planning an MT120 ! trebor |
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roborg wrote: