@Davey , looks very like. Not sure I understand but if you have a sure understanding of the filter...especially the medium units'one, I would be glad about your input.
@planet10 , I think it was not in a good global layout at your friend's place. It is a very honnest sounding (for the price of it at seing nowadays prices) and still ok for its old age.
@planet10 , I think it was not in a good global layout at your friend's place. It is a very honnest sounding (for the price of it at seing nowadays prices) and still ok for its old age.
This is the part I suggested was misleading. TM itself is not asymmetrical as shown.. unless you begin to consider secondary factors, which can apply to either configuration in any case.
Not sure what this means or why it is a concern.
@planet10,
May I ask if (relative to the dashboard i posted above) and looking at your offseted T full range in your MTfrM picture : would it makes sense to offset more the tweeter if getting closer the midwoofers with each others ? Assuming not low cut off like you did (<400 hz) but a higher 2 Khz CtC ?
May I ask if (relative to the dashboard i posted above) and looking at your offseted T full range in your MTfrM picture : would it makes sense to offset more the tweeter if getting closer the midwoofers with each others ? Assuming not low cut off like you did (<400 hz) but a higher 2 Khz CtC ?
About Kef not being truly an mtm: as soon as one of the woofer is not filtered like the other it's not an MTM anymore.
Around 2010 it was kind of trend to do mtm and when people disliked outcome they switched to this kind of arrangement ( sometime 0.5 or threeways).
Diyiggy, don't you have a simulation software like Vcad availlable? It is very efficient way to try the kind of configuration you are interested in.
As a Quick answer, it'll help wrt diffraction issues and will lower ctc distance. All in all can be ok, i would prototype to see how it work in Real life.
Around 2010 it was kind of trend to do mtm and when people disliked outcome they switched to this kind of arrangement ( sometime 0.5 or threeways).
Diyiggy, don't you have a simulation software like Vcad availlable? It is very efficient way to try the kind of configuration you are interested in.
As a Quick answer, it'll help wrt diffraction issues and will lower ctc distance. All in all can be ok, i would prototype to see how it work in Real life.
from my eternal absolute beginner point of view, when seing the midrange filter of this Kef MTM, two mids share one 18db slope low pass and one of the M has another 18 db slope low pass in serie. (with some LCR as well for the impedance) but it is too much complex for my understanding, not saying the L values are not printed on the shematic. While the second M 18db cell is maybe not a serie low pass, I dunno ?!
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@krivium , I have Vtuix, and standalone Edge, but I found such shape I posted above too much complex. And it lacks also the behavior of the cabinet sides for such complex diffraction (but simple to understand a baffle loss equal to 7 to 8 dB due to the lowhished width and baffle surface. Deserve a specific thread and protos indeed.
The 104/2 system is a much more complicated scheme. I had pair of those, actually. Many years ago. 🙂
The midrange drivers are not receiving the same signal and thus you don't have a MTM configuration.......even though they're physically arranged like that.
Dave.
The closer you can get the better AFAIC.
My first MTM (1975) was a trianglular TL with twin Dalesford (?) 8” woofers, a Philips tweeter and a crappy XO, but they were mirror image dpairs with offset tweeters.
dave
Well, i don't find your sketch misleading at all.
In fact, i think it gives a nice explanation of what happen:
If you take front lobe or tm and mt and you sum them up, then you obtain a larger one which ls on axis with the tweeter.
Now If you take the secondary ones ( both pointing downward and upward) of both tm and mt and you sum them too you'll end up with the typical UP and down lobe and the 'notch' In directivity circa +/-30* you find in vertical plots of MTM.
Iow you juste explained the overall shape seen in the 3D rendering imho.
PlanetX, these pictures are not mine, but I think I would've had them with me if they were there. And I'm still trying to remember where I got them.
Also, there's this other paper: http://www.birotechnology.com/articles/VSTWLA.html
Your sketch is just fine. But it doesn't demonstrate your premise.
The bottom one clearly shows a symmetrical MTM polar pattern.
I've lost track of what your point is.
I guess you just have a difference of definition of "symmetrical" because you live south of the equator and I live north??????
I don't have a clue.
But don't believe me......There have already been posted (in this very thread) references from other folks that outline the symmetrical polar-response behavior of an MTM configuration.
I suggest to just step back and reset your understanding of this topic.
Cheers,
Dave.
1/4 wl spacing, in phase on the 0 degree axis gives a single lobe which is -3dB at +/- 90 degrees.
Something like this..
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