Another TMM vs MTM questions thread.

But adding a different perspective. My Top priorities are image coherency over different angles with possible, a magic so far I'm achieving the best with 1nd order series crossover and a cut-off below 1/2 lambda. Thanks to planet10 following his recommendation.

To learn first, I built something (ATTACHED BELLOW) like a FAST with a Vifa MG14SK ML-TL and a Visaton FRS5 in a pseudo OB Г-frame with stuffing behind. It turned out wonderful, exactly the kind of sound I need.

But now I'm thinking about something bigger with the Vifa MG18WK I have in stock. I'm fan of the idea to have 2 times the amount of surface area for lesser bass distortion due to reduced cone movement. And I need that nice lobbing behavior of low cut-offs crossover.

-MTM. What are the benefits really? As far as lobing goes, it is the hardest to achieve. I could use a fullrange like Monacor SPH32 or Faital Pro 3FE25 as a Tweeter and try cutting at 500Hz, putting it into aperiodic tapered TL or something.

-TMM. Here I could use a tweeter, due to the lesser (TM) distance. Or attempt a second concept as the previous one - ML-TL + OB.

-Offset 2 way bipole. I like the idea of kind of more surround sound feeling, together with the fact I rarely sit in a sweet spot due to a lot of work. Including the fact a bipole doesn't need BSC and my system is powered via tube amps.

What could be your recommendations?
 

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I beg you pardon? Measure, but you have to build it first. Why building something if flawed or not meeting design criteria. There is enough literature and simulation programs for basic outcome data, I think.
 
Nowadays we're lucky to have answers to basic speaker knowledge and simulation programs to give us quite predictable basic outcome.

This can save you lots of mistakes.

Why building something without common sense first?
 
Sure. I attached:

1. SPL combined with little internal stuffing (vent + driver) Leonard audio simulator
2. GD, Leonard audio simulator
3. Vertical lobing, Xdir.
4. Some build photos
 

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No. Here are measurements done into a close to 4pi environment and crossover simulations. Afterwards I had to readjust the port tuning, but no second measurements are done yet.
 

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on other note, you can shimulate TM or TMM as long as you like, its inherently flawed because the highs and mid/lows are not coincidental

in MTM, you get more coherency because its like coaxial, highs emanating from the center of the mid/lows
in horizontal dimension off course, vertically, there is lobing

but we evolved as a species living on the planes of africa, where it was of utmost importance to follow horizon for sights and sounds, to follow pray or predators, hence we have ears and eyes in horizontal domain
horizontal performance of the speaker is important, we can tolerate minor deviations in vertical domain

my listening and measurements between TMM and MTM always favored MTM
 
on other note, you can shimulate TM or TMM as long as you like, its inherently flawed because the highs and mid/lows are not coincidental

in MTM, you get more coherency because its like coaxial, highs emanating from the center of the mid/lows
in horizontal dimension off course, vertically, there is lobing

but we evolved as a species living on the planes of africa, where it was of utmost importance to follow horizon for sights and sounds, to follow pray or predators, hence we have ears and eyes in horizontal domain
horizontal performance of the speaker is important, we can tolerate minor deviations in vertical domain

my listening and measurements between TMM and MTM always favored MTM

Hey, thanks for the opinion! This was the point.

About the simulation vs measurement, you are quite correct on the tuning and bass contribution. This is something that puzzled me, and I will be studying this discrepancy 🙂