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Multi-Way Conventional loudspeakers with crossovers

First floor-standing 3-way considerations
First floor-standing 3-way considerations
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Old 13th September 2017, 07:46 PM   #11
chrisb is offline chrisb
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No, there's a lot of daylight or "new math" separating "classic" / old school TL theory and the more recent designs thanks to the very generous work of folks like Martin King.

Spending a few days down this rabbit-hole http://www.quarter-wave.com is highly recommended reading. My own personal take away was - let the real math geeks (Scott Lindgren, Bob Brines, Dave D etc) go to town with this - just give me a set of accurately dimensioned drawings.
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Old 13th September 2017, 10:17 PM   #12
planet10 is offline planet10  Canada
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First floor-standing 3-way considerations
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Is there a difference between MLTL and TL, or is MLTL just the technically correct term for all things transmission line?
King & Augspurger’s TL modelers (perhaps more accurately called quarter-wave modelers) showed that the TL space was much larger than we imagined. And that traditional classic TL design was woefully inadequate. A traditional TL is essentially a long line that gets smaller as it approaches the terminus. A TL that expands has in the past been known as a Voigt (or TQWT/TQWP tapered quarter wave tube/pipe). In between are straight pipes with no taper. Mass loading a line means adding a restricted terminus — often in the form of a vent. Turns out tapered TLs are usually best if they have a significant taper ratio, and the Voigts really need to be mass-loaded. A straight pipe can be much shorter if it is mass loaded. Such an ML-TL often looks like a tall skinny bass reflex but isn’t — the way the air works inside is quite different.

This is a ML-Voigt but it gets the idea across.

Click the image to open in full size.

Horns also turn out to be in TL-space but are further out along the axis as Voigts with more exotic taper and other details.

Something else that modern TL modelers showed us is the advantages of having the driver offset from the end of the pipe.

dave
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Old 13th September 2017, 11:55 PM   #13
Brett is offline Brett
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I built my own modular PA and ran it for many years.

My suggestion would be a pair of 15 or 18" units in their own ported enclosures, eg JBL2226 or 2242 or equivalents. Then a midrange horn eg the Pi with a Delta 10 (it's DIYable), and a SEOS12 and a suitable 1" CD.

Buy an active xover.
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Old 14th September 2017, 04:00 AM   #14
kcducttaper is offline kcducttaper  United States
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Ok, cool. It's starting to make sense a little bit after that explanation, and some research. I was picturing a slight modification on a "regular" T line with all of the folds to calculated by the target wavelength...length, and stuff like that. Sounds like the general air behaves similar, but the construction is significantly different with no folds inside (presuming the box size ratios are correct anyways).

It looks like the AviaTrix speakers use an MLTL design. This is essentially what an MLTL's innards would look like, I presume.
Click the image to open in full size.
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Old 14th September 2017, 04:11 AM   #15
planet10 is offline planet10  Canada
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First floor-standing 3-way considerations
Yes, you can see more examples here: Frugal-phile | Box Library / Mark Audio, near the bottom there is a Pensil section, all ML-TLs, and below that a section with random ML-TLs.

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Old 14th September 2017, 07:34 AM   #16
chris661 is offline chris661  United Kingdom
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Some thoughts...

- 38Hz and loud outdoors is difficult. This doesn't need to be loud, so I'm confident we can get something good.

- Econowaves won't go nearly low enough without some kind of EBS alignment, which will end up huge for PA midbass drivers.

- The Tang Band mini-subs need an absolute rocket up them to get going. At demo levels, I had the -6dB light on an NU6000 lit pretty often. That's over 500w peaks for each driver. Their free-space (outdoors on a stand) sensitivity is below 80dB@1w.

If it was mine, I'd consider simplifying and doing an 8" 2-way standmount design. If you only want 90dB, it'll do that just fine, even outdoors. If you wanted an easy life, you could pick up a pair of Behringer B2031A (check the reviews) and be done with it. They'll hit 40Hz and have enough adjustments built-in to make them sound good outdoors.
If you don't fancy just buying some speakers, I'd still recommend the form-factor. That sort of thing is much easier to move around than a tower, and will still do everything you want it to do.

Chris
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Old 14th September 2017, 05:22 PM   #17
kcducttaper is offline kcducttaper  United States
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Is there a popular MLTL sim I can try out and tinker with? Something like WinISD, or HornResp perhaps? I'm understanding that driver location plays a much larger role with MLTL's than it does for BR, so something that can take into consideration driver placement would be ideal.
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Old 14th September 2017, 05:54 PM   #18
chrisb is offline chrisb
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Well, the designs posted that Dave referenced have had all that icky math done already, and you could build probably at least one pair of speakers in the time you tinker around with getting the simulators to "work".


While I generally prefer the sonics of a floorstanding / tower system for home use, I'd have to agree with Chris on the advantages of smaller for portability. But don't forget our old friend mr Hoffman
pick any two:
- efficiency
- deep bass
- compact size
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Old 14th September 2017, 06:13 PM   #19
kcducttaper is offline kcducttaper  United States
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Yeah, I'm working on digesting some of the info there, but it'll take some time for sure. It seems that, like a BR box (or most any other type of box, really), a properly designed MLTL box revolves around the specific driver params and I can't realistically drop in different drivers than the box was designed for and expect good results. Therefore, if I want to use a specific driver, I have to do all the maths to match that driver or driver combo.

Yeah, gotta love Mr Hoffman. I've gone for numbers 2 and leaning more towards 3 with my initial thoughts of the TB 6.5's only being 83dB.
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Old 14th September 2017, 06:18 PM   #20
kcducttaper is offline kcducttaper  United States
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So, with my newfound knowledge of MLTL physics, I'm getting nervous that another build I've lazily been building won't sound like I modeled it up. I modeled it as a BR box MTM style and have the cabinet mostly built, but not complete.

Looks like this with 2x 6.5's and a tweeter:
Click the image to open in full size.

Last edited by kcducttaper; 14th September 2017 at 06:21 PM.
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