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Discussion Starter · #1 ·
Hi, is there one 15 inch driver available that would be considered the "best" driver for LLT sub project? Also could I cross over as high as 200 hz with said driver? I am hoping to build a 3 way active system.

Thankyou
Mike
 

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Maybe someone will prove me wrong but I think if you want to dig low (infrasonic) sound with a LLT you probably don't want to crossover that high. But depending on what your goal is you could tune higher and get to 200 Hz. As far as driver I could not comment on the "best" driver.
 
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Not sure what you can order in Australia. If you want to go active, you might have better luck at the pro audio section. I think they have active three way crossovers with sub out. You might want to go that rout too.

As far as the best.. The best at what? Sound quality, power handling, sensitivity?
 

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Discussion Starter · #5 ·
Hi, yes sorry I should be more specific. Would like to keep efficiency 90 or above. Sound quality is most important, I am hoping to run this as the bass driver in a three way, not just as a sub.

Thanx
 

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Just to add my ten pence. I wouldnt use a true LLT for anything other then HT, and I wouldnt cross it higher than the LFE range. The are best at producing very low material and dont excel at the higher range, especially when it comes to music performance IMHO. They are accurate, but for me personally, they have a very specific role. If you want to incorperate an LLT, I would personally also use a second driver in a sealed section for between 60 and 80 hz to 200 hz.
 

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I think I would second Mike and Moonflys advice. 3way design and a LLT would be two different things and not the same. I know with some sealed designs you can go up 200hz but LLT I would think you wouldn't want to go much past 120hz.

I think for your 3way it is hard to beat Johns AE TD15s. They will go down low if you have the box size. But for the LLT I would use the TC Sounds 15 Mike suggested.
 

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LLTs have good bass within their passband. they lack the punch of high q sealed speakers but instead have a non resonant response - perfect for listening to classical music.

but they will likely have a vent resonance from around 130-180hz

if this resonance is excited it will not be pleasant. a low pass filter at 60 or 80hz is thus necessary - for any vented system for the most part.
 

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Elite Shackster
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LLTs have good bass within their passband. they lack the punch of high q sealed speakers but instead have a non resonant response - perfect for listening to classical music.

but they will likely have a vent resonance from around 130-180hz

if this resonance is excited it will not be pleasant. a low pass filter at 60 or 80hz is thus necessary - for any vented system for the most part.
Interesting considering they essentially use a Helmholtz resonator to increase low frequency output, although I grant you that the resonance is focused at frequencies where you cant hear the actual first port resonance and instead only get the low end effect the design aims to accurately reproduce.

The thing I like about sealed subs though is the fact that when designing one you can choose the Q of the system. I agree a high Q system does sound rather resonant, and can get overly boomy or sound to drone, which is why I think its important to use larger drivers with a good upper bass quality (ideally multi driver setups), in larger cabinets, and lean on the side of a lower system Q. LLTs IMO suffer from a character I can only liken to a very very low Q sound (often below .5 Q), and while this is very accurate in terms of removing the cabinet effects from the drivers production, many drivers have very low Q values for the exact reason they are going into a cabinet and take this into account. As such, I feel LLT's lean too far to one extreme in the search maximum low end clean output, something I consider negative in terms of musicality, but admittedly unmatched in terms of LFE reproduction.

The desirable aspect of reduced size in sealed systems is somewhat overshadowed however, by a considerable cost increase in creating a system that is accurate and clean at low frequencies. If your goals are to get to 25-30hz, then this is pretty comfortable for any system to achieve, even most sealed systems, its when you want to go lower that it gets difficult. This is where LLTs really shine. A sealed system gets expensive when you want to go low and loud, where an LLTs suffers no additional impact in terms of cost to achieve this goal, the trade off simply comes in the form of huge cabinets.
 

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The thing I like about sealed subs though is the fact that when designing one you can choose the Q of the system. I agree a high Q system does sound rather resonant, and can get overly boomy or sound to drone, which is why I think its important to use larger drivers with a good upper bass quality (ideally multi driver setups), in larger cabinets, and lean on the side of a lower system Q. LLTs IMO suffer from a character I can only liken to a very very low Q sound (often below .5 Q), and while this is very accurate in terms of removing the cabinet effects from the drivers production, many drivers have very low Q values for the exact reason they are going into a cabinet and take this into account. As such, I feel LLT's lean too far to one extreme in the search maximum low end clean output, something I consider negative in terms of musicality, but admittedly unmatched in terms of LFE reproduction.
Have you tried modelling an LLT with Martin J King's transmission line software? I guess an ideal Q for me is around .45 to .57 or so. I'd say LLTs are in that general range.I don't get you though. What do you define as "musicality"?

If it's free of any audible resonances, and you've got flat in-room frequency response (which means an anechoic response which slopes towards tuning), and group delay is sufficiently lower than the period of the wavelength (tuning frequency below enough of the audible passband + no HPF) then an LLT with a good driver should sound the same as a proper sealed box. A critically damped Q sound is what I consider "musical" in the sense that it's not adding or subtracting from the recording.

I will say that some ideal LLT drivers have higher inductance and work better with a 60hz crossover point though.
 

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Have you tried modelling an LLT with Martin J King's transmission line software? I guess an ideal Q for me is around .45 to .57 or so. I'd say LLTs are in that general range.I don't get you though. What do you define as "musicality"?
Not touched TL's personally, though I am aware they sound different to a typical LLT style sub. For me, low Q like you state lacks punch that I consider a must for proper musical playback. These systems dont deliver that punch which leaves them with that something missing factor IMO.

If it's free of any audible resonances, and you've got flat in-room frequency response (which means an anechoic response which slopes towards tuning), and group delay is sufficiently lower than the period of the wavelength (tuning frequency below enough of the audible passband + no HPF) then an LLT with a good driver should sound the same as a proper sealed box. A critically damped Q sound is what I consider "musical" in the sense that it's not adding or subtracting from the recording.

I will say that some ideal LLT drivers have higher inductance and work better with a 60hz crossover point though.
The complicated thing is that you can have a higher Q system that is just as accurate as any LLT, it just takes larger drivers in larger cabs. The IB is the ultimate manifestation of this. There are no cabinet influences on the driver at all, yet they have increased system Q.

Ive no doubt that an LLT can sound the same at a higher Q sealed system, but that would need a specifically tailored driver that is suited to cabinets as large as the ones we see in LLTs. If I was ever to consider an LLT style sub for myself, I would probably experiment using an IB driver to begin with. The low QTS drivers we typically see just arent suited IMO.
 

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Do they even still make the Re XXX?
 
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