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.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.
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"?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.
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.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"?
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.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.
Check out the RE Audio XXX 15" D2 with 2000W in 18 cu. ft tuned to 12Hz. 54mm xmax is huge.The best currently available 15" for a LLT would be the T.C. Sounds LMSR-15.