Originally Posted by bass addict
Not to derail this thread, but what is the difference between an LT and say a SMS1/2496/etc?
With an SMS one you would be cutting the upper frequencies (I'm guessing around 30 hz) to compensate for the low frequency roll off. This eats up headroom in the upper frequencies, but is generally less drastic than boosting down low.
An LT adds a "low shelf boost", which eats up headroom as well, does in not?
So what would be the benefit of using this over the other options out there?
A bi-quad filter (L/T) affects the knee before the shelf. A simple shelf cannot. The shelf requires additional filters to do this which, IMHO, requires some additional skill to do properly and introduces phase error, which may adversely affect multiple sub systems.
The L/T is an analog solution. The MiniDSP, Berry EQs, SMS, etc., require an analog-to-digital-to-analog conversion. Most everyone assumes that the AD/DA converters in a $150-300 piece are high quality which is far more optimistic than I am.
The L/T analog circuit can be built with whatever values of DC blocking caps the builder prefers. That means it can easily be built flat-to-2 Hz (under the radar of most AVR+Amplifier roll off profiles), unlike the roll off of the digital solutions whose analog output stages have wildly varying (and mostly unknown) roll off points and orders, none of which approach flat-to-2 Hz.
Regarding so-called low inductance, high sensitivity driver based systems vs so-called inductance hump, low sensitivity driver based systems, it is completely irrelevant whether you choose one and affect a cut on the top end or choose the other and affect a boost on the low end. The end result comes down to displacement capability. Once that capability is maxed, the system is at its limit and the only way to go further from there is to change the systems frequency response by selectable preset curves or severe limiting (less top end cut or less low end boostP.