Excuse the questions of the newbie, but...
Although i have an electronics background and a reasonable understanding of audio (and im slowly getting there with AV) - i don't understand why you would want to use both the high and low level inputs to an active subwoofer at the same time? (and why the manufacturer would provide this option - set up the input circuits to allow them both to be used at the same time without causing issues, i saw the seperate level controls for the inputs on the pic at link below).
There must be some sound improvement, or further options available by doing this but after reading the posts in this thread i still dont understand how this works or what exactly the improvement might be. It seems to revolve around crossover frequencies and integrating the bass between fronts/sub - but how?
Normally i would expect the differnet inputs to be as follows:-
Low level inputs: Normal connection for signal from a decoder on an AV amp. Crossover can be set up on decoder, or left at a high frequency on the decoder (or bypassed?) and use the sub's built in crossover to fine tune lower.
High level inputs: If you are using traditional HiFi seperates comprising of just the amp and front speakers (no AV amp or crossover path) or if you want to bypass the AV amp decoders crossover(?).
For an AV system (with decoder/crossover) using the high level input would likely give more signal degredation as it passes
through an extra amplifier and then voltage level reduction circuit at the sub input before reaching the sub's own built in amp (although probably too small to notice?).
Can anyone provide any information on this and how/why it works?
Can you do this with any normal high quality active sub, or is it an extra feature on only some sub's?
Cheers, Brimstone (Mark).
P.S. Found this info @ homecinemachoice.com.
(
http://www.homecinemachoice.com/tes...ice.com/testbench/Subwoofers/REL/RELQ150E.php)
Connectivity is fairly comprehensive, as is the impressive number of controls on offer. High-level inputs are provided but REL is sticking with an airtight Neutrik Speakon terminal, which means you will have to use the cable and plug supplied. The Q150E does not offer any high-pass filtering, so bear that in mind if you plan to use the speaker hook-up method. Personally, in home theatre speaker systems I much prefer low-level signals since you can use the bass-management in your decoder, and they are accommodated by way of a pair of standard phonos - one of which imparts a 12dB gain if, as unlikely as it may seem, the output of your processor or receiver is insufficient.
Additional controls include a phase switch, an infinitely variable low pass filter (between 26Hz-106Hz), which can be defeated if you're using a decoder crossover, and a control marked 'Slam' and 'Depth'. The 'Slam' position will increase the SPL output between 40Hz-150Hz but at the expense of bass extension, whereas the 'Depth' mode affords maximum low frequency output and a near flat response.
HCC Practical Tip
The Q150E allows high- and low-level connections to be used simultaneously, but in the real world, juggling the two may prove tricky unless you're willing to set your decoder up with large front L/R loudspeakers. Also, be sure that your hardware doesn't send low frequencies to the front L/R loudspeakers and the subwoofer output when listening to matrix or stereo material, otherwise you'll be stuck with unwanted bass doubling.