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My Grotto Subwoofer Experience, Finally Best Possible Blend

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beethovenfan

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Main speakers: reQuest
Processor: Sunfire Theater II
Center: Mirage: OM-C2
Surround: Montage

I listen to stereo music most of the time so I want the two-channel to work at its best. I play DVD movies also, therefore this is a 2-channel/multi-channel system.

I initially connected the subwoofer output to the LFE input, both movie and music have rich and nice base, but, I could tell where the subwoofer was located (behind one of the main speakers, near the corner of the walls). I did some research and found out the problem:

Sunfire Theater II has an internal crossover from 80-120Hz and routes anything below the set crossover point, say, 80Hz, even in stereo mode, to the subwoofer, so apparently it is not a "pure" LFE output. Since the reQuest goes pretty low, I really do not want the Grotto to jump in at 80Hz as the Sunfire processor puts out a bass output even in stereo mode via its subwoofer output, so intead of conneint the subwoofer output from the processor to the LFE input on the Grotto, I ran the interconnect between line out L & R on the processor to the line in L & R on the grotto and set the low pass filter at 30Hz. Played some base-rich fine music and the ingeration is beautiful. While turning the low pass filter up, I started to notice the obvious location of the subwoofer while turning up the low pass filter toward its highest setting. I feel it is hard to tell the location of the subwoofer when its low pass filter is set below 45Hz. I set the processor's internal crossover at 80Hz and center and rear speakers at small, so all the bass below 80Hz from these channels in addition to LFE signal from all channels is rounted to the front speakers. Works even better than the subwoofer out to LFE connection setup. Base is great and subwoofer truly disappears. Also, I am not wasting the high-quality built-in crossover inside the Grotto that may be better than the one inside the Sunfire processor.

ML's recommended solution for 2-channel/multi-channel: connect both the line out L & R AND LFE/0.1 output to the subwoofer, be careful you really need a processor that has a "pure" LFE/0.1 output (not just a subwoofer output, not sure if such a processor exists) that does not put out signal in stereo mode otherwise the base from the subwoofer may not blend well with that produced by the main speaker unless the processor has a lower crossover to start with. Plus, two sources of signal are being fed into the sub simutaneouly when in HT mode or when the LFE output is actually a subwoofer output.

All together, I spent no less than 10 hours over a period of several days to get the Grotto working best for my needs. I am not sure if I did it correctly but my ears so far are happy.
 
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Craig

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Are you sure the Sunfire Theater II does not have a setting to allow adjustment of the sub freqs? To set the sub on my B&K Ref 50 I had to break out the manual and dig through the on-screen menu to find it. You may have to change the sub settings to a different mode before you can get into sub crossover mode within the menu. You may need to set the speakers to "Large" and not small to enable a different sub freq range. The 80Hz-120Hz setting is for small HT speakers with little to no lower bass.

I do know the TGIII (which is similiar but newer) allows you to set the sub freqs in a range of 40Hz to 80Hz. See pg 41 of the TGIII manual.
 
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beethovenfan

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Yes, it is true, the Sunfire Processor II has an internal crossover adjustable between 80Hz and 120Hz while the newer Sunfire went down to 40Hz. BTW, to bypass the the LFE input, the subwoofer mode on the processor is set at "off" and of course the front mains are set at "large". It seems it works very well for multi-channel without compromising stereo and vice versa, the low low base is still there but its location can not be identified from listening position and even from way off the center. Most of the time quite, but when fed with sub-30Hz, it works really hard, to see how hard it works physically, I put my hands on the cone with grill off, it's dancing as vigorously as demanded with the sub-30Hz signal. It seems to me the corssover on the Grottos is really accurate. Before doing this, I was thinking of adding another sub but now it is unnecessary. My room width is 16 ft. My experience also confirms that even for big main speakers of high base capability such as reQuest, a high-precison powered subwoofer is a must have, for stereo or for HT.
 
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