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Help ... Totally stuck (subwoofer topic)

Hi, folks. Hoping you can help me here. Earlier this year I got a JL Audio e110 sub for my two channel system. Using a pre/power combo - no receiver. Set up is B&W N804 speakers, BAT VK-3i preamp, and MF A300cr power amp (225 wpc). Old equipment, I know, but it sounds really good. There are two issues which I can't quite figure out.

First, I use the second output on my preamp into the line level input on the sub. I DON'T use the sub's line out into the power amp because the sound becomes very thin and unengaging. Essentially, I am running the mains full range with the sub doubling the bass. JL Audio specifically recommends that the sub's line out be connected to the power amp's inputs for a better sound. However, that's not occurring in my system. Any thoughts on why this is happening?

Second, in the configuration I use, I find that turning off the internal crossover actually brings a fuller, louder sound with more detail. Am I unknowingly biamping with the sub used this way? Seems like a waste not to use the crossover, so I have no clue as to what's going on.

I am really stumped by this, and could use your collective help. Thanks.
rlb61
8 responses Add your response
keithtexas
352 posts
 
Does the new sub have an adjustable crossover level feature? If so, you should set the level of the crossover fairly low (25Hz), which would then (I think) use the sub's crossover to send only signals >25 Hz to the main speakers.  There are more technical sub experts on this board so you should get a much better answer than I can provide.  Good luck
yogiboy's avatar
yogiboy
5,464 posts
 
If you want to use the high pass on the sub you should use just one pair of outputs from the preamp into the inputs on the sub then the outputs of the sub to the inputs of the amp. There is no need to use the second pair of the outputs from the preamp. BTW, some prefer running the main speakers full range without the subs high pass filter!
rlb61 OP
742 posts
 
Yogiboy ... I understand that would be the case IF I were running it in that configuration. Problem is, it sounds weak and lifeless when run that way. That's why I'm running the secound pre-out into the sub directly. The first pre-out runs into the amp.
yogiboy's avatar
yogiboy
5,464 posts
 
Have you tried different low pass settings?
rlb61 OP
742 posts
 
If you mean xover frequency, yes. No meaningful difference. What really mystifies me is why the sub sounds better without the xover engaged.
yogiboy's avatar
yogiboy
5,464 posts
 
Like I said some prefer running the main speakers full range. I use my sub without the high pass filter. Some speakers blend better with the sub without the use of the high pass option. It all depends on the speaker that you are using with the sub! 
bdp24's avatar
bdp24
9,412 posts
 
Could be a phase issue. Brian Ding discusses this somewhat complicated issue in the technical section of the Rythmik Audio website.
rlb61 OP
742 posts
 
UPDATE ...

As it turns out, both the xover and the phase needed to be re-set once I switched to using the sub's line out. I set the xover to 80Hz and phase to 40 degrees. Now, it sounds really awesome. Much greater headroom for the highs and mids, and the e110 really digs down deep without any bloat. Those things, coupled with my having put in a set of new tweeters, is really making me love this new sound.
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