Using a soundbar as a LFE channel subwoofer with analog->digital conversion via PC

[seoulwithsoul]

Hello,
I am a complete newbie to this field so please be patient with me even though I may sound like an idiot. For my desktop 5.1 setup, and a possible future upgrade to a living-room theater in the long run(a few years later?),I got a 7.1 audio receiver with five nice speakers(about 80~100w/8ohm each) meant for home theaters. The speakers themselves are very loud and on my receiver I run them at -20 db at day, -25 to -30 db at night. I live in an apartment, so possible cross-floor noise is a big issue for me. The problem is with my "subwoofer". It is an LG soundplate LAP-255U. According to its specification, it has a total power of 120w, with two front speakers at 20w/8ohm each, two surround speakers at 20w/8ohm each, and two internal subwoofers at 20w/4ohm each. It advertises of having "two subwoofers" and using "dual-neodymium speaker" which sound somewhat appealing. When seen from below, it does have two large speaker cones about 5 inches each that seem to be the subwoofers it's talking about. Personally, I am satisfied with the desk-shaking performance of this soundplate and am afraid that something more shaky like a room-shaking subwoofer may reverberate through the floor and cause noise complaints.

The problem is that when I converted to the 7.1 receiver, there is no direct connection between the receiver and the soundplate, as the soundplate only has an optical input and the amplifier has no optical outputs. So my solution was to connect the subwoofer pre-out of the receiver to the PC sound card with a RCA cable, and then connect the sound bar from the PC sound card with an optical cable. When I run speaker configuration tests using Windows PCM, Dolby and DTS, the LFE channel does work and generate sound, but I'm not sure if the sound is sufficiently large. I am not sure if this LFE setup is working because I don't think I'm getting the desk-shaking experience as often as before or if at all after changing to the receiver setup. When testing the LFE channel, changing the volume of the sound plate does not seem to affect its loudness, and I can't seem to find any test files with varying LFE channel volume to test whether the sound plate can generate varying LFE channel volume. When I test it on movies encoded in Dolby Digital Plus that provide quite a lot of booms, like for example Saving Private Ryan, muting and unmuting my sound bar doesn't seem to make any difference.

So my questions are,
1. Are there any test files with varying LFE volumes to test if the LFE channel is working correctly in terms of volume?
2. Is there a problem with my receiver analog connection output->PC->soundplate optical input connection? Is this viable at all, or is there something wrong in the receiver setting or the PC setting?
3. If there is a problem with this connection, can a direct analog-to-digital converter module work?
4. Should I just give up on this soundplate and buy a proper subwoofer and just turn its volume down?

Any response would be much appreciated.

 

[Leemix]

Dont do this. It doesnt work as a subwoofer, in addition to many other problems.
What are the speakers you have for the home theater? - chances are they will do a better job on the bass then the soundbar.

You may not need a subwoofer if you are afraid of bothering the neighbours but if you get one mechanically disconnect it from the floor. This will reduce the bass leaking to them but impossible to know how easy they will hear things, not just the low end.


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[Leemix]

Just to note i play even less loud then you do, most tv watching is between -30db and -40db. Bluray movies rarely over -25/-27db.


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[TLS Guy]

I don't think you plan will work.

I have not had a sound bar system on my bench, but have heard a view. Sound bars are a huge fraud. They have small and pretty horrid little tinny speakers with not even low mid or upper bass. The there is a boomy splashy sub that makes you think you have bass.

So I would bet there is no to little sub low end bass in those systems and the subs cross somewhere between 250 and 400 Hz. This is much higher than a receiver would.

So it is my guess that those subs are actually incapable of producing much from the LFE sub out of a receiver.