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Discussion Starter · #1 ·
My (modest) setup:

Onkyo TX-SR608

Front: Polk OWM3

Center/Surround/back: Polk RM7

Sub: Polk PSW505 connected via "subwoofer" port on the subwoofer input side


I just finished finally getting the surround speaker ran last night and tuned my system. After tuning was complete I watched Avatar (I bought it over a year ago but promised myself I wouldn't watch it until I had my surround sound complete) and it sounded amazing, the bass was very clear and intense.


Today I got to thinking about the LFE port in on the sub and decided to try to learn more about it and whether I should be using it or not. My understanding so far is that it is for a discreet subwoofer channel and if the content doesn't have that channel, I won't hear anything from the sub. The problem is that I use my setup as a general purpose system, not only is it for movies but also for music from CDs/HTPC/IPod/ect as well as regular television. Naturally I don't want to lose my subwoofer for stuff like this, so I figured the LFE input wouldn't be the way to go for my usage. I guess the only other choice is to switch the inputs and sub settings any time I switch between content that does or doesn't have the LFE channel? What do I lose by not using LFE?


BTW, my true "Theatre" is down the road, I have many other projects I want to get done before I start pouring money into that pit. I'm guessing this is the kind of setup that I would use an LFE channel for?


Thanks,

Dan
 

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Your AVR should allow you to set your speakers to "small" and route all the bass below the crossover point (say, 80Hz) from those speakers to your sub (via the AVR's Sub/LFE output and the subwoofer's LFE input).


The sub will then handle all the bass from all the speakers PLUS any LFE signal. So, when watching movies, you get the bass + LFE; when listening to music or other audio, you still get the bass.
 

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Discussion Starter · #3 ·
Thanks! There's no size setting for the speakers but I can adjust their bottom end frequency (effectively the same thing).


This is exactly what I thought originally, but then I read this blurb in the manual:
Code:
Code:
Problem: The subwoofer produces no sound.
Solution: When you play source material that contains no
information in the LFE channel, the subwoofer produces
no sound.
Make sure the speakers are configured correctly.
I'm at work currently so I can't test this right now, I guess my best bet is trying when I get home. I'm hoping someone with experience with the Onkyo TR-SX608 can chime in and clarify this.


Edit: On second thought, I may be misunderstanding the manuals formatting, I'm refering to the LFE part on page 67 of the TX-SR608 manual .
 

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If there is no LFE channel in the source, the subwoofer will produce all sounds below the cutoff frequency of all attached speakers. If your main speakers are set to Large, and you are listening in stereo mode, the subwoofer will not do anything.


The Audyssey calibration should have set all of your speaker crossovers correctly, probably around 100-120 Hz for the speakers you listed. That means the sub should be reproducing all sounds below 100 Hz for all sources.


I'm not sure what the "LFE in" you're talking about is.
 

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Oh it's on the sub itself. The "LFE In" port is essentially the same as the red/white input ports, apparently. The only difference is that the red/white are meant for full-range signals and are thus subjected to a low pass filter. The LFE in assumes it's only getting low frequency signals and doesn't do any filtering at all.


Either is really fine to use, but go ahead and use the LFE In port.
 

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What are the settings on the subwoofer amp? What are the knobs set at? How are you hooked up to your subwoofer?


What are the crossovers set at to your speakers?

-OWM3's = set to 100hz

-RM7 center = set to 130hz

-RM7's = set to 140hz
 

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In a "pure sense".


LFE goes strait to the "volume pot" on the plate amp.


RCA red/white go through the crossover pot first...then the volume pot.


Since your AVR is already doing the "mixing", there is no reason to involve the subwoofers crossover, so use LFE.
 

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The Polk 505 sub has a couple different connection options: speaker level, line in R/L (filtered) and LFE in (unfiltered). The filtered input applies a low pass filter to the signal set by the dial on the back of the sub. The LFE in (unfiltered) applies no low pass filter to the signal. It has nothing to do with a dedicated LFE channel. If you are using bass management in your receiver, use the LFE in. You don't want overlapping filters.


Here is the manual:
http://www.polkaudio.com/downloads/m..._505Manual.pdf


Now, for the Onkyo receiver. If you set your speakers to full band (same thing as large) and double bass is off, the sub will only reproduce what is on the dedicated LFE channel in a multi channel mix. So if you are playing a stereo source, like a standard CD, the sub will be doing nothing. If you turn double bass on, bass will be reproduced by both the front speakers and the sub. I could not find the cutoff frequency with double bass turned on. If you set a crossover frequency on the speakers, anything below that frequency will be sent to the sub instead of the speakers.


-Mike
 

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Based on the AVR's manual (pgs. 41 and 42), start by setting:

- all speakers to 80Hz (not "Full Band");

- subwoofer to "yes"';

- LPF of LFE to 120Hz; and

- "Double Bass" to 'no'.


Run a coaxial (RCA-to-RCA) cable from one of the subwoofer pre-outputs on your AVR to the LFE input on your sub. Turn the crossover on the sub itself (it's labelled "Low Pass") to max.


Re-calibrate, and you're good to go!
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by crazyrob425 /forum/post/20838392


What are the settings on the subwoofer amp? What are the knobs set at? How are you hooked up to your subwoofer?


What are the crossovers set at to your speakers?

-OWM3's = set to 100hz

-RM7 center = set to 130hz

-RM7's = set to 140hz

Sadly my receiver doesn't offer that fine grain of a choice. I can do 90/120/150hz (and others but they're irrelevant here).


-OWM3's = 90hz

-RM7 center = 150hz

-RM7's = 150hz


The Audyssey calibration actually set all of the RM7s to 120hz, despite that being below their rating.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by eljaycanuck /forum/post/20838525


Based on the AVR's manual (pgs. 41 and 42), start by setting:

- all speakers to 80Hz (not "Full Band");

- subwoofer to "yes"';

- LPF of LFE to 120Hz; and

- "Double Bass" to 'no'.


Run a coaxial (RCA-to-RCA) cable from one of the subwoofer pre-outputs on your AVR to the LFE input on your sub. Turn the crossover on the sub itself (it's labelled "Low Pass") to max.


Re-calibrate, and you're good to go!

Thanks, this sounds great except for the fact that 80hz is well below the capability of the RM7 speakers. Also, why would I want 40hz of range that would go through both the speakers and sub? Or am I misunderstanding that part? I'm currently at 90hz LPF and 90hz for the OWM3s.
 

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80Hz is the "generally recommended" point for crossing over your speakers to your subwoofer and, as I indicated, that's where you want to start (but not necessarily end). When calibrating, adjust the crossover point upward as required until you get the best blend of sound between your speakers + subwoofer.


The LPF for LFE setting determines the range of LFE frequencies that get sent to the sub. (It has nothing to do with the bass that gets crossed over from your speakers to your sub.) Since the LFE channel can contain content that goes up to 120Hz, there's no reason to set the LPF for the LFE channel to anything less than maximum.


--- Edit ---

I took a look at the AVR manual just now, and at the Polk website for the speakers' specs:

- The manual says the AVR offers per-channel crossover settings (I wish mine did!) at 40/50/60/70/80/90/100/120/150/200Hz.

- The specs for the speakers are:

i) OWM3: 80-25KHz (w/ -3dB at 100Hz)

ii) RM7: 95Hz-22kHz (w/ -3dB at 130Hz)


In that case, I suggest you start with the crossover:

- at 100Hz for the OWM3s (and also try 120Hz); and

- at 120Hz for the RM7s (and also try 150Hz).
 

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Quote:
Originally Posted by DracoDan /forum/post/20839034


Sadly my receiver doesn't offer that fine grain of a choice. I can do 90/120/150hz (and others but they're irrelevant here).


-OWM3's = 90hz

-RM7 center = 150hz

-RM7's = 150hz


The Audyssey calibration actually set all of the RM7s to 120hz, despite that being below their rating.

If Audyssey set the speakers to 120 Hz, do not lower it. It has measured the in-room response of your speakers and determined that the -3 dB point is slightly below 120 Hz. Therefore, it has set the speakers to 120 Hz crossovers. If you lower the crossover, there will be no Audyssey room correction applied below 120 Hz. The only correction Audyssey could apply below 120 Hz would be boost. Since your speakers can't reproduce that signal anyway, there is no benefit to boosting the signal, and there is potential danger to your speakers and/or amps.


If you want to *raise* the crossover above 120 Hz, that's fine. Just be aware you might have issues with subwoofer localization. Make sure the sub is in the front of the room and you can minimize the impact of localization. Also, make sure your sub can reproduce *high* enough to effectively play back those higher frequency signals. (Edit: I just looked at the spec's for your sub on the Polk website. It lists the FR as 23 to 160 Hz, but it doesn't list a -3 dB point on either end of the range. I suggest you stick with 120 Hz for all your speakers just to be sure your well within the capabilities of your sub.)


Alternatively, add another sub.


Craig
 
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