RM 6880,Onkyo 805 - LFE frequency

jingoboy_78

Hi all,

I am using a RM 6880 satelite 5.1 speaker system paired with onkyo 805.I have connected the sub using the polk way(using the speaker level inputs).Also I did the auto calibration using the receiver microphone and it detected all my settings except for the LPF/LFE frequency.
You can find this in the speaker menu => Speaker settings
Does anybody know what should be this frequency.I guess I have options from 80 HZ(THX), 90 HZ, 100 HZ, 120 HZ.I am using 100 HZ right now and its sounds ok.Any body knows how to tweak this system better? What should be the volume of the sub(can I turn it all the way up?) right now I have 3/4th of the volume.
Any body knows how to tweak this system better?any suggestions are welcome

Sorry if this is a dumb question and please help as I am a newbie.

Thanks,
Jingo.

Face

I would try 100 or 120. How about letting the receiver run auto setup?

jingoboy_78

I ran the auto set up and it defaulted to 80hz (THX).I think the receiver doesn't detects the subwoofer as I have connected sub using the polk way.So I have to set up the frequency manually.Dont you think so?

Thanks for the reply Face!

Face

Polk doesn't have a manual for this model online. Did yours come with one? What did it recommend?

jingoboy_78

I dont have a manual too But they gave me a hook up diagram which I followed.And also I read this article(check the URL page 18) and just followed that one.I followed the option A in the hook up diagram

http://www.polkaudio.com/downloads/newspaper/issue11.pdf

Thanks again!

Face

From the article:

What do I do with the Sub Out and LFE
Jacks, you’re asking yourself. Ignore them
when you’re using a compact audio system,
that’s what. When using this hookup
method, choose “No Subwoofer,” or
“ OFF,” even though there’s your sub
sitting on the floor plain as day. Trust
me here, ALL of the bass will get to
your subwoofer.

EDIT: I'm not familiar with this method and have never tried it. I would try searching, I'm sure there are others who have had the same question before.

jingoboy_78

ok go that..But the following is the speaker config menu what I have.When i run the auto cali i guess it detects all the settings except for the LFE frequency because it doesnt detects the subwoofer...

http://images.google.com/imgres?imgurl=http://www.audioholics.com/reviews/receivers/onkyo-tx-sr805/DSC02615.JPG/image_mini&imgrefurl=http://www.audioholics.com/reviews/receivers/onkyo-tx-sr805/tx-sr805-setup&h=150&w=200&sz=9&hl=en&start=2&sig2=lgCRnhtVswqnodZbu0e0Kw&tbnid=yPUKCga2FiPTaM:&tbnh=78&tbnw=104&ei=s2jqR6GUKI_eigGkr_jnCw&prev=/images%3Fq%3Donkyo%2B805%2Bspeaker%2Bset%2Bup%2Bmenu%26gbv%3D2%26hl%3Den%26sa%3DG


I am running a 5.1 set up and have the following settings

I have

Subwoofer - NO
Front - FULL BAND
Center - (some frequency detected by auto cal)
surround - (some frequency detected by auto cal)
Surround back - NONE
Surr back ch - NONE
LPF or LFE - 100hz( this is the one I want to confirm)

Thanks again Face!

kuntasensei

Want an in-depth answer? HERE YOU GO!

On the 805, the "LPF OF LFE" setting has nothing to do with the crossover points of the other channels (which are set independantly). This setting is basically a brickwall filter for the LFE channel ONLY for systems that are THX certified (i.e. where the subwoofer is not designed to produce significant output above 80Hz since 80Hz crossovers are expected all the way around by design). The Onkyos default to the THX setting of 80Hz for this, and it is not changed during the Audyssey MultEQ XT setup. I'll say again: This does NOT affect redirected bass from the other channels; it is just a low pass filter to truncate the upper end of the LFE channel.

Ideally, you always want to set LPF of LFE to 120Hz unless your subwoofer can't handle material up to 120Hz (and if it can't, you bought a crappy subwoofer). The LFE channel is called the .1 channel because it contains 1/10th of the bandwidth of the other channels (i.e. only up to 120Hz, whereas the other channels contain the full range of 20Hz-20kHz). Now, the THX conceit is that while the LFE channel is filtered at 120Hz anyway, little above 80Hz is placed in there by audio engineers doing the sound mix to prevent the subwoofer from being directional. This conceit, however, forgets one major thing: the harmonics of a sound create the "tone" we perceive, especially where bass is concerned.

Now here's the thing: 99% of people will not hear a difference between an 80Hz setting for this and the 120Hz setting, because they won't know what to listen for. A good example of a disc where this tonality comes into play is the opening Sauron scene of LOTR: The Fellowship Of The Ring. When Sauron is killed, there's a sweeping bass tone that is primarily in the LFE channel (though directional bass is in the main channels as well). If you set the LPF of LFE to 80Hz, you should notice a subtle but noticeable difference in the tone that this sweep has as opposed to 120Hz. Will it greatly affect your enjoyment? Probably not. As I said - most people won't notice. But from a strictly technical standpoint, you should set this to 120Hz to ensure that your subwoofer is properly reproducing the full range of the LFE channel.

As far as the way Polk says to wire the RM6880, the only reason I can think of that they would do this is if they're using a gradual high-pass of the L&R satellites to maintain directionality of bass, as opposed to the usual steeper slope of the digital crossovers in a receiver. This may also be because most consumer AVRs use a 80Hz crossover and only offer "LARGE" (i.e. full band) or "SMALL" (i.e. 80Hz) settings. Given the small size of the satellites in the RM6880 package, you certainly wouldn't want to send significant bass down to 80Hz to them.

If I'm being honest, I disagree with their wiring diagram when paired with this particular receiver (or any that allows independantly adjustable crossovers, especially where they're gauged during the auto-setup as Audyssey does). Audyssey's MultEQ XT on the Onkyos does a pretty good job of detecting any -3dB point so long as it is above 80Hz. The Onkyos set any speaker that extends down to 80Hz to FULL BAND, even if they shouldn't. Audyssey pushed for Onkyo to use 40Hz for this threshhold, but that was ultimately Onkyo's call. One big reason that I disagree with their wiring diagram is that they're running the L&R main channels through an active crossover network, which can introduce group delay (which alters the optimal speaker distance/delay settings). Ideally, you would want the receiver to handle these crossover points at a digital level so that there's no group delay involved (which is one of the advantages of AVRs with per-channel independent crossovers). If you're running the mains the way Polk recommends, however, there's no phase variance between the mains and subwoofer since bass is being handled through the same crossover network.

Having said that, don't go out of your way to re-wire it now. While the crossover network in the RM6880 might introduce delay, another thing that Audyssey does is measure the acoustic distance as opposed to physical distance, taking into account any delay introduced by the system. This is why, after running MultEQ XT's auto-setup, the measured speaker distances may differ slightly from the actual physical distance you measure in the room. In the case of systems where the subwoofer is wired seperately from the mains, you may even notice a vastly different setting for the subwoofer than its physical distance, since MultEQ XT is attempting to align the phase of the subwoofer and main channels. Keeping the subwoofer in phase with the other speakers is complicated by placement, especially if your sub is placed within 3-5" of any wall (which can cause phase reversal or reverberation that causes the wall surface to act as a passive radiator, throwing off the time the first impulse of sound arrives at your main listening position).

That was probably WAY more than you ever needed to know. If you want any advice on proper setup of Audyssey MultEQ XT, let me know. Careful mic placement during the setup can make a VAST difference in the equalization filters that Audyssey calculates.

jingoboy_78

Hi kuntasensei

Thanks for your explanation!..Well I got most of the info..Since I am a newbie its all new to me.

Well what if I tried to hook up the sub using Sub pre out(using RCA) from the receiver and get rid of the speaker level connections, and re run the auto cali to set it up with the sub woofer (speakers = SMALL and sub woofer = YES) Will that give a more deeper bass.And also few more things..

1) My powered sub doesn't have a manual cross over frequency set up on its back.I guess the crossover is in built into the sub by default to some frequency.I guess the crossover frequency for 805 will be handled in the auto cali..So will that cause a double filtration?

2) I am a music person and would like to hear more music.So if I am in the stereo mode how far the sub out from the amp will help me.Do I still find the bass what I expect in music too as same as in the movies( since the movies are in 5.1 I guess it has the LFE in th .1 channel) But for stereo do I still get the bass from the sub out from the receiver?


Please clarify..Again thanks a lot!
Jingo

kuntasensei

There will very likely not be much of a perceptable difference between the two wiring methods. My preference would be to hook all speakers up to the receiver and avoid using the crossover circuitry on the subwoofer, letting the crossovers be handled at a digital level. However, as I said, I doubt you'd hear a huge difference between the two methods, especially after running Audyssey.

1) You don't need a crossover control on the sub. If you use the RCA inputs, there's no filtering being done. If you use the speaker-level connections, the crossover for those small satellites should be above 100Hz, so you aren't losing much from the LFE channel. There's no cascading of two crossovers in that case, EXCEPT if the satellites for center and surround are set to a higher crossover point than the unspecified crossover that the speaker level connections use. That's part of why I would avoid using the speaker level connections altogether and let the 805 handle all the crossovers - Polk doesn't publish the crossover point and slope they use on the RM6880's crossover network.

2) You should still get roughly the same bass for music with either connection method. With the 805 in stereo mode, bass from the mains is crossed over to the subwoofer at the same crossover point for surround modes. The only modes that WOULDN'T give you as much bass would be Direct or Pure, which would sound better with the speaker level connection method, only because it is then treating the mains as large speakers.

Something to clarify: "LFE" does not equal "subwoofer" or "bass". The LFE track is a seperate .1 track for low frequency effects in digital surround tracks. This is entirely different from the bass sent to the subwoofer by the receiver's bass management (i.e. the bass redirected by the crossover points set during the auto-setup). Stereo music has no LFE channel... but if there's bass below the crossover point in that track, it is sent to the subwoofer with the receiver in Stereo mode or any of the 2-channel to 5.1 modes (i.e. DPL-IIx, THX music, DTS Music, etc.). The signal sent to your subwoofer is a combination of redirected bass from the other channels and the LFE track when one is present.

Another thing you should be aware of with the 805: Audyssey MultEQ XT's equalization aims for ideal flat response across the entire frequency range. I mention this because MOST people are accustomed to bloated bass with room-induced gain (which normally shows up in the 50-70Hz range, making bass in music sound louder than it should). Because of this, people who hear a system set for flat response (as Audyssey does) may perceive this as being "lacking" in bass with music, despite the fact that it is actually a more accurate representation of the source material. For digital surround tracks, this is ideal, since these soundtracks are based on a set of standards where the original audio mixers have a similar response from the system used to do the mix (so having that same response in-home lets you hear the track as the mixer intended). Music, however, has no consistent mixing standards... so the original mixes are rarely done on systems adjusted for flat response like movies are. After running Audyssey, if you like the way it sounds for movies but not for music, use the TONE controls to add bass. This raises the 50Hz region in the left and right speakers without altering the equalization done by Audyssey, which means you can tweak it for your musical tastes, then set it back to 0 for accurate reproduction of movie soundtracks.

jingoboy_78

Thanks again Kun!..I will try rewiring using the RCAs this weekend and let you know how I feel..In the mean time any suggestions are welcome..Please feel free to advise as I am a newbie ..

Thanks a LOT!!
Jingo

kuntasensei

Here's a link to all the advice you might ever need. This is for the 705, but the 805 isn't horribly different. Post 2 in that thread is my FAQ on proper Audyssey setup and usage, which should give you plenty of info. Enjoy!

jingoboy_78

Hi Kun,

I reconnected my whole set up using the sub preout from the receiver..Sounds almost the same..Only one thing is that I got rid of too many wires..Now I am doing a Y splitter from the receiver pre out to the the Sub..It sounds good.Guess I will stay with this set up...Well my sub kicks when I crank the volume to 3/4th..I can feel the LFE effects very much...Movies sound awesome and when I play music(have the neural THX 5.1 on. - sounds nice to me) from my itunes ..they sound very awesome too...Thanks for all your advice and help..

Jingo..