Crossover settings and LFE advice

[superedge88]

http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/38_LFE.pdf

"The LFE channel carries additional bass information to supplement the bass
information in the main channels. The signal in the LFE channel is calibrated
during soundtrack production to be able to contribute 10 dB higher SPL than the
same bass signal from any one of the screen (front) channels. Even if all three
screen channels are active, enough bass could be delivered by the LFE channel
alone to bring the theatre’s subwoofer into acoustic balance with the screen
channels. This allows filmmakers to unburden the main channels by diverting the
strongest bass to the separate LFE channel, as needed. Under the most demanding
program conditions, where the bass is fully loading the left, center, and right
channels, the LFE channel could increase the bass intensity by up to 6 dB."

Seems that dolby is saying that while it may mix in LFE information with the mains, that is is at a drastically lower level.

[Chris A]

Seems that dolby is saying that while it may mix in LFE information with the mains, that is is at a drastically lower level.

Actually, I believe what it is saying is that the LFE channel must be correctly mixed with the main channels by AV preamps/receivers. The link to the avsforums (above) talks about AV preamps that have trouble doing this and other formatted data streams (DVD-A, SAC-D, etc.). Thankfully, my AV preamps are not on this list...[]

Chris

[DU73]

so when on pre/avr we select Bass output as ‘sub only’ is what we are saying that we are sending 2 separate signals to Sub being LFE and Bass, which Bass would have normally been sent to speakers but have opted for Sub only? my crossover on sub is 120hz, crossover on pre/avr is 60-80hz, speakers set to small..

and is also what we are saying that by doing this we are lowing the levels of LFE and Bass?

[Chris A]

I think that you're best bet in understanding the situation is to download the user manual for your AV processor/receiver. I think that in general, most AVPs/AVRs will send whatever LF content that comes its way to the Subs below the front or center or surround crossover frequencies that you select. It makes sense to do it that way. Why would you send only the (now becoming obsolete) LFE-only signal to the subs? Unless someone thinks that they're factoring out IMD due to the high-gain LFE signal. LFE was a patch when it was born, and is still a patch awaiting better motion picture technology to support LF content that it was not designed to support LF "back in the old days".

So to attempt an answer to your question: my guess is that your AVP/AVR is sending everything below 60-80 Hz from the summed front, surround, and center channel content (that is, whichever channels are set to "small") to your sub, with +10dB gain LFE effects summed in, too.

I'm assuming that you've got a separate low pass filter control on your sub that you are setting above the highest crossover frequency coming on the AVP/AVR for all channels, which is what you should do. If you can turn the sub's low pass filter out of the circuit, then you will be avoiding yet one more analog filter in your electron stream that you don't need, with its attendant phase shifts vs. frequency.

Chris [:^)]

[DU73]

I'm assuming that you've got a separate low pass filter control on your sub that you are setting above the highest crossover frequency coming on the AVP/AVR for all channels, which is what you should do.

i sure do, back of sub crossover is set to the highest [Y]

thanks for answering the question. i find all this Bass stuff very intersting and love looking at the pretty graphs..

[mistermoravec]

what should my settings be? on the receiver? on the sub-12 on the back?

[Frank1938]

what should my settings be? on the receiver? on the sub-12 on the back?

The company recommends crossing over at 80hz. The bass below 80 is sent to the subs along with the LFE. Set the sub to the highest crossover frequency if you don't have a bypass switch on the subs.

[carloslara]

very nice discusion post on the forum.

i have a couple of tech question, since i've doing invesment on equipment, that i desire to be now my hobbie.

my current setup is> front RF82, Center RC62, Rear Surround RS52, Back Rear Surround RS52 , with 2- RT12-D SUBWOOFER, using my Denon Avr-2310.

i was reading on a great dedicated article on AVSFORUMS, about the right setting to each setup, and basics tips for accomplished or archieved good or excelent reproduction of the media. they told me to not use my front speaker as LARGE, always to use on SMALL setting, because that option only make sense when you don't have a subwoofer, make the amplifer on the LFE channel to send low frequency signal to the front pair speakers, make them sound to much boomies if you have subwoofer present. so they recommend to me to use 80hz on the high pass filter frequency for all the main speakers, set all of then to small, and the LFE channel set to 120hz, and LFE ONLY, instead of LFE + MAIN, which deny any low frequency to the main speakers and only leave the low frequency job to the sub woofer. in fact after make this, the sound came more clearly and crystal sound and the bass more satisfy. obviosly you feel the sound less boomie.

here's my question, is my floorstand speakers RF82, are able to handle 30hz-23khz, even setting to small, will be adecuate to leave it on SMALL, and 80hz?

i would like to heard your personal opinion or any other advice or experience by you member of this prestige forums.

regards

[Olorin]

Hi Carlos, and welcome to the forum.

There are lots of guidelines and there is a lot of advice, and there lots of people who whole lots of opinions. At the end of the day, though, you're the only one who lives with your speakers in your room, and you're the only one who gets to decide what you like best and what works best for you. This is part of the fun of audio, the tinkering, the playing, the trying this and that and listening for the differences.

In other words, try the different settings and see what gives you the biggest smile! Maybe the experts are right, but maybe you're in for some nice surprises.

[carloslara]

thank you so much for your advice, to be honest using all the channels at 80hz, and low pass frequency at 120hz, is very, very plenty.

did you have experience, calibrating 2 units RT12D , connected on cascade one each other, i mean, the LFE cable from the receiver to the first RT subs, and the second RT (rear), is connecting to the LINE OUT of the first RT. so when you run the ROOM CORRECTION, the first RT calibrated itself with the presence of the other, what i had test is this. using this method, the sound is good enough on the entire room, but i also test using "Y" monster adaptor to connect the two subwoofer from the same LFE port, and to be honest, using this, there's more boomie bass, but less accurate base response instead when do you use ROOM CORRECTION.

opinion.?