Axiom Home Page Forums General Discussion Home Theater Questions about bass management

When you set all your speakers to SMALL what does this mean in frequencies as compared to setting them to large? I know that by setting them to large they are getting the full range. But what happens when you set them to small, what is the cut-off frequency? The reason I ask is because the LFE frequency goes up to 120. So if you were to set your x-over to 80 then I could see where the frequencies between 80 and 120 could "possibly" get lost even though the rest of the speakers are capable of playing down to 80. Again if they are set to small, at what frequency does the processor cut off the low end?

Now by setting the x-0ver to 40 you could theoretically be losing everything between 40 and 120 depending on where the processor cuts off the low end when the speakers are set to small.

Am I making any sense at all?

What he said! I want to clarify that I don't know the article is incorrect, it just doesn't sound logical to me. Assuming you have different crossover settings for mains, center, and surrounds, and IF the LFE track is low-passed, the question remains, at what frequency is it low-passed?

How many Bass do you guys have that they need to be managed?

I would think that even if you set independant x-overs to your fronts, center, and surrounds, that it filters out everything BELOW those x-over points from entering into those particular speakers because everything up to 120 is in the LFE anyway. That is why we are "usually" encouraged to bypass the x-over on the sub so as not to accidentally eliminate any frequncies up to 120. So again my question is if we set all our speakers to small as most people suggest, and we set the x-over to 80, then everything below 80 gets filtered out from the speakers that are set to small and sent to the sub as it should. But what is the cut off from the processor when all speakers are set to small...is it also 80??? If it is higher than 80 then we all will have a hole in our sound!

So much clearer now!

Thanks John, Mojo, everyone. That all actually makes sense now. My biggest misconception was that the LFE channel only ever got directed to the sub.

I will have to try and modify the graphic to suit but for now, it's off to the beer store and then home to either watch a movie with my newfound bass knowledge intact or play some pool with some tunes cranked.

Either way, Axioms = On!

The way these folks are always talking about 'em around here, it must be a big boatload.

This article may help.

http://forum.ecoustics.com/bbs/messages/34579/119794.html

There is no "large" or "small" crossover. There are only the channel crossovers.

In my opinion, the 0.1 channel is a big mistake. Record and mix the full audio range into each channel and let the pre-pro manage the bass. I'm sure this decision was made because it was economic and practical at the time for existing theatre systems.

With regard to the "missing bass", I have my cut-off at 40Hz. The LFE below 40Hz in the 0.1 channel is routed to my sub; the LFE above 40Hz in the 0.1 channel is presumably lost which is just fine with me because frankly, it doesn't sound that great 9although others that have heard it at my place like it). How much content above 40Hz is in the 0.1 channel and not other channels is anyone's guess.

Now if you set the crossover to 80Hz, you probably won't lose much of the LFE in the 0.1 channel because sound engineers start rolling off at that frequency.

There is an easy way to test this...get some test tones that hit only one speaker and test the response. If I want to check that my LFE is still going to 120, then I need some LFE test tones up to 120hz. If I want to test my fronts to make sure I have a smooth transition, get some test tones for the fronts only. Are there any test tones that I can buy that would do this?

If you have the sub connected through the sub out jack on the receiver and sub is on in the receiver menu, the sub is getting the full LFE signal but you have chosen to filter it out at the sub for sound above 40hz. On Dolby digital tracks you will get that part of the LFE signal on the mains so you are OK and not losing any information.

In a conventional setup you would bypass the sub filter to get the full LFE to the sub but you said it creates too many room issues for you doing it this way. Where you may lose LFE information is on DTS track though I'm less certain about that.

It seems to me now that the "unusual" large + sub setting, (which I never use because I'm trying to keep artifacts to a minimum), would be ideal for you if you are going to use both the receiver and sub filters. That way you don't lose any information because of the way you have engaged the additional crossover at the sub.