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

I was advised to set my m60s to 60hz, my VP100 to 90hz, and my QS8s to 90 hz. But after reading this article, it has me concerned that I should set my system to 90hz all the way around (I don't have 80hz option).

The article basically says that "In the majority of surround sound processors and receivers, FULL RANGE copies of all channels set to "Small" are combined together with the LFE channel, and the sum is low-passed. Think about that. Strictly speaking, any* such processor with a sub/sat crossover frequency set lower than 120 Hz is "discarding" the upper end of the LFE channel. THX units are NOT exempt from this. With the standard THX 80 Hz 4th order crossover, the top of the LFE channel gets chucked."

So if I set my mains to 60 hz and the center to 90, I have a gaping hole b/w 60 and 90 hz on the center, and any LFE is cut off at 60, which is quite a bit of LFE considering LFE goes to 120. What should I do and why are so many people using multiple crossovers. This site has proven in the past to be very accurate.

Interesting question. I hope someone who knows can offer answers to the following (obviously I'm not that "someone" )

1. In a processor/receiver, are full range copies of all channels which are set to "Small" combined together with the LFE channel? Rather than "full range copies" of all channels being combined with the LFE channel, I have assumed that only the info below the crossover point set for each speaker was combined with the LFE channel and sent to the subwoofer.

2. If this summation (full range speaker copies/LFE) is actually low-passed, assuming you're using different crossover points for each speaker (mains at 60Hz, center at 80Hz, surrounds at 100Hz, etc.), which crossover point is used to low-pass the combined signal?

I know little about how the internals of a processor/receiver work, but I would've thought the info from the speakers below the set crossover point (say 80Hz), would be combined with all the info in the LFE channel, and sent to the subwoofer without the need for any more low-passing, or, if more low-passing was necessary, low-passed at a higher frequency (say 120Hz). LFE does stand for LOW frequency effects doesn't it?

Regardless, the article goes on to say:

"Don't panic. This has been going on since day one, and virtually nobody has noticed . . . with good reason......THX looked at an inordinate number of modern 5.1 soundtracks and guess what they found in the LFE channel: not much at all in the region of 80 Hz - 120 Hz, making their original choice of 80Hz rather fortuitous. Dolby Digital's LFE channel has a digital brick wall at 120 Hz, not a roll-off, so content creators almost always roll-off their stuff, usually somewhere around 80 Hz. Therefore, chucking the top band of the LFE is no big deal....."

OK, now I'm really confused.

Yeah, you're telling me! And you have at least 5000 posts on audio forums. I have maybe 250 total. This has confused me since the first time I ever played with different crossovers for my mains. I wanted all the LFE b/w 90 and 60 to go to my mains because my SVS PB12-NSD is not so great at higher frequencies. I studied this for awhile and was never happy with the answers that I was supposed to blindly follow. I've been around long enough to know that consensus does not always mean correctness.

So far, I regard this website as being highly accurate technically. Their article on 1080p vs 1080i was very accurate and clear. I'm pretty well studied on deinterlacing and even I learned a few things over and above my own knowledge, and I never found any thing false. Then again, video and audio are two different realms...

Good post Jack. Keep in mind that that article was written over 5 years ago and processors have come a long way. Most recent AVRs that I know of include the full LFE. Even the article acknowledged it,

"...low-pass a copy of each main channel at the various frequencies I want and sum that with the full LFE channel?". Possible, yes, and if fact there are some SSP models which do this, but at a price: doing so inherently results in frequency response aberrations due to phase issues."

Autoboy, unless you have an older receiver/processor you should be OK.

And even with an older receiver there are often greater benefits depending on the speaker and room from crossing below if you have capable speakers. I still adhere to the principle that best results are usually obtained by crossing at 1/2 octave above where the speaker output is -3db because of the slope of the filters. Nowadays, I'm seeing more gear with variable slope settings ie 12db, 18db or 24db which allows better blending with the speakers at more crossover points.

The latter part of the quote is what bothers me in that there are people who suggest not only phase issues but intermodulation distortion is introduced in the summation. I have never been able to get a clear answer on that one. At the end of the day I've never detected audible artifacts from the summation so I suppose that is all that matters.

My receiver is from 2002 or so. I have a Onkyo 875 on the way. This is where I first heard of the problem. Their review of the 805 states that different crossovers are bad and that even the Onkyo does not process it completely right.

"The crossover frequency can be set independently for each pair of speakers, the soundtrack's bass can be sent to both the main speakers and a subwoofer ("Double Bass" they call it), and the LFE channel can be low-passed at a different frequency from the rest of the bass being sent to the subwoofer . . . all of which we vehemently maintain are bad ideas, and we back that up in our essay on the subject: Miscellaneous Ramblings on Sub Crossover Frequencies. It is no fault to the product's performance, but it questions Onkyo's marketing decision to give the people what they think they want even though it may mean they hang themselves with it (unawares as they may be)."

This whole issue has me so confused...

Actually, Onkyo recommends to leave those options off by default.

Hmm... I thought that I was getting around this with my H/K by setting (all in the receiver, mind you) my mains to 60 Hz, my center to 100, my surrounds to 120, and the sub to 120. I figured that with that last setting, it limits the sub to receiving/outputting nothing above 120Hz from the other channels, and if I set it lower than that, I would have the dreaded hole. Am I wrong?

I am soooooo confused.

It's Unanimous!!!!!


Just a quick word about post counts. I recommend you don't put too much stock in them. It ain't the quantity, it's the quality. Just cuz I've got 5000 posts doesn't mean I've learned anything or, more importantly, that any of those 5000 posts have contained anything worth ingesting. In fact, there are a several forum members who would say none of mine have contained anything worth remembering. (I just wanted to get that in before they did )


Well folks, we've fooled another one.

My understaing is that the "LPF of LFE" only funtctions on the dedicated LFE channel, which normally should be set to 120hz, and it has no bearing on the redirected bass content, which depends on what HPF setting you apply on the other speakers.

John

Seriously: Who ARE you?

Brian Florian who wrote the article is a lone voice on this "problem". In real world applications it is a non-event. Even if he was right, which I disagree with, you get many more benefits by optimizing individual speaker crossovers. My recommendation is find the right crossover setting for each speaker as per 1/2 octave above its lowest extension and enjoy the sound.

Where he has a point is to avoid settings which send the same doubled up bass with the mains and sub ie. settings which allow you to send LFE to full range front mains and the sub at the same time. All that does is create phase issues and sloppy bass. Because the DD LFE track is replicated on the LF and RF mains as per the DD standard it is always best to cross the mains at some frequency to the sub rather than run them completely full range uncrossed.

Bottom line: Florian's article doesn't jive with real world HT listening. Ignore it.

Jakeman,

I have the crossover on the mains(m80's) set to 80 HZ and the crossover is set to LFE + main. I understand this as allowing the m80's to play down as low as they can, but the signal from 80 HZ and below is sent to the sub as well.

I think that the LFE channel is strictly playing through the sub, but some of the Front left and right channel (frequency's below 80 hz) are being sent to both the mains and sub.

Is this the setting that you say should be avoided and causes phase issues/ sloppy bass?

I want to utilize the sub, but Think that setting the mains to small defeats the purpose of having floorstanding speakers. It seems to me that this setting allows me to take advantage of the near full range m80's, but the sub still helps out along the way.

I was actually talking about the Secrets of Home Theater HIFI websites.

Now, I'm pretty sure that nobody here knows what they are talking about. :P

Seriously though, I appreciate your responses, but your explanation just doesn't assuage my fears enough. The way I thought it worked was that each channel was crossed over separately and that the LFE was never crossed over. Each channel's bass was redirected to the subwoofer. The other method just doesn't make any sense to me, but they sound so convinced that multiple crossovers are a bad thing, and they have been very informative in the articles I've read. Their "Bass Management Woes: Trouble on the Slopes" article is also very good and has me worried that not only am I screwed if I use multiple crossover frequencies, but that the fact that I use near full range towers means that I have a bump in output around 90hz (if I crossover mains at 90 like I do now cause of that article). I'm almost so frustrated that I'm considering some M2s for my mains so I can just cross them at 90 and never worry again. I've always wondered what the difference would be b/w m60s crossed at 90 and I've come close to ordering them just to see.

I'm finding that the LFE+Mains setting produces too much bass. I suppose I should set the M80s to small with a 40 Hz crossover for stereo or something.

Terzsaghi,

Your fine with your setting though you can probably improve it further. What receiver/processor/ other speakers are you using and how are they crossed?

The setting I was referring to is often called Large + Sub or something similar. I have been using a 2 year old Arcam processor with that setting which is described in my manual as, "Pure stereo is fed to left and right and extracted bass is sent to the sub woofer. In this case the low frequency information is, effectively, duplicated. "

That's bad. Avoid it if you have a similar setting since it creates problems with room nodes and phase between the speakers and sub unnecessarily.

Yes 40hz is the minimum crossover given the M80s extension to 34hz at the -3db end. It depends how well you blend it with the sub in the context of your room and listening postion. If you have the flexibility I would also try 50hz and 60hz and listen to what sounds better at various volumes. A key benefit of crossing higher is that you free up amplifier bandwidth which can mean less distortion. However, a more powerful amp usually means you can cross much lower with confidence since preserving amp efficiency is less important.

If you didn't take such fabulous photographs I wouldn't talk to you at all.

By Jove, I think he's got it.

I have the denon 3808, m80's vp150, Qs8's, and ep-500

I have my m80's set to large, the crossover is at 80 HZ for movies and 60 Hz for music.

My othercrossovers are set at 60 hz.

Audessey auto set up originally set everything to a 60 hz crossover except the vp150 which was set at 40 hz.

Audessey and just about every other auto-equaliztion program found in the Denons, Pioneers and Yamahas etc. are notoriously bad at setting anything related to frequencies below 100hz. I would ignore any sub, delay or crossover setting and adjust manually. Simply not enough processing power in the receiver chips to find the optimal LF settings.

Here's a few suggestions.

1. For HT don't set the M80's to large because you are duplicating the LFE channel when using Dolby digital tracks as well as introducing phase and other artifacts when in stereo mode. I would suggest turning off the EP500 and just listening to the M80s full range for music if the Denon has such a setting.

2. Set all speakers to small and cross as follows (based on 1/2 octave above low -3db extension for the M80s and close to -3db the other speakers).

M80s 50hz
vp150s 80hz
qs8s 100hz

3, Listen for a few days and then cross all speakers at 80hz. The reason I am suggesting this is that the Denon power rating at 130wpc is likely not accurate for all channels driven so you may benefit sonically from easing the power demands on the amp by crossing the m80s higher. Also keep in mind that depending on the slope of the Denon, which is likely -12db/octave, you are still getting output above the crossover frequency redirected to the EP500 which brickwalls at 100hz. You can also try leaving the qs8s at 100hz.

Depending on your room and your listening habits I suspect you should find an improvement.

I'll give it a shot and see what I think.

Thanks for the advice.

>> Just cuz I've got 5000 posts doesn't mean I've learned anything

I've never learned anything by posting. It would be great to have a score for the number of posts we have *read*

The HK receivers don't let you pick a separate frequency for LFE cutoff but they do let you pick a speaker set (main, center, surround) and have LFE cut off at the same frequency as that speaker. That works pretty well for me as I can cross over the M60s at 80 Hz and the rest at 100 Hz, then pick "surrounds" for LFE to get a 100 Hz cutoff.

I still have a nagging feeling that the system sounds better when all the crossovers are set to the same frequency but have never had the time nor patience to do enough testing to be sure.

I used to like that site for the DVD benchmark charts but now, forcing to register to read content of interest is aggravating.

Only one way to find out for sure John. Having debated this one at length at other forums I'm of the view that if there is a difference the greater effect comes from artifacts which may be created in the summation not by some concern over whether a gap is created which is inaudible and gets overlapped by the slope. Its all academic because no one can tell if the artifacts are there or not and the difference if it exists is swamped by room acoustics anyway. That's why the author of the article hasn't gotten much replay in the 5 years since it was written. Yet another example of a theoretical concept which does not translate into real world listening applications.

I think you misstated this. The Denon LFE+Mains setting does not duplicate the LFE channel. It only copies the signal below the crossover setting that is being sent to any speakers set to large and also sends it to the subwoofer. The LFE channel plays only through the sub as long as the subwoofer is set to “yes.”

First off I don’t dispute the phase and other issues you mentioned or the benefit of not burdening speakers with playing very low frequencies since that’s what the sub specializes in.

But this brings up a question I‘ve been wondering about for some time. If duplicating low frequencies between the “large” speakers and the subwoofer can cause so many problems why do so many people recommend using multiple subwoofers to even out the bass? Won’t the same issues apply or does evening out the bass outweigh the other issues most of the time?

Thanks for clarifying it and I agree with you. When he stated he set the M80s to "large" ( as opposed to small) I intrepreted that to mean he was running them full range and not crossed which would have duplicated the LFE channel.



One of the biggest challenges with integrating subwoofers is getting the speakers and sub(s) to blend properly with as flat FR as possible and minimal phase interference. Getting the speaker/sub frequency interface as smooth as possible is best achieved when you have the low pass filter (frequency and slope) at the crossover point producing a smooth summed response from the sub and speaker. If you have the speaker producing LFE and essentially no low pass filter operating it becomes next to impossible to blend the sub and speaker so the net outcome is more room reinforcemnt and cancellation and phase problems throughout the low bass range.

Now if you have the speakers low frequency output filtered out and you have it crossed to the subs it effectively removes one set of problems to worry about ie. resulting from uneven FR between the sub and speaker. There are other concerns such as getting the multiple subs behaving in a linear fashion but that can be achieved if the speaker interaction is set up right.
In other words getting flat FR in room is easier with the speakers crossed to the subs.

As you go from one to multiple subs studies (such as the famous Harman study on multiple subs) have shown that the greatest benefit to achieving flat response by reducing nodes throughout the room happen when you add a second subwoofer. Adding additional subs helps further but not as much with four subs being about the limit for further improvement in flattening FR. Getting them placed properly and operating in phase is another involved topic but the benefits are clear with less need for room treatments or equalization. A couple of years ago out of curiousity I bought 3 EP 600s and 2 EP500s to see for myself and 4 subs does provide the optimal benefit.

Thanks for the explanation of the speaker subwoofer crossover part of the problem. I still have questions about how to get multiple subs to behave in a linear fashion but I don’t want to hijack this thread so I might start another one later.

Dean

Go ahead and I'll see if I can help. After all we are talking about bass management and some of this stuff can only be figured out by actually going through the process.

I've sold most of my EP subs but recently added some sealed subs to my HT so I am back to having a quad of subwoofers throughout the HT.

Here is an informative discussion by Ian on the topic of multiple subs. He goes through a good summary though I find getting the phase between multiple subs set up properly takes more effort than what is being suggested.

http://www.axiomaudio.com/videocenter.html

I find that when I cross over at 80, the bass is too "fat"
and, dare I say, "slow". It also distracts from the fine details of the music and doesn't provide the right "punch".

Also, when I use LFE+mains, the bass is over-powering. I tried a 60Hz setting like John suggested but I still find it too "fat". 40Hz sounds just right for music and movies. So I paid roughly $100/Hz for the 600 and about $0.07/Hz for the M80s. The 80s are a steal .

Of course all of this is configuration-dependent so every one should tweak until it sounds just right for them.

Mojo- so you have your mains set to small i guess?

Yes, I do. All of my speakers are set to small. Only God knows how many hundreds of hours I've spent tweaking.

If you have a DSP-based Axiom sub, set it to 40Hz and then set your pre-pro to 40Hz as well and see how you like it. One of the most memorable differences was the apartment shooting scene in LFODH. At 80Hz, the rat-tat-tats were thick, slow and rattled the whole house. At 40Hz, they were sharp, fast and we all felt them in the left butt cheek right through the leather couch.

And music's a completely different experience at 40Hz. The sub takes over right where the 80s leave off. Just make sure that you adjust the sub level to match the 80s at 40Hz (using a test tone CD). And if that doesn't sound quite right, don't be afraid to nudge the LFE channel gain up or down.

I just received DVE but haven't really looked through it yet. Do you know if that has the test tones you are talking about?

Interesting. Most people would suggest not having cascading filters like you have ie. both in the processor and at the sub. The recommendation is to use one or the other. The argument is that it causes too steep a slope at the crossover point to blend well and introduces intermodulation distortion, but at 40hz it likely doesn't matter and any artifacts would be inaudible. If its better in your room that way, that is all that matters.

I think one of the recent axiom articles discussed some benefits to applying crossovers both on the receiver and the sub.... There was some explanation for it but I don't recall what it was.

I don't know if DVE has test tones. I've been using the RealTraps tests tones that Randy suggested.

For the longest time I reasoned to myself that cascading filters are "bad" so why try? And then I decided to go for it and was surprised at how much better it sounded. I'm sure this has a a lot to do with my bright room. Bass just hangs around in that room even when it's time is supposed to be up.

DVE has test tones.

And, if anyone could come up with a link to that post/article/thread where the benefits/problems of using both crossovers at the same time was discussed, I'm sure John would be interested is perusing it. I can't even remember what was finally concluded, let alone when or where it was brought up.

When you apply a filter phase becomes an issue because it introduces phase delay (a type of distortion). But its hard to figure out what's happening without knowing what kind of filter is in the receiver. Or maybe there is something unique about the subs DSP which makes it worthwhile. Very interesting indeed.

If I recall correctly, some filters like the Butterworth ones emphasise even frequency response but introduce big phase shifts while others do the opposite. I guess I've been brainwashed into thinking just use one but it sounds like you may have found that using both solves some unique acoustical issues in your room. Always pays to experiment.

Yes I would like to read that article Jack. Thanks.

OK, so I thought I had all the speaker/sub settings straight on my Denon but after reading all this something was bugging me. Being a visual guy, a did a really quick diagram and I now have questions. Please keep in mind, I already know my diagram must be wrong, so my question is all about correcting it. I'm not presenting it as correct. I will correct and repost if I can get it straight and it proves useful to other visual style thinkers.

OK, with the assumption that we keep our sub set to "on"
Question 1
When speakers are sent to Large. I'm assuming the crossover for that speaker(s) is totally ignored and nothing is shared with the sub, as in example #2 and #3. Correct?

Question 2
What am I missing in the scenarios #1 and #4 ? I am missing something as they are producing the same results.

EDITED: fixed an error and shrank more. You still may need scroll down to horizontal scroll bars.

Good visual.

According to the article from HomeTheatherHIFI, the LFE is not always entire channel. Since the entire channel for each speaker is set to small and summed with the LFE, the crossover for the mains is also applied to the LFE.

So, in 1 and 4, the LFE is only 60 down. This is what confuses me so much.

Also, and you probably know this, but crossovers are not a step at 60, 80, or 100, but a gradual slope. You probably just showed it as a slope for ease of use.

Yes, to clarify...
-- I am showing the words "entire channel" under the LFE column just to represent that there is a whole separately recorded channel on a 5.1 recording.

-- Yes, the sloped arrows have nothing to do with sloped verses hard cut offs for a crossover. Just the way I drew it.

-- I also meant to add that I was keeping it in scope with Denon recievers. Just since that is what I have. Others may treat thier terminology and settings different.

Back to your point. Are you saying that a crossover setting is applied to the separate LFE channel as well? I'm not sure if I understood you correctly. That would change things for sure.

What I've wondered about setting up the M22 @ 80 crossover (79 HZ or less to sub), if there is a scene where the Fronts have a 70 HZ signal and the LFE track is 40 HZ, the sub obviously cannot play both signals at the same time. What happens to the 70 HZ signal?

Or are tracks not recorded this way as to cause difficulties?

If the scenario above exists in soundtracks, could I make an argument for x-over at 60 and run LFE+Main so as to not lose anyhting in the mix?

Well... sure it can. Speakers by necessity play multiple frequencies at (just about) the same time.

Reminds me of the old Charlie Brown cartoon where Lucy asks Schroeder to play Jingle Bells for her. He plays several very complex variations of the song for her but she keeps insisting that it's not the correct song. Finally he frustratingly pounds it out one note at a time, using just one finger.
She screams "That's it!!"

Don't want to hijack to hard so back to bass.

Can anyone confirm that a Denon (or any processor) would apply a crossover to the actual LFE channel itself in certain instances? This seems like an odd concept to me. If you had multiple crossovers set for the other speakers, what would be the rule on which number it applies to the LFE channel so as to not lose out on frequencies in between?

Hell, it wouldn't even sound like one note from one instrument, it would sound like one note from a tone generator.

Flutes are said to have the least overtones (additional frequencies), but I'd wager they still have a significant amount.

Otherwise it would sound like a midi file

Edited my last post to add a relevant question but people already out posted me in between.

Sorry but Ill repeat the question for those who might otherwise not go back and notice the edit.

............

Can anyone confirm that a Denon (or any processor) would apply a crossover to the actual LFE channel itself in certain instances? This seems like an odd concept to me. If you had multiple crossovers set for the other speakers, what would be the rule on which number it applies to the LFE channel so as to not lose out on frequencies in between?

Murph you are right. It is an odd concept and I know of no receiver/processor that does that. That's why I discount that article which continues to cause confusion. Florian hasn't figured out that what applied in 2002 doesn't apply today.

As it applies to the FR and FL channels only, dolby digital also replicates the LFE track into those channels. That redirected LFE bass would be taken out so as not to duplicate it in the sub twice. When the standard was developed not everyone had subwoofers and many people had full range floorstanders hence why the LFE exists in the front channels. I doubt there is any loss of sound on any channel on any of the modern receivers and processors we own. The bigger concern is this weird large + sub setting which has the same LFE coming from speakers and subs and messes with phase and FR.

Murph,

Great graphic!

In config 1; fronts, it should read 59Hz down rather than 79Hz down.

The LFE channel is NOT the subwoofer. LFE can be directed at any speaker provided that speaker can handle it. If it can't, the LFE and any other bass that the speaker can't handle, is routed to the sub using the pre-pro's bass management.

So now you need to figure out how to add that to your graphic .

I'm running my M60's as large because it helped solve a problem I was having with a null at 55-60Hz.

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.

RealTraps has tones that you can download.

Really? You mean the 0.1 LFE that doesn't go to the sub gets routed to the mains? That doesn't seem right, does it?



Apparently DTS is encoded the same way as DD as far as LFE goes.



Yes, that would probably work well for movies. I'll have to try it.

(I have a case of the Fridays)

No that isn't what I meant. If I understand right, you are engaging the crossover at the receiver at 40hz by setting the speakers to small and sub on. All LFE is now going to sub out. If you had speakers set large, all the LFE would stay in the main speakers. You are also engaging the crossover on the sub at 40hz and the sub is connected to the sub out on the receiver and you have the sub on in the receiver menu.

If you bypassed the sub as is normal, all LFE would go to the sub as well as redirected bass from the speakers below 40hz. By engaging the crossover on the sub at 40hz you are indeed losing LFE information above 40hz that is being directed to the sub from the receiver sub out. In most receivers, in order to get all that info you must bypass the sub or set the speakers to large. I don't have a Denon but that would be normal processing.

Once you tinker with both filters like you are doing because of room acoustics which is cool experimentation, then it seems to me you must go with the Large + sub to get all the LFE otherwise you aren't getting LFE above 40hz. In essense all LFE will stay in the front speakers which you will hear down to the M80s extension at 35hz and the sub will not give you any sound above 40hz but LFE below.

The real traps test tones create a CD and the test tones are not in 5.1. This is the same for all test tones I have seen. I need a DD 5.1 track with test tones on each channel to see how the bass management of the receiver operates in 5.1 mode. 2 channel is stupid easy to understand.

I want to be able to run a tone to my center channel only while in 5.1. I want to set my system to a 50hz crossover on my m60s, a 90hz crossover on my VP100, and a 90hz crossover on my QS8s, run a tone to each channel, and measure the response of the system. This will tell me right away if the LFE channel is cutoff at 50hz like the hometheaterHIFI article, and the supporting articles (if you read them) state.

Is there such a test tone DVD, or is there a program that allows me to create my own DD 5.1 track? This seems like it would be something people would want for test tones. Why are they all 2 channel?

Crossovers can be way more complicated then I originally thought!

Jakeman, I took your advice and adjust my speakers as follows:
(I do not have the option to cross the m80's over at 50 HZ so I am using 60... I could also try 40.

All of my speakers are set to small and the LFE was changed from 'LFE + main' to 'LFE'

Crossovers are set as follwows:

m80's: 60 hz
vp150: 80 hz
QS8's: 100 hz

LFE: 100hz

I am not sure if I put the right setting for the LFE channel... kinda confusing.


I will listen for a while and see what I think.

Setting your LFE to 100 or 120 is fine.

Yes, that's right. I'll have to try setting the M80s to large during movies to see how my experience changes. I definitely don't like them set to large during music though.

If I remember right the DVE test tones does a sweep for each individual speaker.

Boy, this one has exploded since I looked at it yesterday. Some observations: autoboy, it's very unusual that a receiver offering several crossover frequencies would include 90Hz but not 80Hz.

Andrew(Murph), what you're missing in your #1 and #4 comparison is that LFE+Mains is only effective when the mains are set large; the reason they sounded the same with the mains set small is that they're exactly the same.

Many(most? all?)recent receivers don't handle the LFE channel in the way the Secrets article describes. Some have a fixed low-pass filter on it somewhere between 80-120Hz(e.g. one of mine lab tested as 3dB down at 96Hz); others(e.g.some Denons)offer a user setting such as 80, 100, 120Hz to set the low pass on LFE info; still others(some HKs that John Bridgman mentioned)use a choice of the settings for speaker crossovers as the LFE setting, or use the highest(not lowest)speaker crossover to control it. The exact frequency in the 80-120Hz area set isn't especially important since little or no actual LFE content is there. The reason given for ever setting less than the 120Hz LFE channel max is that some noise content above 80Hz may be reduced.

Generally, the frequent suggestion to set all speakers "small" with a 80Hz crossover appears to work well and no +mains to the sub(with mains "large")is necessary or advisable. Have the sub handle what it should do best(which should be at least up to 80Hz for a good sub)while lessening the lowest bass burden on the speakers and the amplifier driving them. Specific room situations such as the bass null that Tom mentioned for using a "large" mains setting to increase total bass output, might apply occasionally.

Study the manual, of course, to see if it actually clearly describes how the LFE channel is handled(good luck)or as a last resort try to contact customer service.

I have a very large room, and at this point I still use small on everything and 80hz crossover on my Denon. I played around with setting my 80's to large and using LFE+Mains to see if that would help with the nulls/peaks. I did not see much of a difference if any.

Some day I hope to add additional subs on the other 3 walls.

Thanks John. That explained a lot. My Sony receiver, that will soon be replaced by a Onkyo 875 as soon as it arrives, has only 60, 90, 120, and 150 crossover settings. Right now I have all set to 90, but previously I had it set to 60 for mains and 90 for the rest. With music, all 2 channel, I prefered the 60, but I listen to movies the most and so I didn't want to lose the LFE and I set it to 90 for everything. I didn't find any difference in quality for movies, mostly because I don't really listen for that during movies, and the music is not as repeatable like with a nice bass guitar while listening to music. I'll try 60 again. With the Onkyo, I'm thinking 50 will be a good crossover point for my m60s and 100 for the vp100 and qs8.

If you had the capability ie a stereo direct mode for music, how about shutting off the sub and just listening to the M80s large as a stereo pair. While its not as important for HT listening a single sub does introduce phase differences when listening to stereo. Nothing beats floorstanders for music IMO and the M80s are great floorstanders.

I managed to get rid of my phase issues by increasing the sub distance in my Denon's menu. My sub is 11 feet away but, through trial and error, I upped it to 19.

I do indeed have stereo direct but I find that even though the 80s have great low frequency extension, without the sub, they sound thin. Thin is perhaps too harsh a word but you know what I mean. I can't live without a sub now...even for just music.

oh oh Another subhuman.

So you have met Tex in person

I discovered that the M80s have significantly more low frequency prowess (in the subjective sense of gut-thumping bass) when the A1400-8 powers them at higher volumes vs my Yamaha DSP-A1 (110W/ch). For this reason, I prefer the EP-500 off for stereo mode while listening to music.

John

OK, now you're just showing off!!

Showing off is over at the Community section . Merely pointing out that M80s don't have "thin" bass to my ears in my system.

J

Thin bass on those full range M80s is a sure sign that Mojo is underpowering them. There is no getting around having power on tap for accurate and full bass response.

Good post John. The A-1400-8 let's you realize the full dynamics and deep bass of those M80s. Adding a sub to floorstanders just muddies the music unnecessarily when the real problem is lack of power for bass control.

This is very interesting. I truly hope that a half watt nominal out of the 1400 will give me the thump that I'm looking for. I'm even willing to go to a watt nominal but anything beyond that will pose a risk to my hearing.

John was sharing some of his impressions of the A1400 and his M80s with Eric and me yesterday. Rather than me paraphrasing, hopefully he will weigh in again with his views.

Keep in mind that the "unofficial" power handling ability of the M80s is 900W. Also keep in mind that its the woofers and bass transients that require the most power. Anytime my audiophile pals have upgraded to more powerful amps their first comments are always about how much cleaner and distinct bass sounds. Their later comments are then about dynamics and transparency.

I guess whether one uses the M80s with the sub or not is within the realm of the topic of this thread, so I will reluctantly take the risk of boring everyone with Alan's very informative Q/A section here regarding the M80s:

"In the case of the M80s, they have been tested a minimum of five hours using modified pink noise at 400 watts rms from the amplifier. Furthermore, they have been tested at this level for 100 hours using highly dynamic source material. We keep the ratings conservative, i.e. the tests are actually done at 600 watts for a 400-watt maximum power rating. In fact, the M80s have been tested up to 1200 watts without any problems."

So, I was not worried that my M80s could handle a horsepower (745.699872 watts ) each with the A1400-8. Of course, I never plan to run the speakers at this level anyway, but what I noticed with the new amp is that when listening to recordings with fairly wide dynamic range at higher volumes, the sudden peaks in the source resulted in surprisingly powerful and articulate bass in the M80s that I had no idea they were capable of. At higher volumes, where the Yamaha would begin to get disturbingly loud, the A1400-8/M80 combination became decidedly satisfying and I wanted to turn up the volume knob ever more. In summary, I wonder Mojo, whether the M80s are sounding "thin" to you and needing your EP-600 because you are under-powering them, not because they are not built to handle the power and the low frequency extension (in music anyway).

John