LFE, subwoofers and interconnects explained - Page 16

Gotcha. I was under the impression that some players do this incorrectly.

And there is no "redirected LFE". Bass is redirected. The SW output, which contains the summed redirected bass and the LFE at the proper ratio is lowered an additional 5dB when the speakers are set to SMALL. Otherwise, the SW output (which = LFE when the speakers are set to LARGE) is only lowered the appropriate 10dB.

There will be no other sources. The new Panny 55 will replace my current DVD player.

I have been using a DVD version of Video Essentials to calibrate my sound levels.

I've had all my speakers set to small for the last 5 years or so. All my my bass is being handled by my subs as recommended by Tom Vodhanel at SVS. If I set the player's speaker setting to *large* then what happens once it passes to the receiver through the analog 7.1 inputs? Does the receiver's speaker settings of *small* take over? I was under the impression that once I use the analog inputs it completely bypasses all functions of the receiver.

It will be no problem to turn-up the SW level an additional 10db to compensate for the lower LFE... unless it causes me to lose necessary headroom like I mentioned in my original post. I'm worried about the redirected bass from the other channels finding it's way to the subs.

Nothing. It stays LARGE (non-bass-managed). Unless your receiver can bass manage its multichannel analog inputs. Very few receivers can do that. Think of the analog multichannel inputs as nothing but pass-through. You can't apply bass or time management to them. They go straight to the amps. You may be able to adjust their level trims, but that is it.



No. The receiver's bass and time management settings are only applied to what enters the receiver digitally. The only way to bass and time manage the multichannel analog connection is with the player, where the decoding occurs. The settings in the receiver (except for the multichannel analog input level trims) are irrelevant to the multichannel analog inputs.



Right.




If you set the speaker sizes to SMALL in the player, the bass will be rerouted to the subwoofer output. If you can't boost the player's sub out and/or the receiver's sub in, then you will need to find 15dB somewhere. Most receivers allow you to adjust the analog input level trims. So, between the player's channel level trims and the receiver's analog input level trims, you WILL be able to find the 15dB. As I pointed out as a simplified example above, if you set the speakers' levels to -7.5dB in the player and the sub level to +7.5dB in the player, that is a 15dB difference right there. Plus you will probably also be able to adjust the receiver's analog input level trims. Everything is relative. One way or the other you very most likely WILL be able to adjust the subwoofer in/out relative level appropriately.



Now, you should be aware that the bass and time management capabilities of players are usually much more primitive than those available in a receiver. Players often only have a single fixed crossover that can be too high. 80Hz is OK in most instances. But 120Hz is too high, IMO.

Okay, did some real world testing tonight. I had my friend bring over his Sony S550 and we hooked it up via 7.1 analog out to my 3802. Set all speakers to *small* and sub to *yes* in the 550's menu and left all trim levels at 0db (max gain). Used my Video Essentials DVD and reset all the channel volume levels in the 3802. I DID have to raise the SW level 15db (I had incorrectly said it was originally set at -2, it was at -9) to get it to read 75db like the other channels. Oh, and EWL5, you are correct. I can set the levels for both analog and digital independently.

We played Kung Fu Panda and the bass was incredible. It sure sounded like every bit of bass from both the LFE and channel redirect was there, and then some on top of it. I was very impressed with my first Dolby True HD experience.

However, one of my original questions remains. After adding the 15db to the SW level I'm now at +6 out of a possible +12. Have I run out of headroom or is it in effect the same as the previous -9 with the receiver adding the decibels and now I've just added them manually?

Of course you can. The digital connection and multi analog connection are completely independent. The player's settings are only applied to the analog connection. The receiver is incapable of applying anything to its multichannel analog inputs. You may be able to adjust the inputs' individual level trims. If you have this capability, you do this by adjusting them 'on the fly' when in the multi analog input mode the same way you adjust the receiver's channel level trims 'on the fly' when in a digital mode. Your digital connection will pass a bitstream to the receiver where it is decoded and the receiver's settings will be applied.



The receiver doesn't add anything to the analog input. That is the whole point. You have to add the 15dB with the level trim settings of the player and/or receiver. Can you adjust the multi analog inputs' level trims with the receiver? Either way, it doesn't matter, as long as you account for the player's sub out being 15dB too low, which you did. A calibration is a calibration. If you got all the SPL levels to read correctly, then you have calibrated the multi analog connection. And no, you have not run out of headroom. If you are so concerned, you can adjust everything in unison so that the sub level is lower. It is all relative. For example, you can reduce the level trim of all the channels by 5dB (or whatever). You'll still be calibrated, it will just take turning the receiver's master volume up that 5dB (or whatever) to get you back to reference level.

Capeche?

I know this. I was referring to the previous digital coax connection at which the SW level was at -9.

Yep, I think I'm good. Thanks for everyone's advice!

The sub level adjustment you make for your sub with the analog connection are independent of and irrelevant to that which adjust it for your digital connection. The only thing that adjusts the sub's or speakers' levels for the digital connection is the individual speaker and subwoofer level trims in the receiver. The only way you adjust the sub's and speakers' levels for the analog connection is either with the player's level trims or the receiver's analog input level trims. The 2 sets of settings are completely separate and do not affect or influence each other.

In other words, calibrate both the analog and digital connections independently and you will never have to touch either of them.

Right but you failed to mention the order. He should calibrate based on the analog output first since it is limiting with the -15dB followed by the digital connection. It is easier to subtract LFE trim for the digital connection rather than look for LFE trim that will be insufficient for the analog. The order of calibration is important for him. I am assuming he wants one SW gain setting and doesn't want to walk back and forth to change the gain when playing digital vs analog.

Also, I do not believe I am in error when calling it "redirected LFE." LFE stands for Low Frequency Effects and redirected LFE is typically anything less than 80Hz. I don't think they stop being "low frequency" just because it joins the .1 channel. You say tow-may-tow, I say tow-mah-tow...

I must be the world's worst communicator...


With my receiver it saves the digital input calibration and analog input calibrations seperately. It's a simple push of a button on my remote to switch between the 2. So sivadselim is dead-on, I've calibrated both and they do not need to be touched again.

Again, thanks for all the help and advice.

He can figure all that out himself. But you are correct, if he wants both connections to be calibrated with the same exact master volume setting on his receiver, there may be an ideal way to do things. All that is important is that he realize that it is all relative.

Consider a simple hypothetical situation where all the channels of a digital connection are calibrated to "0.0" dB. Now suppose that at the same master volume setting on the receiver and the same master volume setting on the back of the subwoofer, his player's left front channel calibrates at "+1.0" dB, and that the subwoofer output on the player and the analog subwoofer input on the receiver have the same gain as the speaker ins/outs of the player and receiver. This would mean that the subwoofer level trim in the player would need to be set to "+16.0" dB in order to calibrate the sub properly. But his player's level trims only go to "+10.0" dB. There are several ways he can compensate for this. The easiest would be to set all his channels' level trims in the player to a lower relative value, for example, we'll subtract 8.5dB. So his main channels would be set to "-7.5" dB and his subwoofer channel would be set to "+7.5" dB in the player. And his master volume setting on his receiver would have to be adjusted up that same 8.5 dB to achieve his 'reference volume' level. Or, if he wants the 'reference volume' to be the same master volume setting on the receiver, and he is capable of adjusting the individual level trims of his receiver's analog inputs, he can set them all to "+8.5" dB.

If he wanted to find a happy medium between all those settings, he could. All that matters is that, in the end, everything be calibrated to the same relative levels.



No, you are wrong. And this is something very fundamental. The LFE channel is a specifically encoded channel; the .1 channel. As long as a processor is set up as having a subwoofer, the LFE channel is ALWAYS directed to the subwoofer out. Redirected bass below the crossover setting, be it 80Hz or not, is just that; redirected bass. To call it LFE, which you, yourself, have capitalized as Low Frequency Effects, is a gross misuse of the term. The only time LFE is redirected is when a processor is set up as having NO SUB. In this case, the LFE channel is redirected to the LARGE front channels. The LFE channel can contain info as high as 120Hz, which is a common cutoff point used by engineers. But it can contain info even higher that. In fact, there is no reason it cannot carry a full-range signal.

As an aside, players will not reroute LFE to the LARGE front channels when configured as having NO SUB. Instead, in this instance, it is dropped altogether.

1) Nowhere did I even mention the master volume on the receiver. I was talking about "getting up" to change the gain on the subwoofer (you probably know it as the volume knob on the side of the sub). That knob (assuming your sub is amplified) you normally "set and forget." If you calibrate the digital source first, then the knob on the sub will be value X. When you calibrate for analog next, the temptation will be to turn the knob higher than value X. This assumes that you have no more than +10dB available on the analog LFE input of the receiver. We already agreed that the signal is coming in -15dB from setting ANY speakers to SMALL for analog.

2) My Denon 3800BDCI player takes all the redirected bass from the SMALL speakers and gives it to the LARGE speakers. Only question is if the .1 channel is sent also when SW is NO. This player has the guts of the Denon 4308 receiver so it may do it.

There is no reason at all to touch the sub. Unless the gains on the player's analog outs and/or the receiver's analog ins make a strikingly huge difference, the 15dB is easy enough to 'find'. With a player that has trims that can be adjusted from "-10.0" to "+10.0" dB, you have 20dB of leeway right there. Add the capability to adjust the receiver's analog inputs an additional 10dB and there is 30dB of leeway there if you needed it (which you won't ). If you have already adjusted the player's level trims appropriately to account for the 15dB difference, the signal will not be "coming in -15dB". Everything will be hunky-dory.



It is possible as I have, of course, not checked every single player. If you have a disc that has what you know to be pure LFE material on it you can check this very easily. On AVIA the track that is entitled (I think) "Low Frequency Sweep; LFE" is encoded entirely in the LFE channel. Set you player up with NO SUB and set all the channels to LARGE. Play this track. If you hear it from your LARGE fronts, then your player is rerouting the LFE channel to the LARGE fronts. Otherwise, it is not.

BTW, I believe that this 'dropped LFE' on all DVD players (not just universal players) is mandated by Dolby. At least it once was. The reason being so that when a player is connected directly to a TV via a 2-channel analog connection, the LFE channel does not have to be amplified and reproduced, in addition to the L/R channels, by an amplifier and speakers that are wholly incapable of doing so satisfactorily.

I do not know about your player but, AFAIK, unless it has a specific setting to do so, a 4308 only reroutes bass from SMALL channels to the LARGE front channels if it is set up as having NO SUB. Otherwise, it is always mixed in with the LFE channel and redirected to the sub out.

The reason I even brought up the volume knob on the sub was because of scsiraid's reply below. scsciraid clearly states that according to the 3802 manual, there is no capability of increasing the dB on an analog SW input. Then the only source of amplification for the LFE channel becomes that volume knob on the sub for the analog signal. I have not verified the 3802 manual myself; just going by what scsiraid said...

That there is no SW boost on the 3802 does not mean that its multichannel analog input level trims can't be adjusted, although it may not have that capability, either. But, I pointed out clearly how the 15dB difference can very most likely be achieved with only the player's level trims. I even went to the trouble of providing an example. So, even if there is no way to boost the SW level at the receiver with either a specific SW boost setting or more generally with the multichannel analog input level trims, unless the disparity is more than can be covered by the player's level trims, a proper calibration can be achieved without ever having to touch the subwoofer's volume knob.

Page 34 of the Panasonic BD55 manual states the following channel levels are available for the analog out:

Fronts = 0 to -6dB
Center and Surround Speakers = 0 to -12dB

There is no mention of adjustment for the LFE channel. Perhaps another BD55 analog user can step in and help Nick P further but it is my belief that the calibration should be done as I first recommended.

sivadselim, I understand the overall idea is to help someone out but some of your statements did not take equipment limitation into consideration. Probably under most circumstances you would be right but it doesn't hurt to "dig a little deeper." scsiraid had the right idea by looking into the user manual to find the solution.

Well, my new Panasonic 55 arrived today and all is well.


There is no SW boost in the 3802 but the SW trim level can be adjusted.


It does and I did.


Very true as this is what I did to both the digital in and analog in.


The LFE can be adjusted in the Panny player but I found it to be not necessary.


I'm good, really I am. I have a full grasp on the whole thing now. I wasn't too terribley confused in the first place. This was my first experience with hooking up a player via analog out and I just needed a few minor things explained.

Apparently, according to Nick P., it's all good, but you DO have a point, EWL5. Those trims do not allow much leeway, do they? Especially if there is no way to adjust the subwoofer out level trim (remember, it's NOT the LFE ).

But I had said...........

..........so I HAD covered my butt a bit.

It's all good. Everything turned out ok for Nick in the end.

I will use the phrase "redirected bass" since I agree the LFE .1 channel probably can never be redirected and is probably dropped altogether when SW is NO.

Now I'm confused. Are you saying that receivers will re-route LFE to the main L/R speakers if there's no sub, but players will drop the LFE if there's no sub?

Yes, that is exactly what I am saying. When configured as having NO SUB, a receiver will reroute the LFE channel to the front L/R channels. When configured as having NO SUB, a multichannel universal player will not reroute the LFE channel to the front L/R channel analog outputs. Instead, it is discarded. With a non-multichannel, standard DVD player, the LFE channel is also discarded when the player downmixes LFE-channel containing material for 2-channel analog output.

The main implication here, unfortunately, is that it is not possible to properly utilize a multichannel analog connected universal player in a 5.0 system.

"Why do players drop the LFE channel" you may be thinking. This is a Dolby specification that is intended to prevent the passage of the LFE channel from a player via a direct 2-channel analog connection to a television's speakers. Most televisions are equipped with neither an amplifier nor speakers that are capable of reproducing the LFE channel appropriately.

I guess that makes sense. *sigh* Buying home audio gear was so much easier thirty years ago.

Oppo indicates that their 983 DVD player does in fact steer LFE to the mains when configured as Subwoofer = NO. Dont know about their other players.

The Oppo 983 manual states (p. 48, Downmix Mode): "Stereo - This mode down-mixes decoded multi-channel (5.1ch) audio to 2-channel stereo output. For original stereo content the output will still be stereo. For original multi-channel content the surround and center channels will be mixed with the left and right front channels. Recommended for use with TV sets or stereo receiver/amplifiers."

While it doesn't explicitly state that the LFE is dropped, it doesn't say that it is mixed into the L/R channels. They could be a little clearer on the subject.

Well, you're talking about Downmix Mode, and he was talking about Sub=NO. Those are two independent settings. It's certainly possible to set sub=NO without using Downmix Mode, in the Oppo models. It makes sense not to use LFE in the Downmix Mode (anticipating its primary use with TV speakers), but as you see, thre are situations where you would want to keep the LFE too, and reroute it to fronts.

Sivadselim's post was the first I'd ever heard that claimed no universal player will reroute LFE to mains. It may well be true, but with things like 'Downmix Mode' in existence for years, in even the earliest multichannel DVD players I owned, I don't see why Dolby would mandate discarding LFE in all cases where sub=NO.

My bad. I was thrown off by sivadselim's "...to prevent the passage of the LFE channel from a player via a direct 2-channel analog connection to a television's speakers." I scanned the manual looking for LFE info, and by the time I found it I forgot what the question was :-O

A further scan of the manual and I can't find where it says anything about what turning off the subwoofer does, other than turning off the subwoofer, which would seem to indicate that the LFE is discarded.

*sigh* Buying audio equipment was much easier 30 years ago.

I have been pointing this out for several years, now, and no one has been able to refute it. Many people have scurried off to confirm this only to find out that, unfortunately, their universal player is dropping the LFE channel. But that doesn't mean that ALL universal players drop the LFE channel. I have yet to hear of one that doesn't. I suspect that there may be some very high-end players that treat the LFE channel differently. But it is simple enough to test what a particular player does if you have access to a track that you KNOW is specifically encoded in the LFE channel and LFE channel only. With AVIA this would be the LFE tone that is used for the subwoofer in the speaker channel identification track as well as the "Low Frequency Sweep; LFE" track, which is the best track to use. If you set the SUB=NO and cannot hear the LFE channel-encoded material coming from the front speakers, then it is not being rerouted. But be aware that the subwoofer calibration tracks on AVIA are NOT encoded in the LFE channel, and instead are simply encoded in the main channels and intended to be bass-managed. So, the subwoofer calibration tones are NOT at all useful for verifying what happens to the LFE channel.

As far as I know, if you set a universal player up as SUB=NO, no matter how many main channels you are using, the LFE channel will be dropped. I do not know what a specific "Downmix" mode does, but I suspect it will do the same thing that a standard 2-channel DVD player would do when it plays back a 5.1 soundtrack and passes it via its analog outputs; drop the LFE channel. How 2-channel players treat multichannel (i.e. 5.1 material) content is different than the way that a universal player treats such content. My experience with 2 universal players' analog outs and DVD-A playback has been that, without a downmix mode used, when the player is setup as having only 2 front speakers, upon playback of a 5.1 DVD-A soundtrack, only the front 2 channels are reproduced. The other main channels of the 5.1 soundtrack are simply not reproduced. I assume that the same would apply to DD/DTS5.1 soundtracks. So, that is why a specific "downmix mode" is necessary.

Some universal players have a separate pair of R/L-only analog outs which are completely separate from the multichannel analog output cluster and are not affected by any of the channel settings that apply to the multichannel analog outs. These outputs will behave identically to those of a standard 2-channel DVD player and multichannel content is automatically downmixed and the LFE channel is dropped. However, many players have these 2 separate R/L outputs yet they are NOT treated independently of the front L/R channels of the multichannel analog output cluster. Instead, any settings, such as bass management, that are applied to the front R/L channels of the multichannel cluster are also applied to these 2 R/L-only outputs. So, you have to check what your particular player does with these 2 outputs.

Realize that with most movie soundtracks much of what is mixed into the LFE channel will also be mixed, at least in some measure, into the main channels, as well. So, all is not lost when the LFE channel is dropped. I have heard plenty of 2-channel systems with 2-channel-only analog connections that produced quite a bit of low-end energy.

With multichannel SACD and DVD-A passed via multichannel analog connections, though, and SUB=NO, I suspect the lack of an LFE channel MAY be more noticeable as in most cases, unless a soundtrack is specifically recorded for multichannel playback, the LFE channel is derived from the 2 original stereo tracks and placed into the LFE channel. Of course, for a 2-channel-only setup, almost all SACDs and most DVD-As have a specifically encoded 2-channel track that will contain all of the material that is intended to be heard, so this is not an issue.

Likewise, some (fewer than you realize) DVD movies will also include a specifically-mixed 2-channel track that MAY contain some of the low-end material that would have otherwise been encoded specifically into the LFE track in the multichannel soundtrack. Or, these stereo tracks could simply contain very similar content to what would be reproduced in 2-channel by a player when it downmixes a 5.1 mix for 2-channel analog output. Either way, what is encoded into a specifically-mixed 2-channel DVD movie soundtrack should be expected to contain exactly what an engineer intended it to contain and should provide for satisfactory 2-channel experience.

If you do a search, you will find that there have been efforts (apparently successful) at properly rerouting and merging a universal player's subwoofer channel output back into the front L/R channels using Y-adapters and attenuators. This allows one to leave the player setup as SUB=YES so that the LFE channel is preserved.

Also, as I pointed out, many people have used their universal player with analog connections, setup as SUB=NO, in a multichannel system, and never even realized that their LFE channel was missing.


How 2-channel analog players treat multichannel (i.e. 5.1 material) content is different than the way that a universal player treats such content. My experience with 2 universal players' analog outs and DVD-A playback has been that, without a downmix mode used, when the player is setup as having only 2 front speakers, upon playback, only the front 2 channels are reproduced

What is your particular situation that makes this dropped LFE channel a cause for concern?

My intent is not to stir things up or take sides (I'm here to learn, just like everybody else), but in any debate, sivadselim, it's up to the person making an argument to prove it; it's not up to someone else to refute it. That said, I think that playing an LFE track with SUBWOOFER set to NO is a great test of the theory, altho it may only be valid for the specific model of disc player used for the test. I did a search for "LFE" in the Dolby Digital Professional Encoding Guidelines and there was no reference, one way or the other, to what happens if SUBWOOFER is set to off in a disc player, but it did mention (generically) that LFE is redirected to the main L/R speakers:

[p. 95] - "4.11.3 Bass Management
Bass management allows the user to redirect low-frequency information from any of the five main speakers to the subwoofer or conversely, if there is no subwoofer the LFE information can be redirected to the left and right speakers. This is important as the vast majority of consumer home theater speaker systems require some degree of bass management since typically none of the five main speakers are designed to reproduce frequencies below 80 Hz. The DP562 provides the same bass management functions as a consumer Dolby Digital decoder. Even when monitoring with fullrange main speakers that require no bass management, this function is useful for checking how low frequencies redirected from any of the main channels may interact with the LFE channel information."

No mention is made of different decoders being required (or used) in receivers versus disc players.

It's not a concern. I was just reading this thread (I'm buying a new receiver soon and doing research here) and was puzzled by your statement that disc players handle the lack of a sub differently than a receiver does. As I've said, I'm not taking sides or trying to stir things up... just trying to learn.

OK, that's a slightly different, and more nuanced, claim. I have no issue with that.

FWIW I *think* I have checked this with an Oppo 970 player in the past and found it to be as you say, but I'd have to look up the post or do it again, to confirm (for an Oppo 970). I also recall testing this for a Pioneer uni-player, and finding that it did not reroute LFE to mains.