Outlaw ICBM question: Recombine/LFE weirdness?? (1 Viewer)

[Mike Sloan]

I understand that the recombine switch returns the bass directed to the sub back to the Front L/R speakers. With the recombine "on" I also notice that the LFE is also re-directed to the Front L/R speakers. Now here is where it gets weird: With the Spyro Gyro SACD and a few others it seems that the LFE contains "full-range" information and enabling the recombine switch, not only increases the bass, but increases the level of vocals, trumpets, and higher frequency info that normally is not associated with the LFE. Could I be picking up height channel info or non standard LFE stuff? It's happened a lot with Telarc label SACD's! Please explain.

Thanks
Mike Sloan

 

[BeatCrazy]

The "recombine" switch only sends low frequency info from the main speakers at frequencies below the crossover settings that you put on the main speakers. So, there should be no reason to get vocals, etc. out of your sub.

If the LFE channel on the SACD really does contain vocal or "height" information, you should set your SACD player to 5 large speakers + Sub and you should get rid of this problem.

 

[Mike Sloan]

The "recombine" switch only sends low frequency info from the main speakers at frequencies below the crossover settings that you put on the main speakers. So, there should be no reason to get vocals, etc. out of your sub.

If the LFE has full range information....and you have disabled the crossover on the back of your sub...you will get higher freq's out of the sub. The ICBM let's the LFE go through un-processed! It does bass management on the other (5) channels....but sends the LFE untouched. Where I noticed the weird effect was listening to Spyro Gyra. When I turned on the "recombine" switch...the saxophone doubled in volume in the mains. I could reduce the volume of the saxaphone by turning the LFE trim switch down. That told me that Telarc was doing non standard stuff in the LFE! I called Outlaw and they confirmed that Telarc doesn't comply to the Loose standard for LFE use in SACD audio and occasionally puts full-range and height info in the LFE.

So in this situation...setting all speakers to large...really negates the very reason to have an ICBM...and even if you did...the sub would still receive the "un-touched" LFE. The ICBM does no processing of the LFE...it is allowed to pass in it's native state...it is up to the sound engineer to put appropriate info there. In 98% of my SACD/DVD-A there is no problem.

Has anyone else experienced this?

 

[BeatCrazy]

Mike,

You need to do what I suggested in the 2nd part of my post. Set your SACD player to 5 Large speakers + Sub and it should disregard the LFE channel and let your main speakers run full range. You'll have to test what the LFE gets in this situation. This setting (on Sony players) is different that the setting of "Multichannel Direct" which would leave you with the situation you're describing.

 

[Rich Malloy]

This is interesting... I've heard about Telarc's unusual usage of the "sixth channel", but I've never thought about the problems this will cause most systems (how many of us have a "height envelope channel" anyway?).

But I've got another possible workaround. I haven't thought this through entirely, but the ICBM also has an input for a center-rear signal. What would happen if you physically changed the cable from the LFE input to this input, and then did the "bass recombine" thing? Would it then redirect the bass/lfe to your mains, but "throw away" all the signal above the crossover setting for your "center rear" channel? Again, I haven't thought this through, but it might give you some added flexibility.

(And Telarc doesn't recommend anything in particular? Do they simply presume that we all have "height envelope" speakers, and we're out of luck if we don't?)

 

[Mike Sloan]

Rich, I think you are on to something! I think it would through away the full range stuff and send the "crossed-over" info back to the mains and to the sub....I need to think about this because it warps my brain! I did a search on "non-standard LFE" and Telark and Chesky popped up all over! I think it is crazy to master SACD/DVD-A with height channel info....because it screws up everything us "hometheater" guys have set up. Chesky seems to have backed away from the LFE and center rear philosophy and have introduced (2) center height channels....this reaks havok on the conventional setup....since 99% of the multi-channel SACD/DVD-A's are conventional in their use of the LFE. The way I have fixed it now is just to not use the recombine feature of the ICBM (which I probably don't need...double bass thing) and engage the crossover on the sub in it's full up position.....I may try what you suggested...VERY INTERESTING! If you go to the Chesky Website...Mr. Chesky talks about the use of the LFE/Center rear for full range height info...sort of arrogant to through a monkey wrench into this arena...where normal people are struggling just to stay up with the technology.

 

[Rich Malloy]

You're absolutely correct, Mike, but I can't quite fault Telarc for their approach (though I do believe there should be a recommended "work-around" for those with conventional home theater setups). They want to provide the very best music reproduction possible, and I've heard (but not actually heard) that their approach to multichannel creates the most realistic soundstage of any.

Let us know how it works out!

 

[Mike Sloan]

Actually talked to someone at Telark and they confirmed that it is becoming popular for engineers mixing multi-channel music to include full range info in the LFE. He also said that to avoid confusing the average consumer, there will be no instructions provided in the disc’s liner notes on how this combination track is to be employed, only a reference to the record label’s Web site where the curious and adventurous can find setup details on how to optimize their surround systems and include the height channel.

So for us ICBM user, this means splitting the subwoofer out from the ICBM and running one side to the subwoofer (as usual) and then running the other side to the input for the center-rear signal on the ICBM. You would then run the rear center output from the ICBM to an outboard amp and on to your height channel.....NO THANKS! And what if Chesky decides to redirect the Center and use it for a height channel.....man I need a Valium! Thank god the ICBM does an excellent job of bass management....because the poor sap who only uses the BM in the DVD-A player is left out in the cold... According to Telark...When they utilize the LFE for other than Low Info...the bass information for the music is mostly mixed to the front L/R speakers. If one was to set their Front speakers to Large and everything else small..no bass would go to the sub..nada! Another problem of using the LFE track as a height channel is that, in most cases, it will simply be ignored and routed to the system’s subwoofer by default. No damage will result from this signal misdirection, but the subwoofer may not be giving the optimum bass response needed to fill-out the bottom end of the typical satellite surround system. The surround music playback may sound thinner than the movie soundtracks played on the same system. The consumer will be less than satisfied with the audio quality, but won’t know why. Furthermore, since the LFE is left "un-touched" (no BM on LFE) the sub will easily be localized and produce frequencies that are full range..unless you engage the crossover on the sub.

Maybe with persuasion and experimentation I will come to appreciate this...but for now I am skeptical....can you tell?

 

[Mike Sloan]

In my "RANT" above I forgot to get back to the original topic......That is why the ICBM user will hear an increase in "full range" information (as well as bass) from the Front L/R speakers when the Recombine is engaged. It is not only returning the "crossed over bass" back to the mains....but also the "non-standard" full range information added to the LFE for the height channel.....I'll go away now...at-least I determined nothing is wrong with my ICBM....now off to the store to buy more interconnects, more speakers, and another amp...sombody shoot me!

 

[BeatCrazy]

Mike,

Did you ever try the setting I suggested to your SACD player to eliminate the "height" channel completely before it even got to your ICBM?

"It is not only returning the "crossed over bass" back to the mains....but also the "non-standard" full range information added to the LFE for the height channel...."

This is not really what happens. With the recombine switch on, the ICBM is not returning any bass to your fronts, only sending them the original front L/R info untouched.

 

[Rich Malloy]

Some Telarc surround recordings may employ a HEIGHT channel on the disk channel formerly used by the LFE (.1) channel. Your use of this height channel is completely optional. The vast majority of home theater surround receivers and preamplifiers have Bass Management features that allow the listener to derive the subwoofer (LFE) signal from the main audio channels. With Bass Management, the LFE channel from the disc is redundant and we can now use that channel for full-bandwidth audio. The recorded height information on particular surround recordings helps better represent the depth and height of the actual recording space. This channel can also help bridge the gap between front and surround speakers. The height information in the recording is subtle, so if you cannot play this channel back you will still have an excellent surround presentation. A pair of small speakers may be placed high on the side walls about midway between front and surround speakers (see diagram 2). Alternatively, a single small speaker may be placed over and above the central listening position. Small dipole speakers such as those by Magnapan, Bose, Paradigm, or Boston Acoustics would serve well to play the height channel. Set the playback level to be equal to the main channels.

So, don't worry about it! You don't need to derive the "LFE" signal from the height channel because all the bass you need is already being sent to your other speakers. Simply put, the LFE channel is no longer the sole carrier of the very low bass frequencies, but rather just another full range channel like all the others... except it's optional.

(IMO, but I think I'm right!)

 

[Chriss M]

this is one of the reasons why i listen to 2-channel SACD

 

[BeatCrazy]

That is, if the L and R channels are set to a 40Hz crossover with the recombine switch on, then the L and R speakers will be receiving a full-range signal (not crossed over at 40Hz... more on this later in the sentence) plus all redirected bass from other channels (and also LFE?), and then the sub doubles all the bass up to the 40Hz crossover point. If set to 60Hz, then the sub doubles all signals up to 60Hz, etc.

This is not true. The recombine switch does not send all the bass from the other channels into the L&R mains. It is meant primarily for use with a 2.1 system where you want to run your L&R full range but "reinforce" them with a sub below the given crossover point you set.

Still, no one is taking my suggestion to set the SACD player to "5 Large + Sub"?!?! This will solve Mike's original problem. Sony gave you this setting for just such the scenario (eliminate the height channel).

 

[Chriss M]

Still, no one is taking my suggestion to set the SACD player to "5 Large + Sub"?!?! This will solve Mike's original problem. Sony gave you this setting for just such the scenario (eliminate the height channel).

the problem with this is that many people feel using any of the on-board bass management features of the sony SACD players noticeably degrades the sound quality.

 

[Rich Malloy]

Mark, I know you mean well, but you're just flat-out wrong on all counts.

Go to pg. 14 of your ICBM owner's manuel to learn what the recombine switch does (it will do what you say, among other things, but it's primarily intended to redirect bass to the front mains in systems running without a subwoofer).

And as for the "5 large + sub" option, not only will this not solve Mike's "problem" (which isn't a problem, after all), but engaging it will degrade the quality of the signal.

Again, I know you mean well... but your information is incorrect.

 

[Rich Malloy]

Moreover, if one uses an ICBM for bass management (in any configuration) while also using the onboard bass management of the SACD player ("5 large + sub" or any other configuration), then one's setup is completely screwed.

 

[Mike Sloan]

Sam Scamardo,
Sorry for not responding in a timely fashion...I have been in Tucson helping my Brother-in-law with his new HT system.

The "recombine" switch only sends low frequency info from the main speakers at frequencies below the crossover settings that you put on the main speakers. So, there should be no reason to get vocals, etc. out of your sub.

OK a bunch of stuff is happening here:
First off, I have set my Pioneer DV-45A(DVD-A/SACD player) to "all speakers LARGE and SUB-ON." When you do this you are, in effect, bypassing the BM in the DVD-A/SACD player and sending the full range information on all channels to the ICBM...so it can handle the BM. When you set "all speakers LARGE and SUB-ON in the DVD-A player you are isolating the LFE information to the sub output. If you set all speakers large and sub "OFF"...you would blend the LFE into the 5 channels you have set to large (this may be one way to deal with this pesky non-standard LFE.) So now we have all LARGE and SUB-ON coming out of the DVD-A player and going into the ICBM. The ICBM has the capability to do "analog" BM on the (5) channels....but does not perform BM on the SUBWOOFER input! It will send whatever signal it receives on it's respective SUB-IN input unprocessed to the subwoofer. So.....If Telark or Chesky put full range information on the LFE....it will go full range to the subwoofer....OUTLAW AUDIO has confirmed this! The only way you can get rid of the "unwanted" high freq. information is to enable the crossover on the back of the sub...which I do not prefer to do.

Now getting to the "RECOMBINE" issue. If I set my front L/R speakers to be crossed over at 60Hz and turn the recombine switch on...what happens is the ICBM (first) cuts frequencies below 60Hz out of the front L/R speakers and sends it to the sub. It then turns right around and sends the 60Hz and below stuff back to the front L/R.....but one other thing happens.....it also sends the LFE back too....that is the rub...the LFE comes back also....OUTLAW AUDIO has confirmed this! So that is why I heard a doubling (more volume-accentuation) of some higher frequencies coming out of my mains when I flipped the recombine switch to on. Now either I have a faulty ICBM...or Outlaw is not being truthful regarding this! That's all I know???!!!

 

[Rich Malloy]

Mike, remember that the primary purpose of the recombine switch is for systems without a separate subwoofer. If you have no way of redirecting the LFE signal (in addition to the bass below the crossover points of your center and rear speakers), then it's simply lost. That's why it's crucial that the LFE be sent to your mains when the recombine switch is engaged.

Did you read closely the stuff I quoted from the Telarc site? I don't believe this is a problem at all! The so-called "LFE channel" is no longer being used as a discrete bass-carrying channel. Rather, it's being utilized as an optional height envelope channel. Optional.

Just as they should, Telarc sends a full-range signal to all channels. This is the proper, purist approach. Ideally, we'd all have full-range speakers in all channels, but in truth we have a variety of different sized speakers from system to system. It's true that some of us have tiny rear speakers, but of course Telarc certainly shouldn't mix their recordings for the home-theater-in-a-box crowd! Rather, they should provide the "perfect" mix, and then we can bass manage that signal to fit our systems.

So, by ignoring the height-envelope channel (which is referred to as "LFE" merely as convention, not by Telarc's actual use of it), you are not losing any low-bass info. All the low-bass information is being sent to your speakers already in the form of full-range signals.

Which, of course, begs this question: why would any studio utilize an LFE channel for music? Wouldn't this always be a pre-fab compromise for the "home theater in a box" crowd, and an irreversible corruption of the signal for the audiophile community (many of which have large full-range speakers and do not include subwoofers in their system at all)?

First off, I have set my Pioneer DV-45A(DVD-A/SACD player) to "all speakers LARGE and SUB-ON."

I'm not familiar with your player, but if I set my C555ES in this manner ("5 Large + Sub"), I am engaging the bass management circuitry, and causing deleterious effect on the purity of my signal. The proper setting on the C555ES is "Multichannel Direct", which may or may not include a sub or center channel speaker. It just sends whatever signals are encoded on the disc to whatever channels the software identifies. And without corrupting the signal!

 

[John Kotches]

On the use of 6 channels....

Telarc does in fact use the ".1" channel as a 6th "full range" channel on some channels.

It is intended to use an LP/HP combo, with the Low Pass going to the subwoofer, and the High Pass going to the height channel. I think the crossover points are asymmetric (I'm not looking at any documentation) with the subwoofer getting 120Hz and below and the height channel getting 180Hz and above.

Telarc uses a pair of Magnepans at ceiling level on their sides. The speakers are wired in series, so they get a fairly diffuse presentation, with the dipolars radiating above the listening station.

Chesky does have a 6.0 configuration, with height channels. I wrote about this in our DVD-Audio article at Secrets (click here) in late 2001.

MDG and Tacet are doing 6.0 as well.

Regards,

 

[BeatCrazy]

but engaging it will degrade the quality of the signal.

Hey, if we're really worried about him degrading his signal, he should toss the ICBM and use ony a "Multi-Ch Direct" setting and just live with the 1% of SACD that this will be a problem with