Directing LFE to subwoofer

[tonygeno]

Is it possible to route only the LFE to a sub with this processor? I am considering the NHT VT-3 system which has two 10's per side that are make it a full range speaker. I wanted to keep my HSU TN1220HO subs (I have a pair) and use them only for LFE. In going through the set up menus of the RDC7 there seems to be no way of directing only the LFE to subs. If I set all the speakers to large, sub yes, crossover of 120, it appears that the RDC7 doubles the bass from the 5 (or 7) channels and sends anything below 120 to the sub (and to the speakers set to large). Am I missing something?

[Burke Strickland]

Tip:
When setting the speaker size in the Speaker Config
sub-menu, use the guidelines given below.
Large: The complete frequency range for the channel
you are setting will be output from the speaker.
Small: Frequencies of the channel you are setting lower
than 80 Hz will be output from the subwoofer.If the front
speakers are set to “Large,” then the sound may be
output from both the left and right speakers. (All THX
speakers are small.)

Frequencies below this are cut from speakers set to
“Small” and sent to the subwoofer (or to speakers set to
“Large”).

The wording in the manual isn't precise, but as I read it, if a speaker is set to "large", it gets the full range signal. Only if the speaker is set to "small" does the selectable crossover come into play. If all channels are set to "large" and subwoofer is set to "yes", the LFE goes to the sub and the speaker for each of the other channels gets its full range signal. (Of course, if the speakers are set to small, anything below the selected crossover frequency will go to the subwoofer, but NOT the speaker for that channel.)

If the bass still seems too heavy on movies, you might want to check out the LFE Level Setup Sub-menu (Section 1-5 in the original manual) that lets you adjust the sub's output level with Dolby Digital and DTS.

Burke

[tonygeno]

Well, you would think, but that's not how the processor works. If I have subwoofer set to yes, and all the speakers set to large, the subwoofer still plays, even on movies that don't have an LFE. If the sub were only getting the LFE, with all the other speakers set to large, it would be silent on 2.0 movies. It's not. This is not a problem with my current THX setup (M&K S150s), but would be with the NHT VT-3 system I am considering as I would have double bass.

[Razvan]

"If I have subwoofer set to yes, and all the speakers set to large, the subwoofer still plays, even on movies that don't have an LFE."

Same here, the RDC-7 has the double bass problem. Moreover, if you listen to music in stereo or watch movies in 5.1, setting the subwoofer to yes compresses the sound. Try watching a movie with the sub set to no and then set to yes, the yes setting compresses the sound. For a $4500 processor this is totally unacceptable.

Razvan

[Burke Strickland]

I have run the Avia audio Calibrations Verification / Evaluation Low Frequency Sweep, Left-Front with the front speakers set to "large" and then with the speakers set to "small". I turned off the power amp driving the front speakers, so any sound would have to be coming from the subwoofer. With the speakers set to "large", there was absolutely no sound at all. With the speakers other than the sub set to small, the sound picks up where the sub is being handed the signal and continues to the end of the sweep.

I have tried several different DVD movies supposedly with no LFE channel present, first with the speakers other than the sub set to "small" and then with them set to "large". As expected, the sub was in play a lot with the other speakers set to "small". In some cases when the speakers were set to large, I did indeed detect some activity at the sub. But it wasn’t 100% of the time when there was noticeable bass present.

So I am wondering, at least with the RDC-7, if the so-called "double bass" effect is a function of the disc mastering and labeling, not a problem with the bass management of the RDC-7.

Burke

[Razvan]

Burke,

Play a CD in stereo mode with the subwoofer turned off and the front speakers set to large. Then from the listening mode menu - stereo (analog/pcm) - change the sub settings to off and then back to on. Do you notice that when the sub is set to on the sound is more compressed? i.e the bass is not as tight and the midrange is less clear. I tried this on 3 RDC-7's with the same result: setting the sub on in the listening menu compresses the sound.

One more thing: in the OSD setup sub-menu ( page 49 in the manual) the Superimpose Mode can be set to black. I tried it several times but I was never able to change the background to black. Can you change the background to black on your unit?

Razvan

[Burke Strickland]

Can you change the background to black on your unit?

Yes... and no. :>) If there is a video signal onscreen, as from the TV or DVD and I select Black for the Superimpose Mode, the menu is superimposed on a somewhat translucent black square. Some picture elements show through faintly. If the Superimpose Mode is set to Normal, the text "floats" over the video image. If the Superimpose Mode is set to "Off", then the selected "Background Color" fills the screen with the menu text on it, totally blanking out any video image. If there is NO video image being sent to the display, then the "Black" setting has no effect at all -- whatever Background Color has been selected is what appears. This may be because without a video image, there is nothing to "suoerimpose" on top of, but wording of the manual would have us believe that by selecting "Black" fpr Superimpose Mode, the background would be totally black all the time (regardless of the presence of a video signal)

Black: Select to have the OSD menu displayed on a
black background at all times.

This looks like a case of the technical writers losing their synchronization with the product engineers. :>)

Burke

[Burke Strickland]

Do you notice that when the sub is set to on the sound is more compressed? i.e the bass is not as tight and the midrange is less clear.

It's like someone stuck their fingers in my ears. Oh, wait a minute -- that was me doing that. :>) Actually the phenomenon you describe is not immediately obvious to me with the CD music selection I've been playing -- I'm going to try it again with some different music. Is this effect more obvious to you on some kinds of music than on others?

I assume that when you say that you turn the sub "off" and then "on" that you mean via the Listening Mode Setup menu option, and that you do not actually physically flip the "on/off" switch on the sub itself? I notice that if I select Subwoofer: "No" from 1. Speaker Setup / 1. Speaker Config, then option a. Subwoofer under 3. Listening Mode Setup / 5. Surround (Analog/PCM) doesn't appear at all. In that case, you have to go back to Speaker Setup to turn the sub back on rather than toggling it from the Surround (Analog/PCM) menu. I guess that makes sense in that if you've told the system that you do not have a sub, logically it wouldn't then offer you the option of turning on and off a "non-existent" sub.

Burke

[Razvan]

"Actually the phenomenon you describe is not immediately obvious to me with the CD music selection I've been playing -- I'm going to try it again with some different music. Is this effect
more obvious to you on some kinds of music than on others?"

My test CD is Andru Donalds' Let's Talk About It - European pop/reggae. Anything pop/dance would be OK.

"I assume that when you say that you turn the sub "off" and then "on" that you mean via the Listening Mode Setup menu option, and that you do not actually physically flip the "on/off" switch on the sub itself?"

2 steps:

1. I turn off the sub itself by physically flipping the on/off switch. The sub is off for the whole duration of the experiment. With the sub off I then proceed to step:

2. In the listening mode setup menu of the RDC-7 I go to stereo analog/pcm and first set the sub to off and then back to on and compare the sound for when the sub is set to off to when the sub is set to on. The sound is compressed when the sub is set to on.

"I notice that if I select Subwoofer: "No" from 1. Speaker Setup / 1. Speaker Config"

Here you should select subwoofer "Yes" i.e you tell the RDC-7 that a sub is connected to it. Otherwise step 2 above wouldn't be possible.

Razvan

[Burke Strickland]

Hey Razvan –

I’ve tried the sub "on"/sub "off" test with the sub physically turned off using several different music selections including Frager plays Chopin (solo piano) Bernstein conducts his music for Candide (orchestra and chorus) Grateful Dead /Touch of Gray, Gus Gus/Gun and Saint Saens/Third Symphony (Eugene Ormandy/Philadelphia Orchestra). In all cases, I could hear no difference when the "Listening Mode Setup" for "Surround (Analog/PCM)" / "Subwoofer" was toggled between “on” and “off”. I tried it three ways:

1) while watching the OSD for the setting and
2) with “random” number of button pushes to settle on a sub state ("blind” to the OSD so I did not know whether the sub was on or off).
3) toggling back and forth periodically between "on" and "off" with the OSD not displayed so I did not know which state was activated. (Of course I knew which one it started on, but after a few button pushes with the OSD obscured, I lost track.) :>)

I detected no difference to my ears in any of these test modes in listening to any of the music, with the following exception. At one point during the Gus Gus selection, I thought I was hearing what you described. But it had been a while since I had listened to that song, and I had forgotten that it switches back and forth between sounding “compressed” and “full range” within the recording itself. It had just been a coincidence of timing that I had gone from sub “off” to sub “on” when the first switch from “full range” to “compressed” came within the music. (IOW, the switching between "compressed" and "full range"-sounding happens regardless of which sub mod is selected.)

So, while I have no reason to doubt that you are experiencing the phenomenon, particularly since you’ve tried it with three different RDC-7s, I can neither replicate it nor explain it -- unless that particular CD you’re using for your tests has somehow snuck in an LFE channel and so when you select sub “on”, the RDC-7 truncates the bass, (since there is no place for LFE bass to go with no subwoofer available), making it seem like the sound is more compressed.

Out of curiosity, were your trials "blind", or were you watching the OSD to determine each time whether the sub was "on" or "off"? Even unintentionally, it is possible for visual cues about our equipment to influence how we perceive its sound. Sometimes I can "talk myself" into hearing things a certain way if I "know" a particular condition is true, and then when I find out the condition isn't true after all, the way it sounds may or may not change. (For example, seeing a flashing light on the amplifier's front panel and thinking I must be hearing clipping, when in fact, it is merely the indicator bulb itself starting to fail.)

I also wonder, even if the phenomenon is replicable among a wide number of RDC-7s in consumer's' hands, whether it is really something we need to be concerned about, since logically, if there is no sub available (physically turned off at the sub or the sub not even connected), then the sub selection should always be “off” anyway. But it was an interesting exercise, nevertheless, exploring the RDC-7's controls and menu options.

Burke