I know this subject has been discussed before in this link http://ubb.outlawaudio.com/ubb/Forum15/HTML/000816.html but I am still having a problem setting correctly. While redoing some of the equipment I began to run through the normal setup items with the SPL meter and everything is going fine until I get to setting LFE phase using the Chesky disk. I believe there is something odd with the LFE phase tests on this disk. I am having similar problems to Kevin C.Brown in that no matter wat I do the out of phase signal is always louder while using the 6 analog inputs. I now have the system setup so that only the LFE is driving the sub amp and switching the phase makes a slight difference in sound but it doesnt change the fact that the out of phase signal is louder.
While trying to figure this out I wanted to see if the signal being sent to the amp is equal for both the in and out of phase signals. If I measure the voltage coming out of th 950 at the LFE jack the mV reading is a little more than double for the "out of phase" sinal compared to when the signal is "in phase". I don't know if this is a proper way to test for this and that is my reason for asking some of you local electronic experts. It seems to me that the ouput from the 950 (or the DVD player) should be the same reading regardless of it's phase. I can naturally increase or decrease this signal with the volume on the 950 but the variation always seems the same. I tested phase signals using another disk (Avia) and I don't get the variation in the voltage signal.
I guess my question is that if for some reason the "out of phase" signal being produced using the Chesky disk is higher than the "in phase" signal the amp will play louder, would the use of the SPL meter to check phase be useless?

Keta,

The first thing I'm curious about, is how you have your system configured to send only the LFE to the sub amp when in 6 CH BYPASS?

The second issue regarding phase alignment between your mains and sub is that, unless the mains and the sub are exactly the same distance to your meter, you're not likely to ever have the phase correct if you only have a normal/reverse phase switch as your tweak.

There is definitely something at play when switching from the digital filters of the 950 to the analog filters. Exactly what the answer is was never arrived at, at least to my satisfaction.

I personally think that the problem arises from the way digital BM works, creation of a duplicate signal for each channel, 1 that's HP filtered and the duplicate that's LP filtered (selectable triple crossover), volume adjusted and sent to the summing block to be combined with the LFE signal, which has a global, 120 Hz LP filter applied.

Analog BM is a simpler 80 Hz HP/80 Hz LP Linkwitz/Riley active crossover.

Other issues include whether or not your player applies a global LP filter to the LFE signal in the digital output vs. no filter on the analog LFE output.

The fact that some people experience the phase shift when switching from digital BM to analog BM and some do not, indicates that placement distance differences and/or player/950 cascading filters probably have the most to do with the answer, because there's no way I believe that some 950s have properly wired analog crossovers and some do not.

As far as the setup discs that are currently available for multichannel audio systems, I'm not a fan of any of them.

I just use a SACD MC disc that has good LFE content and repeat a track that has a bass line intro and play, meter, reset and pause, adjust phase and repeat until the reading is highest, with the SPL meter in my listening position.

BTW, I don't see a difference when switching back and forth because I keep my 950 in 6 CH BYPASS mode all the time.

Bosso thanks for the response. I will try and answer some of your questions.


Denon sub out --> 950 sub in --> dedeicated sub controller/amp --> speaker



The subs(2) are directy beside the mains. Can't get much closer together and they are the same distanse from the meter. The mains are bi-amped using the Main L/R but were turned off for my testing.



I was only using the analog connections.



Whatever the 950 uses through it's sub out, the the bass management set to off.

I have all the filters disabled and am only using the analog connections. I am not seeing the difference when switching between bypass and digital (although I'm sure I would) because I havn't left the 6 channel bypass yet. The Chesky disk is in DVD-A and that is all that I have used to setup with.

While typing this I went and tried a few other things. I let the Chesky disk repeat it's 60Hz phase test with the SPL meter reading 80dB for "in phase" and 90dB for "out of phase". Switch polarity on the sub and nothing changes. Remove the LFE cable from the DVD player and the SPL readings are 80dB for both phases. Switch sub polarity and nothing changes. I wouldn't expect the sub polarity switch to change anything since during this setup I'm not trying to match the phase of the sub to anything.

So it appears that the 950 sums L/R bass and passes it to the Sub output(double bass syndrome) along with the bass being fed from the DVD players LFE output. But it also appears there is no increase in SPL if the signals being fed are in phase. Does that make any sense?

Anybody have a work around that I might try or should I just do as bosso says and use music. bosso give me a musical suggestion in DVD-A if you can.
Thanks

The chesky disk also has a DD 5.1 phase check. Just set your denon to DVD-Video (in my 3800 that's a option in the set-up menu under the "Etc." tab) and the chesky disc will fire up in DD instead of dvd-a.

Thanks jgubman. I just switched over and I'll run the checks in the morning.

Decided to try the DD track a try and it appears to work fine with the digital input but wrong using the 6 channel input. I had to make some adjustments to the 950's crossover points while using the digital input. I had the fronts set to Large and the sub On and I assumed nothing was taken from the fronts and sent to the subs but alas I was wrong. Not only does it forward information but it is dependent on the crossover point. When i switched to the 6 channel input still using the DD track the problem appears to be the same as using the 6 channel inputs with the DVD-A.

Keta,

are you saying that w/ the speakers set to Large and Sub on in the digital mode you still get summed bass sent to the subs?

That can't be correct, can it?

I agree that w/ the analog outputs, all kind of weird stuff is happening to the bass. I've recently purchased truly full range front speakers (VMPS RM-40s, flat to 24Hz) and the Outlaw's flawed analog bass management is getting really frustrating. There seems to be NO way for me to get the sub-80Hz frequencies to the fronts w/o also going to the subwoofers.

Here's something even more interesting. I have the Lexicon MC-8 now which doesn't have BM on the 5.1 inputs. If I adjust phase correctly using a digital signal to the pre/pro, and then compare to the analog DD signal out of the player, I am OK. (But there are small differences in phase.) But when I check with DVD-A analog, out of phase. I tried both with and w/o BM enabled in the player. Now, I am convinced the player is doing something funky.

One thing I want to check but haven't had time, is just try this using the front L & R speakers. Wierd, huh?

That is exactly what is happening. This is what I'm doing when this happens. Using the Chesky disk, DD setup, track 23 - 60Hz phase test which is a test for setting the phase between the mains and sub. My mains are biamplified and I have the lower bass section of the mains turned off so the only thing reproducing the 60Hz tone is the sub. The sub is being fed it's signal with the LFE output from the 950. I believe by just having the sub reproducing the 60Hz, phase doesn't matter since the sub is acting alone.

DVD playing track 23 repeating, no bass management in the player.

950 set to optiacal input, volume set so RS meter reads 80dB, all speakers set to LARGE, sub ON, crossovers set at 150Hz.

While playing the tone I went to the speaker setup in the 950 and took these readings from the RS meter while lowering the crossover setting for the front speakers:

Crossover setting -------RS meter (dB)
150Hz -------------------80
120Hz -------------------80
100Hz -------------------79
80Hz -------------------78
60Hz -------------------75
40Hz -------------------65

My conclusion is that you do get summed bass to the sub in digital mode and it is crossed over at the front speaker setting. Another odd thing is if you turn the sub setting to OFF it forces the the bass signal to the surrounds as well as the fronts but not the center. It only forces to the surrounds if they are set to large and none of the crossover points change the output. Strange?

[This message has been edited by Keta (edited December 09, 2003).]

Keta,

In one of your posts, you said that you have the mains bi-amped, but shut off for the test.

In the following post, you said that the mains were on for the test.

What are you using for mains and what is their published response (+/-3dB)?

Also, what 'dedicated sub controller' are you using?

Jgubman,

The 950's analog BM is NOT flawed. It works exactly as it was designed. The design is for the switch to be in the 'on' position, in which case, it works as accurately as any active crossover I've ever owned...at any price.

If you insist on switching it 'off', make sure that you are using 5 identical, full range sats, perfectly equidistant from the LP (per ITU standard, which see).

Otherwise, lesser surround and center speakers WILL suffer damage at ref level with many hi-res discs.

If you don't have full range all around, but you still want the switch 'off', then bi-amp your mains and adjust the 950's SW trim until you have a flat response. You'll have to run sine wave sweeps and use a correction chart to draw a graph of your in-room response, but if you do, then you'll see that there is not only no flaw, you will have a better shot at a flat curve result with the analog BM as is.

You can also run the cable from your player's analog SW output directly to your subs instead of the 950's analog SW input.

This will send LFE only to your subs and full range without LFE (since there is now no LFE input into the 950, there will be none in the mains) to your sats.

This is a very simple work around that requires nothing more than redirection of the same cable. The tradeoff is that you'll have to adjust the LFE level manually. The plus side is that you'll be able to do that independent of the sats bass level, to taste, and you'll now know when there is LFE signal on any given source, where otherwise, you have no idea.

BUT...the phase alignment of these 4 subwoofers is crucial to proper playback of any MC source, regardless of the preamp's configuration menu.

When I say equidistant, I mean get out your ruler and place the subs equidistant with the mains to the LP. Measure from the center of the cone to the meter's mic.

This should be done before any testing or EQ is applied.

I'm not into DVD-A. I prefer SACD, so I would have to say, given my limited knowledge of DVD-A titles and their LFE content, that Steely Dan's 'Two Against Nature', Shame About Me or Cousin Dupree are good tracks to do a bass phase test.

Play the beginning of the track, with 1 sub shut off, the speakers placed properly and the SPL meter set up at the LP and note the reading. Reset the track and pause. Change the phase conrol to reverse and repeat. Use the setting that reads highest on the meter then repeat the procedure adjusting the phase control about 1/10th increments from 0 to 180 degrees each time.

Then, leaving that sub on, turn the other sub on and repeat the procedure.

You'll have to note the results and repeat the test for digital mode. If the results are different, you'll have to switch back and forth for each mode before you play.

Sounds like a PITA, but it really isn't when you know you're hearing your system at it's best for any source you play.