based on the statements above, it appears that the sherborn sets the sub LPC at the level of the highest of the three HPCs. of course that could be false, I was just going on what the article said.


brianca..

[This message has been edited by brianca (edited February 14, 2003).]

Kevin, Depends on the material that is being processed (bass management, not surround processing). With discrete multi-channel sources, full range content in each channel exists in the recording. Where ever you set the crossover for each channel, the frequencies below that point should be moved to the subwoofer output. You can set your subwoofer's crossover as high as you want, but the only content to reach the sub should be the frequencies shaved off the other channels. So if you're crossing over your mains at 40Hz, then the subwoofer output should only be putting out content below 40Hz, whether the subwoofer's crossover is set at 40Hz or 400Hz. For there to be bass "doubling", the processor would have to actually generate some duplicate bass content.

With matrix derived sources, it's a different story. Here the processor IS generating additional channels (including the sub). Mind you, the contents of these channels are 100% from the original 2-channel recording (i.e., no generated sounds, echos or reverbs), but the channels themselves are generated by the matrix decoding process.

I used to think that modern matrix decoders (like Neo:6 and PL II) used to first generate 5 full range channels, which would then be bass managed into a 5.1 speaker set-up. However, it turned out to work a little differently than that. In receivers and processor I've had experience with, the matrix decoders did not generated full range signals for every channel unless they were all set to 'large'. If any of them were set to 'small', they got a derived signal that only contained sounds above the crossover point. It's not like that channel was full-range content that existed discretely on the recording. Since it this derived channel never had full-range content, there's no bass to move around. Each channel gets only what's above the crossover point.

So what comes out of the subwoofer output? It's another generated channel, made by summing the original 2 channels of the recording. As with the other derived channels, it will only receive content based on where its crossover is set. There's no need to take frequencies above this crossover point and move them to the main channels because there were no sounds above that crossover point to begin with; i.e., this isn't discrete content from the original recording, like a .1 LFE channel is.

In both cases, I think it's best to set the subwoofer crossover to the same setting as the highest crossover point of the other channels. If the processor is performing bass management correctly, you shouldn't be getting any duplication.

Best,
Sanjay

I thought there was a LPF on the sub at 120 Hz as per DD (DTS/XYZ/?) specs, that was distinct from the triple crossover - IOW a 3000 Hz signal on the .1 would be attenuated by this LPF. Am I wrong? If not, could this be the root of some confusion?

I use distinct crossover fequencies for each of the three sets of channels. It works for me.

However, when switching between 2.1 (e.g. stereo with sub) and 5.1, I encountered a phase shift problem with the subwoofer. As I recall others noticed the same in their set up, when going from mutlichannel to stereo+sub, but it could be problem with the overall room layout, not a pre/pro problem.

Mine works exactly as I described, or as Scott did a better job of describing. I even checked by unplugging channels from the ampindividually and checking the crossovers and how they worked. Flawless.

Hey folks, just to let you know, the Outlaw, Sherbourn and Atlantic all function identically. They have the same exact DSP engine, firmware, and analog design. There really are no differences other than cosmetics. I heard the Blue Dot rev was actually a result of Sherbourn Engineering helping East Tech with cleaning up the analog design.

If you think about it, the Outlaw is the true bargain of the three since it is the cheapest. Thats my take.

Scott- Awesome! (I really mean that, because that means that Brian Florian of Secrets doesn't know what he's talking about, at least as far as the 950 goes...)

I always took that separate 120 Hz value as the low pass for the LFE (0.1) channel, *not* of the crossed over info from the mains, center, surrounds, rears. So the LFE channel isn't allowed to go full range to the sub, which doesn't make sense anyway. But the way that FAQ read, I wasn't sure in terms of how they referenced it. (Tidbit for the Outlaws: the Sony TA-E9000ES allowed you to choose that number. I believe 120, 150, 200 Hz were the choices.)

Cool!

Hey KCB,

Did you get a resolution to the phase shift?

Will

Yeah, that's what I assumed as well, but I can see how it might be confusing - heck, BM is confusing enough as it is. I don't really understand WHY there is a LPF on LFE, (other than a reference to a spec I saw) but I guess it won't hurt, most of the time.

I just came from the H/K website. They claim a triple crossover, but it is only high pass. Then a seperate low pass must be selected for the sub. H/K cautions that the subs low pass must be set at the highest of the triplc crossover settings to avoid creating a bass hole. This would indeed cause a bass doubling in the mains if they were set to crossover at a frequency lower than the sub's crossover. Why the hell would they do something stupid like that???