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In Reply to: Re: John, it gets stranger still... posted by John Kotches on April 14, 2003 at 13:50:14:
Telarc mixes all the bass below 80Hz into the LFE channel but does NOT remove it from the main channels. Thus, you do not have to use a sub and, if you do, you have the choice of adding a HP filter to the main channels or not. If you do not, you also have the option of adding a height amp/speaker running off the "LFE" channel on many of their discs.
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Then those who do nothing end up with an exaggerated FR from 80Hz down to the -3dB point on their main speakers.Now that I've typed a little more, I'd say this is a bad practice, as it assumes the end user will place some type of LPF on their subwoofer channel.
So the end user has to remember "Oh, this is a Telarc disc, so I have to implement that Low Pass Filter on the subwoofer".
Perhaps Michael Bishop can chime in on this topic, because the more I think about it, the worse it seems.
on the Hi Rez Highway under The Emperor's New Format. Obviously, he believes that no discerning audiophile would use bass management on SACD with current players. On the other hand, most of us have a low pass filter on the sub.
Who doesn't have a LP filter on the sub?
Kal,Sorry, let's try this one more time, so I can make my point clearer:
Subwoofer inputs can be filtered or unfiltered. Well designed subwoofers have both filtered and unfiltered inputs.
For movies, which will engage the crossover in the Processor/Receiver, you would want to use an unfiltered input, or for a sub lacking an unfiltered input, you'd set the subs internal LPF as high as possible (150+ would be ideal).
However, with Telarc's method, assuming you have mains with solid response down to 40Hz, you have an octave of information which will be doubled up. So you turn the LPF down to about 40Hz to correspond with the speakers -3dB point. Cool. That handles the mains. Any material on speakers (say surrounds and CC) which don't have the same response characteristics (say a 60Hz -3dB point) you've lost information between the -3dB point and the LPF engaged on the subwoofer.
You are also forced to change the setting of the LPF when you change between movies and Telarc's authoring standards OR use two seperate connections (one to filtered, one to unfiltered) if your subwoofer has appropriate inputs.
BTW, some of us use passive subwoofers, driven by regular amplifiers which don't have low pass filters.
So as I said, the more I think about it th emore potential issues I see.
On my Denon AVR-4800 you choose "LFE + Mains" and the bass from all channels from 35 Hz to 80 Hz is handled by the Studio 100s, even though the subwoofer is low pass filtered at 35 Hz. And much more nimbly than a Servo 15 would handle it.
Jim,This continues to stray ever farther from the defined standards.
LFE+Mains is a nice feature that has very little support in the industry. I haven't worked with Denons receivers, save the 1802, which didn't have this option.
It doesn't change the fact that the vast majority of installations will be problematic, though does it?
This isn't even remotely the "I'll look after you, automatically." type of bass management that consumers need.
Merely another complication in an already overly complex area. As a user of (fairly) full-range speakers all around, I have no problems with the Telarc arrangement.That said, I do now see your point and does require one to make a choice of default setup. Movies are relatively unimportant to me.
Kal,My breakdown is about 60% Music, 40% HDTV and Video, so it's more important to me. I suspect that in the world of multi-channel the norm is going to be much more balanced in music/movies.
As I said earlier, the standardized implementations of DD and DTS do have benefits in terms of ease of use.
We haven't really discussed the differing requirements of implementing the Telarc Height configuration vs MDG and Tacet's 2+2+2 vs. the Chesky 6.0 configuration.
With flexibility comes compexity which has to be deat with somehow.
That is precisely what I do through the "bass enhancer" circuit of my Denon DVM-4800 or through the "mains plus sub" option in the AVR-4800. The result is very convincing bass from the combination of the Paradigm Studio 100s four 8" woofers and the Servo 15, filtered at 35 Hz. You've got to move a lot of air to get convincing bass.Outlaw and Atlantic Technologies are both offering this type of "full range" bass management for the 5.1 inputs on their new processors.
If your system is already set up to mix the bass from the main channels and deliver it to your sub along with the content from the .1 channel, then on Telarc titles you're going to get double the bass to your sub. It might not be as noticeable since you're using a low crossover, but it's still a bad approach IMO, if this is what Telarc is actually doing.
I started this thread to point out non-standard bass implementations in Hi Rez. Personally, I think that the Telarc method could sound good on many players using no bass management - they will get the same result as I'm getting as long as their sub is low pass filtered. But it might sound horrendous on my system or on a system where the sub is not low pass filtered.
It would seem that Telarc's approach only makes sense if you assume the playback system has full range speakers all around. Then you can either use the 6th channel as a height channel or use it to drive a sub with a really low crossover (e.g. 30-40 Hz) to fill in below the main speakers. But how many people have a multichannel setup with full range speakers all around, and how many of those people are going to set up their system just to take advantage of a handful of Telarc titles?It could also work OK for some people who have small speakers all around that just happen to drop off conveniently around 80 Hz so that no additional filtering is required. But presumably, those people will already be employing some sort of bass management so they'll probably end up with the bass being 3dB too high because the .1 channel is getting each channel's bass mixed in twice. Sure they can disable the BM, but who wants to change their setup just to listen to Telarc's material? And what about all the people who have a mix of large & small speakers?
In my worthless opinion, there is only one solution that makes any sense. Everybody who is producing music SACDs and DVD-As should treat all 5 main channels as full range and should never, ever redirect any bass to the .1 channel. Bass management should be entirely the responsibility of the playback system, because only the end user knows how his/her speakers are set up. In fact, I think it's best not to put any music content in the .1 channel at all; leave it for LFE use by DVD-V and DTS. I know it would be nice to use the 6th channel for optional purposes like a height channel, but a lot of systems out there will end up boosting it and sending it to the sub.
While I think that most will agree that Telarc puts out consistent and often amazing recordings, I agree with Dave's assesment of that "redirected" bass via the producer -- Telarc -- and the fact that it shouldn't be done this way. Let the end user have the final say, as he/she is the only one who knows what capabilities exist in his/her playback system.This is just one more problem that needs to be addressed by the recording community and the product manufacturers. Is it really that hard for these two groups to get together and discuss what process will get the most from the new high resolution formats?
As for a "height" channel for channel #6 (the .1), I haven't heard this implemented, so I can't say for sure if this is a good idea vs a discrete rear surround channel a la DTS-ES 6.1 Discrete (for movies). I can see a "height" channel for "effects" in a movie, but I'd think that music is another matter (at least until I've heard it, but I'm not a fan of multichannel for music as it is, so...). Maybe we need a discrete 7.1 system so that we can also have a height channel for movies? Anyone for DTS-ES 7.1 Discrete? It is an option for the codec...
If the Telarc method was standard, you would only need bass management if you had small speakers that really needed to be high pass filtered. Otherwise, you would simply low pass filter your subwoofer to get the best blend between the subwoofer and your speakers. What I don't like is that their approach is non-standard and largely undocumented.
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