This is the first I've heard about the analog LPF on the LFE channel from the 950. That's not written up anywhere as far as I've seen.

Does anybody know if there is a LPF for the LFE channel in the digital domain, as well?

Also, am I to understand that any music above 120 Hz on the LFE does NOT get redirected elsewhere, such as to the main speaker channels?

If it is 120 Hz, then there should be a slope to it, so there's still some info above 120 Hz send to the sub.

On the Sony I had, the low pass on the sub was selectable (120, 150, 180, 200 Hz or something). Something for the 950's big brother when it comes out!

Stuff like that should be in the manual somewhere...

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i agree. if you don't know what's happening to the signal, how the heck can you tailor it properly to your own taste?

question to all:

should the lfe channel be controlled by the (a) processor or (b) outboard or (c) either/or with a bypass option?

what features are necessary to control the lfe channel?:
1.) fixed, selectable x-over points
2.) variable x-over
3.) phase reverse switch
4.) variable phase control
5.) parametric eq
6.) subsonic filter
7.) level control
8.) selectable slopes
9.) delay control (time alignment)

vote: a, b, or c and which, if any #'s, with comments.

The immediate question is, what does the 950 do with high frequency input in the LFE channel, in analog 6 channel processing as well as digital processing. I don't think the manual says.

However, while DVD-A/SACD's may send high frequency signals to the LFE channel, I don't know if DD or DTS may do this as well. How high in frequency can the LFE channel be, in DD and DTS?

[This message has been edited by Will (edited October 17, 2002).]

With regards to the 6 ch analog direct subwoofer input, the LPF filters out high frequency information at 120 hz. It is not redirected anywhere, it's simply gone. I didn't ask what the slope is. I think that this is only problematic if you have a full range speaker hooked up to your subwoofer output. The stuff I heard coming from my subwoofer with my previous unit with DVD-As tended to distort because the speaker is simply not designed to reproduce the higher frequencies.

In the digital domain, I have to imagine the subwoofer channel will get signal based upon the crossover settings which will yield a maximum frequency of 150 hz plus higher frequencies determined by the crossover slope. What happens to an LFE signal in DD or DTS with hypothetically high frequencies is a question the Outlaws would have to answer.

BoB- All of your numbers are desirable. And just to be clear, for the dedicated LFE channel *as well as* all the bass that is crossed over from the mains.

But is rare to nonexistent for any component to have everything you listed, unfortunately!

I believe that there is no reason why all of that can't be incorporated in the pre/pro's software. Digital and analog (although with analog, might have to do high quality digital processing for cost effectiveness, 24/192...).

I have similar experience with surroundophile,regarding the LFE channel phase.It's in phase!

It's not in phase with a PCM coax digital input, or any 2 channel analog input that is A-to-D'ed and back again.

I don't know how that DVD-A test disc test is setup. (I actually have it now, just haven't gotten around to testing it yet. )But by using discrete test tones & an SPL meter, the "problem" is very apparent.

Does this help? From: http://www.extremetech.com/print_article/0%2C3428%2Ca%253D1531%2C00.asp
“The LFE channel is independent of the main channels and is created by decimating a full-bandwidth input bitstream using a 64x or 128x decimation digital filter, yielding a LFE bandwidth of 150Hz or 80Hz respectively. ADPCM coding is then applied.”
From: http://www.snout.org/movies/bam-sound.shtml
BAM: Theatrical Digital Sound Formats

Dolby Digital (DD)
http://www.dolby.com/digital/
Up to five full-range channels (L-C-R-LS-RS @ 20Hz-20kHz) and a 20-120Hz LFE channel in a 384 kbps (kilobits per second) bitstream (a single line of digital data) (Note: bitstream on a movie filmstrip is 320 kbps; DVD uses up to 448 kbps)
115 dB dynamic range for LFE channel; 105 dB dynamic range for the other channels

DTS Digital Surround
http://www.dtsonline.com/
Up to three full-range front (L-C-R) channels, two 80Hz-20KHz surround channels and a 20-80Hz LFE channel in a 1544 kbps (or 1.544 Mbps) bitstream (laserdiscs use two bitstreams that add up to 1.544 Mbps)
Resolution: same as Dolby Digital
96 dB dynamic range
Up to five full-range front channels (L-LC-C-RC-R), two full-range surrounds (LS,RS) and an LFE channel (frequency range should be similar to Dolby Digital's); no information about bitrate on hand
96 dB (approx.) dynamic range

Not on my 950.I observe no such problem.