Actually, the LOTR disc is a poor example, since it seems that the original soundtrack was just recorded hot. For instance, I generally only listen to the Dolby Digital track when it's available, and on LOTR, the Dolby Digital track is 10dB louder than is typical.

DTS did indeed used to have unnatural loud bass on its discs, but I think this problem has been cleared up.

Ironically, this unnaturally boosted bass was received by listeners as "better" and helped establish DTS's largely-undeserved reputation as a "superior" format.

Jeff

it's interesting how the 950 handles dolby 1 (all speakers 'small'). this is from crystal:

"In cases such as Dolby Configuration 1, a gain (e.g.+10 dB) is not directly applied to the LFE channel to drive the subwoofer. Instead, the inputs to summer 802 are attenuated to acheive the same result. In this example, the L,C,R,Ls, and Rs channels are all attenuated by -15 dB and the LFE channel is attenuated by -5 dB. This implements the LFE +10 dB channel specified for Dolby Configuration 1. However, a compensating 15 dB gain should be applied later, usually in analog, after the DACs."

i'm still thinkin' about this one...

I can't imagine why they would do that!

That would explain why the DD5.1 level is so low on the 950 compared to, for instance, the six-channel bypass. At least it is on my Red Dot system. I understand there is more gain implemented with the final Blue Dot units.

On the other hand, it kind of suggests that the entire issue of surround implementation (not JUST on the 950) is a real can of worms. Remember, this is a description of Crystal's solution and their programming appears in other pre/pros in addition to the 950.

Three short comments, if I may …

First, my compliments to all, especially SH, for contributions to an excellent thread. A fully extended range stereo reproduction can help make the playback of acoustic, large space recordings come just a bit closer to ‘real,’ psycho-acoustics coming into play.

Second, I appreciate this bit of knowledge, assuming I interpreted SH correctly: I don’t have to worry about mixing the LFE with either or both of the R and L stereo, because the LFE will not contain the same audio information, either in or out of phase, as either the L or R … correct?

Thirdly, those that think a perfect subwoofer will be ‘fast’ enough to help make the ‘thump’ of a bass drum (or similar source of complex-frequency, sudden and large-amplitude sound) seem like that drum has moved right into the room with them has a conceptual problem. To make that happen, one would need improved capability across more of the sound spectrum than a subwoofer is intended to reproduce. Imagine the perfect loudspeaker that can produce frequencies from 0.1 Hz to a megahertz, flat, without distortion, at amplitudes so low that it actually absorbs any unwanted sound in the room, to levels so high that one could level a city with it. Now simply do one thing to limit its performance: restrict it to frequencies below 80, 60, or 40 Hz. No matter how much amplitude and ‘speed’ the transducer has, so much of the sound of a bass drum thump will be missing. If one needs more realism in sounds such as a bass drum, improvement in the woofer and mid-range may be equally or more important than improvements in the subwoofer.

That said, IMO, you can’t get close to realism without the range of frequencies that are covered by one or more well placed and adjusted subwoofer(s).

By and large, you are correct. Very occasionally, on music there will be a low-passed "copy" of the lowest octaves of the orchestra routed to the LFE channel, in order to augment the mains. However, this information will always be in polarity with the same information from the mains. If it isn't, somebody screwed up somewhere In no instance will there be bass in the LFE (with music) that is not also in the mains.

You're right about the bass drum example. A sub needs good integration with the mains in order to present the sound event without corruption in it's harmonic structure. This is why one benefit of stereo subs comes from the fact that each main channel has it's associated subwoofer as close as possible to it. A coherent sound front relies on placement of the drivers.

SH,

Let's say you have a pair of subwoofers (I do) and you're expecting the arrival of a dedicated LFE subwoofer (I am). Where would you place the LFE sub, or does it not matter very much?

Space is at a premium in my room. There aren't a lot of choices ...

Jeff

in stereo, of course, there is no LFE, so the following concerns multi-channel audio only:

it's not whether you have to worry about mixing LFE to either FR or FL. the mono LFE channel is automatically mixed into them both equally in this configuration which definitely erases the stereo effect. your only option to avoid this is listed below.

"...because the LFE will not contain the same audio information...as either the L or R..."

this is incorrect. almost ALWAYS, when there is LFE signal, it is the same signal as that sent to the L and R.

phase problems MAY occur, not from the source, but either in the filters used (there are 2 high pass filters on the FL/FR woofers, 1 is passive and 1 is active. there are 2 LP filters used for summed redirected bass/LFE, 1 digital and 1 active and there is a global 120 hz digital LP on the LFE), and/or lobing effect caused by the distances from FL/FR vs from the 2 subs. (distances being measured from the voice coils).

because any speaker set to 'small' will have it's bass summed in a summing block before it's sent to the FL and FR, it's my opinion, in multi-channel modes, the only way to preserve stereo bass through subs is to set all speakers to 'large' and use a 3rd sub for dedicated LFE. this avoids any sort of summing, which degrades the stereo effect and, reduces intermod distortion, which occurs any time 2 inharmonic tones are sent to 1 speaker to be reproduced.

duplicate post....

[This message has been edited by soundhound (edited April 10, 2003).]

I would try to place the dedicated LFE sub as close to the mains as you can, wherever that is. That way, at least any common bass from the mains and the LFE would reinforce each other by way of mutual coupling.