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"Official" Audyssey thread (FAQ in post #1) - Page 1790

post #53671 of 62236
5/10/12 at 1:46am
Quote:
Originally Posted by jdsmoothie View Post

^^
Depends on the model, but no, not in your case as each one of the below models has a different mic calibration file as shown:

3806: DM-S205 (hockey puck style)
3808: DM-A405 (tower style)
1610, 1612: DM-A409 (tower style)

Thanks JD - this information has now been added to the FAQ.
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post #53672 of 62236
5/10/12 at 9:20am
Quote:
Originally Posted by craig john View Post

Hi Feri,

I just want to clarify one detail about this. With Dolby Digital and DTS, there was no need for an LPF of LFE because those formats brickwall-filtered the LFE channel during recording/encoding. Therefore, there could not be any content above 120 Hz in the LFE channel on those formats. With the introduction of the "lossless" codecs, Dolby TruHD and DTS-Master Audio, the LFE channel became a "full range," (3 Hz to 20 kHz), channel. Therefore, it became possible for recording engineers to place content in the LFE channel well above 120 Hz, either intentionally or unintentionally. Therefore, it became necessary to filter the channel on playback, and that was when the LPF of LFE became mandatory in receivers and pre/pro's with those codec's.

Craig



DD and DTS AVR's have always used an LFE filter in circuit. Some are just not variable and do not show in the adjustment menu.

All movies do not LP the LFE channel. I assume a defect in the DVD mastering because that is rare, but I have seen it a few times. The "defective" DVDs sound just fine when being played, so the AVR LFE filter takes care of the error.




Quote:
Originally Posted by craig john View Post


Having said that, there is almost never any content above 80 Hz recorded in the LFE channel. I believe Roger Dressler uses an 80 Hz LPF of LFE because his feeling is that, if there is content in the LFE channel above 80 Hz, it probably *shouldn't* be there and he would prefer it be removed. It would be interesting for Roger to confirm this. It would also be interesting to get filmmixer's thoughts on whether 80 to 120 Hz content is ever intentionally placed in the LFE channel.

Craig




There is almost always content above 80 Hz on the LFE channel. It is rare that a non standard 120 Hz 8th order LP filter is not used.

Different mix methods will produce various results, but that is an artistic choice.



Typical example below. LFE signal on the left, center channel on the right. The green line (peak hold) on the top spectrogram shows a steep LFE 30 dB drop off starting at 120 Hz.


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post #53673 of 62236
5/10/12 at 9:32am
Quote:
Originally Posted by kbarnes701 View Post

It's wrong. Content in the 0.1 channel is put there up to 120 Hz by the content creators. If you set the LPF to 80Hz, then everything in the 0.1 channel from 80 to 120 Hz will be lost. It isn't redirected anywhere, just lost. LPF of LFE should always be 120 Hz.




The LFE signal between 80 and 120Hz is not lost if an 80 Hz LFE filter is used in an AVR. The signal level is just lowered based on the slope of the LFE LP filter.
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post #53674 of 62236
5/10/12 at 9:49am
Quote:
Originally Posted by J_Palmer_Cass View Post

The LFE signal between 80 and 120Hz is not lost if an 80 Hz LFE filter is used in an AVR. The signal level is just lowered based on the slope of the LFE LP filter.

What would that slope be?
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post #53675 of 62236
5/10/12 at 10:01am
Quote:
Originally Posted by kbarnes701 View Post

What would that slope be?


Depends on the AVR. 2nd order for my AVR. Perhaps a 4th order LFE LP is more typical.
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post #53676 of 62236
5/10/12 at 10:12am
Quote:
Originally Posted by J_Palmer_Cass View Post

The LFE signal between 80 and 120Hz is not lost if an 80 Hz LFE filter is used in an AVR. The signal level is just lowered based on the slope of the LFE LP filter.

I don't know about anybody else, but I don't want mine "lowered" at all. So I use a 120Hz. In the context of MOVIES, I don't know why there's even any question about where it should be set. Music, yes, as per Roger's findings.

IMO.

Jeff
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post #53677 of 62236
5/10/12 at 10:26am
Quote:
Originally Posted by pepar View Post

I don't know about anybody else, but I don't want mine "lowered" at all. So I use a 120Hz. In the context of MOVIES, I don't know why there's even any question about where it should be set. Music, yes, as per Roger's findings.

IMO.

Jeff



It seems that THX systems expect to see an 80 Hz LFE filter.


"What About THX Systems?

THX is almost a different beast altogether. A THX Select or Ultra2 system is specifically designed to have the bass management set at 80Hz. While you are free to alter the crossover frequency of a THX system, you will not be utilizing the system as it was intended to be heard. In addition, THX processing and DSP assumes (and sometimes initiates) an 80Hz crossover setting for the LFE. While a THX system may not be desired by everyone, we actually recommend those systems (assuming THX speakers in conjunction with a THX receiver/processor) be configured as recommended."


http://www.audioholics.com/tweaks/ge...st-performance
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post #53678 of 62236
5/10/12 at 11:05am
Great. Disagreement.
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post #53679 of 62236
5/10/12 at 12:30pm
Quote:
Originally Posted by J_Palmer_Cass View Post

It seems that THX systems expect to see an 80 Hz LFE filter.


"What About THX Systems?

THX is almost a different beast altogether. A THX Select or Ultra2 system is specifically designed to have the bass management set at 80Hz. While you are free to alter the crossover frequency of a THX system, you will not be utilizing the system as it was intended to be heard. In addition, THX processing and DSP assumes (and sometimes initiates) an 80Hz crossover setting for the LFE. While a THX system may not be desired by everyone, we actually recommend those systems (assuming THX speakers in conjunction with a THX receiver/processor) be configured as recommended."


http://www.audioholics.com/tweaks/ge...st-performance

never mind. misread the quote, "crossover" for the LFE confuses me. Does a THX system send low passed LFE channel material to the mains? Or are they simply (IMO) misidentifying a low pass filter as a crossover (of which the low pass is only half).
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post #53680 of 62236
5/10/12 at 12:43pm
Good point. You'd think they wouldn't conflate these things like some newb.
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post #53681 of 62236
5/10/12 at 12:55pm
Quote:
Originally Posted by JHAz View Post

never mind. misread the quote, "crossover" for the LFE confuses me. Does a THX system send low passed LFE channel material to the mains? Or are they simply (IMO) misidentifying a low pass filter as a crossover (of which the low pass is only half).

They must have had too much audioholics that nite! What a party it was!
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post #53682 of 62236
5/10/12 at 1:40pm
Quote:
Originally Posted by pepar View Post

I don't know about anybody else, but I don't want mine "lowered" at all. So I use a 120Hz. In the context of MOVIES, I don't know why there's even any question about where it should be set. Music, yes, as per Roger's findings.

IMO.

Jeff

Same here. Lost, lowered - more or less the same - it ain't there as it should be.
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post #53683 of 62236
5/10/12 at 1:42pm
Quote:
Originally Posted by J_Palmer_Cass View Post

It seems that THX systems expect to see an 80 Hz LFE filter.


"What About THX Systems?

THX is almost a different beast altogether. A THX Select or Ultra2 system is specifically designed to have the bass management set at 80Hz. While you are free to alter the crossover frequency of a THX system, you will not be utilizing the system as it was intended to be heard. In addition, THX processing and DSP assumes (and sometimes initiates) an 80Hz crossover setting for the LFE. While a THX system may not be desired by everyone, we actually recommend those systems (assuming THX speakers in conjunction with a THX receiver/processor) be configured as recommended."


http://www.audioholics.com/tweaks/ge...st-performance

I can see that - but it requires THX be used right through the chain - AVR, speakers, subs, DSPs, Loudness Plus, Re-EQ on, Audyssey Flat curve. How many people actually do that?

But that quote isn't discussing LPF of LFE - it's talking about crossovers. And the phrase "80Hz crossover setting for the LFE" doesn't actually mean anything. A filter is a filter, not a crossover.
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post #53684 of 62236
5/10/12 at 1:47pm
Quote:
Originally Posted by pepar View Post

Good point. You'd think they wouldn't conflate these things like some newb.

Indeed. It's a bit scary when a respected site like Audioholics apparently doesn't understand the difference between a bass management 80 Hz crossover and a LPF of LFE. Or seems to use the words 'crossover' and 'filter' as though they are interchangeable.
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post #53685 of 62236
5/10/12 at 3:12pm
Quote:
Originally Posted by Gooddoc View Post

The sub distance tweak works in this fashion.

Are you saying that tweaking the sub distance somehow addresses group delay in the sub?
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post #53686 of 62236
5/10/12 at 4:30pm
Quote:
Originally Posted by kbarnes701 View Post

I can see that - but it requires THX be used right through the chain - AVR, speakers, subs, DSPs, Loudness Plus, Re-EQ on, Audyssey Flat curve. How many people actually do that?


Your position is way overstated. Does it really matter how many people do whatever?



Quote:
Originally Posted by kbarnes701 View Post

But that quote isn't discussing LPF of LFE - it's talking about crossovers. And the phrase "80Hz crossover setting for the LFE" doesn't actually mean anything. A filter is a filter, not a crossover.


The quote is in fact discussing the LPF that is being used for the LFE channel regardless.

Playing a sematics game will not get you anywhere. Most subwoofer plate amplifier's call the sub amplifier's built in LP filter a "crossover". According to your logic a crossover is a crossover, not a filter!

My AVR does not have a "LP filter" for the LFE channel. I can only adjust the "High Cut Filter" on the LFE channel via my AVR's menu!


Typical plate amp marking:

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post #53687 of 62236
5/10/12 at 4:45pm
Quote:
Originally Posted by J_Palmer_Cass View Post

Your position is way overstated. Does it really matter how many people do whatever?



Playing a sematics game does get you anywhere. Most subwoofer plate amplifier's call the built in LP filter a "crossover".

Gosh, I can hear the backpedalling from here....
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post #53688 of 62236
5/10/12 at 5:29pm
Quote:
Originally Posted by kbarnes701 View Post

Gosh, I can hear the backpedalling from here....


I can't hear it. After all, you are the one who is driving the tricicle backwards!

I know that you like to talk. However, talk is cheap. Have you ever tested any AVR to confirm your "thoughts"?

Quote:

"In my system, I set all channels, including the LFE, to 80Hz (THX setting) except for the main channels which I set to 100Hz because I achieved better acoustical bass integration with my subwoofers and main satellite speakers."


http://www.audioholics.com/reviews/r...ass-management
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post #53689 of 62236
5/10/12 at 6:26pm
Quote:
Originally Posted by hclarkx View Post


Are you saying that tweaking the sub distance somehow addresses group delay in the sub?

If group delay is defined as "an adjustment that changes phase as a function of frequency", then yes.

When changing sub distances the phase changes as a function of frequency. For example, if one were to move a sub several feet a short frequency might have a phase change of 300 deg. whereas a long frequency might only change a few degrees but the exact change is a function of frequency.

That's my understanding of it, if not correct I'm all ears
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post #53690 of 62236
5/10/12 at 6:42pm
Quote:
Originally Posted by AustinJerry View Post

DJ, listen to JD.....

Ha, I suppose he had a pretty good answer.
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post #53691 of 62236
5/10/12 at 10:29pm
Quote:
Originally Posted by Gooddoc View Post

If group delay is defined as "an adjustment that changes phase as a function of frequency", then yes.

When changing sub distances the phase changes as a function of frequency. For example, if one were to move a sub several feet a short frequency might have a phase change of 300 deg. whereas a long frequency might only change a few degrees but the exact change is a function of frequency.

That's my understanding of it, if not correct I'm all ears

I see what you are saying and what you outline is correct. But what you outline is not group delay. Group delay is not changed when the sub distance setting is changed.

If you increase a sub distance setting by, say, 3.5 feet, to improve the sub-main alignment, you have changed the phase of the sub output at 80Hz by 90 degrees relative to the mains (I'm assuming an 80Hz XO). Stated otherwise, the sub timing has been changed by 3.125ms.

And, that distance change does change the phase at 40Hz by 45 degrees relative to where it would otherwise be. Hence the 40Hz output is improved as well since it's in better alignment with the mains (assuming the sub distance has been increased). But, it's improved by just 45 deg while the sub output at 80Hz is improved by 90 deg. Stated otherwise, the 40Hz timing has been changed by 3.125ms, the same timing change as applied to the sub output at 80Hz.

The group delay is the increase in delay of sub output as frequency drops. I.e., the sub output at 40Hz is delayed relative to it's output at 80Hz. A typical number is about 20ms. That 20ms number is not changed by adjusting the sub distance setting. The 3.125 ms change in sub distance applies at 80Hz and 40Hz and so does not change their relative delay (the 20ms group delay between 80 and 40Hz). The sub 40Hz output is shifted as you contend, but it still lags the sub output at 80Hz by the same 20ms.

If this isn't clear, let me know. I have a sketch in mind that should do a better job.
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post #53692 of 62236
5/11/12 at 2:19am
Quote:
Originally Posted by hclarkx View Post


If this isn't clear, let me know. I have a sketch in mind that should do a better job.

I'd like the sketch, pretty please, Harrison...
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post #53693 of 62236
5/11/12 at 2:21am
Quote:
Originally Posted by J_Palmer_Cass View Post

I can't hear it. After all, you are the one who is driving the tricicle backwards!

I know that you like to talk. However, talk is cheap. Have you ever tested any AVR to confirm your "thoughts"?

Quote:

"In my system, I set all channels, including the LFE, to 80Hz (THX setting) except for the main channels which I set to 100Hz because I achieved better acoustical bass integration with my subwoofers and main satellite speakers."


http://www.audioholics.com/reviews/r...ass-management

Audioholics, in the quote you put forward to support your position, were conflating a Low Pass Filter and a Crossover. That's all that needs to be said IMO.
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post #53694 of 62236
5/11/12 at 4:25am
Quote:
Originally Posted by hclarkx View Post


I see what you are saying and what you outline is correct. But what you outline is not group delay. Group delay is not changed when the sub distance setting is changed.

If you increase a sub distance setting by, say, 3.5 feet, to improve the sub-main alignment, you have changed the phase of the sub output at 80Hz by 90 degrees relative to the mains (I'm assuming an 80Hz XO). Stated otherwise, the sub timing has been changed by 3.125ms.

And, that distance change does change the phase at 40Hz by 45 degrees relative to where it would otherwise be. Hence the 40Hz output is improved as well since it's in better alignment with the mains (assuming the sub distance has been increased). But, it's improved by just 45 deg while the sub output at 80Hz is improved by 90 deg. Stated otherwise, the 40Hz timing has been changed by 3.125ms, the same timing change as applied to the sub output at 80Hz.

The group delay is the increase in delay of sub output as frequency drops. I.e., the sub output at 40Hz is delayed relative to it's output at 80Hz. A typical number is about 20ms. That 20ms number is not changed by adjusting the sub distance setting. The 3.125 ms change in sub distance applies at 80Hz and 40Hz and so does not change their relative delay (the 20ms group delay between 80 and 40Hz). The sub 40Hz output is shifted as you contend, but it still lags the sub output at 80Hz by the same 20ms.

If this isn't clear, let me know. I have a sketch in mind that should do a better job.

I think I understand. Group delay is a measure of "packet" amplitude that looks at signal time delays that vary with frequency, result in phase changes, and are caused by the DUT. Variable phase delay is a measure of phase change that also varies with frequency but with a constant time delay.
Both cause a phase change but by different causes.
Thanks for the explanation, I never understood the group delay vs phase delay issue since they're both interrelated.
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post #53695 of 62236
5/11/12 at 4:42am
^^^
What is DUT?
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post #53696 of 62236
5/11/12 at 4:59am
Device Under Test
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post #53697 of 62236
5/11/12 at 5:42am
Quote:
Originally Posted by kbarnes701 View Post

Audioholics, in the quote you put forward to support your position, were conflating a Low Pass Filter and a Crossover. That's all that needs to be said IMO.


Back peddling again?

I have no position on the single, one size fits all, my way or the highway, one and only "correct" setting for the LFE channel filter (if adjustable), so what is the so called "your position" that am I trying to support?

I checked my receiver's menu, and they list the LFE high cut filter under the subwoofer crossover. No big deal to me, I know what they mean.

The terms "crossover" and "low pass filter" are conflated all the time in the audio business. You should take up that issue with HSU (and other audio equipment manufacturers).
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post #53698 of 62236
5/11/12 at 10:12am
Quote:
Originally Posted by J_Palmer_Cass View Post

The terms "crossover" and "low pass filter" are conflated all the time in the audio business. You should take up that issue with HSU (and other audio equipment manufacturers).

If I say 'black' and you say 'white' but we both mean the same thing, you can see why people may become confused. Given that a crossover and a filter are entirely different, and that a filter is 'one half' of a crossover if you will, I’d expect so-called experts to get their terminology right. And if the experts can't manage it, well, at least I'd expect you to. To get it wrong and then quote an equally wrong source in support is pretty silly isn't it?

But this is a pointless discussion so this is my last word on it. If you care to reply, I will do you the courtesy of reading your reply, but you've had my last word on it.
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post #53699 of 62236
5/11/12 at 10:31am
Quote:
Originally Posted by kbarnes701 View Post

But this is a pointless discussion so this is my last word on it. If you care to reply, I will do you the courtesy of reading your reply, but you've had my last word on it.


You (and others) by-passed the author's point with this needless side issue of terminology.

The author stated that THX recommends an 80 Hz filter for the LFE channel. Rather than deal with that comment, you went down a different road to try to prove the author is "in error".
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post #53700 of 62236
5/11/12 at 10:55am
Quote:
Originally Posted by BigCoolJesus View Post

Do I have to worry about timbre matching? .....I was told surround speakers aren't as noticeable for timbre matching...is the same true for height speakers?

Sorry to resurrect and old subject, but I thought I would share my experiences.

When I originally implemented DSX 11.1, I used several spare Definitive Technology ProMonitor 1000 speakers for Heights, thinking that timbre-matching with my PSB Mains and Wides was not too important. As I evaluated DSX and PLIIz over the last six months, I have not been very impressed with the contribution of the Height speakers. Using PLIIz with music, for example, added an artificial-sounding ambiance that wasn't very pleasing.

So, I replaced the DT's this week with a set of PSB Imagine monitors that are very closely timbre-matched to the PSB Synchrony Mains. The difference was immediately evident during the Audyssey calibration--the chirps sounded much more like the rest of the speakers. After listening for a couple of days, I find the contribution from the Height speakers much more pleasing. My default music listening mode is now PLIIz, and it sounds more natural than with the DT's.

So, in conclusion, I think timbre-matching may be more important than I thought originally.
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