Took some searching but I think I proposed 80Hz, 4th order.
There were some other ideas:
I don't remember anyone else chiming in or objecting, so 100 Hz looks like an average agreement point. Do we need a poll?
One has to be careful about the THD of the speaker in question.
A highish 2nd order and higher harmonics will skew the results...
80Hz. is solid pretty much... but who cares, let's go with 40Hz.!!
As I just said, stand next to a 20Hz. woofer signal, you don't think it coming from the other side of the room? If so, then you have "localization". Quite obviously, if you use multiple subs spread around the room all playing the same signal, then you have very little localization because the ear can't discern that. Whales and elephants otoh may do this as a matter of course...
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A highish 2nd order and higher harmonics will skew the results...
80Hz. is solid pretty much... but who cares, let's go with 40Hz.!!
As I just said, stand next to a 20Hz. woofer signal, you don't think it coming from the other side of the room? If so, then you have "localization". Quite obviously, if you use multiple subs spread around the room all playing the same signal, then you have very little localization because the ear can't discern that. Whales and elephants otoh may do this as a matter of course...
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A 20 Hz pure tone may be impossible to localize. A tone from a woofer is anything but.
_-_-bear
John, that seems to be "rock" oriented set up there?
Yeah... my "other" hobby...
Here's an 8 1/2# emerald chunk I found last week in North carolina
An externally hosted image should be here but it was not working when we last tested it.
John L.
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Going with the existing "standard" is a safe place to start. Then we can rephrase the question to "is the THX standard correct in its assumption that in an otherwise competently installed home or theater system listeners do not distinguish directionality from bass below 80Hz.?"
I'd say "yes" . . .
Proper subwoofer integration and whether to use multiple sources or other techniques to address small-room mode issues are different questions altogether . . . but almost any small room mode control will almost certainly destroy any direction information that might have been retained in the recording anyway. Is it worth it to forego mode control to preserve direction information that probably isn't in the recording and probably couldn't be heard if it was ? ? ?
Please define?
What is a "pure tone" if it does not exist except in theory?
Why is a tone from a woofer not "pure" enough for you?
All woofers, regardless?
Are you sure about that?
Yes it *may* be impossible. But as I said, stand next to it and tell me you think it is across the room.
I think the question here is one of degree and circumstance.
No one has taken up the question/example I gave so far...
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John, nice... now if you can just find a nice BIG chunk of that green rock...
I consider a pure tone to be a sine wave. No harmonics. A woofer cannot produce this. The harmonics usually allow localization, especially if it is run on its own and not as part of a system.Please define?
What is a "pure tone" if it does not exist except in theory?
Why is a tone from a woofer not "pure" enough for you?
All woofers, regardless?
Are you sure about that?
Yes it *may* be impossible. But as I said, stand next to it and tell me you think it is across the room.
I think the question here is one of degree and circumstance.
No one has taken up the question/example I gave so far...
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John, nice... now if you can just find a nice BIG chunk of that green rock...
dewardh did you just ay a woofer cannot play a sinusoidal wavelength?
What is with people around here?
"is the THX standard correct in its assumption that in an otherwise competently installed home or theater system listeners do not distinguish directionality from bass below 80Hz.?"
Who said that is their assumption?
I guarantee this is a financial decision.
What is with people around here?
"is the THX standard correct in its assumption that in an otherwise competently installed home or theater system listeners do not distinguish directionality from bass below 80Hz.?"
Who said that is their assumption?
I guarantee this is a financial decision.
Opps this THX system has two subwoofers.
THX Ultra2 Home Theater System | Klipsch
If you pay enough money for your system they will give you the second woofer for stereo listening pleasure.
Did you know that THX has many different certifications? Like certifications for computer speakers. Does this mean they think we can't hear stereo under out of anything larger then a 2" speaker?
It is an error to use modern multichannel sound effects as the benchmark for hearing.
THX Ultra2 Home Theater System | Klipsch
If you pay enough money for your system they will give you the second woofer for stereo listening pleasure.
Did you know that THX has many different certifications? Like certifications for computer speakers. Does this mean they think we can't hear stereo under out of anything larger then a 2" speaker?
It is an error to use modern multichannel sound effects as the benchmark for hearing.
Hello. I have some questions for Dr. Geddes and other knowledgeable people about markus76's results on near/far-field bass.
Dr. Geddes, in one of your lectures you noted that you are concerned with reproduction of bass only in situation where the ratio of direct/reflected sound is low (i.e., it is not a near-field bass). Markus76's results show that using near-field subwoofers could result in a very flat frequency response - if only across a couch. So.
1) Is there a particular reason that you do not bother with near-field subwoofer setups?
2) Would there be audible differences between far-field and near-field subwoofer setups, given that SPL and frequency response are made equal at the listener position? Does the amount of direct sound matter?
Sorry if those questions were already discussed.
Dr. Geddes, in one of your lectures you noted that you are concerned with reproduction of bass only in situation where the ratio of direct/reflected sound is low (i.e., it is not a near-field bass). Markus76's results show that using near-field subwoofers could result in a very flat frequency response - if only across a couch. So.
1) Is there a particular reason that you do not bother with near-field subwoofer setups?
2) Would there be audible differences between far-field and near-field subwoofer setups, given that SPL and frequency response are made equal at the listener position? Does the amount of direct sound matter?
Sorry if those questions were already discussed.
I can't do the near field sub in my HT because it has rows of seats. The near field sub probably works well but only for one or at most two people, after that I would expect its performance to fall dramatically. I go for the more global solution of multiple subs.
I would not expect any significant audible difference from a near field and far field setups if done correctly.
They did.
Where do we collect?
THX primary goals were uniformly excellent sound at all seating positions in the theater and non-interference with the voice track. 80Hz. satisfies both, and being a "standard" of sorts was quickly adopted by builders of "home theater" systems. It was the only option on many early "receivers".
The plethora of THX "certifications" is a marketing add-on that came much later, and had/has nothing to do with the original THX design specs. or the choice of the 80Hz. crossover frequency (which is not graved in stone . . . it was just the best solution to the original design problem).
In any case you'll almost never find anything below 80Hz. in the voice (center) channel, and while higher than 80Hz may be found in the "effects" channel (up to 150Hz. used to be permitted, as I recall) it is not extracted and blended into the mains (unless there is no sub-woofer present, in which case the whole effects channel is sent to both the mains and the theater does not) get THX certification.
As it turns out the "movie guys" know rather a lot about sound reproduction, and rather a lot more than most "audiophiles".
Indeed. "Works" for some things, anyway, at a substantial expense to others.
Room modes are formed by reflection, and since those reflections occur (in a small room) within no more than a couple wavelengths they qualify as "early". As such they destroy directional information. Anything done to suppress modes (except suppression/cancellation of the reflections that form them) will also remove directional information (which moots any questions about "localization" of bass).
Thanks for the answer!
Well, it seems then that near-field (and perhaps dipole) subwoofers are a legitimate and cheap alternative to expensive multisub configurations. I think that reduced SPL for anything besides prime seats might actually be a very substantial plus for me, as for many other people, because I live in a condo.
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