I think that is a far trickier question than you might think.
For one thing, the frequency being there is very different than you hearing it. At normal volumes I can't hear much below 28hz, and at high volumes, nothing below about 25hz. For me, anything below that isn't perceived as a tone, but just the 'foof' 'foof' 'foof' of the speaker moving.
Next, though just my opinion. I think a lot of what you feel in a action movie sound track, that which we perceive to be ultra-heavy ultra-low frequencies, are not frequencies at all, but phase shifts in higher frequency.
If a 40hz or 50hz tone is modulated with a phase shift of 10hz or 15hz, and a swept between channels that is timed with the phase shift, you will certainly feel that, but I don't consider the 10 to 15hz signal used in this manner a tone or a sound.
So, my point is, there can be subsonic frequencies that are not sounds at all, though you can feel them. I guess I would have to classify them more as effects.
I personally suspect there is really very little sound below 30hz, even though there may be some frequencies that are lower.
Like I said, answering your question gets tricky.
Steve/bluewizard
For one thing, the frequency being there is very different than you hearing it. At normal volumes I can't hear much below 28hz, and at high volumes, nothing below about 25hz. For me, anything below that isn't perceived as a tone, but just the 'foof' 'foof' 'foof' of the speaker moving.
Next, though just my opinion. I think a lot of what you feel in a action movie sound track, that which we perceive to be ultra-heavy ultra-low frequencies, are not frequencies at all, but phase shifts in higher frequency.
If a 40hz or 50hz tone is modulated with a phase shift of 10hz or 15hz, and a swept between channels that is timed with the phase shift, you will certainly feel that, but I don't consider the 10 to 15hz signal used in this manner a tone or a sound.
So, my point is, there can be subsonic frequencies that are not sounds at all, though you can feel them. I guess I would have to classify them more as effects.
I personally suspect there is really very little sound below 30hz, even though there may be some frequencies that are lower.
Like I said, answering your question gets tricky.
Steve/bluewizard
Member
Joined 2003
I think Krips is wondering if these low frequencies actually come out of the main speakers, or if they are sent to the sub channel.
I guess I am curious too, to know if it's really necessary to have say a center or rear surround channels playing down to 20hz, or if there is no information actually being sent to them in movies (as it is sent to the sub channel instead), and hence fine to have them only play down to ~80hz.
I guess I am curious too, to know if it's really necessary to have say a center or rear surround channels playing down to 20hz, or if there is no information actually being sent to them in movies (as it is sent to the sub channel instead), and hence fine to have them only play down to ~80hz.
Someone posted on another thread that the lowest octave on a Bass Guitar is around 40hz and very musical. The lowest key on a piano is around 20hz and is not so musical but for effects is necessary. 20hz and lower would sure put a hurtin' on some small bookshelf sized center and surround speakers.
There may be low frequency content in those channels, but if or how well you hear them depends on what speakers you are using there - if they are two-ways the midwoofers will start rolling off well above the lowest frequencies.
As an experiement, try hooking up a powered sub to any of the satellite channels and see what happens. Make sure you run the channels full range, or "large" on the speaker type selector.
As an experiement, try hooking up a powered sub to any of the satellite channels and see what happens. Make sure you run the channels full range, or "large" on the speaker type selector.
There were some spectra graphs posted on AVS a while back with surround channels showing a lot of high level and deep LF content, for some movies. Probably less of an issue in chick-flicks due to the lower explosion, gunshot, helicopter crash, meteorite and alien invasion to dialogue ratio.
Piano: Low A = 27.5Hz.
On a grand A sounds OK to my uncultured ear, but less good on smaller domestic uprights because of the shorter string length producing less fundamental, and the ear filling it in. Same is true with a 34" scale BG. Even E has insufficient length to produce a strong fundamental, and E is worse. E on a 41" URB is much fuller because of a higher fundamental content.
BG: E = 41Hz, B = 31Hz901Fixer said:
Piano: Low A = 27.5Hz.
On a grand A sounds OK to my uncultured ear, but less good on smaller domestic uprights because of the shorter string length producing less fundamental, and the ear filling it in. Same is true with a 34" scale BG. Even E has insufficient length to produce a strong fundamental, and E is worse. E on a 41" URB is much fuller because of a higher fundamental content.
So for music-ness, 30hz is really the lowest needed, not only to 40hz? This has been discussed some on other threads as to where does music end and effects begin. Low notes on Bass Guitar sound musical to me but the lowest key on even a Grand Piano is well into the seizmic clunk feel in my opinion.
ZilchLab said:
AFAIK they are only available to folks who have become THX certified, but there's now enough info on the THX site to not really need them for setting up a high SQ HT. Reviewing specs of THX certified HT products and JBL's cinema sound manual will fill in a few more 'blanks'.
GM
Interesting. I had no idea that so much LFE would be found in the surround channels. I guess this begs the question - is there a point where there is no benefit to having the LFE played through your 5. speakers vs your subwoofer, and if so, what is that point? I've heard several different points where people claim you can't localize anymore.
It varies depending on the room and person, but generally in the 40-80 Hz BW. Note that unless the reference has changed in recent years, all channels are summed mono below 120 Hz. Regardless, for HT it is best overall to use bass management to redirect all the channel's LF below 80 Hz to the LFE channel and use it to drive a separate sub system for each channel as shown on the THX site. A more in-depth study of multiple sub placements: http://www.harman.com/wp/pdf/multsubs.pdf
GM
GM
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