Re: Treble.

THX Sound System
- The Audience is Listening

(from the "quality assurance system" developed by Tomlinson Holman, with George Lucas's Lucasfilm Ltd)







THX is the trade name of a high-fidelity sound reproduction standard for movie theaters, screening rooms, home theaters, computer speakers, gaming consoles, and car audio systems. THX stands for Tomlinson Holman's eXperiment. THX was developed by Tomlinson Holman at George Lucas's company Lucasfilm in 1982 to ensure that the soundtrack for the third Star Wars film, Return of the Jedi, would be accurately reproduced in the best venues.

The THX system is not a recording technology, and it does not specify a sound recording format: all sound formats, whether digital (Dolby Digital, SDDS) or analog (Dolby SR, Ultra-Stereo), can be "shown in THX." THX is mainly a quality assurance system. THX-certified theaters provide a high-quality, predictable playback environment to ensure that any film soundtrack mixed in THX will sound as near as possible to the intentions of the mixing engineer. THX also provides certified theaters with a special crossover circuit whose use is part of the standard. Certification of an auditorium entails specific acoustic and other technical requirements architectural requirements include a floating floor, baffled and acoustically treated walls, no parallel walls (to reduce standing waves), a perforated screen (to allow center channel continuity), and NC30 rating for background noise.











~ These are for Eddie (posters5)...











_____________
-JIMI McLovin (the Voodoo Child)

[Post edited by Love Hendrix! on May 22, 2008]

Slave Leia pillow fight...mmmmm.

OMG, Why do you do that Love? You have officially weirded me out...

Quote:
It is always important to keep the 45 rule in place ...

Could you give more info on this, I never heard that before.

The whole idea is that you wan to keep roughly a 45 degree pattern placement of you speakers. The speakers should be pointing in your direction but the degree radius of each speaker should be roughly within 45 degrees of each other. So thing like IE panning left to right and FR to BR should sound natural. Most speakers project anywheres from 90 degree to 120 degrees, depending on the manufacture. You want to make sure that your within 45 degrees of the speaker overlapping each other. You want to create the perfect circle, or sweet spot, to get the most of your listening experience.

ReaggieP
Now I get it. I wasn't quite sure what you meant at first.
Thanks.

I've got a question. not on treble, but on frequency. I was looking at what my frequency was on my speakers and don't quite get something. not a big deal, but i'm just curious. On Polk's site they give these specs.

Overall Frequency Response 55Hz - 25kHz
Lower -3dB Limit 63Hz
Upper -3dB Limit 24kHz

i was just wondering whats the difference between the response numbers and the limit numbers. Why is it that the response is 55Hz and the limit is 63Hz.

Also would changing the frequency on my Onkyo to 60Hz mess anything up...though i know its not going to make any difference if i switch it since the sub is set for a 80Hz crossover. Again just wondering.

"Overall Frequency Response 55Hz - 25kHz
Lower -3dB Limit 63Hz
Upper -3dB Limit 24kHz

i was just wondering whats the difference between the response numbers and the limit numbers. Why is it that the response is 55Hz and the limit is 63Hz.

Also would changing the frequency on my Onkyo to 60Hz mess anything up...though i know its not going to make any difference if i switch it since the sub is set for a 80Hz crossover. Again just wondering" --Revolution

Yeah, the numbers can be confusing. Starting with the "overall frequency response," these are the numbers your manufacturer says are the lowest and highest frequencies your speakers can reproduce. In your case, Polk says your speaker can reach down into the bass as far as 55Hz (55 cycles per second), and it can reach up into the high notes, the treble, to 25k Hz (25,000 cycles per second, well above most human hearing).

However, the manufacturer also notes that just because your speakers reach down to 55Hz, that doesn't mean you may actually be able to hear it, because as they go on to say, the minus 3db point in the bass is actually 63Hz (at 63Hz the response is 3 db lower than the midrange). That means that below probably 70Hz your speakers' frequency response starts falling off (compared to its response at a midrange point, usually 1K Hz). By 55Hz (their lower usable limit), your speakers are probably 6-10 db down (meaning you could measure the reponse but probably not hear it in actual audio content). Same with the high end, except that they seem to hold up pretty well to beyond 20K Hz, which is quite good. Of course, you have to trust Polk that these numbers are accurate.

As for changing the crossover point in your receiver, if you have a subwoofer crossed over at 80Hz, I'd keep the receiver at 80Hz as well.

John

[Post edited by John J. Puccio on May 26, 2008]

So in other words their just throwing out number that don't really matter for a general consumer with the overall frequency. Thanks for the answers.

I've got another question while that i'm pretty sure someone can answer. Kind of tricky...possibly. About my sub. A while back i noticed that my PC speakers had a stringer sub than my theater system. So i switched the subs. The question is since its a PC sub do you think there is a lot lost in the translation since i have to use a wire converter. I'm only asking because i was thinking of getting a new sub.

but after looking up the specs for the PC sub it seems to have a decent low frequency (35Hz) and 100 watts power. which is good enough for the size of the room. So don't know if it would even be worth getting a new sub. though with a new one i would have a bigger woofer (i was thinking a 10 in woofer would do) and all the normal inputs and options.

i would imagine a bigger woofer would have clearer bass hits. and that loosing the wire converter would probably have less audio loss. So my question is would it be worth it to spend another $200 on a sub since i just updated the rest of the speakers and receiver.

i know it sounds like a dumb question but i don't really need more than 100 watts and 35Hz (from what i read) is a good low.

Just knowing that the manufacturer says your subwoofer will reach down to 35Hz and uses 100w of power probably isn't telling you enough. You'll have to use your own ears or measurements. Does your sub do the job for you?

Remember, when a manufacturer says a speaker will go down to a certain frequency, that doesn't mean a person can actually hear it. Your sub may measure down to 35Hz, but that 35Hz frequency note may be ten or twenty decibels lower in volume than the midrange. That's where the minus-three-decibel point comes in handy when reading specifications. (For instance, my floor-standing VMPS RM40 living-room stereo speakers can easily reproduce a 20Hz note, but it's about six decibels lower than the midrange. The point at which the RM40s begin to roll off is actually about 25Hz. And my measurement of their -3 db point is about 22.5Hz. Needless to say, I don't need a subwoofer in the living-room stereo system, but I do use one in the home-theater room with bookshelf speakers, even though they're still relatively large speakers.)

Good subwoofers in the 10"-15" range can vary in price from a few hundred to many thousands of dollars, with everything in between. If you really want to change subs, I'd research what's available in your price range and then ask for recommendations from readers here at the Message Board.

John

[Post edited by John J. Puccio on May 26, 2008]