Sorting the "feel" from the "heard"...

[HornEd]

The first octave (16-32hz) probably holds a lot more potential to be "felt" rather than "heard." But, as the hz rises, there is a point where essentially "non-directional" bass begins to take on a directional character.

1. Within what hz range can the average human detect direction (Legendary Sub-Human excepted )? Further, how long (in feet/inches) is the wave that is created at the point when sound direction can be established?

2. Does the use of floor standing speakers for mains, surrounds and rear center channel create a harmful standing wave potential that leads to lesser performance. Can such waves be avoided by setting all rear effects speakers (L&R surrounds and rear center) to "SMALL?" and channeling the low range to a rear power sub?

(3) Is there a practical way to tie the rear effects speakers (set to "LARGE") to a single rear power sub to provide a "kick" to the rear sound stage that is in sync with their respective discrete 6.1 channels?

Separate power subs for front and rear seem to make a substantial HT difference... particularly by providing the a strategic kick in the bass. Who among you will cast the first stone? ...or, perhaps, some insight into what you think is significant in creating the illusion of direction between your own Klipsch fed ears. HornEd

------------------

"Klipsch by the Dozen"

KLF 30's Front Mains

KLF C-7 Front Center

KSW-15 Front Pwr Sub

SB-2 Front Effects

KSW-12 + KLF 10 Rear L&R

KSW-12 + KLF 10 Rear Ctr.

Speaker Support Systems:

Mitsubishi RPHD1080 65"

Yamaha RX-V3000 Receiver

[T2K]

Ed,don't now about the stones,but I have a question for you.I too have front and rear subs.What do you mean exactly,and don't spare the words,by "set at different phases"?

Keith

[boa12]

ed & keith, hey this could be a case where 180 degree phase shift by switch could help.

actually the 180 setting on my vel in it's new location, up front between klf, sounds much better. guess that standing wave needed

shifting for me.

ed, i've heard bass is non-directional up to 250hz, but i think it's directional for me much lower, like down to 120hz.

since i was 1 of your 1st klipsch bb pals i can throw a lil pebble i think i mentioned & was a lil concerned about all that rear channel sub output vs a single ksw-15 for the front, lfe & front center channels. tv's, who's the true sub expert, i think said something like my 1st instinct. that is a big sub or 2 (like the vel hgs-18 was a good example )) for the main/front sub & may be a lil ksw-12 or 2 for the rear channel. jmgi (just my gut instinct) though.

------------------

Klipsch KLF-30 (front), KLF-C7, Cornwall I (rear)

Velodyne HGS-18 sub woofer

Monsterbass 400 sub interconnect & Monster S-12 cable

Sony STR-DE935 a/v receiver

Sony DVP-C650D cd/dvd player

Sony Trinitron 27" stereo tv

Toshiba hi-fi stereo vcr

Technics dual cassette deck

Technics direct drive turntable

Scientific Atlanta Explorer 2000 digital cable box

2nd room:

Klipsch RF-3 (front), RC-3, cheap little Technics (rear)

Kenwood KR-9600 AM/FM stereo receiver (vintage '75)

Teac PD-D1200 5-disk cd player

Sega Genesis game player

Sub: None yet

rock on!

[Btrigg]

The only question I can partically answer is the first. I've read that a true subs xover is 40 and below, but there a lot of main speakers that can't go that, so there is a hole in the spectrum. I think you should set the xover to as low as your mains can go before they roll off. I also think that sounds are directional above 60 hz.

[HornEd]

Keith, as Boa noted, many subs have 0 and 180 degree phase markings. For example, if you had two subs up front, they could tend to cancel each other out if they were out of phase (i.e., the excursion were traveling in opposite directions) but would reinforce one another if they were in phase (moving air in the same direction at the same time). That's why SVS recommends two subs in the same corner... to physically move more air and get their clean low a few db's lower.

And yes, Boa, I remember well your post. Actually the KSW-15 more than holds its own given its size and BASH circuitry. I have been experimenting with various phase relationships and cutoff points. I have no doubt that there is enough "contrary air" being pushed around to impair the bass a bit... but there is still plenty to go around for my neighbors... and plenty to emphasize deep sounds that occur on the three rear effects channels. As Tom the SVS Sub-Human correctly opined, this rig can be pretty dynamic above 30hz but is not well represented in the first octave. That may change in the near future.

I too tend to sense bass direction at lower levels than many "experts" claim as non-directional limits. The above post was a fishing expedition to find out if others have the same directional bass opinion.

Since three KLF-10's see, to work well in the rear array of my effects boosted 6.1 system, it follows that beyond the standing wave problem is the potential for some better kick from carefully placed powered subs that take the discrete feeds and send the upper range to the KLF-10's.

I know that the simplest route to ear-satisfaction is putting in a large front and rear sub... in fact, that's what I had before I tried this Klipsch experiment. They are now part of the downstairs system... which probably has more sonic muscle than the experimental system... but no super efficient horns or cylindrical subs.

This house is built on a hillside with the bottom garden tier closed in by the house and two "earthquake proof" concrete retaining walls. A bridge runs from the back of the house to the second tier garden. I have been tempted to build a theater out of the bottom tier with a stair stepped ceiling to help break up standing waves. But first, I want to understand the acoustic dynamics of the first two octaves a whole lot better. In any event, thank you both for contributing. I have a lot of respect for those who lurk about this kind of board. And, Keith, the comment about casting stones was a feeble attempt to avert the avalanche of "conventional wisdom" that might flow down upon the head of someone playing with four subs in a 14' x 24' room. This time, I'll put away the stones and go with Boa's theme... rock on! HornEd

[boa12]

ed, i think i passed the 1st stone

it looks like svs & maybe those new klipsch rsw could be in your crystal ball.

rock on but be careful w/ those longer waves

[T2K]

Horned guy, let me re-phase the question, please.You said " particularly,it seems,when subs are set at different phases".The way I read your post I understood you to say that front AND rear subs make a large contribution

to HT and moreso when those front and rear subs are set at different phases.Elaborate please.And Thank You,

Keith

[HornEd]

The easiest (and many say best) "pwr sub" plot is one "big mother" positioned to bring it best lows to the greatest listening portion of the room. Put your SPL meter on a solid pan head tripod angled toward the ceiling in the direction you usually face during an HT experience (and not directly pointed at any speaker). When lacking a heavy pro tripod, I have used a step ladder and cradled the SPL meter, correctly angled, in some sound absorbent material. You might try a few readings below the level of your main listening chair as well (sometimes the sound absorption factor of your chair/sofa back will improve the sound to your knees... but not your ears). I like to thoroughly "SPL map" the listening area with one good big sub first. In this, the idea is to keep everything the same except the position of the SPL meter. There are enough variables to placing subs to keep it exciting... without having to labor in the ignorance of where your tail was on square one.

Theoretically, if the sub is delivering non-directional bass (and providing it is quick and full throated enough) it will augment any speaker in the room to which it has the low range data.

And thereby hangs up my earlier tail! The trend in multi-channel sound is to have entirely discrete channels... which means that the primary subwoofer does not receive all the low hz info... and, therefore, does not provide the kick you desire. Obviously, matrixed channels synthesized from channels linked to your main sub continue to be supported (particularly if they are set to SMALL). As an aside, in many cases, giving the low stuff to your sub can really improve the high-bass/mid-range capability of your mains.

Thus, for HT purposes, running discrete channel surrounds through a decent rear powered subwoofer provides the bass reinforcement needed but not available through the main subwoofer (provided it does not receive the low bass info... which can be a function of your particular receiver/amp system). Then, using "pink noise" on selected frequencies to the rear sub woofer, I "SPL map" the prime listening area twice. Once to establish the best position and a second time to roughly establish the acoustic dynamics of the room. It is in this phase that I learn to place other objects (hanging tapestries or closing drapes for best sound, etc.) in the room to shape the sound and contain the bottom dwelling "standing wave monsters" that are ALWAYS lurking.

Since there are so many variables (acoustics, hardware, individual ears, etc.) that affect achieving the right sound for you (and your significant other(s)... including close friends, family, etc.), I try to use everything at my disposal to control "big bad-boy waves" that contribute so much feel of a Klipsch experience. With Klipsch, I find the better the bass (better not necessarily louder) the sweeter all those loaded horns become.

And now to the phase (as I have opined elsewhere on this board). When two subs are in the same direction in their excursion to the same sound... they are in phase. If they are opposite they are out of phase... pushing air in opposite directions... and, therefore, tending to cancel out each others bass waves.

So, in our discussion, we now have two factors which would destroy bass waves... the always present standing wave potential and subs out of phase with each other... (and potentially with the low end of other speakers in your rig that hit the lows). It is a physical thing. To enjoy the lowest of the low, you have very long physical waves that must be relatively intact when they hit your eardrum... or they become some other sound than the one intended on the sound source.

In the main, having all your large wave making speakers in phase with one another tends to simplify the problem that all multiple speaker systems encounter in virtually every living space/home theater environment.

In experimenting, I have found that, under certain conditions and program material, that I have been able to improve some large-wave dynamics in my environment by switching phases until the right sound is shaped.

Because of the all variables, setting up multiple subwoofers is a daunting task that can create some hard-to-believe scenarios. Witness the tongue-in-cheek animations on the "Video Essentials" set up disc in the chapter on subwoofer placement. While that disc needs conceptual updating (in my humble but considered opinion)... it does point up the fact that overwhelming "here/gear/ear" variables make all-things-to-all-people particularly inappropriate when it comes to the care and management of bottom feeders. In the interest of more accurately conveying my esoteric experience I may have offended you with redundancy. Mea culpa and good luck. HornEd

[T2K]

HornEd,now I have a headache.I understand and completely agree with you.I will use few words and say Thanks,

Keith

[T2K]

Horned fella,how's Mom?

Just wanted to let you in on something.As I told you I'm running KSP300's(12"powered sub)

in the four corners of my room.Have a Klipsch

SW12II front and SW8II rear(for the time being).Didn't seem to be getting the bass that I expected out of the SW12,although there was certainly no shortage at that end. Had tried changing phase on the sub(infinitely variable)and although the sound was good,as was output according to the RS meter,had a gut feeling something was missing.Removed jumpers from back of 300's and ran low level sub cables from the reciever to left front,left front to right front,and right front to sub(daisy chained front three).WOW! Even MORE tight,fast,ear candy bass.Sounds like someone is on the back

side of the front wall pounding the wallboard!The low end seemed to move from its previous position at the rear of the room

to the front of the room.I got up and walked to the front of the room and the bass seemed to be somewhere else.Just couldn't localize the low end.The only thing I could figure(or make that Trey at Klipsch)was that maybe the sub preout on my reciever was wired out of phase.Anyway,I was terribly happy with the setup before and now am amazed everytime I listen to some good 'ole Texas Swing.I wish everyone had some of these KSP300's and am convinced they are the best sounding speakers

I have ever heard.Glad I bought a few extras!

Keith

[KGeist]

After reading this thread I realized that there is some confusion over the difference between the dispersion characteristics of a loudspeaker and an individual's ability to localize where the sound is coming from.

Almost all consumer loudspeakers are omnidirectional at frequencies below 100 Hz. All this means is that the loudspeaker can be pointed in any direction and the sound will still reach the listener ears equally well. A listener's ability to localize that sound is a psychoacoustic phenomenon, having more to do with the distance between ones ears. It is generally accepted that our ability to localize sounds significantly decreases below 250 Hz.

Subwoofers are typically operated at 100 Hz or below, and therefore are omnidirectional sources. However, this does not means their position can not be localized. The reasons for this are twofold; First, subwoofers generate distortion components which are higher in frequency and therefore may fall in the frequency band where our ears are more sensitive. And second, low-pass filters in subwoofers are not brick-wall filters, therefore there is "some" output above the cutoff frequency of the sub. If the slope of the filter isn't high enough, our keen ears can detect the location of those sounds. The latter reason is generally not a problem with modern subs due to the fact that most filters use 24 db/oct slopes or higher. This is usually sufficient to prevent localization due to this effect. On the other hand, distortion in loudspeakers continues to be a big problem in loudspeakers and it manages to manifest itself in a variety of ways other than the one issue pointed out above.

Kerry

[HornEd]

Thanks KGeist for your perseverance and perception re: this thread. Essentially, I agree with your assessment but was trying not to color potential comments. In addition to my lifelong infatuation with audio, I have had formal training in the use of Pavlovian theory in environmental structuring. I could not agree with you more about the psycho-acoustic aspect... with a possible extra attention paid to those frequencies that tend to be "felt" rather than heard.

Obviously, the most important sound processor is the one between the ears that creates an illusion based upon an ongoing "clue assessment" process. And, as you so aptly point out, the source of these clues, for better or worse, are legion.

But, for all that, it would seem that significant parameters could be elicited to provide greater control of what is fed to a given set of ears to enhance the quality of perception potential.

By this post, I have sought to get more folks ideas as to what some of these variables may be. Your post was in keeping with what I sought... sadly many others were not. The fault is with the person who set up the post. Mea culpa, mea culpa, mea culpa!

Thanks, Kerry, for the good words, they help me create a sound environment for mom. HornEd

PS: Click the photo Keith and see how mom is.

[dougdrake]

quote:

---

Originally posted by KGeist:

A listener's ability to localize that sound is a psychoacoustic phenomenon, having more to do with the distance between ones ears.

---

Oh no! Does this mean that tweaking the sizes of our heads is the next audiophile frontier??!!?? (LOL)

[DLUngurait]

LOL Doug...but I believe your comment belongs in the "Updating Older Listeners" (I mean speakers) section on the BB

Dave

[T2K]

WOW!

Ed,enjoyed the picture of your Mom.Give her my big'ol HOWDY MA'M from deep in the Heart of Dixie.

Keith

[Guest BobG]

Do a 'net search on "head related transfer function". Lots of interesting stuff there regarding localization, imaging, how the shape of the pinna and head relate and how narrow band amplitude changes can impact perception of source location. It's a big topic so I suggest you allow time to track the results of the search.

[HornEd]

Hooray BobG! You are right on target! This is EXACTLY the break I was looking for... but had been fumbling until you gave the right hand off. This is the time posters like me really appreciate our "Klipsch Kover" guys. It will take awhile... but I look forward to sharing the fruits of the search... maybe even a nut or two... we will see what develops. Thanks again, HornEd