[James Romeyn]

I was a diehard two-channel fan, but my enthusiasm died. I now prefer converting stereo CD’s into DPL IIx 8.1 (an appropriate center channel can not be integrated into this system). My future sound room will have an 8’ ceiling, be 33’ long, & have a 14’ front wall & 16’ rear wall. This thread concerns the preferred floor covering for the above room with the following 8.1 surround speaker system.

All eight full range speakers will be high-passed crossed around 80 Hz. There is an EQ'd sub. The L-R main front speakers are VMPS RM30C's. The six surrounds are VMPS 8” 2-ways sited a few inches from the ceiling. Two front side-axis speakers are 404 SE monopoles (inverted woofer-tweeter), sited at the side walls, on the same vertical plane as the main front speakers, & angled down & toed-in toward listeners. The side surrounds are misnamed "Dipoles", they arrive from the factory as bipoles. I converted them into true dipoles. They are sited at the side walls on the listener’s vertical plane, the null facing listeners. The rear surrounds are 404 SE monopoles, sited near the side walls a few feet behind the listeners, & angled at 45-degrees toward the ceiling to diffuse radiation.

Two-channel fanatics sing the praises of LEDE rooms. If you are familiar, skip to next paragraph. LEDE is an acronym for live-end dead-end. The room is divided into thirds. All surfaces on the third of the room toward the front speakers is heavily damped (carpeted floor, front/ceiling/side walls covered with 4” Sonex or appropriate substitute). All surfaces on the remaining 2/3rds of the room are kept live (hard floor & no wall treatments). The goal is to minimize the early reflections because they are so close in time to the direct path lengths that the ear perceives them as distortion, & to maximize late reflections because the ear perceives them as separate signals adding ambience. One you hear music reproduced in such an environment it’s hard to go back.

For reasons explained above, LEDE specs will be strictly followed except for one potential modification: In DPL IIx 8.1, how much audible performance may be lost if the rear 2/3rds floor covering is carpeted rather than hard as per LEDE specs?

I’m leaning toward carpeting the entire floor for reasons stated below, but I’d like to know how much performance might suffer. A hard surface is colder, the slight carpet step above the tile could be awkward, the split surface will look quite strange 11’ from the front wall, & tile or wood costs much more than carpet (please have mercy on a Filipino/Dutch/Czech cheapskate).

What say members? Anyone have experience or supernatural wisdom along these lines? I’m all ears (pun intended).

[Red Dragon Audio]

For reasons explained above, LEDE specs will be strictly followed for all surfaces of the front third of the room & all remaining wall/ceiling surfaces.

 

It sounds like you wish to cover ALL bare surfaces with foam/absorptive materials.  Is that correct?

[James Romeyn]

Sorry I wrote it so confused.  I edited it.  LEDE definition is (All surfaces) rear 2/3rds live, front third dead.  Post now reads:

"...For reasons explained above, LEDE specs will be strictly followed except for one potential modification: In DPL IIx 8.1, how much audible performance may be lost if the rear 2/3rds floor covering is carpeted rather than hard as per LEDE specs?..."

In other words: LEDE specs are hard rear 2/3rds floor.  What if it is carpeted?

[Red Dragon Audio]

LEDE will apply even if you have carpeted floors.  

The main point of LEDE is that you eliminate first spurious reflections in front of you.  So the marjority of sound arriving at your ears first is DIRECT radiated sound from the drivers - untainted by reflections from the ceiling and walls.

The secondary effect of LEDE is to maintain ambience of the sound generated by the room. Laying carpet around the rest of the room will still leave around 60% bare surfaces in the other 2/3rds of the room.  That should be plenty of bare surface area for ambient reflections to occur.

[James Romeyn]

That was my general consensus.  I was curious to read opposed opinions if any existed.  One obvious source, a two channel specialty manufacturer, of course said LEDE all the way.  He might be right & he might be an excellent 8.1 info source, but I'm looking for the cheaper more convenient way out, as usual.

[BrunoB]

That was my general consensus.  I was curious to read opposed opinions if any existed.  One obvious source, a two channel specialty manufacturer, of course said LEDE all the way.  He might be right & he might be an excellent 8.1 info source, but I'm looking for the cheaper more convenient way out, as usual.

If you have a 8.1 system, than the ambience will come from the surround speakers and you might not need to have the back end live. Furthermore, removing early reflection for the surround speakers might improve the sound the same way as it does for the front speakers.

Bruno

[James Romeyn]

The front side axis speaker area will be damped.  The side dipoles rely on reflected sound, & the rears are pointed at the ceiling for diffusion.  This would seem to contraindicate damping for those speakers.

[csero]

If you want to use 8 channels there is no use of the LEDE setup, go for a fully damped room front and back.
The half baked idea behind LEDE is  that stereo doesn't and can't have enough ambience recorded, so you need a live room for playback, but the early reflection structure of your room does not match the original venue, and it is rather destructive than helping, so you have to damp those. LEDE just successfully combined the disadvantages  
BTW DPL is not the best way to get the extra channels. You can not "extract" ambience from stereo signal with steering or matrixing.

[ScottMayo]

Jim's asked me to chime in with an opinion. And how can I say no to a VMPS guy?

Typical carpeting usually doesn't have a huge effect on room acoustics. It has some, obviously, and a thick shag over a thick foam pad can offer significant diffusion and absorption. But run of the mill carpeting doesn't absorb all that much very quickly. Stick to standard short nap stuff and you won't lose anything you needed to keep.

Because of this, I generally tell people to plan their floor covering around the other constraints in their life, not the acoustics. If you want carpet, put down carpet. The rest of the room can be adjusted to suit. The only exception is an *all* bare floor - that's almost always a mistake. You want something on the floor between the listeners and the speaker, at a minimum.

That said...

I'm a fan of LEDE in theory. In practice, I think it ought to be modified in large rooms, and when the speaker count goes up. It definitely ought to be modified if you have 8 speakers, front, side and back. Even if the rear channels don't do much, what they usually do is generally provide ambience. But that's what an LEDE room tries to do, too. The result is a complicated interaction that might, or might not, work for you. Over 33' of space, might not is as likely as might.

I'm not going to design a room plan here, but as for general suggestions, look into diffusion, both front and rear - your room is big enough to get benefit from it. And don't be afraid to put a few traps behind you. 33' is a long corridor of space and with 9 speakers going, you will build up a fair amount of energy. Dissipating all that just with curtains and foam in the front, is probably asking more than curtains and foam can deliver. I think putting down carpet everywhere might be a good idea in this room, not a bad one.

(All this is in my humble opinion, and with the obvious caveat that I do acoustic plans and could be trying to drum up business here. And also, room "liveness" is a personal thing - some people love a deeply reverberant sound.)

I do 5.1 in my room (25x'28'x11') and I have a complicated treatment scheme (inevitably - it's my lab), but I have a more treatment behind me than LEDE would call for, and less in front than some.

[James Romeyn]

If you want to use 8 channels there is no use of the LEDE setup, go for a fully damped room front and back.

The half baked idea behind LEDE is that stereo doesn't and can't have enough ambience recorded, so you need a live room for playback, but the early reflection structure of your room does not match the original venue, and it is rather destructive than helping, so you have to damp those. LEDE just successfully combined the disadvantages  
BTW DPL is not the best way to get the extra channels. You can not "extract" ambience from stereo signal with steering or matrixing.

My audio goal is to increase the goosebumps when listening.  My sum total interest in adhering to or adopting any audio theory is 0 or less than that.  Sometimes I find audio jargon & rules misleadindg or of little use.  If the jargon provides joy &/or satisfaction to others, fine.  My described listening preferences are based on my personal experience, not necessarily anyone else's.  I prefer LEDE rooms to non-LEDE rooms for stereo playback.  My experience is the opposite of the apparent above theory against LEDE.  

I prefer DPL IIx more than stereo systems costing multiples more.  My personal experience is that stereo speakers are physically incapable of reproducing satisfactory side & rear ambience cues compared to DPL IIx.  I have heard no stereo playback system that contradicts this rule.  By 2015 I think stereo playback will be as relevant to audiophiles as tea bags are to a polar bear.    

The only processing for reproducing satisfactory ambience cues from stereo sources, that interest me more than DPL IIx, is the Meridian & another competitor whose name escapes me (similar to Meridian's).  The Meridian won Tech TV's Best of CES a few years ago & an audio engineer judge/friend whose ears I trust voted for it & said it worked.  The Meridian processor is costly though at about $10k last I heard.

[ctviggen]

The LEDE theory makes perfect sense to me, although people will differ about the amount of diffusion they'd like.  In terms of 8 speakers, I think LEDE would have to be modified to include at least absorption at the reflection points.  I would think you could still include diffusion at other than the first reflection points.  As for stereo versus 8 speakers, I still like stereo over 8 speakers.  I think I'll wait until the TACT for 8 speakers arrives and acoustics theory gets to the point where it can adequately describe what's going on with 8 speakers.

[James Romeyn]

I appreciate any honest opposing opinions.  I should clarify & say I prefer my particular 4.1 system (expanding to 8.1) to most stereo playback, at even multiples more cost.  One very large exception might be the Infinity IRS III's auditioned in the late '80s/early '90s, but there was nothing remotely ordinary about that location including the 12' ceilings (owner of Landmark calendars/greeting cards).  The system matched the house, the wall-to-wall SF Bay views, the floor theater lamps, the indirect lights reflecting off the ceiling, the red Ferrari, & the black Rolls.  

The point is that I generally yawn at to strongly dislike every multi-channel system I've auditioned except the one in my room.  So you could say, by pure numbers, I more often prefer stereo systems to multi-channel, as might most audiophiles.  But this system was assembled & tuned by a musician/audiophile first, who came to the MC party very very late.  MC systems generally use inferior speakers, are setup carelessly, &/or are aimed at impressing deaf store customers used to awful TV sound (the lowest common denominator in the HT universe).

[BrunoB]

The front side axis speaker area will be damped.  The side dipoles rely on reflected sound, & the rears are pointed at the ceiling for diffusion.  This would seem to contraindicate damping for those speakers.

What about using 180 deg. CD speakers for surround instead of dipoles? They would not need reflections to throw sound evenly in the room. A multichannel system  with  8 CD speakers would be very special and unique.


Bruno

[James Romeyn]

Bruno
That is idea intriguing.  I must seriously consider it.  It would require the expense of six 626R's, but the potential results seem too good to pass up.  

Oh, the curses of inviting people to share their great ideas!

[JohninCR]

I believe the increased directivity of dipole is the whole reason they are used in some HT applications.  While multichannel music is a different animal, I'm not sure whether all the extra reflections would be a good thing.  I understand their benefit with stereo, but 8 might turn into a sonic mess forcing you to go to a very dead room to get right.