[John Casler]

Very seldom do I get such a dramatic improvement from a simple adjustment, but this one was startling!!!

It relates to the LARGER VMPS SUBwoofer and alternative orientation and operation.

Normal orientation is with the Slot Base Rails on the floor so that the Passive Radiator fires "into" the floor and is directed toward the listener via the frontal opening in the Base Rails.

Now I'm not sure if this incredible improvement is due to my room, the fact that I have a QUAD LARGER set up, or what, but the bass "POWER" and "DEPTH" were immediatly increased.

While with the RM30s, my listening chair certainaly has been transmitting "impact" by tactile sensation, this tweak has the chair jumping and vibrating to all the deep bass notes.

Flight of the Cosmic Hippo??? It is like a 25 cent vibrating bed in a hotel, but it moves more. (and this is on a concrete floor)

So what I'm saying is "in the sweet seat" my bass is now deeper and more powerful than ever, and not by a small margin.

So what did I do?

Well here is the set up.

I have placed the RM30s with the 10" woofs firing inward.  Flanking them on the outside, I had one LARGER on each side.  

Each LARGER was in the "vertical" orientation.  That is, it was up on its end.  Because of this, I have the "base plate" that comes with the LARGER attached, so that the plate acts like the floor would in horizontal orientation, and directs the Passive Radiator wave forward to the listener.

The LARGERS are also oriented with the PR's facing each other (firing inward) , but the plate re-directs the wave.

OK.....

So I am having this severe "rattle" during deep bass passages.

Turns out that I only put two screws in the plate on the right LARGER, and "IT" is rattling.

They had worked loose and when I pulled on it the plate to see if it was loose, it actually came off.

Immediatley, I noticed an openess, depth, and a "largeness" to the bass in the room.

WHoa!!!! I said and sat back in the sweet seat.

Holy Macaroni!! I was digging this.

So I grabbed my trusty screw driver and off came the plate on the opposing LARGER.

Back to the sweet seat and "Bob's your Uncle", my freakin chair is rockin like never before.

And the "cavernous" envelopment (in a natural sense) is much greater.

Let's try Stevie Ray Vaughn's Tin Pan Alley..... Awsome deep rich quality detail and depth like never before.

Then BAD PLUS and the bass in the right channel!!!!  The dam thing doubled in size!!..

Now again, I cannot say that this improvement will work for everyone who doesn't have the same room and such, but it is a simple thing to try, and the results were BIG!!

I also cannot be responsible for the way it looks (sorry) but it is freaky good if you get a chance to try it.

I did not try it other ways yet, but will and report.

That is, since it doesn't look that hot, I might simply face the PR toward the front wall and fire the active drivers at each other, and see what happens.

This is without a doubt the best I have ever heard the LARGERS to sound.

If you get a change give it a try.

Happy Tweaking.

PS -- I do have a 95# dumbbell sitting atop each LARGER, since this puts the smooth side on the carpet and reduces mechanical coupling.  I will be adding more once I get them in the final position (like that will ever happen)

[woodsyi]

John,

You have two larger on the outside but in front of RM30s with open radiator facing each other, standing tall.  Do you have them in phase or push/pull?  Are the 12 and 15' woofers aligned or crossed?  I am gonna try tonight but no way I keep it that way with its belly exposed when wife comes down.

[John Casler]

John,

You have two larger on the outside but in front of RM30s with open radiator facing each other, standing tall.  Do you have them in phase or push/pull?  Are the 12 and 15' woofers aligned or crossed?  I am gonna try tonight but no way I keep it that way with its belly exposed when wife comes down.

Hi Woodsyi,

They are "in phase with each other".

I just tried it with the Passive Radiator "facing the front wall" and the Actives firing inward and it sounded darn close, maybe slightly soft, but that could be because of my rear LARGERs then being 90 degrees out of phase rather than 180.

But having the nice wood finish facing out and the PR facing the front wall looks better than "normal".

Much of the "quality" of improvement (if any) will also be dependant on how far you have the subs from the front wall, so you may have to "play" with that.

Not sure what you mean by "aligned or crossed"

Good luck, hope it does the same for you.

[woodsyi]

John,

My brain fart. With the passive facing one way there can only be one way the woofers stack up.

[CornellAlum]

Since we are on the subject...what cables is everyone using with their sub?

[John Casler]

John,

My brain fart. With the passive facing one way there can only be one way the woofers stack up.

Actually, in my case with 2 LARGERs one side has the 12" on top and the 15" on the bottom, and the other side is reversed, so that the Passive Radiator is firing inward on both.

[John Casler]

Well I have had an opportunity to get a few more cuts in and the transformation is complete.

My WOOFs have cause a "TEAR" in the BASS TIME CONTINUUM.

You know the one Q, talked about?

Again I don't know if I just hit a lucky, exact, room placement or what, but I would bet I have gone from 25Hz down to 16Hz.  I haven't measured yet, but my last measurment showed a pretty steep drop after 25Hz.  It is "MUCH" below that now and with Caverness Power.

In any event, one of the best "bass test" CD's is the "Original Score" from American Beauty (make sure it is "NOT" the soundtrack) if you don't have it, is should be in your BASS COLLECTION.  

I also don't know if this pheneomenon is directly related to my "Push/Pull", but I havent changed that.

The only change has been the RM30's and removing the "base plates" from the "vertically oriented" LARGER subs, and the dramatic difference came when taking off the plates.    

The bass is just "SICK".

Also a couple more ideas for those who wish to try this with their subs

1) first method to try, is to Face the Passive radiator toward the wall, so that the "ugly part" is not visiable.  My front Subs are at least 3-4 feet "off" the front wall.

2) Second method is to Lay the sub on its back, with the active woofs facing the ceiling and the PR facing the front wall.  This may reguire putty adjustment (removal of) since the weight of the active cones generally don't have to be lifted by the motor system.

Both of these "possible" positionings should provide a good WAF.

If anyone gets it to work for them, let me know.  My result is spectacular

[ctviggen]

John,

Do you find any change in bass when you orient the subs with the PR toward the wall?  I wouldn't mind doing that.  I tried them up (PR oriented toward the sidewall, drivers oriented toward the listener), but you can see inside the sub, which I didn't like.

[rosconey]

your a little late -
i stood mine on end a few years ago-

been wanting to make a old style tall boy cabinet -just too dam lazy

[John Casler]

John,

Do you find any change in bass when you orient the subs with the PR toward the wall?  I wouldn't mind doing that.  I tried them up (PR oriented toward the sidewall, drivers oriented toward the listener), but you can see inside the sub, which I didn't like.

Hi Bob,

The whole deal with bass is "path".  What this does is it takes the path of the PR, which is normally directed to you along the floor, and allows it to radiate hemispherically, but be launched along a differing path from the Active Drivers.

Now someone will certainly say "all" sound radiates hemisherically, but if is launched through the slot along the floor it is directed along the floor to you.

In the case of the LARGER the active and passive waves are limited by the floor in their forward radiation.  This means their reflected paths will also be similar and "son of a gun", they cancel at the same spots.

Sending the PR radiation along a slightly different path helps change the reflection paths slightly.

AND WOWWY KaZOWY, in my room is is "KILLER".

Now to answer your question:

When I turned the sub so the PR faced the wall the only change I noticed was an "oh so slight", attenuation (I would guess 1-2 db)

That said, the key issue will be how far you place the subs from the wall.

In my case, I have my system set up on the "LONG" wall and the subs are probably 5-6 feet off the front wall.  When I turned them in so the actives face the mains and the PR faces the front wall, that is what I got.

Also try the actives facing up (to the ceiling) and the PR facing the front wall. (also so you can't see it)

If it does for your room, what it did for mine, you will be truly amazed.

The incredible thing is the "sweet spot".  Low, "AIR SHAKING" bass is breathtaking in the sweetspot.  It is like I just went out an bought a new $15K bass system

Now again, It might have something to do with the push/pull I have set up, but I have only felt this type of bass "POWER" (which I am not generally after) in big HT software and LFE channels.

Never in two channel systems have I heard this, type of BASS before .

And do yourself a favor and "as fast as you can" get a copy of the American Beauty (Original Score . .... not the Soundtrack   ) and if you are getting truly deep bass, "THIS" will tell you.  It is the deepest bass I have heard from "ANY" CD ever.

[John Casler]

your a little late -
i stood mine on end a few years ago-

been wanting to make a old style tall boy cabinet -just too dam lazy

You've certainly heard of "Johnny come lately"?

But Rosconey, did you take the base plate off the PR slot, or did you just never use it at all?

[rosconey]

it was against the wall so it stayed slot loaded
when i moved into the dedicated room i went back to the standard way -havent retried it-sounds great were it is -

if i dont ever get around to doing a tallboy i thought about a tru corner install-make a face that connects to the wall at a 45% angle floor to ceiling and install all drivers on the front  - or slot load the passive on the bottom-add a top inside to keep volume about the stock size and fill the rest-

again just to dam lazy

[ScottMayo]

Speaking of which... anyone know the frequency response of the Largers below 17Hz? I know they will do 17Hz at -3db; I'm asking about 15Hz, 12Hz and 8Hz.

It's a tactile thing.

[zybar]

Scott,

I will look at my measurements when I get home and send you a PM.

George

[John Casler]

Speaking of which... anyone know the frequency response of the Largers below 17Hz? I know they will do 17Hz at -3db; I'm asking about 15Hz, 12Hz and 8Hz.

It's a tactile thing.

Hmmm (I say scratching my chin)

While the LARGER may be capable of 15Hz, to go lower than that with any authority, you might need "stacked" LARGERs.

Four LARGERs in front and two in the rear would probably put you there.

Even at retail list, that is only around $5.5K and would have both musical and WMD (weapon of mass destruction) qualities too

Your biggest problem would be a room that would support it, and not destroy/fight it.   Those are big and powerful wave lengths and the energy released "has" to go somewhere or be dealt with quickly.

[brj]

I will look at my measurements when I get home and send you a PM.

Actually, that might be of general interest... if you don't mind, George, would you consider posting it?

Thanks!

[ekovalsky]

I still have saved measurements of the RM/X that I can post if anyone is interested.  George & I were exchanging measurements when we were newbies with the TacT and his RM-40's and Largers had about the same bass cutoff as the RM/X -- in the low 30's in room.  Ted_B had similar findings, I believe, using the DEQX.  We all had very different rooms, ranging from small to fairly large, and two different measuring systems yet results were quite similar.

The "-3dB @ 17hz" spec may be reproducible at 1m on the floor, or with the mic shoved up the slot.  At the listening position (where it counts) don't expect much output below 30hz.  And stacking two, four, or more won't affect this very much -- it is a function of the passive radiator design with 24dB/octave drop off below the resonant frequency.  Stacking will obviously increase maximum SPL at any given frequency by 3dB which can definitely be a good thing, and it also helps load the room more evenly.

The resonant frequency for the big VMPS systems seems to be in the mid-30's, and with the rapid falloff below that there is no usable output to equalize.  Ported systems are no different in this regard, but many have lower resonant frequencies which translates into better extension.  For instance my Alon sub towers are tuned to 19hz according to the designer, but I have found them to be a bit higher in the low 20's.

Sealed systems on the other hand have a much more gentle 6dB/octave rolloff below their resonant frequency, so even though the -3dB point is much higher you will likely have better output in the bottom octave.  In smaller rooms, with room gain (+12dB/octave below the first node) considered it isn't hard to get flat response to 20hz with a bit of EQ.  I had modeled a sealed sub with a 12" TC Sounds TC2+ in a 2.5 cubic foot box that would have basically been flat to 20hz in my current smallish room.   Only downside was somewhat low sensitivity, but that can be fixed with stacked arrays.  Yeah I know computer models and reality are not always the same, but had I built it I bet it would have been awesome!  Though the TC Sounds drivers may not meed VMPS 'requirements' they can be incredibly good -- just ask George how his single 10" (ported) TC Sounds compares in the bass to the RM-40s with three 10" woofers, two active and one passive, in a larger cabinet  I doubt he has lost much if any extension even compared to the RM-40's with dual Largers.

All this being said, most music program matieral doesn't have much content below 35hz and the VMPS systems can put out a lot of clean SPL down to the mid-30 range which is a lot better than many speakers can do.  Many designs are either distorting severely at 30-35hz with any significant watts or they cut off much higher despite manufacturer specs stating otherwise.  Of course when there is high level signal in the teens and 20's (mainly organ and synthesizer, also movie special effects) it is most impressive on a system that can reproduce it cleanly  

[WerTicus]

Speaking of which... anyone know the frequency response of the Largers below 17Hz? I know they will do 17Hz at -3db; I'm asking about 15Hz, 12Hz and 8Hz.

It's a tactile thing.

holy sh*t... I dont even think any amount of largers would actually do this.  I also dont think you have a clue how low 12 or 8 hz actually is.

I can think of ONE setup that had 12, 18inch drivers in a room sized cabinet that went to 10hz flat.  so... you would need something like that

[ScottMayo]

All this being said, most music program matieral doesn't have much content below 35hz and the VMPS systems can put out a lot of clean SPL down to the mid-30 range which is a lot better than many speakers can do.

Music matters to me, but the other use of what I'm building is what I'll loosely call entertainment. Movies for friends, experimenting with sound effects for games... and for that stuff, you can never go too low. Besides, I'm an audiophile. There doesn't have to be a reason for getting flat to 8Hz, just like there's never really a reason to climb Mt. Everest...

Anyway, anyone wants to publish specs (or at least measurements) on any VMPS speakers, I'm all ears, as they say.

[ScottMayo]

Speaking of which... anyone know the frequency response of the Largers below 17Hz? I know they will do 17Hz at -3db; I'm asking about 15Hz, 12Hz and 8Hz.

It's a tactile thing.

holy sh*t... I dont even think any amount of largers would actually do this.  I also dont think you have a clue how low 12 or 8 hz actually is.

Yeah, I do, though. Some of the stuff I mess with (hobby, not career, sadly) is acoustics for game software. People can't hear below 20Hz, roughly (I hear 22Hz as separate beats, and I think my wife resolves higher frequencies than I do), but you can feel stuff right down under 1Hz under the right circumstances. If you want to make someone... vaguely uncomfortable, a 2hz "tone" can be helpful. If you want to mess with their intestines, a prolonged 8Hz tone at high SPL can do the trick. And people have reported experiencing distortions in vision when exposted to high SPL of 18-19Hz.  (People considering buying "bass shakers", take note.)

Unfortunately, the usual gear that goes with computer audio deliberately rolls off 20Hz (or higher), so a lot of interesting special effects get skipped in games.

I can think of ONE setup that had 12, 18inch drivers in a room sized cabinet that went to 10hz flat.  so... you would need something like that

Theaters, right? In my dreams...