[azryan]

Heard the RM/X's in Eric's (ekovalsky) system last Sat.

Review in Critic's Circle...

http://www.audiocircle.com/index.php?topic=8137.msg69392#69392&sid=39b8690b93ef4f635fbee5d85f4b3950#69392

Great speaker! (for those who want the short version).

[azryan]

Oh...

What's the theory of 'no spikes' on VMPS?
And does it only relate to VMPS speakers maybe 'cuz of the slot loaded pas. rad?

[jgubman]

MGD speculates the no spikes rule is because Brian wants to control how close to the floor the bass driver is located.

Makes sense to me.

[jgubman]

Ryan,

what is your speaker that you compare the RM/X to in your review? GR Alpha LS?

[azryan]

Yes, the GR Alphas.

About the 'no spikes'... can anyone confirm jgubman's guess here?

[ekovalsky]

Brian's speakers are designed to be directly coupled to the floor.  He has always (to my knowledge) recommended against spikes.  It says so emphatically in the instructions that come with the speakers (at least the RM-40 and RM-X)

"Cross-firing" the speakers (i.e. towed in enough so that the drivers axes cross in front of the listening position) works well with VMPS.  It enlarges the sweet spot since as one moves to the left or right of center, the ears become more on axis with the channel further away.  I find no loss of center image with cross-fire.  Interestingly, some of the best rooms I heard at CES used this type of setup, including the awesome TAD room.  The Gilmore rooms, at least some of them, had it too, but I was more interested in the girl than the speakers  

In my room, cross-firing also allows enough toe in that I have the centers of both the side and front woofers positioned at a Golden's ratio (1.618:1) from the side and front walls, respectively.  Mathematically this should ideally disperse bass nodes and from my critical listening I think it works.  See my room setup diagram in the gallery.

I've spent most of my time tweaking the bass system and am pretty sure I got it right.  The last few days I've spent several hours working on the tweeter pods and finally got them identically aligned and firing directly towards the listening position.  When azryan heard them they were aimed slightly higher and, as supplied by the factory, the pods weren't aligned with perfect symmetry.  Julian had told me about this and with some effort I was able to get a perfect alignment without cutting the wires, removing the pods, and remounting them which is what he did.  A multi-plane bubble level is an essential tuning tool for these speakers!

Adjusting the pods, and substituting a BPT 3.5 Sig for the PS Audio P1000, has further improved the sound.  The BPT 3.5 Sig took a few days to wake up but is now stunningly good.

[Horsehead]

Eric- Glad to see the 3.5 Sig has finally opened up and improved the sound.  I am still impressed to this day the improvements it made in my system over the PS Audio PowerPlants. I just have to investigate the "new" changes Chris made to the units.  I wish I had an excuse to fly to Arizona, I am dying to hear your system

The concept of "break-in" or "burn-in" cannot be discounted in my experience.  My Wadia 861SE from GNSC was not impressing me that much the first few days in my system.  Two weeks later and it is absolutely one of the finest source components I have heard.  I just added an Elrod Statement II which took it up another notch.  You thought the BMI cord was big.............. Sorry for getting off topic.

[ekovalsky]

Eric- Glad to see the 3.5 Sig has finally opened up and improved the sound.  I am still impressed to this day the improvements it made in my system over the PS Audio PowerPlants. I just have to investigate the "new" changes Chris made to the units.  I wish I had an excuse to fly to Arizona, I am dying to hear your system

The concept of "break-in" or "burn-in" cannot be discounted in my experience.  My Wadia 861SE from GNSC was not impressing me that much the first few days in my system.  Two wee ...

I'm starting to become a believe in "burn-in".  I always thought, with the exception of speakers drivers, it was just time needed for the ear to adjust to something new.

Grab some Southwest tix when they're on sale and come for a visit!

[John Casler]

I've spent most of my time tweaking the bass system and am pretty sure I got it right. The last few days I've spent several hours working on the tweeter pods and finally got them identically aligned and firing directly towards the listening position. When azryan heard them they were aimed slightly higher and, as supplied by the factory, the pods weren't aligned with perfect symmetry. Julian had told me about this and with some effort I was able to get a perfect alignment without cutting the wires, removing the pods, and remounting them which is what he did. A multi-plane bubble level is an essential tuning tool for these speakers!

A good method to "converge" and "align" the pods is to secure a small mirror to the front, and while sitting in the listening position, adjust them until you can see your left ear in the left speaker and right ear in the right speaker. (without moving your head)

If your convergence point is in front of you, use that for the listening position.

This can be done very simply if you have a friend/relative make the adjustment.

It is as accurate as laser alignment if your take care to secure the small mirrors equally.

I use it to also get the exact convergence for both "toe in" and "vertical firing".

You can purchase the mirrors for less than a dollar each at most any drug store.

And I'm glad you are finding the 3.5 Sig to be improving your sonics.

I will be talking to Chris about your questions and getting back to you

[ekovalsky]

Good idea John.  My wife has plenty of little mirrors!  

[azryan]

"-Brian's speakers are designed to be directly coupled to the floor.-"

I was asking 'why' though. I know he doesn't use spikes on purpose. It's the 'purpose' I'm asking about though and if that reason then also relates to other speakers according to Brian's theory.

Just curious though 'cuz pretty much most other speaker designers consider spikes a benefit. Personally I mostly just find them to keep large heavy speakers from mashing rectangles in my carpet.
Forget I asked.

"-I find no loss of center image with cross-fire.-"

Yeah, I thought your center image was great. Nice and sharp. I had zero prob. with it.

I didn't get a good center image sitting in the off-center chairs, but I can't get that on my speakers nor any speakers I've ever heard. Just the nature of 'stereo'.

Have you tried 'Amused to Death' on your current system?

I wish I woulda tried that to see if it could still do that Q-Sound surround phase effect when the speakers are cross-firing?

My Chesky Test CD also has some surround effects that I wish I woulda tested too.

"-A multi-plane bubble level is an essential tuning tool for these speakers!-"

If it takes this level of dead on exact aim of the FST's doesn't that also mean that the listener has to be at the exact right ear height to get the 'just right' benefit of perfect FST aim?

Perhaps a set of laser pointers aimed at the listener's forehead so they know just exactly how much to sit up or slouch to get the angle right? Careful of the eyes though. heh

Actually lasers coming out of those FST's would look like something you should expect from the X's! hehe

Cool looking speaker though. Not ripping on it. I dig it.

Is there a good test to see if bass is overdamped?

I'd like to hear Eric's system again, 'cuz I'm feeling it might be overdamped? I could be wrong though.

That Chinese drum track I played there has these really large transients from the HUGE drums and as far as I'm remembering I think it might have been too tight.

The woofers are also probably not hardly broken in at all either being a month old and having never played any bass as loud as that. That seems like that could be part of it too.

The X's seem to have tighter bass than my Alphas, but my woofers can't hardly be seen moving on that track at ~the volume we played it at your place so I'm thinking that's got to mean they're starting and stopping about as fast as any woofer can..... unless it's sealed w/ a low Q or an overdamped passive rad., and/or stiffer unbroken in spider and surround?

Note... I'm talking small things here though. Tweaks to refine things, and to my opinion not ness. anyone else's opinion.

It may seem like I'm totally insulting Eric's system and ripping on the X's 'esp this being on VMPS's forum and not Critic's Circle where my actual review comments are posted.
 
That's NOT at all what I'm intending.

As I said at the top "Great speakers!"

[John Casler]

I was asking 'why' though. I know he doesn't use spikes on purpose. It's the 'purpose' I'm asking about though and if that reason then also relates to other speakers according to Brian's theory.

Hey AZ,

I don't think Brian is totally against "mechanically coupling" using short spikes (he can correct me if I'm wrong) but he is against raising the speaker with those adjustable spikes that leave a gap between the speaker bottom and the floor.

I think it basically has to do with the fact that a gap (even small ones) is like a bass leak for the Front firing Passive Radiator slot.

I think Brian envisioned users, placing adjustable spikes in such a way as they used them tonot only "raise the speaker" but "tilt" the speaker back to adjust vertical firing angle.  In some cases this could open up a significant 1-2" gap below the PR slot.

In reality it is a trade off, since the mechanical coupling of "short" spikes (no gap) can also contribute to much more defined bass response.

I find the biggest drawback of spikes is making small positioning adjustments, especially with the larger speakers.

If a VMPS user does decide to use spikes, all they need to do is simply place a solid extension of the bottom of the speaker (in front) so the "bass leak" doesn't occur, like a small board that fills the gap.

[azryan]

Thanks John!

[LAL]

John,
I suspect that the question of whether or not to spike a speaker depends on the type of speaker and the type of floor.  My experience is that a full range speaker tends to excite the resonances in a suspended wood floor. Seems to be that spiking would only make this situation worse.  I believe sound may travel faster through the wooden floor than through the air and consequently muddy the bass at the listening position. I built a base for my RM40's that functions like a Symposium platform. It forms a sandwich of 1.25 MDF/1.5 Foam/.75 MDF. Bass is tighter and floor vibrations are lessened. I experimented first by placing the speakers on a piece of the polyethylene foam. I noticed an immediate improvement in the bass. The speakers were more stable and less prone to rocking back and forth when I tried bouncing a little on the floor between them. Also on music with lots of bass I could feel the speaker vibration on the foam while floor vibrations were reduced, telling me that the foam was doing its job in disappating the vibrations before they reached the floor.

[ctviggen]

I do think that suspended wood floors introduce problems.  I had my sub on a suspended wood floor and I couldn't turn it up without shaking the entire house (and introducing rattles).  I ended up buying some rubber "bumpers" made to put speakers/equipment on, and those helped tremendously.  So much so that when I move into my new house, which has a tile floor, I'm thinking of buying the bumpers for the main speakers.  They have a variety for different weights and you just order the correctly sized versions, although I don't think they make them large enough for the RM40s.  However, I did put spikes on my speakers, and this wasn't too bad, but I also didn't do any testing between base w/o spikes, spikes, and bumpers.

[ctviggen]

I do think that suspended wood floors introduce problems.  I had my sub on a suspended wood floor and I couldn't turn it up without shaking the entire house (and introducing rattles).  I ended up buying some rubber "bumpers" made to put speakers/equipment on, and those helped tremendously.  So much so that when I move into my new house, which has a tile floor, I'm thinking of buying the bumpers for the main speakers.  They have a variety for different weights and you just order the correctly sized versions, although I don't think they make them large enough for the RM40s.  However, I did put spikes on my speakers, and this wasn't too bad, but I also didn't do any testing between base w/o spikes, spikes, and bumpers.

[John Casler]

Hi Guys,

I might interject a few "ideas" here regarding mechanical coupling, wooden floors, sound transmission and the like.

There is little doubt that mechanical coupling a larger speaker (one with large bass abilities) to the floor will produce a prefered bass response simply by reducing the effect of some of the "reactive" forces on the cabinet itself.

This means that as the woofer responds, the cabinet reacts less by moving in the opposite direction.  Much like firing a shotgun in a canoe.  Reducing this reaction makes for "cleaner" leading edges of the sound waves and subsequently tighter, cleaner bass.

To reduce this "reaction" one can mechanically couple, and/or add mass.  Both will help "tighten" things up by reducing the "push away" reaction, which softens sonically.

Now regarding wooden floors.  My experience is that it might still be better to "couple" than to "float", suspend or isolate the speaker.  I would also suggest that adding mass will also help reduce any floor transmitted vibration imparted from the coupling.

Now keep in mind that a great portion of the of the movement experienced in the floor and or couch you are sitting on is actually produced by "airborne" sound pressure and not the mechanical transmission it would seem.

The actual energy in a 20Hz sound wave is quite impressive.  In some of the early advertisments for Brian's LARGER sub, he mentions that it was used for "Vibration" testing by the Space Agency.  Let me assure you they didn't set the sub on something to test it for vibration, they put it in the path of the radiated Low frequncies.

The option of de-coupling the speaker then would seem to have the possibility to "reduce" the rather insignificant mechainical transmission "and" by actually "softening" the airborne transmission it will also reduce the "airborne" effect on the floor.

Only problem is, it also has a tendency to reduce "impact, body, and cleanliness" because the speaker cabinet has to "react" to a greater degree since it has no other option, and does not have the benefit of the stability offered by "mechanical coupling".

I might also add that it is correct that sound will travel faster through a solid than a "liquid" (air) but since the solid (in this case the floor) is also acted upon to a greater degree by the air borne vibrations this presents very little problem.  

Additionally, unless you have your ear on the floor it is not heard at all, and more felt as a sensation.  This sensation is not comparatively associated by the brain in a fashion that would cause any decorrelation of actually hearing the sound accurately.  Plus the distance is so small that any time/arrival decorrelation would not seem significant.

In a perfect "sonic reproduction world" stiffness, stability, and vibration would be perfectly controlled, but they are not.

The hard part is finding a "best" combination of coupling, de-coupling, mass, no mass, and vibration creation and vibration control, since these are the physics we are to contend with.

If one does choose to "suspend" the speaker and de-couple, I suggest adding maximum mass.  Now keep in mind that this mass also has a tendency to reduce the "de-coupling effect" you are using also if it is a compressable vibration damping substance, since it adds compression.

So what is a simple "mass builder"?  Weights!!.  I use either rubber coated dumbbells (not plastic) or rubber coated Olympic plates

Without vibration, we have no sound.  With too much or in the wrong place, we have lousy performance.

Hope all these thoughts made sense, and might add to your ability to deal with vibration creation and control

It's tough being an audiophile

[azryan]

"-I might also add that it is correct that sound will travel faster through a solid than a "liquid" (air)-"

I was under the impression that air was a gas? Did your section of CA sink into the Pacific? hehe

kiddin' with ya.

[PLMONROE]

Technically there are solids and fluids. Fluids are in turn either gases such as oxygen or liquids such as water.  And of course the same substance can be either solid (ice), liquid (water) or gas (water vapor).iPicky,picky,picky

[John Casler]

"-I might also add that it is correct that sound will travel faster through a solid than a "liquid" (air)-"

I was under the impression that air was a gas? Did your section of CA sink into the Pacific? hehe

kiddin' with ya.

See Paul knows

Sorry guys, didn't mean to confuse.  I have just been involved in writing a couple US patents recently and air is refered to as a liquid.

Hey AZ, CA hasn't fallen yet, but you'll know when your front door has an Ocean View..    

But to further clarify, sound travels fastest in dense solids, then "real" liquids, and then slowest in the gaseous states of liquids.

It is because of more effective molecular agitation and translation.

It has to do with the space between molecules being smaller to greater.

So if I say it has a "liquid" midrange, I'm not really listening underwater