[KJ]

Not to speak for George, but I'm guessing he might be referring to the build quality (not the materials' quality).

-KJ

[John Casler]

It seems there is some confusion as to what the adjustments allow and what they do.

I should also mention B, is on vacation so I doubt he will be commenting until after he gets back.

First, there are multitudes of "adjustments" system wide that affect the sound you hear.

You can go through each of them one, by one, and decide for youself if they help your system.

Some have mentioned how they use "measurements" to help them get their systems "right".  Others use the "ear" method.  I would submit that one is no better than the other considering the goal is to get a sound we like, not a sound that some one else tells us is correct.

While measurements might give some a confidence that they are hearing what they should, I can assure you that what the ear hears and what a mike measures "in room" may not have exact, direct, and meaningful corelation, beyond the "basics" .

While it would seem so, the interaction of the room will always affect the measured signal, especially with designs that interact with the room like dipoles, etc.

Additionally, a microphone does not hear like the ear hears.  It simply measures frequency, amplitude, spl, phase, and dynamics.  It also can only do so with test tones, and not music.  

No instrument that I am aware of measures "music" except the ear/brain.

Anechoic measurments will certainly tell what the "system" is putting out for test tones, but cannot predict what happens in room.  In room measuments can tell you only what the mike is hearing for test tones.

So the point is, those looking to "fine tune" their systems to "their" preferences cannot do so with any instrument other than their ear/brain, since this can "only" be done with music.

The above doesn't mean that measured initial tuning isn't valuable beacuse it certainl can be, but it cannot do anything but offer a "starting point" for fine tuning to preference.

To that end, the adjustments of the VMPS speakers allow only three adjustments.

1) Bass Damping
2) Adjustment of tweeter level
3) Adjustment of neopanel level

First to clear up any "misconception" of what the bass damping is capable of.

The bass system as a whole has a "resistance" to action.  That is, it has a "mass".  This mass is acted upon by the action of the active woofers, which are also affected by the mass of the Passive Radiator since it is a closed system.

All amps have a specific ability to move the active woofers and this ability is called a "damping ratio".  In general a Tube amp has a lower ratio and a SS amp has a higher ratio.

Because B, knows that the speakers will be used with both tube and SS, and because even within those groups damping ratios vary, he found that an adjustable system allowed the ability to "adjust and even fine tune" the system to the electronics used.

This "will not" make bass louder, or add significant SPL, except to the small extent that it might offer a very small increase in efficiency.

It also "will not" change room modes or nodes, since those are dictated by room dimensions and can only be affected by equalization or room treatment.

Bass is a "very complex" area to "get right".  It cannot be solved by pinching putty alone.  Almost all BASS problems are room and postition related and cannot be solved by putty adjustment.

I would suggest that the "frustration" that some mention is that they expect the putty to solve the boom and spend countless hours attempting such and cannot.

The VMPS are no different than any other speaker in this regard.  Room placement, and room treatment should be first line of defense for this with LF equalization, being next on the list.

The putty then is the icing on the cake that will bring out the "detail and resolution" that can then be fine tuned.

The L-pad adjustments are offered to provide the ability to "adjust and blend the drivers" and their associated bandwidths to your preferences, equipment or room.

I find it intersting that so many with "non-adjustable" speakers try to adjust the sonics from their speakers by adding/swapping very expensive components and to acheive their preferences or to match their main components charateristics.

While the L-pads certainly have a limited ability, they can go a long way toward dialing down brightness or adding same more resolution if a component suffers or enjoys that trait.

They can also be used to balance and blend with each other.  Dialing down the L-pads can have the same affect as "dialing up" the woofers and vice versa.

Or if you have a midrange rich sound and you wish to add a bit more highend, then you can.

They can also be used to offer a slight bit of "balance control" or room adjustment (if one speaker is closer to a wall and subsequently sets up an imbalance).

All of these are slight, and have a limited range, but can be usefull in solving sound problems.

So there is little doubt that these functions are useful, since I have used them hundreds of times, to a great result to get the sound I want.

Is that sound accurate to a mike and test tones?  I don't know and frankly don't care, since I don't listen to tones and my ears are not connected to mikes.

Measuring to a flat "in room" response, is only valuable as a starting point, and there is certainly nothing wrong with setting up ones system in total that way, it the end results is what you want.

So in the end, if you are going to go "digital" the Direct Drive system addresses your needs, and will allow you to move closer to a pure system to give you the best result.

If you go conventional, then you have a choice between the adjustability of VMPS, or a speaker that allows no adjustment and you will need to focus more time and money on component matching (And this is valuable with any speaker adjustable ot not) to get it the way you want it.

The greater point of this thread, was to say that the speakers now arrive at your door, in a condition similar to "non-adjustable" speakers.

That is they "are" plug an play as much as any speaker on the market.

However, it you want to further "dial in" your system, you do have that option.

And a final word about "tweaks and upgrades".

Very few speakers are perfect, and considering what they must do, I doubt that they ever can be.

Since they are placed in differing environments and different systems they have to be "Chameleon like".

But to that end, there will always be component parts inline or "in speaker" that may improve a given system.

I also find "external tweaks" help meet my listening preferences.  It is not because the speakers are deficient in some way, it is because my room and preferences benefit from manipulating the signal that "doesn't" reach my ears directly.

If I had $200K speakers, I would be suggesting the same (or new) tweaks to try.

I will say that most VMPS owners are a special group, who have a sound and a preference they wish to express with their systems.

Brian no doubt has interest in also expressing himself and his design philosophy with his product.  But he also recognizes that there will be those who wish to strike out into new "technologies" as early adaptors, and to that end, he has created the "Direct Drive" system for those so inclined.

It is simply another way for you to "adjust" your speakers, system and sound, to hear what you want.

[brj]

What's wrong with the looks of the MLS cabinets?  I think they look stunning, at least to my eyes

MLS cabinets look fantastic, but MLS doesn't make all VMPS cabinets (most significantly, not the RM30).

Most concerns are not related to veneering or cabinet solidity, but assembly issues.


As an example, I'll comment on my impressions of the RM30s, a pair of speakers that I've been trying to audition ever since they were announced.  I finally heard them over the U.S. Memorial Day weekend.  These speakers had every upgrade available except the "direct drive".  Specifically, they had the Analysis Plus wire, mega-woofers, Soundcoat, FST, TRT caps and Rosewood veneer.

My impression of the sound - absolutely stunning.  Among the best I've ever heard (with some allowance for room treatments and upstream equipment).  I wanted that sound for my own.  Right now.

My impression of the fit and finish - disappointing for a multi-thousand dollar pair of speakers with an "upgraded" finish.

Issues:

- the veneer was separating from one of the front round-over edges (owner told to glue it down and clamp it)

 - the finish had several minor, but visible scratches (Explanation offered: shipping related.  Proposed solution: purchase turtle wax and buff)

 - the screws used to mount the bases were off-center and mis-aligned, causing the wood to split on one of them (Brian sent a replacement that wasn't split, but its screw holes were no better)

 - 3 of the 4 mid-woofers had to be replaced due to static issues (Credit to Brian: no questions asked)

 - mid-woofer driver holes are not the same shape as the drivers themselves and recessed too deeply[/list:u]
And yes, you could see the silver screw heads and green PCB boards of the midrange panels.  This was a fact known at ordering, and Josh is correct in that a little black enamel will cover it.  This does seem like an easy thing to do at the factory, however.

In short, the sonics were everything that everyone raves about, and I would love to have that sound in my own home.  I applaud Brian for the quality of acoustics at each of his price points, as he truly is a leader in this regard.  That does not mean, however, that the speakers are inexpensive in absolute terms.  What I might excuse in a multi-hundred dollar speaker, I have a very hard time over-looking in a multi-thousand dollar speaker.

I'm not saying that the fit and finish needs to be "museum quality" at his current price points - the point is that every flaw I saw (except for the driver cutouts) would have been cheap and easy to fix prior to shipping, but wasn't.

I hope the VMPS line of speakers continues to improve their fit and finish, because nothing should be allowed to detract from that quality of sound.

[Brian Cheney]

Fit and finish is a primary concern for us, now that I have that thing working with the sound quality!

Domestic cabinetshops I have dealt with for decades have been devastated by Chinese competition.  The RM 30 builder changed hands and the new owners will not fix problems such as misaligned base rails.  I am paying to have some new ones made locally, which should solve that problem.  More to follow as I catch up from that "vacation".

[KJ]

The RM 30 builder changed hands and the new owners will not fix problems such as misaligned base rails.

Brian,

Was the ownership change recent?

-KJ

[ekovalsky]

Many times you may see discussions about "tuning" VMPS Speakers.

All VMPS Floorstanding models came "over damped" with slightly more putty added to the Passive Radiator than one might need.  This then meant that all one need do is remove a pea sized "pinch", let the woofers break in, and then maybe remove a fingernail or two to get it perfect.

A similar procedure was suggested with the "pots" or L-Pads equaliing a basic setting and the a "fine tuning" after breakin.

Well B, now does most of that be ...

Getting back on topic, and hopefully stimulating some intelligent discussion on VMPS bass system...    

The PR tuning must be done in very small increments. While amplitude response changes little with tuning, harmonic distortion changes greatly. I published curves right on this Forum last year, showing 10% THD at 20Hz on the RMX with the PR untuned and 1% THD with about half a gram of putty removed. The sound becomes dramatically clearer and the bass response subjectively (emphasis here) somes up when the tuning is done properly. I invented this bass system in 1979 and was highly gratified to see a Klipsch speaker adopt it a few years later. Imitation and flattery, you know.  

Do you happen to have any graphs showing impedance sweeps done with a tuned versus untuned passive radiator ?  From a physics standpoint I'm not exactly understanding how a very minute change in mass would affect distortion.  Large changes in mass, added or subtracted, would shift the tuning frequency of course, but even then only by a few Hz.  

I'm interested in reconciling what you said with my frustrating experience with the VMPS bass tuning.  My wife once thought she could hear a difference with me playing around with the putty (she's got a great ear -- better than mine for sure) but I never came to any consistent conclusions with adding or subtracting mass despite many hours of listening and fingernail scraping.

The impedance data will come in handy when I submit my mail order speaker designer Ph.D thesis  

[warnerwh]

Eric: I don't know about impedance data but when I tune my speakers the sound difference in the midrange is what I find most annoying. If you put too much putty back on it ruins the midrange smoothness.  The bass is also affected but it's not what as sonically aggravating. Also I believe the reason such a small amount  of putty can make a difference is due to the velocity of the cone.  I wondered about that too until someone brought up the extreme velocity a cone can have.

[John Casler]

I had these bookmarked on my computer so I was able to "cut and paste", to here.

These are the graphs B, refered to (I think)

I ran a long series of nearfield (room-independent) bass measurements on the RM/X (w/vitrified high-compliance PR) today and faxed them to John Casler with a request to post (something I have never figured out how to do).

For Scott and other owners let me say the measurements show very smooth response (within 2dB) from below 20Hz to above 200Hz where I stopped the measurement.

There are dramatic differences in THD with PR tuning. As you will see, 2nd and 3rd harmonic distortion drops from max 10.57% 2nd at 20Hz before tuning the PR, to 1.35% 2nd at 20Hz after tuning (tuning also smooths overall frequency response and raises 20Hz output by about 0.2dB.) I removed about 5 fingernail fulls of putty to tune.

Please examine these curves carefully.

Scott wanted measurements on the bass system of the RM/X so I ran 10Hz to 200Hz sweeps with 1/24th octave resolution and a little less than one watt input.
The sensitivity (without room gain) is about 85dB at 48Hz where the system has its maximum output.  Room gain (which everybody uses when quoting bass sensitivity) adds about 6 dB.

Nearfield means the mic is basically almost touching the woofer cones and is flush with the center of the PR slot.

Good midrange and HF measurements require an anechoic chamber. Unfortunately there is no anechoic chamber in this hemisphere large enough to make good bass measurements below around 80Hz.

In-room fullrange measurements are worse than useless, since the room plays such a large role in the outcome. See my curves on the Quad 57 taken in-room some years back, as published by Stereophile.

The biggest surprise in the change in 2nd and 3rd harmonics when the PR is tuned. From 10.57% 2nd harmonic at 20Hz, distortion drops to 1.31% (with 3rd harmonic even lower) merely by my removing a very small amount of putty from the PR. Amplitude response at 20Hz can also be boosted about .2dB with the PR adjustment.
There is about a .5dB improvement in overall linearity when the PR is mass-optimized. The measurement degrades if another fingernailfull of putty is added or subtracted to the (vitrified, high-compliant) PR cone.

Note that the system meets its -3dB point at 20Hz precisely and is only minus 4.5dB (relative to 48Hz) at 17Hz. If you neglect the 1.5dB rise between 30Hz and 60Hz the system is -3dB at 17Hz. This is outstanding linearity and bass extension.

There are many more measurements that Clio and Sysid can make but this is your basic bass performance, i.e. better than any High Fidelity speaker I have encountered these past 27 years.

If you have questions feel free to ask.
_________________
Big B...

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[ekovalsky]

Thanks John.

I've seen those before, posted here and also Big B sent me a copy of the printouts a while back.  Frequency response looks great.  Great sweet spot for a chihuaua or mouse at 2- 4" off the floor and right in front of the slot   Any quasi-anechoic measurements at 1m or 2m ?  With the big 31' LEDE room they should not be too hard to get.  Stereophile posted some ways of getting these measurements with decent accuracy a while back.  Too involved for a home user, but certainly within the realm of a manufacturer or reviewer with the appropriate equipment and software.

Do you know if these published distortion measurements were all obtained with the same power output ?  Significant changes in distortion would be expected with varying power.   Distortion will rise with very  lower power, as there is no pressurization in the cabinet, and of course to a greater degree at higher volumes also.  After several years of thinking about it, I still don't see how 1/10th of a gram of subtracted mass will make a difference.  

And what about changing from the plain passive radiator to the "high compliance" vitrified -- i.e. glue painted -- unit ?  Certainly the weight of the glue solids is more than 1/10th gram, and the physical properties of the passive radiator will significantly change.  Since these measurements were done with the vitrified PR of an RM/X, the distortion figures and maybe frequency response of the initial RM/X PRs may have been a lot different.  

Also, none of these graphs show impedance sweep which is what would show the actual tuning frequency.  That's what I'm really curious to see.

PS -- JBL offered tunable passive radiators back in the 60's in the form of  kits and DIY subwoofers.  Tuning was accomplished by mass loading -- the user was instructed to bolt some specified number of heavy steel washers to the dust cap to achieve a particular tuning frequency  

[Brian Cheney]

Measurements were made at 1.9V input into a 4 Ohm load, just under a Watt.

Nearfield measurements are the only accurate measurements for bass, as I have pointed out in the past.  They have nothing to do with the "sweet spot".

I am puzzled by your posts, Eric.  You tout amateur in-room measurements made at the listening position as some measure of the loudspeaker, which is not the case.  Given accurate measurements, you quibble and contest.

You're a man of science, but persist in drawing erroneous conclusions from poor quality data, just because you obtained them yourself. You also make recommendations for competing equipment from zero experience with it, which is even more puzzling.

[ekovalsky]

I am puzzled by your posts, Eric. You tout amateur in-room measurements made at the listening position as some measure of the loudspeaker, which is not the case. Given accurate measurements, you quibble and contest.

You're a man of science, but persist in drawing erroneous conclusions from poor quality data, just because you obtained them yourself. You also make recommendations for competing equipment from zero experience with it, which is even more puzzling.

You may be right on the second account.  I do apologize if I came across as promoting products from your competitors on your forums, that is inappropriate.  Several of the products I have mentioned I have not heard myself, though what I said is based on subjective impressions and amateur measurements of other audiophiles, several of which have owned VMPS thus have a good basis for comparison.

I have not invested in CLIO, MLISSA, etc. nor do I have the technical background to give a pair of speakers a thorough lab evaluation.  TacT and DEQX measurements are of limited value.  But, having an objective tool to give me an indication of how my speakers and room interact has been very valuable and has greatly increased my audiophile acumen.  When I see something undesirable on my amateur measurements, I listen carefully and usually can hear the problem then try to fix it.  In the past I would be oblivious to it, subconsciously attributing most sonic imperfections to the room, recording, or my equipment.  That definitely contributing to a long and expensive cycle of equipment upgrades which never got me what I wanted.

Hell, at one point I thought I was getting some really kick ass bass in my room.  Great placement for the speakers !  Turns out I was getting a 12dB boost from a 40hz room node

The TacT definitely helped me get the most out of your speakers, alas it also eventually made me realize there were speaker-room interactions and  what I thought might be some design issues that I could not overcome, hence my decision to move on.

Amateur though the TacT (and I) may be, I have found it to be a wonderful tool and a damn good preamp and DAC too.  To say that it greatly enhanced my time with the VMPS speakers is an understatement.  These products can be an audiophiles best friend and a speaker designer's nightmare at the same time.

[John Casler]

To keep this thread "on topic" and offer a more topical thread for those interested, I have split this thread to address the VMPS and DSP conversation.