[pmcneil]

First, I would like to thank Brian Cheney for his support. I bought a pair of RM2s third hand (via Audiogon), one of which had a defective mid panel upon arrival. He replaced it free of charge, and helped me solve via e-mail another problem, shipping-based damage to a cross-over. Wow, what other speaker company would do that!?

Now I am working with the addition/subtraction of putty on the passive radiator. And I realize, from reading various AudioCircle threads, that this is an activity that occupies many VMPS owners. First, of course, I removed putty, and the bass got worse...more boomy and muddy, and especially awful (chesty and congested) were male voices. So, I went to Home Depot (Lowes, I found, had none) and bought the (Mortite) putty (enough for 100 more pairs of RM2s!). The more putty I added (now almost 6 oz) the better the sound. How could this be, based on what I read that I should subtract putty (but who knows what happened before I got the speakers, with the previous two owners; how much was on there to begin with?)? So, next, not trusting my ears, I used my Velodyne bass equalizer system (microphone, black box, video record of measured bass output 20-120 hz) to measure plus and minus putty response. With this, can I measure the bass output (subwoofers disconnected) objectively? Well, the spectrum of measured output was improved with the extra putty mass, and so was the sound, assessed subjectively (with my ears). But should I add more, given that the major advice is to subtract?

Any thoughts?

[Regalma]

So what is wrong with a better sounding system?

6oz is a lot compared to my setup but it is going to be room and speaker location sensitive. I would add whatever makes it sound good to you. The fact that it measures better as well is all that much better. That also tells me you would never be happy with a Bose system:)

[decal]

So, next, not trusting my ears, I used my Velodyne bass equalizer system (microphone, black box, video record of measured bass output 20-120 hz) to measure plus and minus putty response. With this, can I measure the bass output (subwoofers disconnected) objectively?

You should always trust your ears over measurements.

[pmcneil]

You should always trust your ears over measurements.


Thanks guys for your support.

I'm going to add even more putty!

It could be that either my ears or the woofers/radiators are faulty, but who cares if I feel that the sound is improved.

[Dawkus]

Hi PMCNeil,I too was going to use Mortite on a pair of Dyna A-25's.I have in the past used the modeling clay suggested by Frank VanAlstine that you can get at the art store.The A-25 has a paper thin rubber gasket from woofer to cabinet.It looks like it could do nothing for dampening,to thin,but cost effective for the day.Mortite,so easy to use,specially when you get a wallpaper seam roller(a little tiny rolling pin with a handle)at the paint store.But,on this forum,I read by either Frank VanAlstine or Wayner that Mortite has an acidic base that might harm woofers.If I were you I would pose the question to either one of the guys before you (seal the deal)for your own conscence(I can't spell that well)Mark Korda(mark.korda@myfairpoint.net)

[John Casler]

First, I would like to thank Brian Cheney for his support. I bought a pair of RM2s third hand (via Audiogon), one of which had a defective mid panel upon arrival. He replaced it free of charge, and helped me solve via e-mail another problem, shipping-based damage to a cross-over. Wow, what other speaker company would do that!?

Now I am working with the addition/subtraction of putty on the passive radiator. And I realize, from reading various AudioCircle threads, that this is an activity that occupies many VMPS owners. First, of course, I removed putty, and the bass got worse...more boomy and muddy, and especially awful (chesty and congested) were male voices. So, I went to Home Depot (Lowes, I found, had none) and bought the (Mortite) putty (enough for 100 more pairs of RM2s!). The more putty I added (now almost 6 oz) the better the sound. How could this be, based on what I read that I should subtract putty (but who knows what happened before I got the speakers, with the previous two owners; how much was on there to begin with?)? So, next, not trusting my ears, I used my Velodyne bass equalizer system (microphone, black box, video record of measured bass output 20-120 hz) to measure plus and minus putty response. With this, can I measure the bass output (subwoofers disconnected) objectively? Well, the spectrum of measured output was improved with the extra putty mass, and so was the sound, assessed subjectively (with my ears). But should I add more, given that the major advice is to subtract?

Any thoughts?

Since adding and subtracting putty is generally measured subjectively you will find answers "all over the map" attached to advice.

Look in the "Set Up" sticky here regarding what the putty does, and why it does it.

The PRIMARY function of the MASS is to "coordinate" lower frequency reactive, passive action of the Passive Radiator to the higher frequency active driver.

That is, the active driver moves and creates pressure variations in the cabinet.  These variations cause a slightly slower (lower) reactive action in the Passive Radiator.

But to be useful, these reaction need to be "coordinated" to a precise reaction, or else they cause a ragged, or dull, or muddied, or wooly bass.

Adding mass to the PR will slightly slow its reaction.  Reducing mass will allow it to react more quickly.

When the reaction is "tuned" via this adjustment, it also reduces overall distortion.

Brian's custom made woofers already have some of the lowest distortion available, and tuning the PR "tunes" the system as a whole.

HOW?  well even the active drivers are affected in their action by the internal cabinet pressure (resistance).  "TUNING" the reactive resistance of the Passive also affects this.

The putty, and even the air pressure of the "slot" can play a part in this physical chain of compliances and resistances.  But the adjustability is what makes the SYSTEM work and function as a WHOLE. 

Brian says he has on occasion measured bass system distortions deep into the single digits.

While the rage in bass is for high SPL's now days, you will find that the VMPS manually adjustable damping system to be a simple and effective way to "hear" more, tone, texture, definition, resolution, and timbre.

There is a World of Bass, that many have never heard due to the generally higher distortions of a bass system.

Brian has offered up a way to clean that window into hearing bass that you might not have known existed.

If you can find it, the Bela Fleck and the Flectones LIVE album with the cut AMAZING GRACE is a good example of a tune and cut recorded well enough to display BASS Quality like you have NEVER heard it before. . . . IF, you have your PR's tuned properly.

Victor Wooten (the bassist) is phenomenal with what he can do with a BASS GUITAR and all the complex sounds and music it can make.  It is a good REFERENCE CUT for VMPS Bass lovers.

I might mention it is the INTRODUCTION and AMAZING GRACE (like you have never heard it before) that will tell you WHEN you have your VMPS BASS SYSTEM well tuned.

[lateralgs]

OK, I am a novice here as far as VMPS ownership goes.  In fact, I've never had the opportunity to even HEAR a VMPS loudspeaker.  Nonetheless, I have the RM30M Signature as one of my finalists for my speaker upgrade planned for next month, as a result of research I've been doing for about a year now in anticipation of this coming upgrade.

But I have questions for John and/or Brian.  I imagine I am thinking "all wrong," but here goes anyway.

Simply stated, why is it not possible to correctly tune the PR's to the theoretical best-fit mass damping at the factory, and do it without such a tool as putty?  Is it because of variabilities in the speakers themselves, or is it because by design Brian wants each owner to be able to tune to his/her own taste?  Does it have anything to do with the variability in the possible combinations of build options allowed when you order a pair of VMPS speakers?  Lord knows, NOBODY allows as much leeway in customizing the build of a set of speakers to-order as VMPS does.  Or if they do, I haven't found them!

I can understand the potential need to tune overall output at certain frequencies, perhaps, to the unique challenges that may be encountered in trying to make a given design function near its peak performance capabilities within wildly different room acoustics.

But it seems to me a theoretical best fit should be the starting point at the time of manufacture, and perhaps the tuning would be better served digitally with some sort of EQ.  Given consistent quality of manufacture of the active woofers, the passive radiators, the crossovers and the cabinets, thereby assuring consistent behavior, would it not be better to construct to the theoretical ideal instead of resorting to putty?

I'm both intrigued and confused by this design approach.  On the one hand, I can see the potential for the almost "infinite" tunability.  On the other hand, I can see how this could lead to all sorts of grief.  It seems to me the primary potential "failure mode" with this sort of tunability function is bound to either be repeatability, or patience.  In fact, in performing my due diligence before undertaking my purchase next month, I have come across a number of threads here and there that would seem to indicate that a lot of people get this tuning business all wrong, get frustrated, and give up.

It's not that I lack confidence, exactly, but I am a little concerned I'll be fiddling forevever, first as the speakers begin to break-in, then as I react to different things I'm hearing from the source side, especially new media.  Ultimately, I want to listen to music.  I enjoy a little tweaking on things (stereos and cars and bikes), but eventually, I just want to enjoy the the music.

It's a little intimidating at the thought of it.  On the other hand, I am set on a ribbon/planar/dynamic hybrid design for this purchase, and I don't want to eliminate what very well may be the best available for the money on the planet due to any misplaced misgivings!

Any and all handholding would be most appreciated.  And don't be at all afraid to call me a dolt.  I'm fairly thick-skinned!

[John Casler]

OK, I am a novice here as far as VMPS ownership goes.  In fact, I've never had the opportunity to even HEAR a VMPS loudspeaker.  Nonetheless, I have the RM30M Signature as one of my finalists for my speaker upgrade planned for next month, as a result of research I've been doing for about a year now in anticipation of this coming upgrade.

But I have questions for John and/or Brian.  I imagine I am thinking "all wrong," but here goes anyway.

Simply stated, why is it not possible to correctly tune the PR's to the theoretical best-fit mass damping at the factory, and do it without such a tool as putty?  Is it because of variabilities in the speakers themselves, or is it because by design Brian wants each owner to be able to tune to his/her own taste?  Does it have anything to do with the variability in the possible combinations of build options allowed when you order a pair of VMPS speakers?  Lord knows, NOBODY allows as much leeway in customizing the build of a set of speakers to-order as VMPS does.  Or if they do, I haven't found them!

I can understand the potential need to tune overall output at certain frequencies, perhaps, to the unique challenges that may be encountered in trying to make a given design function near its peak performance capabilities within wildly different room acoustics.

But it seems to me a theoretical best fit should be the starting point at the time of manufacture, and perhaps the tuning would be better served digitally with some sort of EQ.  Given consistent quality of manufacture of the active woofers, the passive radiators, the crossovers and the cabinets, thereby assuring consistent behavior, would it not be better to construct to the theoretical ideal instead of resorting to putty?

I'm both intrigued and confused by this design approach.  On the one hand, I can see the potential for the almost "infinite" tunability.  On the other hand, I can see how this could lead to all sorts of grief.  It seems to me the primary potential "failure mode" with this sort of tunability function is bound to either be repeatability, or patience.  In fact, in performing my due diligence before undertaking my purchase next month, I have come across a number of threads here and there that would seem to indicate that a lot of people get this tuning business all wrong, get frustrated, and give up.

It's not that I lack confidence, exactly, but I am a little concerned I'll be fiddling forevever, first as the speakers begin to break-in, then as I react to different things I'm hearing from the source side, especially new media.  Ultimately, I want to listen to music.  I enjoy a little tweaking on things (stereos and cars and bikes), but eventually, I just want to enjoy the the music.

It's a little intimidating at the thought of it.  On the other hand, I am set on a ribbon/planar/dynamic hybrid design for this purchase, and I don't want to eliminate what very well may be the best available for the money on the planet due to any misplaced misgivings!

Any and all handholding would be most appreciated.  And don't be at all afraid to call me a dolt.  I'm fairly thick-skinned!

Welcome to the VMPS Circle.

What sometimes gets "lost in translation" regarding the tuning capability of the Passive Radiator is the Brian does "just that". 

He pre-tunes each speaker optimally before it leaves the factory.

So for all comparison purposes it sounds as good or better than any normally available speaker system.

However each system is affected by various elements.

1) No Dynamically compliant systems of multiple interactive drivers will maintain interactive stasis.  Surrounds, suspensions, cone flex/pliability/stiffness, and other mechanical and electrical components change in their contributions over time.

2) System Synergy of your system may be different than Brian's.  The bass control factors of damping, and overal available power can make the active driver more or less active.  So your speaker wires, their length, you amps power, power reserves, and even if they are tubed or SS may mean that a little pinch here or there will help the sytem be a bit more accurate.  A Tube amp might not have the same woofer control of a megawatt SS amp.  This might mean just a smidge less putty would reduce system resistance and a slightly more accurate sonic.

3) Atmaspheric Pressures;  Brian lives at virtual sea level.  If you live in Denver, the atmospheric pressure is lower meaning the woofer cones encounter less resistance than at sea level.  This might mean you would find more accuracy with a "bit" more putty on the system.

4) In a system like Woofers and PR's where moving mass is adjusted based on the physics involved, a system can be ultimatly tuned to be more accurate at your prefered SPL.  That is, if you listen between 70 and 85db, you might get a more accurate sonic by tuning to the physics involved at your listening levels.  If you listen at lower levels the PR mass might offer a better result with a lower mass.  If you listen at far higher levels then a pnich or two more might offer a more accurate tracking.

All other systems that do not have this tuning capability are unable to respond to these changes. 

So one has the option of simply treating the VMPS bass system like they would a regular non-tunable bass system (not knowing what they are missing) or they can make small adjustments along the way to hear what others are likely missing.

A couple things the putty adjustments "won't" do is:

1) It won't make the bass play louder to any appreciable degree
2) It will not correct for room anomalies

So to recap, VMPS speakers and subs come pre-tuned and never have to be touched again to be enjoyed like most any other speaker.  I have plenty of VMPS clients who have NEVER touched their putty or pots.  Or (if you are so inclined) you can make micro-adjustments to experience the "finer" detailed capabilities seldom heard by others.

The key fact is you have a "choice" with VMPS.

I might add, that I tuned my RM40 PRs at 6 months and then again 2 years later, and haven't touched them since.  So it is not a monthly process or even a yearly process unless you play your system for hours a day very loud or change much of your system monthly.

Strangely enough I had a LONG phone conversation with one of my VMPS clients and friend, this afternoon.

He has owned RM40s for over 5 years, and we were talking about just how the sound just KEEPS improving with the smallest subtle changes to small things.

Now he hasn't touched his putty for years, but he has played with amp upgrades, wiring changes, room treatments, and with each change he is simply amazed at the increased listening pleasure he gets.  He just keeps hearing deeper and deeper into recordings that he has heard hundreds of times before.

That is what I call, "istening enjoyment".  While he will likely continue to make various improvements, he is totally happy and content to sit and enjoy his RM40s even more than he did over 5 years ago when he first began to hear what is possible.

[lateralgs]

Thank you, John, for the welcome, and especially for the comprehensive reply.

I'm with you on most points now.  One point I'm having a bit of a hard time with is No.3.  Even in a sealed system, I would think the internal and external pressures would equalize over time at different altitudes, probably negating the advantage of PR damping tunability for that issue.  But I understand the other points made.  I guess in summary, the best way to put it, if I am clear, is that the tunabilities offered should be considered as "extra" flexibility when compared to more typical designs.  While not necessary for excellent performance, they may bring out that last bit of coherence and synergy between the drivers as well as with the upchain equipment, etc.

I don't frequently change equipment, and I don't frequently change environments.  So for me, the potential need for retuining in those circumstances wouldn't be necessary.

One thing still troubles me a bit.  You mentioned tuning to typical listening levels.  Well, I have no typical listening levels.  Sometimes are quiet times...sometimes very quiet...and other times are blow the doors off time.  So I suppose as opposed to tuning to a particular loudness range, I would have to listen to a lot of different material at a lot of different volume levels to settle on a "best fit."  That too seems as though it could be a fairly involved iterative process if taken seriously.

The only other comment I have is that it still strikes me as "idiosyncratic" when you consider that no other manufacturer (at least not that I'm aware) offers the same tunability.  Oftentimes total uniqueness can indicate genius.  Sometimes, not.  And therein lies a potential pitfall, perhaps.  Not everyone can appreciate genius when they see it.

I imagine that Brian has long since ceased worrying himself about such trivial matters, however.  From what I'm reading, it certainly seems as though when a person is able to get a pair of his speakers working "right," he has something very special indeed. I'm going to have to think long and hard about whether I am someone who can deliver on that promise with my own efforts.

Edit:  One last question.  I've noted in a lot of pictures that it seems most VMPS floorstanders are set up to converge a little in front of the primary listening spot.  I know some people do this occasionally with some speakers in some environments, but why do I see this so often with the RM40's and RM30's?  It seems a little counterintuitive to me. There must be something about the planar panels and ribbon tweeter implementation....

[Hipper]

I believe Brian recommends the arrangement of converging around 1.5 to 2 feet in front of the listener.

I have RM30Ms and in my set up with nearfield listening I like it best converging on my ears. I also removed the waveguides as I preferred that too. I should point out though that I use a digital equaliser so I can dabble a bit with that.

I understand that the tweeter gives out a signal of 25 degrees horizontally and 30 degrees vertically. I would be interested to know in what form the mid range panels radiate?

[lateralgs]

Yes, I recall reading the 18" to 24" convergence in front of the listening position recommendation.  But it still doesn't explain the "why."  I have noticed, however, that most pics of VMPS set-ups, especially the RM30's, seem to be set up that way.  Still seems a little odd to me.  I'd just like to know the technical reasons for it.

I am a nearfield listener as well, by requirements imposed in my dedicated listening room.  About 8' to 9' is the maximum distance I can achieve, depending on how far out from the front wall the speaker needs to be.  I actually prefer the nearfield (or "nearly nearfield" ) listening experince for solo listening anyway.

[John Casler]

Thank you, John, for the welcome, and especially for the comprehensive reply.

I'm with you on most points now.  One point I'm having a bit of a hard time with is No.3.  Even in a sealed system, I would think the internal and external pressures would equalize over time at different altitudes, probably negating the advantage of PR damping tunability for that issue.  But I understand the other points made.  I guess in summary, the best way to put it, if I am clear, is that the tunabilities offered should be considered as "extra" flexibility when compared to more typical designs.  While not necessary for excellent performance, they may bring out that last bit of coherence and synergy between the drivers as well as with the upchain equipment, etc.

I don't frequently change equipment, and I don't frequently change environments.  So for me, the potential need for retuining in those circumstances wouldn't be necessary.

Yes those are the main points:

1) Tuning is simply a reduction of distortion, by coordinating the interaction of the system.

2) Once you have it tuned there is no need for continuous re-tuning unless a major change is made.

3) Most bass distortion in other speakers is considered acceptable in the teens.  When well tuned, the VMPS can be half that.

One thing still troubles me a bit.  You mentioned tuning to typical listening levels.  Well, I have no typical listening levels.  Sometimes are quiet times...sometimes very quiet...and other times are blow the doors off time.  So I suppose as opposed to tuning to a particular loudness range, I would have to listen to a lot of different material at a lot of different volume levels to settle on a "best fit."  That too seems as though it could be a fairly involved iterative process if taken seriously.

Not to worry.  In a fixed system you don't have that flexibility and never notice it.  I only mentioned it since it has a small effect.  When you are dealing such small levels of distortion, some would even argue you can't hear the difference, but when you have heard or can hear it, it is certainly an advantage to have the ability.

The only other comment I have is that it still strikes me as "idiosyncratic" when you consider that no other manufacturer (at least not that I'm aware) offers the same tunability.  Oftentimes total uniqueness can indicate genius.  Sometimes, not.  And therein lies a potential pitfall, perhaps.  Not everyone can appreciate genius when they see it.

The pitfall is thinking it needs be adjusted too often and for each recording.  It is but a method to allow those so inclined to go the distance for that last level.

The lack of others doing it is based on their choice of bass systems.  Sealed and ported do not have the mechanics to offer such an ability, and are at a fixed level of distortion (they consider acceptable)  just like a VMPS system that has not been adjusted after Brian set it.

I imagine that Brian has long since ceased worrying himself about such trivial matters, however.  From what I'm reading, it certainly seems as though when a person is able to get a pair of his speakers working "right," he has something very special indeed. I'm going to have to think long and hard about whether I am someone who can deliver on that promise with my own efforts.

Again, it is having the ability to do this.  There is no price if you NEVER touch the putty.  It, then is just like every other system.

Edit:  One last question.  I've noted in a lot of pictures that it seems most VMPS floorstanders are set up to converge a little in front of the primary listening spot.  I know some people do this occasionally with some speakers in some environments, but why do I see this so often with the RM40's and RM30's?  It seems a little counterintuitive to me. There must be something about the planar panels and ribbon tweeter implementation....

The initial convergence suggestion was due to the focused soundfield of planar and ribbon drivers.

This high angle type of convergence created a "larger" sweet spot for those who wanted such a quality.  For example if you sat left of the sweet spot, you would be further "of axis" of the left speaker, and more "on axis" to the right.

You would also be closer to the left and further from the right.  The mixture of being closer and off axis to the left, and further away but on axis to the right created a balance in the sound, increasing the sweet spot.

While it is still a preferred positioning, (angling toward the listener) with the CDWG, the directivity is now so much greater that the convergence angles need not be as sharp.

[John Casler]

Yes, I recall reading the 18" to 24" convergence in front of the listening position recommendation.  But it still doesn't explain the "why."  I have noticed, however, that most pics of VMPS set-ups, especially the RM30's, seem to be set up that way.  Still seems a little odd to me.  I'd just like to know the technical reasons for it.

I am a nearfield listener as well, by requirements imposed in my dedicated listening room.  About 8' to 9' is the maximum distance I can achieve, depending on how far out from the front wall the speaker needs to be.  I actually prefer the nearfield (or "nearly nearfield" ) listening experince for solo listening anyway.

VMPS and Nearfield are a match made in heaven.  B, blends the drivers in such a way that you can sit as close as you like.

I sit about 7ft from a pair of RM40's and the effect is like being at a concert and moving to a closer seating postition.

Sit farfield and it is like moving a few rows back in the hall or venue.

I prefer nearfield because it tends to reduce perception of room distortions (perception of reflected sounds)

[lateralgs]

Thank you, John, for all your comprehensive replies.  I think I have a much better handle on everything at this point.

I particulalry appreciate you "hanging with me" on the tunability questions, and I also appreciate your clear reply on the technical reasoning for the toe-in convergence.  One last question about that and I'll stop:  Does the implementation of the CDWG, while broadening the overall dispersion of the line source, also result in a somewhat less resolved image?  This would be of little consequence to me, in my current listening environment (nearfield, you know, so I probably would not even use the wave guides), so I'm just curious about that for academic reasons mostly.

Speaking of nearfield, sounds like the speaker may be right along the lines (no pun intended) of what I'm looking for in that regard.

You have given me much to consider, and I appreciate it.

[John Casler]

Thank you, John, for all your comprehensive replies.  I think I have a much better handle on everything at this point.

I particulalry appreciate you "hanging with me" on the tunability questions, and I also appreciate your clear reply on the technical reasoning for the toe-in convergence.  One last question about that and I'll stop:  Does the implementation of the CDWG, while broadening the overall dispersion of the line source, also result in a somewhat less resolved image?  This would be of little consequence to me, in my current listening environment (nearfield, you know, so I probably would not even use the wave guides), so I'm just curious about that for academic reasons mostly.

Speaking of nearfield, sounds like the speaker may be right along the lines (no pun intended) of what I'm looking for in that regard.

You have given me much to consider, and I appreciate it.

I had believed that increased dispersion/directivity would have that effect.

That belief was based on the "precision" of images I would hear when comparing speakers like those of a more focused variety like VMPS ribbons before CDWGs, with speakers of higher directivity, like all cones or horns.

And one must know that it is true that "dispersing" Sound Pressure over a larger area "reduces" the general level of pressure.  This means at a given system setting the SPL's might be lower at a specific point in space, with a the higher directivty system.

So the actual answer is that given that you measure the actual SPL at the ear, that BOTH systems will have the same imaging capabilities (assuming you are in a treated room sitting very nearfield) but the system with higher dispersion will be at a higher system setting to equalize the SPL at the ear.

Personally, I, like you, would prefer to run the system under less stress per driver and since I sit nearfield and without Wave Guides I get the exact combination I want for "High Performance Listening".

As well for that type of "solo" listening (I often compare it to Formula ONE racing where only one person fits in the "sonic" cockpit) you wish to restrict or reduce reflected sound, so sans CDWG is a special way to enjoy the VMPS speaker if you are so inclined.

[lateralgs]

John:

I see, and that makes a lot of sense.  I was thinking more along the lines of image specificity and resolution, but I think you answered that as well.  And again, the speakers sound almost tailor-made for the way I really prefer to listen, which is very intently, usually after dark, and usually solo.

And don't even get me started on Formula 1.  Or Moto GP.  Or World Superbike.  Those are all some of my other passions!