Discuss The Viv Lab Rigid Arm


I am trying to do my due diligence about this arm. I am just having a hard time getting my head around this idea of zero overhang and no offset. Does this arm really work the way it is reported to do?

neonknight

Showing 13 responses by atmasphere

Exactly, and that has been my point in this thread. To make real progress, we need to correlate measurements with what we hear.

@cleeds Its been my experience that's what you do to sort out what's going on.

That is what led me to increasing rigidity in the plinth of our turntable; increasing coupling between arm and platter surface and overall making it dead as possible- damped platter, damped plinth. As I did these things the impervious nature of the system began to emerge; when I started the system was sensitive to volume pressures of 90dB; after I was done even at 105dB it was measurably and audibly superior. 

My technique was to place the stylus on the platter pad and measure the phono preamp output while playing a 100Hz tone thru the line stage of the preamp, amps and speakers. 'Success' was in reducing the output. I found that the better the coupling, the more dead the system, the lower the output at any frequency accompanied by a perceived improvement in bass, mids and highs- the system sounded less congested.

Damping the platter was easy but the plinth got tricky since it had to be machined out of solid aluminum.

I've been trying to correlate amplifier distortion vs how the amplifier 'sounds' for a very long time. My experience with that is both the measurement guys and those that prefer to only trust their ears hate what I've been finding. I think this is because the work messes with their world view. Its not surprising to find some pushback on this thread on the same account.

 

I understand the mathematic fundamentals behind digital audio, for example (Fourier, Shannon/Nyquist), yet intuitively it still seems impossible to me.

Like any technology digital had an uphill path to follow. For example jitter was a thing known to cause problems... I have a transport from the early 1990s  (Teac) that was highly respected at the time. But over time its pretty obvious its gone out of date. People update them with better clocks. The newer clock boards you can get on eBay for $20.00 have two orders of magnitude greater frequency stability; after installation this aged transport sounds a lot better...

Some people are dumbfounded by how 'dragging a rock thru a groove' could possibly work; not really realizing that their old saw isn't describing what's happening, because:

There is no substitute for experience.

This is correct.

Its also helpful to know what people have experienced prior to making blanket statements about them. Is mechanical design experience helpful? Is the experience of learning from your mistakes helpful? Is the experience of connecting what measurements we can make with what we hear helpful?

 

 

 

 With diffusion panels directly behind the speaker is it possible to shorten that 5 foot distance by a small amount?

@neonknight No. But if the speakers are closer than the 5 feet having something absorptive might help with the harshness that will result.

What about the phase anomalies you and I happily live with, caused by dipole speakers where the rear radiation is 180 degrees out of phase with the front?

@lewm @mijostyn The reason any speaker with rear firing information should be at least 5 feet from the wall behind it has to do with how the ear processes near term reflections. When 5 feet from the wall behind the speaker the delay time is about 10ms. When the ear hears a sound, it makes a short term copy and looks for other examples in near term. If less than 10ms or so, the ear interprets similar examples as harshness (which is why side wall reflections have to be tamed), but if 10ms and over the ear can use it as echo location information, which means the sound stage of such speakers can be more palpable.

So I'd be unconcerned about 'phase anomalies' in this regard. 

Thinking you are going to have a setup that won't mistrack is akin to planning on getting into the ring and not getting hit.

You expect trouble when designed analog equipment! It is for that reason- vibration (whether from the LP, airborne or otherwise) that you want the rigid coupling I mentioned, as well as preventing any play in the arm bearings or platter bearings- otherwise that play will result in the arm not being where its supposed to be: directly over the cartridge.

WRT cutting level and mistracking, it seems there is not a good definition of what mistracking actually is.  My take is any movement in a direction not cut on the record is mistracking which means it is  constant occurrence from numerous causes.

When mastering an LP, and then playing back a problematic cut, what any engineer is looking for is that the pickup will make it thru the cut without any breakup or sense of strain; IOW breezes through and wonders what the fuss is about. 

But obviously the arm will have motion such that it will not always be directly above the cartridge as wished. Any offset is picked up by the cartridge as noise or coloration depending on the motion involved. To minimize that you simply have to do everything I previously described.

I suspect the longer arm, like any other longer arm, suffers the issue of greater mass. You may well need a cartridge of lower compliance. That issue alone (or cost...) is likely why the shorter arm is preferred. 

The problem with the ’mechanical engineering’ view is when you define a "goal" or a "standard" then it can easily be seen if that goal is met and an unassailable judgement made. No consideration is given to the absolute magnitude or the underlying importance of the goal to begin with. As Lew pointed out above....if vanishingly low distortion is set as the goal then the system with the lowest distortion must always be best.

@intactaudio 

Regarding the distortion comment (since I can’t seem to just let that lay there...), it matters what kind of distortion it is. This is part of why the measurements are important- some kinds of distortions are unpleasent and other kinds are innocuous to the ear. I’ve talked probably too much about this elsewhere so won’t go into it more than that.

Regarding your comment about ’no consideration is given...’ as far as I can make out this simply isn’t true. What is true is we have a lot of designers that lack education that would be useful in their field. Lacking that they rely on stories to get around the elephant in the room. Human nature being what it is, often we can be convinced to believe those stories too.

what happens when the modulation is so extreme that it is actually considered mistracking? Is it at all possible that not being 100% rigidly coupled could cause the recovery from mistracking to be more benign? Now consider that mistracking is not an all or nothing type of proposition and is constantly happening and I seriously have to question the importance of the rigid coupling anyone demands. Everyone is allowed their choice of compromise and the choices by Viv Labs and the supporting anecdotal information is really interesting to me. Productive discussion about the factors involved is helpful to all and it seems at least plausible to me that the lack of rock solid coupling and anti-skate could make say 5° of tracking error on the Viv Labs more sonically benign than a lesser amount of TAE on a ’traditional arm’. One other thing that strikes me as odd in this all is that if TAE is truly the sole arbiter then why do the shorter underhung arms seem to be preferred?

Having run an LP mastering studio I can tell you that the limitation of modulation in the groove and the most of the distortion of the LP are all in the playback side rather than record. This places the performance (or lack thereof) almost entirely in the hands of the end user.

Mastering engineers know this, and so they really don’t put so much modulation in the groove as to cause a reasonable pickup to mistrack (we used an old SL1200 with a Grado Gold for our ’reasonable pickup’; if it could track the cuts we were making we knew we were in good shape). That’s a pretty old lesson, going way back to the Living Stereo era, when RCA cut the original Pines of Rome that tended to knock the rather primitive pickups of the time right out of the groove. Put simply, what you propose in your first question isn’t a thing.

If the coupling isn’t there as I have talked about, one of the results is more mistracking. IOW it works opposite of what you propose. This is simply because the arm is putting more energy into the cantilever.

Most audiophiles I know really want to get as close to the musical event as they can. The idea that the rig is designed to not do that is anathema. At any rate if the system has the rigid coupling (and deadness) as I wrote about, one thing that is instantly audible is how much better the bass is, which, if compared to CDs or RtR tape of the same recording, will be shown to be every bit as good, much to the chagrin of both camps’ advocates. But its more than that, with the rigidity also comes a more transparent midrange and smoother highs (particularly at volume), since its less susceptible to airborne vibration. This is one of those things that is not just easy to measure; its also easy to hear.

Regarding your last question, how do you know that underhung arms are actually preferred? Do you know of a poll regarding such??

 

 

@intactaudio

I'm not sure about the 'world view' bit. This is a mechanical engineering problem.

The arm tube doesn't appear rigidly coupled to its base (being suspended by yarn), so if vibration is present at the platter the pickup will be able to interpret the difference in motion as a coloration. 

Any arm that lacks rigid coupling between the arm tube and the base of the amp has this problem. How profoundly is a different matter but you can know with certainty that coloration will be present.

Of course the better the tt is suspended/damped to prevent vibration helps reduce this issue, but modulation on the LP itself will result in the arm not being perfectly in locus above the groove as it should be. 

 

 

 

Furthermore, I would venture to guess that neither Raul nor Mijostyn is actually making measurements of his audio gear and the signal that comes out of them. They are most likely going by data supplied by manufacturers and their own considerable funds of knowledge about electronics and distortion. But history is replete with instances where measurements lie. In the early days of solid-state amplification, we had amplifiers that measured harmonic distortion in the order of .000001%.

FWIW, times have changed and for the better. We can now measure the differences we hear between components- if the knowledge is there to know what to look for and how to do the measurements. IOW if the measurements are done properly they don't lie.

Time hasn't changed human nature though.

Drawing the line between what we hear and what we can now measure is likely to draw ire from both the subjective and objective camps. The very idea! But if you want to get down to knowing what's really going on, that's what has to be done. The acrimony between the two camps has to end.

The hardness of the metal in the bearing is not the only issue. The fineness of the machining is fundamental.

@clearthinker 

Yes. The bearings in the Triplanar are tiny.

The problem you have with any arm with a short arm section is any record warp will be audible as a speed variation and will affect the bass impact since the tracking force changes with warp and bass modulation. To get around that the bearing must be in the plane of the LP. Think about two people carrying a couch upstairs. Who is carrying the most weight?

I think the slop problem arises because the liquid pivot allows too much movement.  Just a few microns will allow the stylus to change location relative to the platter and read signals that are not imparted by the groove.  I sometimes wonder whether conventional gimbal bearings are really good enough to give zero slop.

@clearthinker I was thinking the same thing. FWIW Triplanar uses the hardest metal bearings made worldwide to achieve 'zero slop'. To that end to my understanding they have a security clearance to obtain the bearings. 

but in a analysis of a variety of designs, there are to be discovered elements in the designs seen that veer away from this.

Certainly. I see that as a mistake on their part, nothing more. The physics is inescapable.

As best I can make out from their website, the Viv breaks a fundamental rule of tonearm design (other than the tracking angle thing).

That rule is that there must be profound coupling between the surface of the platter and the mount of the cartridge. To this effect, there can be no slop in the platter bearings or arm bearings. In addition, the arm must be rigidly mounted to the plinth (and the plinth must be both dead and very rigid) such that any vibration that might occur at the platter will be in the same plane as that of the cartridge mount.

If there are any differences (or decoupling) between the plinth and the arm, it will be interpreted by the cartridge and perceived as a coloration.

The mechanical engineering problem here is very much like that of an automobile steering and suspension. Any slop that is present between the wheel and the steering wheel will result in obvious handling problems and can be dangerous. The stylus is doing much the same as the wheel on a car does as it is the interface between the mechanism and the media. It must be kept in perfect contact with the media and the arm can't be vibrating or moving in any way above the locus of the stylus, otherwise that motion will generate a signal.