Cartridge ISOLATION; What Say You?

The design of The Cartridgeman‘s Insulator is precisely addressing that issue while avoiding your concern of cartridge displacement by choosing a polymer too stiff to be displaced by the cantilever, which displacement -as you point out yourself- is magnitudes smaller than the former. On my system (Zyx Universe, Dynavector DV 507MkII) the benefit is so obvious, that I can only recommend that people try it rather than defer to principle based pontification.

If the cartridge transmits vibration to the arm, the arm hasn't done its job properly. But its a simple fact that no arm is perfect in this regard. So what really becomes the question is whether the arm tube should be damped to absorb such vibration or whether you want to decouple the cartridge from the arm in trying to do the same thing?


From an engineering perspective damping the arm tube seems the more elegant approach. But this is by no means universal so you may well perceive a difference (hopefully better). I alluded to this earlier.

string quartet in the mastering room….what an idea….

w both high speed tape and a really good ADC ( Wadia 17 ), imagine that….

Or direct to disc.

The simple answer is the device may compensate for some design flaws in lesser arms/tables and may change things in a way that some find to be better. While it may be a universal truth that it changes things, it is not a universal truth that it makes things better

+1 exactly and eloquently stated. I was trying to beat about the bush so as not to insult anyone's system, but this is the nub of it.

Can you please tell me what tomwh is talking about?

@mijostyn No, I can't.

I am no Rega fanboy, but I find the approach taken in their flagship TT to be very interesting: Super low mass plinth made of materials that are not likely to store energy efficiently and of low enough mass also to further reduce energy storage, but with a rigid beam connecting the base of the tonearm mount to the bearing assembly. I'd like to hear it.

@lewm I'm not a fan of Rega either, but that plinth design sounds like what I'm talking about.

^^This.
If the cartridge is moving with the stylus it will have less output. But it isn't; its mass and that of the arm is magnitudes higher than the stylus and cantilever. At any given instant the arm is relatively still so in fact the stylus is moving in the groove with respect to the cartridge body.

The more the system deviates from this simple fact the more coloration it will have. Decouple the cartridge from the arm, even if that decoupling provides some damping, and you increase coloration. If you want to damp the arm the place to put that is probably on the top side of the headshell so while the cartridge is properly coupled to the arm, any excess vibration (which really shouldn't be there in theory; the better the arm the more it approaches this ideal) can be damped.

I recommend for anyone engaging in this sort of stuff if you really want to know what's going on, study the engineering of turntables, arms and cartridges and then build one that works. That is what I did; its how I can state with absolute certainty that the best turntable and pickup will have the platter rigidly coupled to the base of the arm and neither the bearings of the platter or arm will have any slop. Further, the plinth will be dead and massive so it can resist airborne vibration. The rigidity is there so if there is vibration transmitted to the turntable system from its platform or the like the pickup will be unable to transduce it. And finally of course the tonearm is also rigid and dead (arm tube is damped) so the cartridge, which is rigidly coupled to the arm, can do its job.


If you deviate from this ideal there will be coloration plain and simple no ifs and or buts.


Some years back a friend of mine developed the Analog Survival Kit which was sold by Sumiko. It was basically a polymer wrap for the arm tube that allowed you to damp the arm tube of vibration. It worked because it did not interfere with the coupling between the arm and cartridge. You did have to be careful about effective mass and resulting mechanical resonance though. 


One of the most challenging issues I had to face as a manufacturer was how to establish a reference. What was I hearing when I played any recording? How much of the coloration in my system was influencing what I thought I was hearing? That was tricky and the only way I could figure my way out of it was thru professional recording equipment, which I had to assume was competent since it made the recordings we listen to. So we got some mics and I had a musician play in front of them and we compared what we heard to the mic feed in the stereo. This taught us very quickly what was going on. Since I've been running a recording studio since the 1970s (Steve Tibbetts recorded 'Yr' in my first one) I've had access to master tapes which I've often used for reference.


My point here is you have to know what you are hearing. If there are colorations in your system of which you are unaware, its very common to introduce other colorations that might seem as if you are approaching a more neutral presentation. But IME synergies don't work; you're far better off if each bit of your system stands on its own merits and does not need the brightness or darkness of another component in order to work.

These record grooves by the way, they are at right angles to each other which means each side is 45 degrees to vertical, which means Ralph is wrong all the vibrational energy is not in the plane of the platter.  

When I made this comment I was not referring to vibration of the stylus in the groove. I was referring to vibration from elsewhere- airborne, from the motor, etc.


What we are looking for with respect to the cartridge is that the cartridge body is held in locus so that the cantilever transfers the maximum energy to the coils within. If the cartridge body is able to move in anyway during that process it will be causing a coloration. Its only means of being held in locus is the tonearm. If it is able to move with respect to the arm, its a coloration. Therefore it must be coupled to the arm and the arm in turn must be competent so that it actually does its job.

FWIW I use LPs I recorded myself and also LPs that I mastered myself... I recommend doing the same for anyone who really wants to establish a reference.

I found this, makes my head spin, especially with short term memory issues.

https://forum.audiogon.com/discussions/tonearm-damping-damped-or-not-useless-welcomed

Raul is referring to damping the movement of the arm, rather than the arm tube. These are different topics.

In any case, I gather you do not advocate adding a soft layer under the tonearm base, or adding a soft layer above any cartridge, correct?

IOW, these 'soft' treatments can only be an improvement if they are solving a problem that could/should be otherwise avoided/eliminated, correct?

@elliotbnewcombjr

Exactly!

If the arm tube is not damped you're going to have problems! But decoupling the cartridge from the arm will not be a solution in that it will be akin to placing a bandaid over a rash that won't go away.


The platter supports the LP; in theory at least there will be no slop in the platter bearing so the platter, if there is any vibration, will be vibrating in the same plane as the plinth. The arm must be also rigidly coupled to the plinth in the same manner as the platter. The plinth thus must be both rigid and dead. The arm will have no slop in its bearings and the arm tube is non-resonant.


If these parameters are met then the pickup will not transduce vibration in the platter as it will be vibrating in the same plane.


If the arm is decoupled from the plinth a coloration will be introduced. But if the plinth simply isn't up to the task in the first place, this may actually be perceived as a good thing.


My comments are based on the idea that the platter, plinth and arm are properly engineered. Introducing isolation at the base of the arm or the mounting of the cartridge is guaranteed to introduce a coloration. But if the equipment isn't engineered properly in the first place it might actually be perceived as an 'improvement', but what's really happening is a lucky compensation for an inadequacy has been found. It won't work the same on every machine, that's for sure!

another comment in the article: reviewer mentioned a layer of isolation under the tonearm base (he tried blu-tac). Also against my 'instinct'.

Your instinct is correct. The arm must be as rigidly coupled to the plinth as possible, and the cartridge as rigidly coupled to the arm as possible.


The engineering issue hear is really similar to that of steering in a car. You want the wheel to stay on the ground and you need to have control over which direction its pointed. Imagine having something squishy between the steering wheel and the wheel on the road! You would not want to drive that car.

Fortunately this isn't as dangerous :)  but don't do it unless you want to hear what degraded performance sounds like.