Cartridge loading

lower R presents obviously more breaking force, opposing the stylus movement. This is the electromagnetic induction law in action: the current (flowing through R) creates the magnetic field that opposes the stylus movement. This force behaves like ~f/R.

This is what I've been maintaining all along.

Just to be precise, the energy is not presented in a form of a voltage because voltage alone cannot perform work. The energy is presented in a form of a heat, dissipated in the combined resistance of the circuit (R_load, the coil DCR, the cables etc), caused by the induced voltage applied to the resistance. This is ok. The question is so what? To speak of energy conservation, you have to look at all the forces acting on the stylus:
- the driving force, coming from the diamond tracking a rotating, modulated groove, say at freq. f; this force is the source of all the energy flows- the restoring force of the suspension- various damping forces, including the electromagnetic one ~f/R

In a word, yup.

The only *qualitative* change in R can happen is in the 1st, spurious part. Lowering the R changes the suspension character from underdamped to critically damped to overdamped. But this is not the signal we are trying to get! This is an artefact added to the real signal of freq. f.
Of course if the motor is so weak that the stylus tracing a HF track into low R will make it slow, we are in trouble but let's assume a healthy TT design.

Since we have been in agreement all along on the first two bits, maybe its this last bit that is the stumbling block. I used to load MM cartridges to critical damping by simply ringing the cartridge/cable combination with a square wave and observing the resultant output and taming it with a loading resistor. MM cartridges have a lot more inductance so its easy for that inductance to ring. But attempts to do this with LOMC failed, simply because with any loading I could not detect anything other than a nice looking square output since the inductance is so low. So I am challenging the idea of critical damping of the mechanical aspect of the suspension, not because I don't think it can happen but more because I'd like to see the evidence. Its an interesting idea- I am assuming that the electrical damping used to do this is similar to a shock absorber in a car; with the right amount the stylus in better contact with the groove, just like a shock absorber keeps a wheel on the road.


My exposure to all this is through phono preamplifier design; about 35 years ago I discovered that the phono section itself can contribute to ticks and pops. I discovered this serendipitously but once I understood it was real it was then a matter of sorting out why.  And the answer (as I have mentioned earlier on this thread) has a lot to do with this ultrasonic/RF resonant tank circuit that I've been talking about. I've also noticed that while I can cut a 35KHz groove on my Scully lathe, depending on loading you can't always play it back, depending also on the cartridge.


So now I am curious- at what frequencies did you make your measurements?  At this point it appears that the taming of the resonant peak requires a different value as opposed to that which might tame the cantilever; the two aspects are caused by entirely different mechanisms. However, **any** resistance in parallel with a tank circuit will detune it; for most phono sections to be happy the detuning must be enough to kill the tank circuit altogether.

I too use 1000 ohms on my Ortofon.....experiment and find your own perfection.

Since we have been in agreement all along on the first two bits, maybe its this last bit that is the stumbling block. I used to load MM cartridges to critical damping by simply ringing the cartridge/cable combination with a square wave and observing the resultant output and taming it with a loading resistor. MM cartridges have a lot more inductance so its easy for that inductance to ring. But attempts to do this with LOMC failed, simply because with any loading I could not detect anything other than a nice looking square output since the inductance is so low. So I am challenging the idea of critical damping of the mechanical aspect of the suspension, not because I don't think it can happen but more because I'd like to see the evidence.

I don't say that achieving critical damping is doable or even desirable from the sonic perspective.

I've also noticed that while I can cut a 35KHz groove on my Scully lathe, depending on loading you can't always play it back, depending also on the cartridge. 

I think here lies the answer - "depending on the cartridge". I can imagine that for some cartridges, or better yet, some cartridge/tonearm combinations, the extra damping from a low R, combined with  other factors may compromise the tracking. What I fail to see however is that this should be some universal law.

So now I am curious- at what frequencies did you make your measurements?

I did not do any measurements. I tune R_load by ear, usually preferring lower values, and have never experienced any HF mistracking.

I don't say that achieving critical damping is doable or even desirable from the sonic perspective.

I got that from @intactaudio 's comment about sidebands. I apologize as I did conflate your comments and his. Critical damping of the cantilever is one of the very few explanations I can think of for the phenom he described.

I think here lies the answer - "depending on the cartridge". I can imagine that for some cartridges, or better yet, some cartridge/tonearm combinations, the extra damping from a low R, combined with other factors may compromise the tracking. What I fail to see however is that this should be some universal law.

Its not so much a universal law as it is something to be aware of. If you have to use loading to achieve proper sound, it is a flag that something could be amiss: Instability in the phono section, a mismatch between arm and cartridge, that sort of thing.

Dear @atmasphere please treat all my writings as a friendly argument in a search for the truth, so there is no need to apologize :)

If you have to use loading to achieve proper sound, it is a flag that something could be amiss: Instability in the phono section, a mismatch between arm and cartridge, that sort of thing.

I'd respectfully disagree. I'd say much depends on how the cart is designed. Electromagnetic damping due to a low R is actually quite an attractive (at least on paper) way of damping. Look at it from this perspective: linear just by the physics, no deterriortion, easy to implement and easy to control *by the user* with a great accuracy by changing R. Mechanical damping on the other hand, could be more challenging to implement with non-linerities, aging effects, no user control etc.