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Cartridge loading

Presently I am using a ZU/Denon DL103 mc cartridge with ZU Audio's highest tolerances.  I had this cartridge mounted on my VPI Prime and after going through all the various loading combinations, I settled on 200 ohms.  I was always satisfied with my choice of setting.  I no longer have the Prime and now use the Technics SL1200G turntable.  After having the same cartridge mounted and aligned by the dealer, I inserted it into my system and enjoyed the sound immensely, never touching the 200 ohm setting.

Yesterday I was listening to vinyl most of the day and for some reason I found the sound to be better than ever, mostly in the treble area.  The highs had shimmer when needed and I had played the same records many times before on the Prime and they never sounded as good as they did yesterday.  Just for the heck of it, I checked the cartridge loading and found it was now set at 1000 ohms.  As I said, when I put the Technics into the system, I never bothered changing the loading which was at 200 ohms as it was the same cartridge, just a different turntable.

I believe I know what happened, when I last used the tone controls on my McIntosh preamp, (you have to shuffle through a menu) I must have inadvertently put the cartridge loading at 1000 ohms.  It truly sounds fantastic, better than I ever thought possible.  The Bass is still very deep and taut, midrange is the same but the treble, oh my, so much better.  Now the million dollar question is why should it now sound better at 1000 ohms, when it sounded great before at 200 ohms?  Can the tonearm on the Technics have an effect on cartridge loading?  I always thought it was all dependent on the preamp, amp and speakers.  What am I missing here?  I am very curious to know.  The specs for my cartridge say greater than 50 ohms for loading.

Thanks
128x128stereo5
lewm
13,347 posts
 
I think it’s analogous to “back EMF” that affects the interface between amplifier and electromagnetic speakers. The movement of the coil on the cantilever that is excited by the groove is not perfectly damped. Any spurious motion thus created would generate a voltage. The load resistor affects the degree to which the spurious motion of cantilever is damped out. Why is it hard to imagine that the damping force makes the cantilever also do more work?
But I’m just guessing pending an opinion fro Ralph or Dave.
whoopycat
169 posts
 
I just read this review and thought of Ralph's comments:

http://www.10audio.com/aurorasound_VIDA_Prima.htm

Just being curious, I unloaded the Madake by switching the loading to 47k Ohms. WOW! The upper frequencies opened up and became noticeably clearer and with finer resolution. Update to my advice above, start your tests for the optimum loading setting with the MM (47k) settings.

The VIDA Prima and Pass XP-25 share an important attribute: they both sound best when the Miyajima cartridge is loaded at 47k Ohms. This suggests circuits that are designed to manage a MC cartridges’ tendency to sound better loaded, a weakness we refer to as “ringing”. Some of this artifact could be an issue with the phono preamplifier. The VIDA Prima does not seem to have any tendency to exacerbate ringing.

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rauliruegas
13,112 posts
 
Dear @lewm : """ is not perfectly damped... "" almost nothing in audio is perfect. Where do you read what you posted not only that but about that sporious motion that stiffens the cantilever?

Everything in a cartridge quality performance is important in its design and building quality but the cartridge suspension is CRITICAL and you can ask Ortofon about and you will know what they have to say in that issue.

The problem is that for years atmasphere posted here and in other net sites the same with out shows any single foundation ( numbers/charts, white papers, etc. ) that can attest that the cartridge lost high frequency tracking abilities ( " it can also affect the compliance of the cantilever of the cartridge. " """ will limit the ability of the cartridge to trace higher frequencies .."""   These are statements he posted.) and till we have true facts about by his side what he said on the subject is just false and with no true sense of that lost high frequency tracking ability by the cartridge. Maybe makes sense to you, not to me.

R.


bydlo
142 posts
 
"[Lowering the R_load]... of course will limit the ability of the cartridge to trace higher frequencies. "
I fail to see it either, unless the below reasoning is wrong. I think of a simple cart model as a damped harmonic oscillator, excited by an external force of freq. f (the movement of the diamond induced by tracing the groove with a tone of freq. f). Loading the coils creates a current flow in them, which results in a damping force, opposing the movement of the coils in the magnetic field of the pole pieces. This is just a well known electromagnetic breaking force, proportional to the velocity of the movement (in turn proportional to the frequency) and inversely proportional to the R. It is just plainly ~f/R, like any other linear damping force. It adds to the total damping force, acting on the cantilever (the rest comes e.g. for the mechanical damping in the suspension). Lowering the R, just lowers the output across the entire spectrum but the nature of the output (its functional dependence on f) does not change at all. No additional damping of higher frequencies beyond the normal behavior of a damped oscillator. Just the damping coefficient increases.

I’m much more intrigued by @intactaudio dave’s observations of lowering the IMD. Have you tried plotting the IMD vs. R dependence?
Cheers


earthtones
111 posts
 
i have a Kiseki Purpleheart mounted on an SME 312S feeding a Pass XP 17. I don’t know the capacitance of the included tonearm cable, though I may try to find that out. I’m pretty sure that when I did the tonearm/cartridge resonance calculation, the value was in range, something like 10cu. I had been playing around with all manner of load settings, mainly in the range of 100 to 452 ohms, and had settled for the most part on 452, though I sensed something was off, not a lack of high frequencies per se but a sense of harshness. When I increased the loading value to 1000 ohms, the sound became smoother and had better spectral balance. FWIW, 1000 ohms is in the 800 to 1000 ohm range recommended adamantly in Bob Levi’s Purpleheart review, as opposed to the Kiseki recommenced 400 ohms. His equipment is different than mine however. Still, it sounds like stereo5 made the same conclusion as me with a totally different setup. I don’t want to generalize here, but it’s tempting to think that these lower load recommendations are not optimal in many situations.
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