2. analog
  3. 153132-541

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
atmasphere's avatar
atmasphere
11,973 posts
 
atmasphere I'm not questioning if you have a conversation with JC.
Good. Because you misread an earlier comment of mine and came up with this nonsense:
Atmasphere mentioned WBF where JC participated and in that forum JC never mentioned that " limit trace... " that ( for me ) exist only in the atmasphere imagination
What I had said was not that Jonathon had written about it, I said that he and I had a conversation about this issue at Munich. Very specifically it was he that brought up the compliance of the cantilever being affected by the load the cartridge has to drive IOW becomes stiffer as the load resistance is reduced. Anyone familiar with electronics would instantly see how this is the case.

Now, if someone can find International Audio Review 5, 1980 pp.31-159, the answer to the existental challenge of prove-it may be answered.
A simple understanding of how electro-mechanical transducers like loudspeakers and cartridges work is all that is needed. It should be no surprise that Moncrieff experienced something like this; what is surprising is that it was not reported earlier, but its been my position for the last 20 years or so that the implications of using a transducer based on an inductive principle haven't been fully realized by the hifi industry.


It was pretty obvious to me all that time ago that most phono section preamp designers were not taking into account how the resonance created by the cartridge inductance and the capacitance of the tone arm cable interacts with the phono preamp. Its not just a matter of enough gain and proper EQ; its also a matter of RFI immunity and internal stability of the circuit. If the latter two are properly addressed the need for cartridge loading for a LOMC cartridge is moot.

antinn
408 posts
 
Atmasphere,

No arguments of the electrical-mechanical fundamentals, but the aspect is not well doucumented for cartridges, and therefore, the nay-sayer(s) will debate.  However, that being said, this document shows how the phono-preamp design can affect the performance. And, lets not even begin to discuss how Impedance is often incorrectly used for resistance, with Impedance = Resistance + Reactance and is frequency dependent, whereas resistance is fixed.
 http://www.pmillett.com/file_downloads/LR%20Phono%20Preamps.pdf
clearthink
1,421 posts
 
rauliruegas"The issue is that no evidence/measurements/numbers of that non-existent " limit trace "

That has been clearly and definitively explained in thorough and complete detail so what is it that you are arguing about it is a mystery to some of us hear!
intactaudio
302 posts
 
 Now, if someone can find International Audio Review 5, 1980 pp.31-159, the answer to the existental challenge of prove-it may be answered.

Have a copy in hand....   which is why I took exception to the thought that loading a cartridge down must adversely effect the ability to trace high frequencies.    I think the following text from IAR 5 sums it up pretty well

Now, as the force against the groove wall lessens
momentarily, the stylus’ motion is no longer as damped
by the compliance (springiness) of the vinyl interacting
with the mechanical impedance of the stylus assembly.
The stylus assembly is, as John Curl has put it, more
on its own. And that’s when the additional damping
imposed on the stylus motion by the electromagneto-
motive effects of Lenz’ law and a low load resistor can
come into play. Stylus tip damping, from whatever
source, helps the stylus assembly to cope with groove
rattling problems (note that cantilever pivot damping
in the cartridge might not, especially at higher fre-
quencies).

maybe accurately tracing high frequencies is the wrong term and loading can help prevent the creation of "non-source contained" high frequency information.

dave
atmasphere's avatar
atmasphere
11,973 posts
 
@intactaudio That is what the 47K input standard is supposed to be for- a slight amount of damping. I don't see in the text you quoted how the cartridge was set up- was it driving a very high impedance as a control or 47K?
@antinn  The interesting article you linked refers to self-resonance of inductors as a consequence of using them in equalization circuits. I don't see anything in that article about how the RFI generated by a cartridge can interact with the phono section. Pete Millet's website is quite an asset to those interested in audio!


What I have found is that there are two aspects of RFI issues in phono preamps. The first is pretty obvious; the resonance of the tank circuit caused by the cartridge inductance and the tone arm cable capacitance. This can cause overload of the input circuit if it has poor overload margins. The other is less obvious which is the inherent stability of the circuit. There is a device known as a 'stopping resistor' which is used to prevent oscillation at the input of a grid (in the case of tubes) or gate (in the case of FETs). But some designs don't use stopping resistors and can oscillate briefly if presented with the right circumstances. This is how a phono section can generate ticks and pops; this is a fairly common problem is why many people think than LPs are a lot noisier format than they really are. 
More to discover