Ortofon Per Windfeld Load Impedance?

Mr. Karsten,

How, in layman's terms, would one go about "ringing" a cartridge with a square wave and observing the waveform? Are you talking about a special test record and an oscilloscope, or feeding an electrical signal (square wave)into the cartridge and viewing the returning signal?

Is this something that the manufacturer could do to give a precise recommended loading? I ask this because some manufacturers recommendations fall into a huge range (I believe my Lyra Titan came with a recommendation of 100 ohms to 47k ohms) while others give an incredibly precise figure, such as the loading recommendation for Allaerte cartridges.

Larry, ya know, that's something I've often wondered myself- not only how manufacturers arrive at their loading specs but also why more of them don't do anything at all. This is a technique that does not require a test LP, or even a turntable, and is something any manufacturer could do.

One thing to be aware of though is that individual units, especially those that are hand-made, will differ from one example to another. My thoughts are that the manufacturer could bother to chart the critical damping on the same sheet of paper that the bandwidth is charted on, included with the cartridge itself when you buy it... sure make my like easier- people are asking us for cartridge loading values all the time!

This loading question was a concern until I received an answer from Graham Tricker Tron designer. I have an Allaerts Finish cartridge and Jan recommends exact 845 Ohm load, so I asked Graham to do so with the Tron Seven Tube phonostage. Here his answer: " the Seven you have is set for 117 ohms wich it presents to the cartridge. Don't get hung up on the "loading" issue. It is a much misunderstood subject. Loading is normaly quoted for solid state electronics and can only be set by putting a resister directly across the signal path. This degrades the performance by a huge margin. The Seven is transformer coupled so the loading works completely differently and there is no harmful resistor across the cartridge coils. Jan Allaerts uses a Krell PAM 5 preamp wich is solid state, he has always used SS and there is only one way to load a cartridge with SS phonostages, that is with a resistor.
Loading is basicaly what the designer found worked best in his "test" system, and in his test environment ( listening room ). Loading is NOT calculated or worked out by measurements- it is an arbitrary figure made by listening tests. This changes in individual systems so there is no one correct setting. Also I have found that it is not a good idea to load a cartridge, as it is like putting a lot of weight in a car compared to driving the same car without any weight fitted. As you will know the car performs much better the lighter it is- same sort of thing with loading really.The more you load the cartridge the worse it sounds. Also the Seven is AC loaded so there is no harmful DC component interfering with the fragile cartridge coils so it is allowed to perform at it best without external influence. TW Acustic did some experiments with different loading values on the Seven and found it made no difference at all."
My Allaerts "845" ohm is paired with the "117" ohm Seven and is a great match.

>>As you will know the car performs much better the lighter it is<<

That's a bad analogy. The car may accelerate faster but not handle as well without proper weight and weight distribution.

I hope Ralph addresses the other technical errors and misunderstandings in your post.

Jloveys, when you can measure a thing in audio, and also hear the same thing, then you have a powerful correlation that cannot be denied. Critical damping of any inductive device, whether it is a coupling/setup transformer, phono cartridge or tape head is an excellent example of such a correlation.

Putting a resistor across an inductive device to effect Critical Damping is quite beneficial. Harmonic distortion is reduced, revealing more detail while simultaneously producing a smoother sound, and bandwidth is extended while simultaneously flattening the frequency response curve.

These effect are easily demonstrated by measurement and listening tests. As an example I've included a link to the Jensen transformer website; Jensen is one of the world's leading manufacturers of MC step-up transformers (and other transformers as well; they have been in business for decades). On the page of the link you will see a pdf that can be downloaded that shows the various loading values to be used depending on the phono cartridge in use.
http://www.jensen-transformers.com/mc.html

Whoever you were communicating with regarding this issue is misinformed and missing out on getting better performance.