Ortofon Per Windfeld Load Impedance?

FWIW when you have a loading resistance of only 100 ohms, the capacitance of the cable can be neglected. To illustrate this point, even if your capacitance was as high as 0.001uf, the frequencies affected would be measured in MHz.

There **might** be some audible quality of the cable, but in the case of a 100 (or even 500) ohm loading value, the capacitance of the cable will have nothing to do with it.

Result: you can ignore the phono cable as a variable.

I recommend against using the cartridge loading as a tone control. Instead, the cartridge should be loaded to what is known as 'critical damping'. This is the point wherin the loading value damps ringing, but does not roll off the normal response of the cartridge. An excellent way to do this is to 'ring' the cartridge with a squarewave generator and observe the output on an oscilloscope. A ringing waveform will be seen in an unloaded cartridge. Installing a loading resistance will reduce the ringing until a bare amount of overshoot is seen, this will be at or near critical damping.

Once this is done the cartridge can be installed in the arm without fear that the arm or interconnect will be affecting the determined value. Once the cartridge is then set up properly and broken in, then and only then can the phono interconnect be evaluated. **If you use the loading value to 'tune' the phono cable, you are introducing colorations!** I considered capitalizing that but I don't like to shout.

Zieman, since our preamp is balanced we tried exactly that, since the cartridge is a low impedance source. The result- no difference. Single-ended; hard to say what you might hear since single-ended cables tend to be more susceptible to coloration.

You can indeed hear the effect of the load being too low or too high. **That** is why you need to load the cartridge at critical damping *before* you mess with cables!

First, my apologies for this thread going OT...

Zieman, perhaps a discussion of cables is appropriate here.

Cables have what is known as 'characteristic impedance'. This value is an impedance such that when the cable is terminated with this impedance, there will be no reflections in the cable. The characteristic impedance of any cable is a combination of its resistance, capacitance and inductance, plus dielectric constants, lead spacing and geometry. The formula for predicting this value is a bit tricky, and measuring it is best done on a Time Delay Reflectometer.

The place where this cable quality really comes into play in audio is speaker cables, not so much interconnects. There is a termination standard in place for balanced line (600 ohms) but for single-ended there really isn't a standard (although single ended cables would benefit from one). This lack of a standard causes single-ended cables to exhibit audible artifacts, which has given rise to the high end audio cable industry, and is the primary reason we decided to produce what was at the time the first balanced line preamplifier for home audio.

The termination of the cartridge at the input of the preamp will also take care of most cable issues. The reason I stress doing the loading properly is I have seen audiophiles compensate for a bright amplifier, amp/speaker mismatch, poor room acoustics and the like by messing with the cartridge loading. The problem is, you can't get it right and the result is often blamed on other equipment which is not at fault.

You can set the load for the cartridge by ear- to do so, you need a variable resistance across the input of the preamp, which starts out very high. It is then decreased (noting that there will be less high frequency energy as this is done). If any change in volume is detected you have gone too far. This is a less accurate technique but IME I have not seen the cable play a role in the final value.

Zieman, the traditional problem with long interconnects is loss of high frequencies. I say traditional because the case of a low output moving coil is a special case. The source impedance of the cartridge is very low- often only a few ohms. Although they don't make much **voltage**, they do make quite a lot of **current**, else it would not be possible for one to drive a 100 ohm load with no loss of output. Try doing that with a tube preamp (the only one I know of that can do that is our own MP-1...)!

So- this is what you have to understand: **There will be no loss in volume, even if the cable is 50 feet!** The source impedance of the cartridge will be unperturbed by the very slight resistance of only a couple of ohms presented by a long cable. The load of the cartridge remains the important variable, and it is here that you will likely hear more difference on account of the quality of the resistor than you will the cable.

You will also hear changes that have little to do with the cable- just pulling the cable out of the back of the preamp and plugging it in again can result in a change if you have any corrosion on your connectors (gold notwithstanding...), plus minor changes that resulted from your messing with the connection at the base of the arm.

This is one of the reasons I like the Triplanar- the only connection is at the cartridge (no removable headshell) and at the preamp- the cable is integrated. The variables of connections are eliminated.

Larryi, if you just use your ears for loading a cartridge, you will indeed arrive at different values for different phono sections. That is because different phono sections sound different, some are brighter than others due to the use of negative feedback or the like. That is why I recommend a more exact method, so that the loading is not used as a tone control to counter other effects that should be dealt with in other ways.

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!

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.

Jloveys, that might be true on a track. But trucks are intended for use on the road, something that Formula cars suck at- their engines are not tractable since they are intended for power at high rpm. Additionally, many trucks will handle and ride better with a bit of a load...

Do you see now that its not a good analogy? If you want to use cars as an analogy, an unloaded cartridge is like a car with no shock absorbers- it will ring (bounce) and oscillate with any input. A loaded cartridge is like a car with tuned gas shocks- the output will reflect only what is on the surface of the LP.