Cartridge Loading.....Part II

The lower value 200 ohm vs. 47k ohms means more loading which tends to attenuate higher frequencies (because we hear things in terms of overall balance, attenuating highs can also  be perceived as more bass).

If light loading is entirely added intermodulated distortion and the "real" and "accurate" sound is what you get with high loading, I will take distortion. 

The loading has no effect on the cartridge other than making the cantilever harder to move. You can take any LOMC cartridge and put it on the bench. Using a squarewave generator (at a very low loutput, so as to not damage the cartridge), you can put the cartridge in series with the squarewave and then measure the output. With no resistor in parallel this is an unloaded inductor. What you will see on the oscilloscope is a nice squarewave, looking really quite a lot like the input, neither attenuated or rounded and with no overshoot! This is simply because the inductance of the coil is too tiny to ring at audio frequencies.

So the 'brightness' we often hear is coming from somewhere else!

Putting a resistor in parallel will not affect that. So the resistor is not affecting the bandwidth of the cartridge. But it is interacting directly with the electrical resonance, which is a product of the inductance of the cartridge and the capacitance of the tonearm cable.

As we can see from the page http://www.hagtech.com/loading.html

the peak can be substantial. The reason is something called 'Quality' or simply 'Q'. Inductive coils can be long and narrow, having a low Q value, or short and wide, having a much higher Q value. The higher the Q value the higher the peak and the narrower the band of frequencies it covers. LOMC cartridge have high Q coils in them for lowest mass.

Some preamps don't like having all that RF noise caused by the peak at their input. So they do weird things and one of them is distortion. Loading knocks out the electrical resonance and if the preamp has a problem with the RFI, the brightness along with it.

One would have to compensate for the loss of gain from using such a resistor, but, one will hear quite a difference in sound

This statement is only true if the preamp is sensitive to the RFI at its input. If not, no difference will be heard. Most designers simply don't take the implications of this electrical resonance into account in their phono designs, which is why this loading conversation persists.

Sort of makes a good argument for transimpedance as the initial stage of a phono preamp . . .

Ralph

The loading has no effect on the cartridge other than making the cantilever harder to move.

Isn't that essentially suggesting that compliance has no effect on the sound of a cartridge?

did you ever get a chance to look at the copy of IAR #5 I sent you?  I find it entirely plausible that making the cantilever easier / harder to move would have a sonic impact on the sound of a cartridge.  Add to this that this effect will be dynamic based on the musical content and things get interesting.  If you trust the measurements made by Moncrief, he clearly shows a reduction of IMD and it isn't a huge leap of faith to believe that the degree of measured IMD change he shows would have an audible result.

dave

@rauliruegas

What Jcarr and in parallel Ralph are saying is completely different than what is presented by moncrief.  They all agree that loading has no effect on the measured frequency response of a cartridge but any similarities end there.  Ralph and Jcarr suggest the unloaded "harshness" is caused by the MC cartridge inductance resonating with cable/input capacitance resulting in input overload of a phono stage that is not "RFI stable".  Moncrief suggests (and shows) that for MC carts, IMD distortion levels are directly related to applied cartridge load.

dave

What it boils down to is that loading matters to the sound, but there is some disagreement here as to why it matters and the cause of the sonic difference.  One position is that low loading is preferred because it CAUSES distortion that is perceived as high frequency information and people have grown accustomed to, and prefer, the distortion.  Another point made here is that RFI overloads some electronics causing distortion which is ameliorated by loading that damps RFI.  I suppose these are not contradictory statements and they may both account for some preferring low loading and others preferring more loading.  Jonathan Carr (Lyra cartridge designer/builder) says that low lading is preferable, because it preserves the high frequency response, which is one of the things people pay big bucks to get from MC cartridges, but, that higher loading might be necessary to kill RFI that can overload some gear (Atmasphere's position, and I tend to agree). 

As to Atmasphere's response to my statements about the sonic effects of loading-- that loading has no effect on the cartridge, except to make the cantilever harder to move-- I was merely stating that the effects of loading changes can be heard, not that loading physically affects the cartridge.  There are cartridge experts that say that the back EMF changes from loading are so negligible that the effect on movement of the cantilever is mostly theoretical an not a practical reality.  

Perhaps my statement about having to compensate for difference in loudness where a low value resistor is used (high loading) was misconstrued.  I was merely pointing out that when making a comparison, to be fair, one might have to increase the volume a bit for the high load scenario to compensate for the voltage drop across the load resistor; with a high value resistor (low load), that drop is less significant