@rauliruegas To be clear, at no point have I stated that loading affects the frequency response of a LOMC cartridge. Your statements to the contrary are false. Please cease and desist. When you engage in such statements and then debunk them, you are engaging in a logical fallacy known as a strawman. Logical fallacies are inherently false.
How does one safely send a square wave through a cartridge? Just curious as I have no intention of trying it.
Apparently PS Audio did their homework.
I suspect if you put too much energy through the cartridge you might be able to damage the magnetic field generated by the magnet structure, so your reticence is wise. I used a square wave generator set to a very low output. I put the cartridge in series with a nominal resistance so I could read the square wave across the resistor- essentially if the coil of the cartridge were a problem for the square wave, it would be readily visible. The signal was low enough (I have to admit I was a bit concerned about damage to the cartridge when I did this the first time) that the cartridge was unaffected. This meant the scope was at a very high gain setting.
Note that a load to the cartridge would be a resistance in parallel with the cartridge, not in series. Anyway, I found that the cartridge could pass a square wave at any frequency- even 20KHz, with no ringing at all.
This surprised me at the time, since the reason for doing this was to create a box that would allow you to plug in the cartridge and easily determine the ideal load (this was about 35 years ago). When I saw that the cartridge could pass a perfect square wave at any audio frequency, I realized that the loading was not affecting its frequency response so something else was afoot.
One of the side issues associated with this topic is that of ticks and pops. If the phono section has good RFI immunity and if it also has good high frequency overload margins, that peak at 1 or 2MHz won't overload the input of the phono and you'll get less ticks and pops. I had this graphically demonstrated to me when an employee complained of a noisy LP he had bought. His LP played fine on the shop system so he brought in his preamp and there were the ticks and pops, sounding for all the world as if they were on the LP surface.
How that works is the energy of the cartridge can set off the electrical resonance, even though that peak is well outside of the audio band. This phenomena is known as 'excitation' in the radio world. Once the peak has gone into excitation, it puts out a signal at its resonant frequency which is applied to the input of the phono section. Since its a good 20-30dB higher than the cartridge signal, it can overload some phono sections if they have not taken this phenomena into account. I suspect such phono sections are a lot more common than we like to think- that preamp I mentioned earlier was a Toshiba and Toshiba is a supplier of semiconductors so you would expect good engineering... this has led me to think this problem was an epidemic back in the 1970s and 80s.
