SUT - electrical theory and practical experience

Dear @phoenixengr : If LOMC cartridges are almost no sensitive to load impedance then which your real point that I don’t understand for sure and which is your solution and advantages on the cartridge quality level performance?

For some years in my system the active high gain phono stage came with a 100 ohm input resistor and through all those years I had not any single trouble ( that I been aware of. ) with several and different LOMC cartridges that I owned and own.

" recommended load impedances are specified over a large range (100Ω-1K), and they are all usually 10x the cart source impedance so the voltage divider effect will be small, but in some cases, it could have a significant impact on the output. "

Ly ra states that load range with its different cartridge models and Ortofon says over 10 Ohms even that its cartridges internal DC resistance is 7 Ohms. Clearaudio even does not gives any advise and in all its LOMC models the internal cartridge impedance is 50 Ohms and I tested the Goldfinger in my phono stage with n very good cartridge quality levels. I owned/own the Discovery and Insider Gold that came with the same internal impedance and again I had no trouble with even that in the past the Clearaudio advise was over 500 ohms ( 10x ) and that I remember that input resistor was not changed  but before my today phonolinepreamp I owned the Classé DR-7 that is an active high gain design too and performed very well with that same resistor value.

So other that a change in SPL which is that " significant impact on the output generated by the cartridge not by the phono stage it self but the cartridge that’s what you and me( I understand ) are talking about.

Your answer is appreciated. Always is time to learn for all of us.

R.

@rauliruegas 

My point about the specified impedance along with the output voltage was to make the necessary gain calculations easier.  In your Lyra example, using a 10 Ohm load with a 7 Ohm impedance cart will drop the output level by 4.6dB, which could be significant.  The output level will only be insensitive to the load if the load is 10x the cart impedance or higher.

My point about conjugating the imaginary (reactive) impedance of the cart is to cancel out any inductive or capacitive reactance so the cart sees a purely resistive load which will give the flatest frequency response with no peaking at high frequencies.  If the complex impedance of the cart could be measured or calculated, then the proper termination could be easily determined instead of guessing or by changing loads and listening for a difference.

For some years in my system the active high gain phono stage came with a 100 ohm input resistor and through all those years I had not any single trouble ( that I been aware of. ) with several and different LOMC cartridges that I owned and own.

If you never tried any load other than 100 ohm, then you cannot know if there was a problem due to loading at 100 ohm .

My point about conjugating the imaginary (reactive) impedance of the cart is to cancel out any inductive or capacitive reactance so the cart sees a purely resistive load which will give the flatest frequency response with no peaking at high frequencies. 

@phoenixengr 

Flattest frequency response or best square wave ? Are these codependent ?

With Jensen SUT's that are designed to be used with a zobel network  they suggest  adjusting the network to the source load by scoping a square wave.