MC Load Resistance

Lewm,
+++ ... Axel, are you saying that you now like a 47-ohm resistor on the primary side of your SUT? I presume you also have a 47K-ohm resistor on the secondary side. Is this correct? +++
No! please see below.

A 30dB SUT (1:31.6 ratio) has a "natural impedance" of 47 ohm when going into a 47k secondary input impedance (the phono-pre).

Since the primary impedance = secondary input imp./ ratio ^2 = 47k/31.6*31.6 = ~ 47 ohm primary impedance.

So what I now like is the 47 ohm primary *impedance* of the SUT without ANY resistive loading (other then the negligible 1.1 ohm of the primary coil winding itself...)

I hope this should clarify the matter.
Greetings,

Thanks, Axel. I am comforted to know that you like that set-up, because I never could quite understand how a 13-ohm load could be superior to any higher value resistance, using your cartridge. 47 ohms is more in the ballpark of what I would guess would work well.

Dertonearm, thanks for the tip. Unfortunately or fortunately, I modified the phono input stage of my MP1 to use an MAT02 bipolar transistor as the bottom half of a cascode, where the top half of the cascode is now an ECC99, in dual-differential configuration. This, in conjunction with the output stage gain section, gives oodles of gain, even for the Orto MC7500. (The MAT02 has a Gm of 400!) And I am very pleased with the sound quality. I guess I could use a VERY low step-up ratio SUT, just to test your hypothesis. And there are tricks I could use to reduce the gain at the input, as well, without changing the topology. (I have to do this when I use the Colibri, which puts out 1.0mV.)

Lewm, I am very familiar with hybrid cascoded phono-inputs.
Getting gain galore in teh 1st stage is always tempting. I am currently using a full balanced differential all triode phono stage with split passive RIAA. I have experimented with a hybrid cascode input stage too, but I went back to the "conservative" triode input stage.

Dertonearm, Re your sentiments on the hybrid cascode, we have another subject where you and Atmasphere are in agreement. Ralph also recommended that I stick with tubes in both positions. I have no axe to grind; I know for a fact that the topology can sound very good either way. The MAT02 is pretty special in this application, so conclusions drawn using other solid state devices on the bottom of the cascode may not be so applicable. But I am a neophyte in these matters and not qualified to argue either way, except based on my own particular listening experience with this set-up. If I get the energy, I could go back to an all-ECC99 cascode and use a low gain SUT to make up the difference.

Lewm, please do not get me wrong. A hybrid casode phono input stage is favored by many and for good reason. Technically seen it looks like the best of both worlds and addresses many important technical aspects and solutions in a very smart and tempting manner.
But - as always in life (sic...) there is a price to pay.
That price is NOT high, it is not anything really worth mention, but in the end it is the very tiniest point which keeps the doors of (sonic ...) heaven closed for the demanding listener.
There are sonic trade-offs (as in ALL designs) in ANY hybrid cascode phono input stage. Its open, airy, fast, dynamic and direct sounding. It gives you gain to burn the house and rock the street.
Yes.
But regardless of the tube or FET/J-FET/Bipolar etc. in use - you loose on color, you loose on 3-dimensionality, you loose on micro detail.
The picture is clear, in bright light and alive if a little bit artificial - but less convincing, less like the real thing.

I have favored hybrid cascode (and all-tube cascode...) phono-inputs for a long time and years before they showed up in custom gear in high-end showrooms.
Similar as with my earlier years preference for active phono input stages, I have gone a long way to find out that this is not yet the end of the road.

One should always remember, that the sonic impression is never a lonely one - its the impression we get from a certain set-up and is always depending on the periphery.
You do favor the hybrid cascode phono input now - in the set-up you have put together and listen to with joy.
This is fine and correct.
This may however change (as preferences, individual parts of the set-up or room conditions may change) and you may go back to the original or an input-stage with a different tube one day and may find it suits you better.
Maybe - not necessarily.