New Lyra Delos Cartridge

Your answer lies in the fact that your load directly into the MC phono input will be different from the load via a step-up transformer.

When you use an MC phono preamp, the recommended load is between 91-47k Ohms directly into MC input. When you use a step-up transformer, the recommended load is between 5-15 Ohms. So you got it right.

Btw, it's all explained in the Delos manual.

RTFM!!!

I didn't see that in the manual. Well, it is reassuring that what I arrived at empirically is exactly that same as the manual. BTW, 15 ohms still seems a little hot to me. 8 ohms seems to sound better.

I wish I understood the theory behind the differences when loading with a tranny -vs- a mc phono pre. My intuition (for what it is worth) suggests that the loading impedance should be the same. How does the cartridge know that it is driving a mc phono pre or a SUT if the loads are identical?

To reiterate, I am loading the secondary with an 820 ohm resistor in parallel with the 47k. That gives 805 ohms. Divide the the square of the turns ratio (10x10) and I get 8 ohms.

At least you know you can trust your ears :) The loading values with a step-up transformer are listed in the Specifications section at the very end of the manual.

I don't understand the technical aspects of loading directly into the MC input vs. a step-up tranny, but I know there are many here who do and they will hopefully provide an explanation. In the alternative, you could post this question in the Tech Talk forum, if you don't get an answer here.

I finally got it dialed in. Seems that 15 ohms is good.

I first went back to no parallel resistors, 1x10 tranny, 47k at the secondary for a 470 ohm load. In my system that is positively brutal. I had a friend over because I was getting confused with what I was hearing. He is a musician with very good ears (classically trained pianist). He agreed that that setup was unobtainable.

We were listening to Van Morrison's 'Poetic Champions Compose'. Van's studio work is, for the most part, exemplary. But at 470 ohms, while you could hear detail (too much transient attack) you could not tell that on a number of cuts he was using a string section as opposed to a synth. The string timbres were that poor. I changed to 15 ohms, and the string section became obvious to the point that you could actually discern individual instruments.

Listening to Respighi ('Church Windows' - Geoffrey Simon, Chandos digital, 'The Birds' - Dorati, Mercury Living Presence) the worldwide were very ambiguous at 470 ohms. At 15 ohms, there is no doubt which instruments you are hearing.

Finally, all you tube rollers, DO NOT overlook the Sovtek 12ax7lps. I figured that it would not work in the phono pre with the Delos, since the Delos is so sensitive. Wrong. I am using two of them into pair of RCA cleartop 12au7 buffer tubes. They sound far and away better, than the Telefunkens, Mullard long plates, GE long plates, or anything else that I tried. They are the icing on the cake in this setup. What ever ambiguities in sonic definition that remained after the loading experiment were completely cleared up with the Sovteks.

Great sound but a pain in the a** to get there...

Didn't edit the previous post - accidentally submitted it. This brilliant tablet has a mind of its own when it comes to offering alternative spellings and word without asking me first...

apologies.