Help with cartridge loading. . .

I think Doug that your question might be more related than you give yourself credit for, simply because (I suspect) Ortofon would normally intend that their LO MC be used with their own step-up tranny (not a necessity with the Pass phonostage). I would second Tom's advice in principle, but having said that would also add that auditioning at home is free except for your time, and that David shouldn't pass up the opportunity for a bit of 'ear-education' by going ahead and listening to the results with a small variety of loading options chosen at strategically placed intervals. As a rough suggestion, I would try the lowest setting, then double that, and double that, and so on for a few to several iterations, depending on how low the lowest possible setting is. Listen not only for natural frequency response (not constricted, not overhyped), but also for good tradeoffs of image focus vs. image size, bass definition and tautness vs. bass openness and weight, and unfettered dynamics vs. transient and decay cleanliness. The 'sweet spot' of the loading range that you find will not only have much to do with the electrical properties of your cartridge and phonostage, but also your total system and room response and set-up, not to mention personal preferences. Try it, it's fun! :-)

Again, the two ubiquitous schools of thought in present day audio rear their head. I would say that you should go with what the manufacturer of the cartridge suggests, which, I guess, tips my hand. From your question it certainly appears to me that you are of the aesthetics first credo. If my assumption is right, you will have to wait for like-minded people to reply to your question, but, in the final analysis, you will not be able to avoid experimentation. Think about it another way, if preamps still had tone controls, and if you had the type of tone controls providing various curves in the response, how many different settings do you think you could conjure up? How many would you, intuitively, reject out of hand? The situation is somewhat analogous. Don't freak yourself out with the theoretical possibilities. Good luck.

In theory, I agree with both Zaikesman and Pbb! :)

Start with the manufacturer's recommended setting and listen long enough to get a good understanding of how it sounds. Then experiment, listening critically to decide if the differences you hear are actually improvements. It's easy to get fooled into thinking something is better just because it's different. Having a second listener to give independent feedback reduces errors and is more fun.

Zaikesman's protocol is much better than the step-by-step chinese water torture method in Meriweth's owner's manual. Make a big move down from the starting point and get a handle on the sound there. Then make a big move up. This will help you hear and understand the differences quickly and easily. Make big enough moves so that you surround the sweet spot. Homing in on your one preferred setting can be done with more confidence if you've established your upper and lower tolerance limits first.

Pbb: cartridge loading has WAY more going on than just tonal balance. One of the most obvious changes in cartridge performance when varying terminating impedances are those of transient response and noise characteristics. While it is true that tonal balance can be altered to suit one's personal preferences, careful attention paid while experimenting will typically show that a cartridge will have a "sweet spot" where it works best at. This "best" is typically a compromise between tonal balance, transient response and noise floor. In my experience, most cartridges do NOT work best where the manufacturer recommends they be adjusted for. I don't know if this is because of production tolerances differing from unit to unit or if they had specific design objectives ( specific tonal / noise / transient characteristics ) that they thought were more important than how the cartridge performed on the whole.

Moncrieff touched on this in IAR a long time ago and gave some very specific recommendations with plenty of graphs to interpret. Even he comments that samples from the same batch of cartridges sent him by the manufacturer typically had measurable variances in them. In some instances, he even comments that three cartridges sent him measured much quite different from one another, so he typically gave the manufacturer the benefit of doubt and posted the test results and his observations for the "best of the bunch".

Like anything else, there is a certain amount of "science" involved in getting the best performance out of a component or system. One can strive to obtain that OR simply go for something that they think sounds "good" to their ears. Hopefully, the best performance and what sounds "good" to that person are one and the same : ) Sean
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And, when you have driven yourself half-crazy diddling with the load resistance, you can go the rest of the way to fully crazy by playing with capacitance.

My old Tandberg 3008 preamp has three resistance settings (100K, 47K, and 33K) and three capacitance settings (20, 120, 350 pF). Don't forget the turntable interconnect capacitance.

What with this pickup loading issue and all the arm setup angles and forces, it's enough to drive you digital!