Help with cartridge loading. . .


Hello,

I recently purchased a Pass X-Ono phono pre-amp, and both to my joy and horror I learned at once that there are over 500 different possible resistances I can choose to load my low output MC cartridge with. The manual gives the very helpful: "start with 100 ohms, then move up one setting; if it sounds better, then move up two. . .", which means of course I will be obsessing around in a circle forever.

Are there any rules of thumb that might help me zero in on an optimal loading more quickly? Better, is there a theory behind the settings, such that I could calculate the load given the output of the cartridge, etc.?

My analog front end: Orbe SE/SME IV/Ortofon MC3000.II. Any help would be much appreciated. Sad to say, I am a "fixed price" kind of guy.

Regards,
David Meriwether
meriweth
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!
I don't know, but it was refreshing to read the manual (if you can call it that) that comes with the Rega P9. It seems the designer takes a simpler view of things as they pertain to playing a black disc. I guess everybody is right! My feelings are that unit to unit variability obviously exists, but is probably over hyped. I guess I just don't have that tweaker fibre! I like the notion that vinyl records don't require cleaning since the stylus will simply shove away the dirt in its path. I will soon see how much shovelling of dirt the P9 can actually accomplish. As for me, I will set it to whatever the cart manufacturer recommends and pray for a mild winter.
Sean, good post. According to my in-house scientist, raising the electrical impedance to a cartridge not only requires the cantilever to move more forcefully to generate a signal, it also makes the cartridge more resistant to such movement. Almost like you had the ability to stiffen the suspension. Reducing impedance has the opposite effect of course. Clearly this will effect transient response as well as tracking accuracy at different frequencies. Next time I have a vacation week to spare I'll look up that article by Moncrieff. He's good, but this whole forum combined couldn't outwrite him. :)

Pbb, near the end of an unwashed record the other day I noticed my cantilever had a big pile of fluff on top. Watching more closely, I saw the stylus shovelling stuff out of the groove at a prodigious rate. Most of it ended up on top of the cantilever somehow. When the pile got big enough some of it would actually topple off, only to be replaced by more junk being dug out by the stylus. Who needs TV? I can watch this for hours!

Happily for your "damn the washing, full speed ahead" philosopy, I couldn't hear any degradation of sound, even after I knew the grooves were full of junk. (My old cartridge would have sounded very scratchy in such circumstances, so YMMV. I'm sure stylus geometry controls how well it deals with dirt.)

Of course playing dirty vinyl will shorten the life of both stylus and record. That's just common sense. In my case, while I can apparently play through mounds of loose fluff, the slightest layer of anything is quite audible (mold release agents, inadequate rinse, smog from NJ, whatever). So I wash. That's also the only way to remove anything so stuck in the groove that the stylus won't dislodge it. That stuff causes those annoying pops and clicks, and can do real damage to a stylus.

OTOH, maybe you really should just enjoy the new table. The rest of us are pretty wacko anyway, as you well know!