Impedance loading low-output MC cartridges...


Does anyone know if there is a general "rule of thumb" regarding impedance loading of low-output MC cartridges? Most manufacturers do provide some guidlines as to a range of impedance settings that will work well with a particular cartidge, and I have fiddled around with this a bit.

Since it takes at least a few minutes to power down my system, reconfigure some DIP switches in my phono preamplifier, and then power up the system, it is not easy to do a reasonable A/B comparison.

My setup is Basis 1400 / Basis RB300 / Benz Micro ACE (low-output version) / MS Phonomena.

Please fill in the blanks. As impedance increases the sound should _______, and as the impedance decreases the sound should _______.
I'm shure that ACE will do excellent with 47K load and 100Ohm load as well with almost no difference. Your numerous experiments most likely bring you nothing(I've tried that with Glider and with M.09). I've been soldering in parallel different resistors one at a time so I get desirable impedance value, listen for few days or so and heard only smallish changes which I cannot describe as an improvement of sound since something was getting better and something compromised. Finally I've realised that leaving standard 47K load on your phono is OK with almost all Benz cartridges(which is realy good for any phono preamps!)

Usually if the cartridge isn't loaded properly, some of the freequencies(especially bass) might be appear too dim and unresolved. So there is no general rule of thumb rather relaying on your own ear.

And finally friendly advise:
Do not waste your time -- You're OK with 47K!
I have done a great deal of experimenting with this and find that the results are system dependant. I hear a great deal of difference with loading, and have experimented with Benz Glider, Benz Ruby and Benz Reference. Also the EMT and Koetsu.

To answer your question, I do not know what the new Benz ACE likes, but generally the higher the load (47K) the more splashy the sound and more dynamic, but with some distortion. When the number is lowered (28K) the opposite occurs. This result is based on the more expensive Benz cartridges I listed (above). The Koetsu seems to love 1K ohms exclusively, at least among all the experiments I have done.

As Marakanetz says, your OK with 47K, but if you want to experiment you might try some of the same loads to determine what the ACE responds to.

By the way, a small change such as 40K down from 47K is extremely difficult to hear, except on a ultra high resolution system.

It costs nothing to try another setting, and may be of value, even if only to learn. Be sure before you draw conclusions about load that you have the alignment, overhang, VTA, Azimuth and tracking force all set as perfect as possible. Any of these set wrong will ruin the outcome of your loading tests.
I recently bought a phono stage with variable impedance-loading options, and found the instructions to be in agreement with my previously experiment-based findings: that is...
"Loading should be set for about 2 to 3 times the rated impedance of the cartridge". I feel that this is basically correct because during my experimenting, I didn't even bother to initially check my cartridge's impedance rating, I just started plugging away with different values & ended up with 110 ohm load on a 30 ohm cartridge (OK that's close) which sounded good to my uneducated ear. Nice to know that at least sometimes, a subjective result can even approximate the objective ideal.
I have an older Benz low output (model 3 or something) and when I had my crummy Forte 2 preamp I could also hear a great deal of difference between 47K ohm setting and 100 ohm setting.. the 100 ohm was better. I am told by my dealer Benz likes to see a load of 1000 ohms.. I am using the Benz PP1 phono preamp which I believe is preset to this setting. What I could never hear a difference in was the capacitance settings..
I can only agree with all which has been said above. I loved the sound of my old Koetsus at 1000 ohms, as ALBERT did, however with the Helikon and also with Peter Suchy's stuff I settled for 47k. Here the dynamics were best and what Albert called splashy, I found especially with sopranos and solo violins a far better rendering of transients. Distortions I only could discover, when the instruments were too closely miked and hence don't think this is systeminherent. A lower setting, will indeed mask this ocurrence, but since it is rare, I didn't mind.
Played around with my Benz Ruby 11 extensively, This cartidge seems to like 700 ohms. At 47K it looses a little bit of dimensionality and top end extension. Also ,the sound stage is a little less wide.
So with a great resistor like Vishays, 700k is the way to go with this cartridge. Unfortunately, I have found that every cartidge is diff in regards to the loading question. But once you get it there you know it. Just trial and error seems to be no set rule.