Ohm Loads for cartridges


What difference does the ohm load make on a cartridge? I have the ability to change the cartridge load via my pre-amp, what changes will it make?
martnan
Brian,
Thanks for the help. Unfortunatly answering one questions leads to more questions, so it is said. (Especially among people who know more about the biological world than the electronic world.)
Maybe you can address this problem as it relates to cartridge loading. I was fortunate, (or unfortunate as the case may be) in one swoop replace my table, arm and cartridge. The problem is is that I now have much more emphasis in the HF spectrum than before and the surface noise on LP's is accented quite a bit more than in the past.
Since the first cartridge failed after 6 months I hoped the second one would do better. Surface noise is still too prominent. Even on virgin LP's.
So, in talking to Benz I am told that my phon stage, which is permanently set at 560 ohms, is too low and should be at 10K-20K. And that this is a major cause for my problems. The 2 phono stages I have tried have allowed me to either agjust to a 10K or are set at 20K. In either case the HF emphasis was reduced with more emphasis placed in the med-low range and surface noise was improved a fair amount. So, was it the loading charecteristics of the phonostages or the phonosatges as a whole which made this improvement?
Also, sorry for asking what does "RLC" refer to as you mentioned?
Thanks!
Hi Gerard,

Which Benz do you have? I have never used one so I hesitate to comment.

All of the Benz cartridges are MC, and generally speaking, MC cartridges are not as sensitive to the load as MM cartridges (due to the low coil inductance). However connecting an MC to a low resistance load (such as 100 Ohms) results in a larger current, and this mechanically dampens the cantilever. This may be the more rolled off kind of sound you are looking for.

However, returning to your original observations, the two phono stages you tried gave a preferable sound (ie less HF emphasis), even when the input impedance was set high (10K, or 20K). Since your phono stage is already set to a lowish impedance, and you think you still have too much HF emphasis, then I can't see how you can cure the problem with your existing phono stage. Increasing the resistance will make it worse if anything.

Best regards,

Brian

PS An RLC circuit is a circuit containing a resistor (R), an inductor (L), and a Capacitor (C).
Brian,
I am using a Benz Ruby2. Up until I bought one I had only heard the Benz LO.4. It sounded good so I thought I would try and do better. Hmmm! It has lots of good praise through out the audio bulletin boards.
I have a very strong feeling that the phono stage is just not compatable for some reason. It took me 2 years to get the RF problem solved with it now the sound semi-sucks. It worked so well with my Linn Klyde that I did not worry. The other issue is the the Michell Orbe is alot more revealing a deck than my LP12 was.
Can you expand a bit on the fact that a low resisive load on the cart. mechanically dampens the cantilever? I would have thought that, (let me try this), increasing the resistive load which leads to a decrease in signal strength (thus loading is reduced) would impeed the signal enough to slow or dampen the cantilever. But your saying that as the resistive load approaches zero the machanical dampening of the cart. increases? I was trying to use the water hose and faucet idea to try and convince myself that when you reduce the water flow by closing the faucet down (increasing resistive flow) you cause a pressure build up behind the faucet and a subsequent dampening effect.
Any more help would be great!
Hi Geradff, A few points on moving coil cartridges. Decreasing the size of the load resistor (say from 47Kohms to 1Kohms) will tend to dampen the high end, Which may or may not be a good thing depending on the rest of your system. Some say a large resistor is more natural and some say it is too bright. Trust your ears.
I think you may still be a little confused on the subject of loading. A large load is one that draws a lot of current from a device. Small resistors draw more current than large resistors, so small resistors are said to be bigger loads. Your terminolgy of "increasing the resistive load" is a bit confusing. It would be better to say "increase the resistance", which means to draw less current with a bigger resistor.
As far as damping the cantilever, as the coils move in the magnetic field, they generate alternating current. First it flows in one direction and then in the other. As you decrease the resistance of the load, you generate more current. This creates a sort of electrical inertia that has to be overcome every time they change direction. The current in the coils creates a magnetic field that must be reversed to get the current to flow in the opposite direction. You get the same effect when you try to hand crank a generator. It gets harder to crank if you increase the load, i.e. you load it with a smaller resitance and draw more current from it. Hope this has been of some help.
Bruce,
Hey thanks for the explanation and clarification! I can't tell you how long I have been asking, searching for a clearer precise answer to my questions. At least it now makes sense when people talk about resistive loading and seem to say one thing and mean another.
I now feel confident to at least begin to address my loading issues.
Thanks to all who answered!!!