The Mystery of MC Cartridge Load?

I have a MC cart with a manufacturer recommended load of 100-250 ohms.

But from everything I've read on the topic, the load people run the carts at can fluctuate greatly from the recommended load.

For instance, the knowledgeable and respected dealer runs the same cart as mine at 1,000 ohms, which he says "is wide open no load dampening. If the system is neutral then it allows all the beauty of the cartridge to shine."

So I'm confused, basically because I really don't know what's going on electrically. What are the ohms doing? Why the fluctuations? Should I start at 100 ohms then listen for improvement while upping the ohms?

If anyone has ever read anything that explains this in layman's terms, please point me in the right direction.

 

I find loading to be completely subjective and system based. It's like tone controls to a certain extent. Flat would be to load the cartridge at 10 times it's internal impedance. Once you hear that then you move up and down to see what works best in your system for you.

 

100 ohms should be fine. My Benz runs on that.
Reccomendstions is 100 - 47k
Or ask the dealer.

 

Phono cables also come into play......Do you low or high capacitance cables? For example my Delos, Lyra suggests low capacitance cables but mine are high, so I run the Delos at 121 ohms, vs around 400 ohms if I was using low cap cables.
100 ohms sounds fine, but I can fine tune the loading on my phono stage and 121 ohms is for sure the sweet spot that gives me more than 100 ohms does.

 

Use your ears!!!!!! Every system is different and we all hear somewhat differently. I don't know what my preamp is set at but I do know it's different than what the cart manufacturer said is ideal and that includes gain.

 

My cables are low cap...

 

I'm coming to the conclusion that these "ohms" are like tubes...there's a lot of magic to the "hows" and "whys."

 

MC carts tend not to be a sensitive to either load resistance or capacitance due to their low inductance. That said I'm not sure running them unloaded or with a super light load is ideal either. You might wind up with a hotter but brighter and lighter weight sound that might not be that pleasant, or worse, potentially run into RF oscillation.

Best to start at the manufacturer's recommended loading. As a general rule of thumb with audio circuits, to minimize voltage loss at the input of the load you want the load impedance to be 10X or more the source impedance, but with a phono cart you might not want to go crazy with the "or more." Start with a load that's 10X the cart's internal impedance and everything will likely be fine.

 

Forgive my ignorance but my amplifier does not allow me to change my "ohms" I have a Cronus Magnum II and my gain is 45 db. I know it runs my 2M Black perfectly and I just got a second arm with a Dynavector 10x5 which I am re-tipping and it is a 2.5mv high output cart. Everyone says I can run that cartridge with no problem.

So please explain if the ability to change your ohms is only on seperate preamps added to the system and is it also only an adjustment necessary when you use Low output MC cartridges?

I'd like to learn more but I guess my system doesn't allow these fine adjustments.

 

The 10X5 should be good with the 47k Ohm you typically see in phono stages that are designed for MM cartridges. However, the 10x5 would presumably be flatter with 1.5k Ohm if we're following the rules. My phono preamp also does not have load adjustments, so I've added a parallel 1k Ohm resistor on a splitter to get closer to the load typically recommended for a Dynavector HOMC. There's an explanation of this idea here:

Parallel Resistive Loading

 

I'm running my Hana SL with a Graham Slee Elevator MS Step Up Amplifier and a pair of their loading plugs to get the recommended 400 ohms. Its awesome sounding.

https://www.hifisystemcomponents.com/phono-preamps/elevator-exp-mc-step-up-amp.html

 

You will be fine at 47k with the high output Dyna. The lower ohms and high gain stuff is for low output MCs

 

The Cronos Magnum and most integrated amplifiers are designed for MM cartridges through their phono inputs.

The industry standard is 47K ohms for MM cartridges.

This way, all MM should work well with a MM phono preamps.

The reason that higher output MC cartridges are built, is to be able to be used with standard MM type phono preamps.

This way you don't need to purchase a SUT and a different external phono preamp that has settings specifically designed for MC cartridges.

 

It's more critical with low output MC cartridges, but it is still definitely desirable to be able to experiment with the load on high output MC cartridges too. Many have found they prefer something closer to the minimum that Dynavector recommends (>1000 ohms). I don't have this cartridge, but have found something around 10K or lower a better fit for me and my system with similar cartridges, but we are all different. In your case, it would be difficult to experiment since it is fixed. If handy with a soldering iron, you can make some inline adaptors with different resistor values that plug into the preamp input, and then the cables plug into them. Some use Y or Tee adaptors with plug in terminators, but they often harm the sound more than the loading change may help. Another option if you aren't too handy with DIY, is to contact John in the Stereo/Mono switch thread in the FS forum and ask him if he can make you a custom box with another switch for changing the load on the stereo path, maybe with a few assorted values, say 1000, 5000, 10000, 20000, or something like that. Each of those resistors would be in parallel with the 47K on the preamp input, so the actual value would of course be lower (simple calculation, they could be sized to provide whatever parallels value you want).

 

I was browsing another audiophile forum and a member named atmasphere, was swearing by 47k load for MC carts. As long as the phono stage wasn't susceptible to RFI. I decided to try it and to my surprise, my Sutherland 20/20 sounds clean and fantastic running the Benz Wood. I am ripping a few albums that I know very well to compare. But I (think I) am hearing a more open, dynamic and faster cartridge. And being as I've logged over 1k hours on the Wood, I tend to believe what I'm hearing and not imagining it. Fun start to the weekend

 

I ran mine at 47k unknowingly.
My transformer i thought was loaded
Internally, but it was not.
So i loaded to 100 ohms. Personally
The sound was fuller and a lot less bright.

 

Is there a clear formula for determining 1) Input loading resistance and 2) Input loading capacitance

I have the Hana Sl mc, its
Impedance @ 1 kHz: 30 Ohms,
Suggested Load: 400 Omms
output .5 mv,

I guess that the "Suggested load" in the Hana spec sheet is "Loading Resistance." If that is true, that would leave capacitance. How would one determine the proper loading capacitance given the specs of the cart.

The phono preamp instruction manual says: "The input loading capacitance can be set to 120, 220, 340 or 440pF to best match the specifications of your cartridge." However, i do not see a specific "loading capacitance" number in my cart specs. How would one determine this setting given the specs provided for the cart above?

thanks

 

The loading that the owner adds is a resistor in parallel to the signal path. That means that the higher the value of that resistor, the LOWER the amount of loading. Higher loading (lower value of the resistor) tends to damp high frequency peaks. With modern cartridges, the peak is usually well into the ultrasonic range, so loading is not needed as much as was the case in the past to correct for peaks. Jonathan Carr, the designer and builder of Lyra cartridges is among those who believe that additional loading is not needed to damp such peaks and it takes away some of the extension and open and airy sound on top. However, even though the peak is outside of the normal hearing range, it can be high enough in amplitude to overload some phono stages. He believes that loading is more important for preventing such overloading than in taming the frequency response of cartridges. I tend to agree with this. I happen to have a phono stage that does not overload and I like to run my MC cartridges (Lyra Titan and Transfiguration Orpheus L) wide open.

Sometimes, loading helps to suppress RF interference. A friend had a Hovland preamp that was passing a lot of hashy noise. It turned out that the factory default loading was 100k (essentially no loading). When we increased loading, the noise went away.

There is absolutely no harm in utilizing any particular amount of loading so one can experiment. I tend to find that higher levels of loading, say any value lower than 100 ohms, makes the sound warmer, more bass prevalent and shut down on top. Also, the lower the resistor value, the lower the total output so that volume level will go down. As a very rough rule, with most cartridges, a load of about 125 to 150 works perfectly well, and no much difference is heard if a higher value resistor (lower loading) than that is used.

 

It's not just the cartridge, the capacitance of the individual arm and turntable wiring which is in parallel and adding to what is at the phono input is what you are compensating for. Without test equipment you are working by experiment. Try them all, if you hear no difference (which is likely) leave it at the lowest value.

 

The cartridge load is not there to benefit the cartridge.

It is to benefit the phono section, in the case where the phono section is unhappy with RFI. This comment excludes SUTs; that is a different topic.

The cartridge has an inductance, the tone arm and its cable have a capacitance. Together they form a circuit that resonates, often at several MHz. If your preamp doesn't like the resulting RFI at its input, the loading resistor detunes the resonant circuit, and kills the RFI. Then it sounds better, usually less bright, but maybe less hashy.

Like anything else, there are tradeoffs with this situation. You are forcing the cartridge to do more work, and this can in turn affect the stiffness of the cantilever (that extra energy has to come from somewhere). This can affect how it acts in the arm and may cause high frequency losses. Also, a phono section that has troubles with RFI may have other stability issues since such goes hand in hand. If there is also poor overload margin, you can get more ticks and pops, which sound for all the world like they are on the surface of the vinyl. The resonant peak we're talking about here can be a good 30db higher than that of the signal (1000x higher is 30db)! That's why overload margin can be important. A low capacitance cable is too


The bottom line is that not all phono sections are equal- if the designer thinks that you only need the gain and the EQ then loading might be required. Its a pretty good bet that if you see a loading switch on the preamp that the designer isn't aware of this resonance issue. Price, the use of feedback, solid state or tube has nothing to do with it. Understanding what the design parameters are does. Most inexpensive phono sections coming out of Japan in integrated amps and receivers over the last 40 years were unstable- so we have entire generations of audiophiles that grew up thinking ticks and pops are part of the LP experience. It does not have to be that way.

You are far better off with a phono section that does not require loading to sound right! A good phono section will be free of ticks and pops and will have correct tonal balance without the need for any loading.