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Cartridge loading

Presently I am using a ZU/Denon DL103 mc cartridge with ZU Audio's highest tolerances.  I had this cartridge mounted on my VPI Prime and after going through all the various loading combinations, I settled on 200 ohms.  I was always satisfied with my choice of setting.  I no longer have the Prime and now use the Technics SL1200G turntable.  After having the same cartridge mounted and aligned by the dealer, I inserted it into my system and enjoyed the sound immensely, never touching the 200 ohm setting.

Yesterday I was listening to vinyl most of the day and for some reason I found the sound to be better than ever, mostly in the treble area.  The highs had shimmer when needed and I had played the same records many times before on the Prime and they never sounded as good as they did yesterday.  Just for the heck of it, I checked the cartridge loading and found it was now set at 1000 ohms.  As I said, when I put the Technics into the system, I never bothered changing the loading which was at 200 ohms as it was the same cartridge, just a different turntable.

I believe I know what happened, when I last used the tone controls on my McIntosh preamp, (you have to shuffle through a menu) I must have inadvertently put the cartridge loading at 1000 ohms.  It truly sounds fantastic, better than I ever thought possible.  The Bass is still very deep and taut, midrange is the same but the treble, oh my, so much better.  Now the million dollar question is why should it now sound better at 1000 ohms, when it sounded great before at 200 ohms?  Can the tonearm on the Technics have an effect on cartridge loading?  I always thought it was all dependent on the preamp, amp and speakers.  What am I missing here?  I am very curious to know.  The specs for my cartridge say greater than 50 ohms for loading.

Thanks
128x128stereo5
atmasphere's avatar
atmasphere
11,577 posts
 
I run my Benz Wood SL "unloaded" at 47K on my Pass XP15. It sounds the most open, with airier highs, but admittedly I'd be hard pressed to tell the difference between 47K and 1000 ohms, maybe even 500 ohms. Seems the Pass XP15 just isn't that sensitive to loading.
You are correct- when I've pointed this stuff out on other threads, Pass Labs phono section owners respond as you have.
I don't understand this comment... a Manley Steelhead is unstable? The Steelhead lets you switch loading on the fly and the tonal differences were easily audible.

If the loading is affecting the sound like that its a good bet that the phono section is sensitive to the resonant peak' RFI as I mentioned earlier. Now I should point out that MM cartridges do behave differently- if you have one of those then loading is critical IME moreso that LOMC. This is partially because MM cartridges do ring at audio frequencies if not critically damped. LOMC cartridges don't ring anywhere near audio frequencies- if you 'ring' them with a square wave the input and output waveforms look the same.


There are IMO/IME four parameters that have to do with phono preamp design:
1) enough gain with low enough noise2) accurate EQ3) resistance to RFI4) good internal stability
It is the last two on the list where many phono sections have problems. If you find for example that you get lots of ticks and pops even with new vinyl, this is a sign that the preamp has troubles with these last two parameters. Needing to have a low resistance load on the cartridge is another (keeping in mind that we are talking about LOMC); if the phono section is set up right 47K as a load will be found to work just fine, assuming that normal low capacitance phono cables are in use.

tomwh
150 posts
 
Seems like  most everyone else seems to hear differences with load changes.  Maybe by building a phono pre so quiet or with certain tubes, etc... kills the music from coming totally through.  

Dave brings up a interesting point and another variable which may explain why most people hear differences between loading.  You also notice he did not make make blanket statement about do this and your  home free!!!

I only thing I know for certain is there are so many things we do not know about energy.  And the only real way to know if you are reproducing something that sounds like Real music is to listen, change, listen, change, listen etc...!!!

I realize this is not building forum so you are at the mercy of manufacturer and the ad copy.  And being able to experiment with infinite amount of different resistors and capacitors to load your cartridge just right, is not in the cards, for most people.

Enjoy the ride
Tom
mijostyn's avatar
mijostyn
8,183 posts
 
After meticulous Tonearm set up I have always just used the manufacturer's recommendation. Switching around on an ARC phono amp I can not make out any difference in sound quality.
Ralph, how does cartridge impedance affect all of this? I assume on a good phono amp not at all. If a higher load increases the motor's stiffness why wouldn't a cartridge track better at lower loads?
mijostyn's avatar
mijostyn
8,183 posts
 
I forgot. How would this affect the resonance of the cartridge in a particular tonearm. It sound like lowering the load might lower the resonance frequency?
whoopycat
165 posts
 
@atmasphere

Is there a measurement on Stereophile or whatever that will show if a phono stage has resistance to RFI and/or good internal stability?

Otherwise the only way to know is to compare the sound of a LOMC at say 300 ohms vs 47k, right?
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