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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
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atmasphere's avatar
atmasphere
9,437 posts
The Zu Denon is very much a "salt to taste" kind of cartridge when it comes to loading. When I used one it could indeed sound quite different when using 100/200/300/500/1000 ohms. And Zu will tell you there is no wrong answer here, just use what sounds best to you
Again: loading has no effect on the sound of a **low output** cartridge- it has everything to do with the stability of the phono preamp.

@intactaudio While I agree generally with Peter in this regard, I am suspect of the idea that loading causes the cartridge to track better in all cases. I have seen this where the cartridge was otherwise incompatible with a tone arm; a good example is a Grado in a Graham 2.0. The loading prevents the 'Grado dance' that can otherwise occur especially in lead-in grooves. However that is all about tone arm compatibility, and as I mentioned earlier, when you load the cartridge it stiffens the cantilever. So you will get different results in different tone arms! Peter wasn't being entirely scientific in this regard as his data was limited to one tone arm/cartridge combination.

intactaudio
159 posts
I did repeat the experiment with a completely different setup and my results paralleled Moncrief's.   I would expect different absolute results with different tonearm / cartridge combos.  I did see a pattern of behavior that was consistent with both low and high compliance cartridges.

I do believe that the effect of the load is showing up as an adjustment of the compliance and would expect this to be a dynamic behavior.  

dave
gakerty's avatar
gakerty
50 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.  I suppose that's a good thing.  My brother has a Project Phono Box and the loading dial might as well be a treble knob!
whoopycat
139 posts
Again: loading has no effect on the sound of a **low output** cartridge- it has everything to do with the stability of the phono preamp.
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.
atmasphere's avatar
atmasphere
9,437 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.

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