Question about cartridge loading with a SUT

hugz

Well-Known Member
This is a question so dumb and basic that I can't find an answer online. I guess no one bothered explaining it because it's common knowledge.

Ok, so MC cartridges like resistant loading. Where does this loading actually go? before or after the SUT?? How to I apply it anyway? I imagine sticking little resistors on the pins of the cartridges... but I doubt that's it. Maybe a box with an RCA-in, some resistors inside and RCA-out? If that's it, is a potentiometer a good way to have 'infinite' loading options? Or is it too noisy? Perhaps a stepped attenuator instead?

and finally (for now), where do I apply the resistors to? The hot/positive only? (white and red, typically)

Thanks :)
 
Hugz, give us some more information about what you are trying to achieve. Which cartridge are you using, and which SUT and into which pre-amp. Resistor loading can be used in some circumstances to fine tune a setup and with others it may not work, but we need to know what you are wanting to do!
 
AT31E cartridge. AT630 SUT. "Muffsy" DIY preamp (it has little variable resistor inputs, but I've never changed them from 47k). Alternatively, just my Marantz amp's built-in preamp

What am I trying to achieve? I understand that people use cartridge loading to alter the sound of a cartridge, often for the better. I want to play around to see how I like the sound changes from loading it. It might improve, so I'll keep it at that value if it does.

I often see people say "I didn't quite like the sound of X cartridge at first, but I tried loading it at Y ohms and it sounded amazing".

Feels wasteful to not play around with loading. I'm not unhappy with my sound, but curious nonetheless
 
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IMO the effects of cartridge loading (in the case of MC cartridges) are usually vastly exaggerated - it's true by lowering the load enough you get some dampening of the high frequencies and if you go low enough you start to also affect the mechanical behaviour of the cartridge, which will also change the sound, but usually for the worse at least objectively speaking. However some people might prefer that, and it does have a certain kind of 'sound' - you start to loose 'air' from the presentation and soundstaging starts to collapse a bit.

10x the impedance of the cartridge is a really good rule of thumb starting point and I'd say it's quite rare you need to deviate from there. When using a SUT, in my experience loading matters even less. Also the AT630 was the SUT which was sold as a bundle with that cartridge, so I'd imagine it should work pretty well as is. I have the AT30E which is really close to the AT31E and honestly I don't think you have much if anything to gain fussing with loading plugs.

Of course that won't satisfy your curiosity and who knows, maybe you'll find better sound loading it down somewhat. Easiest way to do that is to get some Y-adapters (2x RCA female -> 1x male) and make "loading plugs". Google is your friend here, I'm sure there are several threads where there are precise instructions. You want to insert the load to the SUT inputs, that way you'll be loading the cartridge. If you change the load at the preamp, you'll be also loading the SUT and it would probably be the determining factor in any change. That SUT I'm sure was designed for 47k load, anything else wouldn't make sense.
 
I agree with everything muovimies says above.
I'll add that you will find advice on the internet to add resistive loading after the SUT - this is wrong imo for technical reasons that I don't want to go into right now (too long). I advocate the use of loading resistors before the SUT if you want to use them at all, but it's rarely necessary or beneficial.
I think that transformer has a turns ratio of 1:10, so if you add a resistive load after the SUT it will appear as a load 100 times smaller to the SUT, eg a 10k load on the secondary will appear to the cartridge as if it was 100 ohms.

There's a post (#75)on this thread ...http://theartofsound.net/forum/showthread.php?48785-Opinions-on-Tribute-SUTs/page8 where I go into a bit more detail.
 
Thank you both very much :) This gives me a good starting point so at least I can start to do research about practice rather than merely theory
 
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