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Cartridge Loading into Step-Up Transformer

I have read a lot about preamps and phono stages having the ability to put a load resistor in parallel to the cartridge.  Some products have flip switches, others have solderable terminals inside the unit to put in a custom valued resistor and others have a pair of external RCA jacks to put a resistor here.  Mt preamp has the latter.  However, if an external  setup transformer is used into a MM input, what is typically done to accommodate a load resistor?  Is the resistor in parallel with the primary or the secondary?  And is the resistance value typically different for a given cartridge that worked well into an active MC stage vs. a setup?  Any experiences, ideas, suggestions, etc., would be greatly appreciated.
John
jafox

Showing 2 responses by chakster

chakster's avatar
chakster
6,144 posts
 
Most of the SUTs has written value near the input RCA, so you can go wrong with cartridge you can or can’t connect to this particular SUT.

For example: 3 Ohms, 10 Ohms, 40 Ohms.

If your MC cartridge impedance is 2-3 Ohm then you need a SUT with 3 Ohms value written just near the input RCA and so on. Pretty easy.

The SUT itself is always connected to MM (47k Ohm) input of your phono stage.
chakster's avatar
chakster
6,144 posts
 
I just bought to Hashimoto HMU-7 SU transformers to use with a newly diamond re-tipped AQ 7000 which has one of the lowest coil resistances at 2 ohms.

99% of my LOMC cartridges are about 2 Ohms too.
This is one of my SUTs: Luxman toroidal silver SUT
I can swap the SUT in the base, as you can see there is a recommendation for use a cartridge with certain coil impedance (under 3 Ohm is one SUT, there is another for about 40 ohms).

So it's not necessary to count 1:10 , 1:15, 1:30 or whatever ... just looks at the recommended connection impedance printed on the SUT input and choose the SUT for your cartridge self impedance accordingly


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