Cartridge Loading into Step-Up Transformer
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. |
This is a pretty complex and tendentious subject. See for example http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html http://www.6moons.com/audioreviews/stepup/primer.html best advice is to work with who ever designed your step up to ensure it matches your cartridge. Some step ups (such as the MFA I use) do actually offer variable “loading” so you can fine tune the response to suit the cartridge and recording but simply adding a resistor in parallel to the transformer can cause problems such as ringing so stick with the methods the step up maker designed |
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Thank you very much for the input here. The pasted links above provide for much education on the handling of the required gain and ultimately the loading. I read this material several times to understand the subtleties. 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. And I will look to use both the 1:15 and 1:30 options of this SU. Using the rule that the input impedance of component B (the SU transformer) must be at least 10x the output impedance of component A (the cartridge), I have just done the math to determine the starting points for some load resistors in parallel with the 47k MM input and compare with none here at all. Then I can tune by ear to get the optimal. This will be fun. Thank you again. |
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 |
