Hi All, I wish to revive this thread for a related question on loading the Shelter 501 II, please.
I have one, and the manual appears to say to use a 100R load if it is driving an active stage, or a 10R load if it is driving an input transformer.
Does that make any sense? Or am I misunderstanding the manual that appears to be a translation. It literally says "DCR: 12 ohm, step up trans: within 10 ohms, head amp: within 100 ohm."
cheers
I have one, and the manual appears to say to use a 100R load if it is driving an active stage, or a 10R load if it is driving an input transformer.
Does that make any sense? Or am I misunderstanding the manual that appears to be a translation. It literally says "DCR: 12 ohm, step up trans: within 10 ohms, head amp: within 100 ohm."
cheers
That's the difference of inductive and resistive loading.
A head amp (or directly into a high-gain phonostage) will want a 100R resistor across the cartridge coils (I.E., the phonostage input),
A Step-up transformer loads the cartridge with the inductance of it's primary coil, and it has to be wound in a way that presents the proper impedance (about 10R) to the cartridge.
Either way, there needs to be some thought and selection given to load matching, or you will have a resonant peak or dip in the audible range.
A head amp (or directly into a high-gain phonostage) will want a 100R resistor across the cartridge coils (I.E., the phonostage input),
A Step-up transformer loads the cartridge with the inductance of it's primary coil, and it has to be wound in a way that presents the proper impedance (about 10R) to the cartridge.
Either way, there needs to be some thought and selection given to load matching, or you will have a resonant peak or dip in the audible range.
If you can borrow a few transformers that would be ideal, otherwise Lundahl makes several excellent SUTs, and I would ask K Carter at K&K which would be most suitable for use with the shelter.
I'm always a bit leery when I see those recommendations particularly where some overmatching is implied, transformers "designed" for 10 ohm primary impedance usually like cartridges with much lower source impedances. Note that unless the ratio is high the reflected load impedance to the primary is always quite a bit higher than the cartridge source impedance.
If the transformer is correctly designed it reflects a resistive load to the cartridge until the inductance falls below a critical level. (usually when xl of at the frequency in question is still several times higher than the source impedance)
Experimenting is always best in so far as an SUT is concerned IMLE.
I'm always a bit leery when I see those recommendations particularly where some overmatching is implied, transformers "designed" for 10 ohm primary impedance usually like cartridges with much lower source impedances. Note that unless the ratio is high the reflected load impedance to the primary is always quite a bit higher than the cartridge source impedance.
If the transformer is correctly designed it reflects a resistive load to the cartridge until the inductance falls below a critical level. (usually when xl of at the frequency in question is still several times higher than the source impedance)
Experimenting is always best in so far as an SUT is concerned IMLE.
Thank you 6L6. Your explanation makes sense, though I would need help to understand why a device would perform equally under an inductive load of 10 ohms and an resistive load of 100 ohms.
Do all MC cartridges have similar instructions for setting up? I am not familiar so I looked up a couple of Ortofon MC user manuals and they make no distinction between SUT and head amp loadings, merely saying ">10 ohms".
Do all MC cartridges have similar instructions for setting up? I am not familiar so I looked up a couple of Ortofon MC user manuals and they make no distinction between SUT and head amp loadings, merely saying ">10 ohms".
Thank you also Kevin. I have LL1681 SUT that I bought from K&K, so it's a bit late for me to do "SUT tasting". I was planning to load the secondary of the 1681 at 1:13 with 2690 ohms so create a 10 ohm load for the Shelter MC. But I wasn't sure that I was reading the instructions correctly, to use one tenth of the load when using a SUT compared to using a head amp. I am starting to think I was doing it correctly.
I would try a range of loading on the secondary, also bear in mind that the leakage inductance appears in series with your load and will cause an HF roll off if the value on the secondary gets too low.
Honestly I would be inclined to try something in the 10K range despite the manufacturer's recommendation. Be sure to try a range of values.
Honestly I would be inclined to try something in the 10K range despite the manufacturer's recommendation. Be sure to try a range of values.
It is common, and I am clueless as to why. I actually follow the recommendations in only a very general sense unless the cartridge was designed by engineers. (Yes, Ortofon) I have a bunch of Ortofon SPUs which all like transformers designed for 10 ohm or lower source impedances, and which in my pre-pre are loaded by 100 ohm resistor.. (Not very fussy about load resistance) Note that the rated source impedances of these cartridges is between 2 and 6 ohms, not the significantly higher 12 ohms of the Shelter.
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